[Federal Register Volume 87, Number 7 (Tuesday, January 11, 2022)]
[Proposed Rules]
[Pages 1554-1614]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-27004]



[[Page 1553]]

Vol. 87

Tuesday,

No. 7

January 11, 2022

Part IV





Department of Energy





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10 CFR Parts 429, 430, and 431





Energy Conservation Program: Test Procedure for Consumer Water Heaters 
and Residential-Duty Commercial Water Heaters; Proposed Rule

  Federal Register / Vol. 87 , No. 7 / Tuesday, January 11, 2022 / 
Proposed Rules  

[[Page 1554]]


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DEPARTMENT OF ENERGY

10 CFR Parts 429, 430, and 431

[EERE-2019-BT-TP-0032]
RIN 1904-AE77


Energy Conservation Program: Test Procedure for Consumer Water 
Heaters and Residential-Duty Commercial Water Heaters

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of 
Energy.

ACTION: Notice of proposed rulemaking and request for comment.

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SUMMARY: The U.S. Department of Energy (DOE) proposes to amend the test 
procedure for consumer water heaters and residential-duty commercial 
water heaters to update the procedure to the latest versions of the 
industry standards that are incorporated by reference and to consider 
procedures that are included in a draft industry standard, which is not 
currently incorporated by reference. DOE also proposes to interpret the 
statutory definition of consumer water heater to cover larger capacity 
heat pump type units as commercial equipment and proposes several new 
definitions for water heaters that cannot be appropriately tested with 
the current DOE test procedure, along with test methods to test these 
products. DOE is seeking comment from interested parties on the 
proposals.

DATES: 
    Comments: DOE will accept comments, data, and information regarding 
this notice of proposed rulemaking (NOPR) on or before March 14, 2022. 
See section V, ``Public Participation,'' for details.
    Meeting: DOE will hold a webinar on Tuesday, January 25, 2022, from 
1:00 p.m. to 5:00 p.m. See section V, ``Public Participation,'' for 
webinar registration information, participant instructions, and 
information about the capabilities available to webinar participants.

ADDRESSES: Interested persons are encouraged to submit comments using 
the Federal eRulemaking Portal at www.regulations.gov. Follow the 
instructions for submitting comments. Alternatively, interested persons 
may submit comments, identified by docket number EERE-2019-BT-TP-0032, 
by any of the following methods:
    1. Federal eRulemaking Portal: www.regulations.gov. Follow the 
instructions for submitting comments.
    2. Email to: [email protected]. Include the docket 
number EERE-2019-BT-TP-0032 in the subject line of the message.
    No telefacsimilies (faxes) will be accepted. For detailed 
instructions on submitting comments and additional information on this 
process, see section V of this document.
    Although DOE has routinely accepted public comment submissions 
through a variety of mechanisms, including postal mail and hand 
delivery/courier, the Department has found it necessary to make 
temporary modifications to the comment submission process in light of 
the ongoing COVID-19 pandemic. DOE is currently suspending receipt of 
public comments via postal mail and hand delivery/courier, and instead, 
the Department is only accepting electronic submissions at this time. 
If a commenter finds that this change poses an undue hardship, please 
contact Appliance Standards Program staff at (202) 586-1445 to discuss 
the need for alternative arrangements. Once the COVID-19 pandemic 
health emergency is resolved, DOE anticipates resuming all of its 
regular options for public comment submission, including postal mail 
and hand delivery/courier.
    Docket: The docket, which includes Federal Register notices, public 
meeting attendee lists and transcripts (if a public meeting is held), 
comments, and other supporting documents/materials, is available for 
review at www.regulations.gov. All documents in the docket are listed 
in the www.regulations.gov index. However, some documents listed in the 
index, such as those containing information that is exempt from public 
disclosure, may not be publicly available.
    The docket web page can be found at www.regulations.gov/docket?D=EERE-2019-BT-TP-0032. The docket web page contains 
instructions on how to access all documents, including public comments, 
in the docket. See section V for information on how to submit comments 
through www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: 
    Ms. Julia Hegarty, U.S. Department of Energy, Office of Energy 
Efficiency and Renewable Energy, Building Technologies Office, EE-5B, 
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: 
(202) 597-6737. Email [email protected].
    Ms. Kristin Koernig, U.S. Department of Energy, Office of the 
General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 
20585-0121. Telephone: (202) 586-3593. Email: 
[email protected].
    For further information on how to submit a comment, review other 
public comments and the docket, or participate in a public meeting (if 
one is held), contact the Appliance and Equipment Standards Program 
staff at (202) 287-1445 or by email: 
[email protected].

SUPPLEMENTARY INFORMATION: DOE proposes to incorporate by reference the 
following industry standards into part 430:
    American Society of Heating, Refrigerating, and Air-Conditioning 
Engineers (ASHRAE) Standard 41.1-2020, (ASHRAE 41.1-2020), ``Standard 
Methods for Temperature Measurement,'' approved June 30, 2020.
    American National Standards Institute (ANSI)/ASHRAE Standard 41.6-
2014, (ASHRAE 41.6-2014), ``Standard Method for Humidity Measurement,'' 
ANSI approved July 3, 2014.
    Copies of ASHRAE 41.1-2020 and ASHRAE 41.6-2014 can be obtained 
from the American Society of Heating, Refrigerating, and Air-
Conditioning Engineers, Inc., 1791 Tullie Circle NE, Atlanta, GA 30329, 
(800) 527-4723 or (404) 636-8400, or online at: www.ashrae.org.
    American Society for Testing and Materials International (ASTM) 
Standard D2156-09 (Reapproved 2018) (ASTM D2156-09 (RA 2018)), 
``Standard Test Method for Smoke Density in Flue Gases from Burning 
Distillate Fuels,'' reapproved October 1, 2018.
    ASTM Standard E97-1987 (ASTM E97-1987 (W1991)), ``Standard Test 
Methods for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque 
Specimens by Broad-Band Filter Reflectometry,'' approved January 1987, 
withdrawn 1991.
    Copies of ASTM D2156-09 (RA 2018) and ASTM E97-1987 (W1991) can be 
obtained from the American Society for Testing and Materials 
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, 
PA 19428-2959 or online at: www.astm.org.
    See section IV.M of this document for a further discussion of these 
industry standards.

Table of Contents

I. Authority and Background
    A. Authority
    B. Background
II. Synopsis of the Notice of Proposed Rulemaking
III. Discussion
    A. Scope of Applicability
    1. Definitions
    B. Updates to Industry Standards

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    1. ASHRAE 41.1
    2. ASHRAE 118.2
    C. Test Procedure Requirements
    1. Commercial Water Heater Draw Pattern
    2. Terminology
    3. Test Conditions
    4. Mixing Valve
    5. Mass Measurements
    6. Very Small Draw Pattern Flow Rate
    7. Low Temperature Water Heaters
    8. Heat Pump Water Heater Heaters
    9. Circulating Gas-Fired Water Heaters
    10. Solar Water Heaters
    11. Connected Water Heaters
    12. Drain Down Test Method
    13. Alternate Order 24-Hour Simulated-Use Test
    14. Untested Provisions
    D. Reporting
    E. Test Procedure Costs and Harmonization
    1. Test Procedure Costs and Impact
    2. Harmonization With Industry Standards
    F. Compliance Date and Waivers
IV. Procedural Issues and Regulatory Review
    A. Review Under Executive Order 12866
    B. Review Under the Regulatory Flexibility Act
    1. Description of Reasons Why Action Is Being Considered
    2. Objectives of, and Legal Basis for, Rule
    3. Description and Estimate of Small Entities Regulated
    4. Description and Estimate of Compliance Requirements
    5. Duplication, Overlap, and Conflict With Other Rules and 
Regulations
    6. Significant Alternatives to the Rule
    C. Review Under the Paperwork Reduction Act of 1995
    D. Review Under the National Environmental Policy Act of 1969
    E. Review Under Executive Order 13132
    F. Review Under Executive Order 12988
    G. Review Under the Unfunded Mandates Reform Act of 1995
    H. Review Under the Treasury and General Government 
Appropriations Act, 1999
    I. Review Under Executive Order 12630
    J. Review Under Treasury and General Government Appropriations 
Act, 2001
    K. Review Under Executive Order 13211
    L. Review Under Section 32 of the Federal Energy Administration 
Act of 1974
    M. Description of Materials Incorporated by Reference
V. Public Participation
    A. Participation in the Webinar
    B. Submission of Comments
VI. Approval of the Office of the Secretary

I. Authority and Background

    Consumer water heaters are included in the list of ``covered 
products'' for which DOE is authorized to establish and amend energy 
conservation standards and test procedures. (42 U.S.C. 6292(a)(4)) 
DOE's energy conservation standards and test procedure for consumer 
water heaters are currently prescribed at Title 10 of the Code of 
Federal Regulations (CFR), part 430, section 32(d), and 10 CFR part 
430, subpart B, appendix E (appendix E). As discussed in this NOPR, 
residential-duty commercial water heaters, for which DOE is also 
authorized to establish and amend energy conservation standards and 
test procedures (42 U.S.C. 6311(1)(K)), must also be tested according 
to appendix E. 10 CFR 431.106(b)(1) (See 42 U.S.C. 6295(e)(5)(H)). 
DOE's energy conservation standards for residential-duty commercial 
water heaters are currently prescribed at 10 CFR 431.110(b)(1). The 
following sections discuss DOE's authority to establish and amend test 
procedures for consumer water heaters and residential-duty commercial 
water heaters, as well as relevant background information regarding 
DOE's consideration of test procedures for these products and 
equipment.

A. Authority

    The Energy Policy and Conservation Act, as amended (EPCA),\1\ 
authorizes DOE to regulate the energy efficiency of a number of 
consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317, as codified) Title III, Part B \2\ of EPCA established the Energy 
Conservation Program for Consumer Products Other Than Automobiles, 
which sets forth a variety of provisions designed to improve energy 
efficiency. (42 U.S.C. 6291-6309, as codified) These products include 
consumer water heaters, the subject of this document. (42 U.S.C. 
6292(a)(4)) Title III, Part C \3\ of EPCA, added by Public Law 95-619, 
Title IV, section 441(a), established the Energy Conservation Program 
for Certain Industrial Equipment, which again sets forth a variety of 
provisions designed to improve energy efficiency. (42 U.S.C. 6311-6317, 
as codified) This equipment includes commercial water heaters, which 
are also the subject of this document. (42 U.S.C. 6311(1)(k))
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    \1\ All references to EPCA in this document refer to the statute 
as amended through Energy Act of 2020, Public Law 116-260 (Dec. 27, 
2020).
    \2\ For editorial reasons, upon codification in the U.S. Code, 
Part B was redesignated Part A.
    \3\ For editorial reasons, upon codification in the U.S. Code, 
Part C was redesignated Part A-1.
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    The energy conservation program under EPCA consists essentially of 
four parts: (1) Testing, (2) labeling, (3) the establishment of Federal 
energy conservation standards, and (4) certification and enforcement 
procedures. Relevant provisions of EPCA specifically include 
definitions (42 U.S.C. 6291; 42 U.S.C. 6311), test procedures (42 
U.S.C. 6293; 42 U.S.C. 6314), labeling provisions (42 U.S.C. 6294; 42 
U.S.C. 6315), energy conservation standards (42 U.S.C. 6295; 42 U.S.C. 
6313), and the authority to require information and reports from 
manufacturers (42 U.S.C. 6296; 42 U.S.C. 6316).
    The Federal testing requirements consist of test procedures that 
manufacturers of covered products and commercial equipment must use as 
the basis for: (1) Certifying to DOE that their products comply with 
the applicable energy conservation standards adopted pursuant to EPCA 
(42 U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C. 6316(a)-(b)), and (2) 
making representations about the efficiency of those products (42 
U.S.C. 6293(c); 42 U.S.C. 6314(d)). Similarly, DOE must use these test 
procedures to determine whether the products comply with relevant 
standards promulgated under EPCA. (42 U.S.C. 6295(s))
    Federal energy efficiency requirements for covered products and 
covered equipment established under EPCA generally supersede State laws 
and regulations concerning energy conservation testing, labeling, and 
standards. (42 U.S.C. 6297(a)-(c); 42 U.S.C. 6316(a)-(b)) However, DOE 
may grant waivers of Federal preemption in limited circumstances for 
particular State laws or regulations, in accordance with the procedures 
and other provisions of EPCA. (42 U.S.C. 6297(d); 42 U.S.C. 6316(a); 42 
U.S.C. 6316(b)(2)(D))
    Under 42 U.S.C. 6293, the statute sets forth the criteria and 
procedures DOE must follow when prescribing or amending test procedures 
for covered products. Specifically, EPCA requires that any test 
procedures prescribed or amended shall be reasonably designed to 
produce test results which measure energy efficiency, energy use, or 
estimated annual operating cost of a covered product during a 
representative average use cycle or period of use and shall not be 
unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) Under 42 U.S.C. 
6314, the statute sets forth the criteria and procedures DOE must 
follow when prescribing or amending test procedures for covered 
equipment, reciting similar requirements at 42 U.S.C. 6314(a)(2).
    In addition, the Energy Independence and Security Act of 2007 (EISA 
2007) amended EPCA to require that DOE amend its test procedures for 
all covered consumer products to integrate measures of standby mode and 
off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Standby mode 
and off mode energy consumption must be incorporated into the overall 
energy efficiency, energy consumption, or other energy descriptor for 
each covered product unless the current test procedures already account 
for and incorporate standby and off mode energy consumption or such 
integration

[[Page 1556]]

is technically infeasible. (42 U.S.C. 6295(gg)(2)(A)(i)-(ii)) If an 
integrated test procedure is technically infeasible, DOE must prescribe 
a separate standby mode and off mode energy use test procedure for the 
covered product, if technically feasible. (42 U.S.C. 
6295(gg)(2)(A)(ii)) Any such amendment must consider the most current 
versions of the International Electrotechnical Commission (IEC) 
Standard 62301 \4\ and IEC Standard 62087,\5\ as applicable. (42 U.S.C. 
6295(gg)(2)(A))
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    \4\ IEC 62301, Household electrical appliances--Measurement of 
standby power (Edition 2.0, 2011-01).
    \5\ IEC 62087, Methods of measurement for the power consumption 
of audio, video, and related equipment (Edition 3.0, 2011-04).
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    The American Energy Manufacturing Technical Corrections Act 
(AEMTCA), Public Law 112-210, further amended EPCA to require that DOE 
establish a uniform efficiency descriptor and accompanying test methods 
to replace the energy factor (EF) metric for covered consumer water 
heaters and the thermal efficiency (TE) and standby loss (SL) metrics 
for commercial water-heating equipment \6\ within one year of the 
enactment of AEMTCA. (42 U.S.C. 6295(e)(5)(B)-(C)) The uniform 
efficiency descriptor and accompanying test method were required to 
apply, to the maximum extent practicable, to all water-heating 
technologies in use at the time and to future water-heating 
technologies, but could exclude specific categories of covered water 
heaters that do not have residential uses, can be clearly described, 
and are effectively rated using the TE and SL descriptors. (42 U.S.C. 
6295(e)(5)(F) and (H)) In addition, beginning one year after the date 
of publication of DOE's final rule establishing the uniform descriptor, 
the efficiency standards for covered water heaters were required to be 
denominated according to the uniform efficiency descriptor established 
in the final rule (42 U.S.C. 6295(e)(5)(D)); and for affected covered 
water heaters tested prior to the effective date of the test procedure 
final rule, DOE was required to develop a mathematical factor for 
converting the measurement of their energy efficiency from the EF, TE, 
and SL metrics to the new uniform energy descriptor. (42 U.S.C. 
6295(e)(5)(E)(i)-(ii))
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    \6\ The initial thermal efficiency and standby loss test 
procedures for commercial water heating equipment (including 
residential-duty commercial water heaters) were added to EPCA by the 
Energy Policy Act of 1992 (EPACT 1992), Public Law 102-486, and 
corresponded to those referenced in the ASHRAE and Illuminating 
Engineering Society of North America (IESNA) Standard 90.1-1989 
(i.e., ASHRAE Standard 90.1-1989). (42 U.S.C. 6314(a)(4)(A)) DOE 
subsequently updated the commercial water heating equipment test 
procedures on two separate occasions--once in a direct final rule 
published on October 21, 2004, and again in a final rule published 
on May 16, 2012. These rules incorporated by reference certain 
sections of the latest versions of ANSI Standard Z21.10.3, Gas Water 
Heaters, Volume III, Storage Water Heaters with Input Ratings Above 
75,000 Btu Per Hour, Circulating and Instantaneous, available at the 
time (i.e., ANSI Z21.10.3-1998 and ANSI Z21.10.3-2011, 
respectively). 69 FR 61974, 61983 (Oct. 21, 2004) and 77 FR 28928, 
28996 (May 16, 2012).
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    EPCA also requires that, at least once every 7 years, DOE evaluate 
test procedures for each type of covered product and covered equipment, 
including consumer water heaters and commercial water heaters that are 
the subject of this document, to determine whether amended test 
procedures would more accurately or fully comply with the requirements 
for the test procedures to not be unduly burdensome to conduct and be 
reasonably designed to produce test results that reflect energy 
efficiency, energy use, and estimated operating costs during a 
representative average use cycle (or additionally, period of use for 
consumer products). (42 U.S.C. 6293(b)(1)(A); 6314(a)(1))
    If the Secretary determines, on her own behalf or in response to a 
petition by any interested person, that a test procedure should be 
prescribed or amended, the Secretary shall promptly publish in the 
Federal Register proposed test procedures and afford interested persons 
an opportunity to present oral and written data, views, and arguments 
with respect to such procedures. (42 U.S.C. 6293(b)(2); 42 U.S.C. 
6314(b)) The comment period on a proposed rule to amend a test 
procedure shall be at least 60 days \7\ and may not exceed 270 days. 
(42 U.S.C. 6293(b)(2)) In prescribing or amending a test procedure, the 
Secretary shall take into account such information as the Secretary 
determines relevant to such procedure, including technological 
developments relating to energy use or energy efficiency of the type 
(or class) of covered products involved. (42 U.S.C. 6293(b)(2)). If DOE 
determines that test procedure revisions are not appropriate, DOE must 
publish in the Federal Register its determination not to amend the test 
procedures. (42 U.S.C. 6293(b)(1)(A)(ii); 42 U.S.C. 6314(a)(1)(A)(ii)) 
DOE is publishing this NOPR in satisfaction of the 7-year review 
requirement specified in EPCA.
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    \7\ For covered equipment, if the Secretary determines that a 
test procedure amendment is warranted, the Secretary must publish 
proposed test procedures in the Federal Register, and afford 
interested persons an opportunity (of not less than 45 days' 
duration) to present oral and written data, views, and arguments on 
the proposed test procedures. (42 U.S.C. 6314(b))
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B. Background

    As stated previously in this document, DOE's current test procedure 
for consumer water heaters appears at appendix E.
    Pursuant to the requirements of the AEMTCA amendments to EPCA 
discussed previously, DOE updated the consumer water heater test 
procedure through a final rule published on July 11, 2014 (July 2014 
final rule). 79 FR 40542. The July 2014 final rule: Established a 
uniform energy descriptor (i.e., uniform energy factor (UEF)) for all 
consumer water heaters and for commercial water heaters with consumer 
applications (i.e., those commercial water heaters that met the newly 
established definition of a ``residential-duty commercial water 
heater''); extended coverage to eliminate certain gaps in the previous 
version of the consumer water heater test procedure, including small-
volume storage water heaters (i.e., with storage volumes between 2 and 
20 gallons), large volume water heaters (i.e., greater than 100 gallons 
for gas-fired and oil-fired storage water heaters and greater than 120 
gallons for electric storage water heaters), and electric instantaneous 
water heaters; updated the draw pattern from a single 24-hour 
simulated-use test draw pattern to include several different draw 
patterns that vary depending on equipment capacity as measured by the 
first-hour rating (FHR) or maximum gallons per minute (Max GPM) test; 
and updated the outlet water temperature test condition requirement. 79 
FR 40542, 40545, 40548, 40551-40554 (July 11, 2014).
    As indicated, the uniform energy descriptor and the consumer water 
heater test procedure apply to ``residential-duty commercial water 
heaters,'' which were initially defined in the July 2014 final rule and 
include commercial water heaters with consumer applications. Id. at 79 
FR 40586; 10 CFR 431.106(b)(1) and 10 CFR 431.110(b). DOE later amended 
the definition of a ``residential-duty commercial water heater'' in a 
final rule published on November 10, 2016 (November 2016 final rule), 
to define such equipment as any gas-fired storage, oil-fired storage, 
or electric instantaneous commercial water heater that meets the 
following conditions: (1) For models requiring electricity, uses 
single-phase external power supply; (2) Is not designed to provide 
outlet hot water at temperatures greater than

[[Page 1557]]

180 [deg]F; and (3) Does not meet any of the following criteria:

------------------------------------------------------------------------
                                           Indicator of non-residential
           Water heater type                       application
------------------------------------------------------------------------
Gas-fired Storage......................  Rated input >105 kBtu/h; Rated
                                          storage volume >120 gallons.
Oil-fired Storage......................  Rated input >140 kBtu/h; Rated
                                          storage volume >120 gallons.
Electric Instantaneous.................  Rated input >58.6 kW; Rated
                                          storage volume >2 gallons.
------------------------------------------------------------------------

81 FR 79261, 79321-79322; 10 CFR 431.102.

    In the November 2016 final rule DOE also, in relevant part, revised 
some of the definitions for consumer water heater product classes and 
removed others. Definitions for both ``electric heat pump water 
heater'' and ``gas-fired heat pump water heater'' were removed, and 
revisions were made to the definitions of ``electric storage water 
heater'' and ``gas-fired storage water heater,'' which made each 
sufficiently broad to cover electric heat pump water heaters and gas-
fired heat pump water heaters, respectively. 81 FR 79261, 79320-79321 
(Nov. 10, 2016). The November 2016 final rule also amended the 
definitions of ``electric instantaneous water heater'', ``gas-fired 
instantaneous water heater'', ``oil-fired instantaneous water heater'', 
and ``oil-fired storage water heater.'' Id.
    On December 29, 2016, DOE published a final rule (December 2016 
final rule) that denominated the efficiency standards for consumer 
water heaters and residential-duty commercial water heaters in terms of 
the uniform efficiency descriptor (i.e., the UEF metric) and 
established mathematical conversion factors to translate the EF, TE, 
and SL metrics to the UEF metric. 81 FR 96204. The published conversion 
factors were applicable for converting test results for a period of one 
year after the publication of the December 2016 final rule as required 
by EPCA, as amended by AEMTCA. 42 U.S.C. 6295(e)(5)(E)(v)(II); 81 FR 
96204, 96208 (Dec. 29, 2016). The conversion factors translating 
previously tested EF, TE, and SL values to converted UEF values were 
removed from 10 CFR 429.17 on December 29, 2017, at which time all 
rated UEF values were to be based on actual testing to the test 
procedure published in the July 2014 final rule (i.e., to the UEF test 
procedure). 81 FR 96204, 96235.
    Most recently, on April 16, 2020, DOE published in the Federal 
Register a request for information (April 2020 RFI) seeking comments on 
the existing DOE test procedure for consumer water heaters and 
residential-duty commercial water heaters. 85 FR 21104. The April 2020 
RFI discussed a draft version of the ANSI/ASHRAE Standard 118.2, which 
was published in March 2019 (March 2019 ASHRAE Draft 118.2), which is 
very similar to the existing DOE test procedure of consumer water 
heaters and residential-duty commercial water heaters. 85 FR 21104, 
21108-21110 (April 16, 2020).
    In the April 2020 RFI, DOE requested comments, information, and 
data about a number of issues, including: (1) Differences between the 
March 2019 ASHRAE Draft 118.2 and the existing DOE test procedure; (2) 
test tolerances for supply water temperature, ambient temperature, 
relative humidity, voltage, and gas pressure; (3) the location of the 
instrumentation that measures water volume or mass; and (4) how to test 
certain types of consumer water heaters that cannot be easily tested to 
the existing DOE test procedure (i.e., recirculating gas-fired 
instantaneous water heaters, water heaters that cannot deliver water at 
125 [deg]F 5 [deg]F, and water heaters with storage volumes 
greater than 2 gallons that cannot have their internal tank 
temperatures measured). Id. at 85 FR 21109-21114.
    DOE received comments in response to the April 2020 RFI from the 
interested parties listed in Table I.1.

            Table I.1--List of Commenters With Written Submissions in Response to the April 2020 RFI
----------------------------------------------------------------------------------------------------------------
               Commenter(s)                         Reference in this NOPR                Commenter type *
----------------------------------------------------------------------------------------------------------------
A.O. Smith Corporation....................  A.O. SMITH...........................  M.
Air-Conditioning, Heating, and              AHRI.................................  TA.
 Refrigeration Institute.
American Public Gas Association...........  APGA.................................  TA.
Appliance Standards Awareness Project,      Joint Advocates......................  AG.
 American Council for an Energy-Efficient
 Economy, Consumer Federation of America,
 National Consumer Law Center, Natural
 Resources Defense Council, and Northeast
 Energy Efficiency Partnerships.
Bradford White Corporation................  BWC..................................  M.
California Energy Commission..............  CEC..................................  State.
CSA Group.................................  CSA..................................  TL.
Edison Electric Institute.................  EEI..................................  U.
Keltech Inc...............................  Keltech..............................  M.
M C.......................................  M C..................................  I.
Northwest Energy Efficiency Alliance......  NEEA.................................  AG.
Pacific Gas and Electric Company, San       CA IOUs..............................  U.
 Diego Gas and Electric, and Southern
 California Edison.
Rheem Manufacturing Company...............  Rheem................................  M.
Rinnai America Corporation................  Rinnai...............................  M.
Stone Mountain Technologies, Inc..........  SMTI.................................  M.
----------------------------------------------------------------------------------------------------------------
* AG: Advocacy Group; State: Government Organization; I: Individual; M: Manufacturer; TA: Trade Association; TL:
  Test Laboratory; U: Utility or Utility Trade Association.


[[Page 1558]]

    A parenthetical reference at the end of a comment quotation or 
paraphrase provides the location of the item in the public record.\8\
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    \8\ The parenthetical reference provides a reference for 
information located in the docket of DOE's rulemaking to develop 
test procedures for consumer water heaters and residential-duty 
commercial water heaters. (Docket No. EERE-2019-BT-TP-0032, which is 
maintained at: www.regulations.gov/docket/EERE-2019-BT-TP-0032). The 
references are arranged as follows: (Commenter name, comment docket 
ID number, page of that document).
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II. Synopsis of the Notice of Proposed Rulemaking

    In this NOPR, DOE proposes to update appendix E, and related 
sections of the CFR, as follows:

    (1) Incorporate by reference current versions of industry 
standards referenced by the current and proposed DOE test 
procedures: ASHRAE 41.1, ASHRAE 41.6, the pending update to ASHRAE 
118.2 (contingent on it being substantively the same as the current 
draft under review), ASTM D2156, and ASTM E97.
    (2) Add definitions for ``circulating water heater'', ``low 
temperature water heater'', and ``tabletop water heater''.
    (3) Specify how a mixing valve should be installed when the 
water heater is designed to operate with one.
    (4) Modify flow rate requirements during the FHR test for water 
heaters with a rated storage volume less than 20 gallons.
    (5) Modify timing of the first measurement in each draw of the 
24-hour simulated-use test.
    (6) Clarify the determination of the first recovery period.
    (7) Clarify the mass of water to be used to calculate recovery 
efficiency.
    (8) Modify the terminology throughout appendix E to explicitly 
state ``non-flow activated'' and ``flow-activated'' water heater, 
where appropriate.
    (9) Clarify the descriptions of defined measured values for the 
standby period measurements.
    (10) Modify the test condition specifications and tolerances, 
including electric supply voltage tolerance, ambient temperature, 
ambient dry bulb temperature, ambient relative humidity, standard 
temperature and pressure definition, gas supply pressure, and 
manifold pressure.
    (11) Add provisions to address gas-fired water heaters with 
measured fuel input rates that deviate from the certified input 
rate.
    (12) Clarify provisions for calculating the volume or mass 
delivered.
    (13) Add specifications for testing for the newly defined ``low 
temperature water heaters''.
    (14) Clarify testing requirements for the heat pump part of a 
split-system heat pump water heater.
    (15) Define the use of a separate unfired hot water storage tank 
for testing water heaters designed to operate with a separately sold 
hot water storage tank.
    (16) Clarify that any connection to an external network or 
control be disconnected during testing.
    (17) Add procedures for estimating internal stored water 
temperature for water heater designs in which the internal tank 
temperature cannot be directly measured.
    (18) Modify the provisions for untested water heater basic 
models within 10 CFR 429.70(g) to include electric instantaneous 
water heaters.

    DOE's proposed actions are summarized in Table II.1 and compared to 
the current test procedure; the reason for the proposed change is also 
listed.

  Table II.1--Summary of Changes in Proposed Test Procedure Relative to
                         Current Test Procedure
------------------------------------------------------------------------
                                     Proposed test
   Current DOE test procedure          procedure          Attribution
------------------------------------------------------------------------
References the 1986 (Reaffirmed   References the      Industry TP Update
 2006) version of ASHRAE 41.1      updated 2020        to ASHRAE 41.1.
 for methods for temperature       version of ASHRAE
 measurement.                      41.1.
The 1982 version of ASHRAE 41.6   References the      Industry TP Update
 for methods for humidity          2014 version of     to ASHRAE 41.6.
 measurement is referenced         ASHRAE 41.6,
 within the 1986 version of        which is
 ASHRAE 41.1.                      referenced by
                                   ASHRAE 41.1-2020.
References the 2009 version of    References the      Industry TP Update
 ASTM D2156 for testing smoke      version of ASTM     to ASTM D2156.
 density in flue gases from        D2156 that was
 burning distillate fuels.         reaffirmed in
                                   2018.
The 1987 version of ASTM E97 for  References the      Industry TP Update
 testing directional reflectance   1987 version of     to ASTM E97.
 factor, 45-deg 0-deg, of opaque   ASTM E97, which
 specimens by broad-band filter    is referenced by
 reflectometry is referenced       ASTM D2156-09
 within ASTM D2156-09.             (2018).
Does not define a ``circulating   Adds a definition   To improve the
 water heater'' as used in 10      for ``circulating   representativenes
 CFR 430.2.                        water heater'' to   s of the test
                                   10 CFR 430.2.       procedure.
Does not define a ``tabletop      Adds a definition   Reinstate
 water heater'' as used as a       for ``tabletop      definition
 product class distinction at 10   water heater'' to   inadvertently
 CFR 430.32(d).                    10 CFR 430.2.       removed by
                                                       previous final
                                                       rule.
Does not address how to           Specifies how a     To improve the
 configure a water heater for      mixing valve        repeatability of
 test when a mixing valve is       should be           the test
 required for proper operation.    installed when      procedure.
                                   the water heater
                                   is designed to
                                   operate with one.
Requires the flow rate during     Requires the flow   To improve the
 the FHR test to be 1.0 0.25 gpm (3.8 0.95 L/min) for water       1.5 0.25 gpm      align with the
 volume less than 20 gallons.      (3.8 0.95 L/min)   procedure ASHRAE
                                   for water heaters   118.2.
                                   with a rated
                                   storage volume
                                   less than 20
                                   gallons.
Does not address the situation    Clarifies that the  To improve the
 in which the first recovery       first recovery      repeatability of
 ends during a draw when testing   period will         the test
 to the 24-hour simulated-use      extend to the end   procedure.
 test.                             of the draw in
                                   which the first
                                   recovery ended,
                                   and that if a
                                   second recovery
                                   initiates prior
                                   to the end of the
                                   draw, that the
                                   second recovery
                                   is part of the
                                   first recovery
                                   period as well.
The recovery efficiency equation  Clarifies that,     To improve the
 for storage-type water heaters    for the             repeatability of
 refers to the mass of water       calculation of      the test
 removed from the start of the     recovery            procedure.
 test to the end of the first      efficiency, the
 recovery period.                  mass of water
                                   removed during
                                   the first
                                   recovery period
                                   includes water
                                   removed during
                                   all draws from
                                   the start of the
                                   test until the
                                   end of the first
                                   recovery period.

[[Page 1559]]

 
Appendix E uses the phrases       Uses the terms      Clarification.
 ``storage-type'' and              ``non-flow
 ``instantaneous-type'' to refer   activated'' and
 to ``non-flow activated'' and     ``flow-
 ``flow-activated'' water          activated'' water
 heaters, respectively.            heater, where
                                   appropriate.
The descriptions for Qsu,0,       The descriptions    Clarification.
 Qsu,f, Tsu,0, Tsu,f,              for Qsu,0, Qsu,f,
 [tau]stby,1, Tt,stby,1, and       Tsu,0, Tsu,f,
 Ta,stby,1 only address when the   [tau]stby,1,
 standby period occurs between     Tt,stby,1, and
 draw clusters 1 and 2.            Ta,stby,1 are
                                   generalized to
                                   refer to the
                                   section where the
                                   standby period is
                                   determined.
Specifies that the first          Specifies that the  Reduce burden.
 required measurement for each     first required
 draw of the 24-hour simulated-    measurement for
 use test is 5 seconds after the   each draw of the
 draw is initiated.                24-hour simulated-
                                   use test is 15
                                   seconds after the
                                   draw is initiated.
Requires the electric supply      Requires the        Reduce burden.
 voltage to be within 1 percent of the rated      voltage to be
 voltage for the entire test.      within 2 percent
                                   of the rated
                                   voltage beginning
                                   5 seconds after
                                   the start of a
                                   recovery and
                                   ending 5 seconds
                                   before the end of
                                   a recovery.
Requires maintaining ambient      Requires            Reduce burden.
 temperature for non-heat pump     maintaining the
 water heaters within a range of   ambient
 67.5 [deg]F 2.5       temperature for
 [deg]F.                           non-heat pump
                                   water heaters
                                   within a range of
                                   67.5 [deg]F 5 [deg]F,
                                   and with an
                                   average of 67.5
                                   [deg]F 2.5 [deg]F.
Requires maintaining the dry      Requires            Reduce burden.
 bulb temperature for heat pump    maintaining the
 water heaters within a range of   dry bulb
 67.5 [deg]F 1         temperature for
 [deg]F.                           heat pump water
                                   heaters within a
                                   range of 67.5
                                   [deg]F 5 [deg]F,
                                   and with an
                                   average of 67.5
                                   [deg]F 1 [deg]F
                                   during recoveries
                                   and an average of
                                   67.5 [deg]F 2.5 [deg]F
                                   when not
                                   recovering.
Requires maintaining the          Requires            Reduce burden.
 relative humidity for heat pump   maintaining the
 water heaters within a range of   relative humidity
 50 percent 2          for heat pump
 percent.                          water heaters
                                   within a range of
                                   50 percent 5 percent,
                                   and at an average
                                   of 50 percent
                                   2
                                   percent during
                                   recoveries.
Requires that the heating value   States that the     To improve the
 be corrected to a standard        standard            repeatability of
 temperature and pressure, but     temperature is 60   the test
 does not state what temperature   [deg]F (15.6        procedure.
 and pressure is standard or how   [deg]C) and the
 to correct the heating value to   standard pressure
 the standard temperature and      is 30 inches of
 pressure.                         mercury column
                                   (101.6 kPa).
                                   Provides a method
                                   for converting
                                   heating value
                                   from the measured
                                   to the standard
                                   conditions.
Requires that the manifold        Clarifies that the  Reduce burden.
 pressure be within 10 percent of the           tolerance applies
 manufacturer recommended value.   only to water
                                   heaters with a
                                   pressure
                                   regulator that
                                   can be adjusted.
                                   Requires that the
                                   manifold pressure
                                   be within the
                                   greater of 10 percent
                                   of the
                                   manufacturer
                                   recommended value
                                   or 0.2 inches
                                   water column.
Does not specify the input rate   Specifies that the  Clarification.
 at which the gas supply           gas supply
 pressure tolerance is             pressure
 determined.                       tolerance is to
                                   be maintained
                                   when operating at
                                   the maximum input
                                   rate.
Does not contain procedures for   Adds provisions     To improve the
 modifying the orifice of a        regarding the       repeatability of
 water heater that is not          modification of     the test
 operating at the manufacturer     the orifice.        procedure.
 specified input rate.
Does not specify how to           Specifies how to    To improve the
 calculate the mass removed from   calculate the       repeatability of
 the water heater when mass is     mass of water       the test
 calculated indirectly using       indirectly using    procedure.
 density and volume measurements.  density and
                                   volume
                                   measurements.
Does not accommodate testing of   Adds a definition   To improve the
 ``low temperature water           of ``low            representativenes
 heaters'' in appendix E.          temperature water   s and
                                   heater'' in 10      repeatability of
                                   CFR 430.2 and       the test
                                   requires low        procedure.
                                   temperature water
                                   heaters to be
                                   tested to their
                                   maximum possible
                                   delivery
                                   temperature in
                                   appendix E.
Does not explicitly define the    Explicitly states   To improve the
 test conditions required for      that the heat       repeatability of
 each part of a split-system       pump part of a      the test
 heat pump water heater.           split-system heat   procedure.
                                   pump water heater
                                   is tested at the
                                   dry bulb
                                   temperature and
                                   relative humidity
                                   conditions
                                   required for heat
                                   pump water
                                   heaters, and that
                                   the storage tank
                                   is tested at the
                                   ambient
                                   temperature and
                                   relative humidity
                                   conditions
                                   required for non-
                                   heat pump water
                                   heaters.
Does not accommodate testing of   Requires water      To improve the
 water heaters that require a      heaters designed    representativenes
 separately-sold hot water         to operate with a   s of the test
 storage tank to properly          separately-sold     procedure.
 operate.                          hot water storage
                                   tank to use an 80-
                                   gallon unfired
                                   hot water storage
                                   tank for testing.
Does not address water heaters    Explicitly states   To improve the
 with network connection           that any            repeatability of
 capabilities.                     connection to an    the test
                                   external network    procedure.
                                   or control be
                                   disconnected
                                   during testing.
Does not accommodate certain      Adds a ``drain      To improve the
 water heaters for which the       down'' procedure    representativenes
 mean tank temperature cannot be   to estimate the     s of the test
 directly measured.                mean tank           procedure.
                                   temperature for
                                   certain water
                                   heaters for which
                                   the mean tank
                                   temperature
                                   cannot be
                                   directly measured.

[[Page 1560]]

 
10 CFR 429.70(g) does not allow   Extends the         Reduce burden.
 untested electric instantaneous   untested
 water heaters to be certified,    provisions within
 but does allow untested           10 CFR 429.70(g)
 electric storage water heaters    to include
 to be certified.                  electric
                                   instantaneous
                                   water heaters.
------------------------------------------------------------------------

    Additionally, DOE proposes to interpret the statutory definition of 
consumer water heater to exclude certain larger capacity heat pump type 
units and that such units would be covered as commercial equipment.
    DOE has tentatively determined that the proposed amendments 
described in section III of this NOPR would not significantly affect 
the measured efficiency of consumer and residential-duty commercial 
water heaters. Discussion of DOE's proposed actions are addressed in 
detail in section III of this NOPR.

III. Discussion

A. Scope of Applicability

    This document covers those products that meet the definition of 
consumer ``water heater,'' as defined in the statute at 42 U.S.C. 
6291(27), as codified at 10 CFR 430.2. This document also covers 
commercial water heating equipment with residential applications, i.e., 
``residential-duty commercial water heater'' (10 CFR 431.102).
1. Definitions
    In the context of covered consumer products, EPCA defines ``water 
heater'' as a product which utilizes oil, gas, or electricity to heat 
potable water for use outside the heater upon demand, including--
    (a) Storage type units which heat and store water at a 
thermostatically controlled temperature, including gas storage water 
heaters with an input of 75,000 Btu per hour or less, oil storage water 
heaters with an input of 105,000 Btu per hour or less, and electric 
storage water heaters with an input of 12 kilowatts or less;
    (b) Instantaneous type units which heat water but contain no more 
than one gallon of water per 4,000 Btu per hour of input, including gas 
instantaneous water heaters with an input of 200,000 Btu per hour or 
less, oil instantaneous water heaters with an input of 210,000 Btu per 
hour or less, and electric instantaneous water heaters with an input of 
12 kilowatts or less; and
    (c) Heat pump type units, with a maximum current rating of 24 
amperes at a voltage no greater than 250 volts, which are products 
designed to transfer thermal energy from one temperature level to a 
higher temperature level for the purpose of heating water, including 
all ancillary equipment such as fans, storage tanks, pumps, or controls 
necessary for the device to perform its function. (42 U.S.C. 6291(27); 
10 CFR 430.2)
    In addition, at 10 CFR 430.2, DOE defines several specific 
categories of consumer water heaters, as follows:

    (1) ``Electric instantaneous water heater'' means a water heater 
that uses electricity as the energy source, has a nameplate input 
rating of 12 kW or less, and contains no more than one gallon of 
water per 4,000 Btu per hour of input.
    (2) ``Electric storage water heater'' means a water heater that 
uses electricity as the energy source, has a nameplate input rating 
of 12 kW or less, and contains more than one gallon of water per 
4,000 Btu per hour of input.
    (3) ``Gas-fired instantaneous water heater'' means a water 
heater that uses gas as the main energy source, has a nameplate 
input rating less than 200,000 Btu/h, and contains no more than one 
gallon of water per 4,000 Btu per hour of input.
    (4) ``Gas-fired storage water heater'' means a water heater that 
uses gas as the main energy source, has a nameplate input rating of 
75,000 Btu/h or less, and contains more than one gallon of water per 
4,000 Btu per hour of input.
    (5) ``Grid-enabled water heater'' means an electric resistance 
water heater that--
    (a) Has a rated storage tank volume of more than 75 gallons;
    (b) Is manufactured on or after April 16, 2015;
    (c) Is equipped at the point of manufacture with an activation 
lock and;
    (d) Bears a permanent label applied by the manufacturer that--
    (i) Is made of material not adversely affected by water;
    (ii) Is attached by means of non-water-soluble adhesive; and
    (iii) Advises purchasers and end-users of the intended and 
appropriate use of the product with the following notice printed in 
16.5 point Arial Narrow Bold font: ``IMPORTANT INFORMATION: This 
water heater is intended only for use as part of an electric thermal 
storage or demand response program. It will not provide adequate hot 
water unless enrolled in such a program and activated by your 
utility company or another program operator. Confirm the 
availability of a program in your local area before purchasing or 
installing this product.''
    (6) ``Oil-fired instantaneous water heater'' means a water 
heater that uses oil as the main energy source, has a nameplate 
input rating of 210,000 Btu/h or less, and contains no more than one 
gallon of water per 4,000 Btu per hour of input.
    (7) ``Oil-fired storage water heater'' means a water heater that 
uses oil as the main energy source, has a nameplate input rating of 
105,000 Btu/h or less, and contains more than one gallon of water 
per 4,000 Btu per hour of input.

    The definition for ``grid-enabled water heater'' includes the term 
``activation lock,'' which is defined to mean a control mechanism 
(either by a physical device directly on the water heater or a control 
system integrated into the water heater) that is locked by default and 
contains a physical, software, or digital communication that must be 
activated with an activation key to enable the product to operate at 
its designed specifications and capabilities and without which the 
activation of the product will provide not greater than 50 percent of 
the rated first-hour delivery of hot water certified by the 
manufacturer. 10 CFR 430.2. As specified in this definition, the 
control mechanism must be physically incorporated into the water heater 
or, if a control system, integrated into the water heater to qualify as 
an activation lock. DOE is aware of certain state programs that 
encourage water heaters to be equipped with communication ports that 
allow for demand-response communication between the water heater and 
the utility.\9\ DOE notes that

[[Page 1561]]

presence of such a communication port, in and of itself, would not 
qualify as an activation lock for the purpose of classifying a water 
heater as a grid-enabled water heater.
---------------------------------------------------------------------------

    \9\ On May 7, 2019, the State of Washington signed House Bill 
1444, which amended the Revised Code of Washington (RCW) (i.e., the 
statutory code in the State of Washington), Title 19, Chapter 19.260 
(RCW 19.260). On January 6, 2020, the State of Washington amended 
the Washington Administrative Code (WAC) (i.e., the regulatory code 
in the State of Washington), Title 194, Chapter 194-24 (WAC 194-24) 
(Washington January 2020 Amendment) to align with RCW 19.260. 
Similarly, the State of Oregon published a final rule (Oregon August 
2020 final rule) on August 8, 2020, which amended the Oregon 
Administrative Rules (OAR), Chapter 330, Division 92 (OAR-330-092). 
The Washington House Bill 1444 and the Oregon August 2020 final rule 
established a definition for electric storage water heater (RCW 
19.260.020(14); OAR-330-092-0010(10)), an effective date of January 
1, 2021 in Washington and January 1, 2022 in Oregon (RCW 
19.260.080(1); OAR-330-092-0015(17)), a requirement that electric 
storage water heaters must have a modular demand response 
communications port compliant with the March 2018 version of the 
ANSI/CTA-2045-A communication interface standard, or a standard 
determined to be equivalent (RCW 19.260.080(1)(a)-(b); OAR-330-092-
0020(17)), and, in Oregon, must bear a label or marking on the 
products stating either ``DR-ready: CTA-2045-A'' or ``DR-ready: CTA-
2045-A and [equivalent DR system protocol]'' (OAR-330-092-0045(17)).
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested comment on the definitions 
currently applicable to consumer water heaters. 85 FR 21104, 21108 
(April 16, 2020). Sections III.A.1.a through III.A.1.e address specific 
issues either requested by DOE or submitted by commenters.
a. Electric Heat Pump Storage Water Heater
    In the April 2020 RFI, DOE requested feedback on the need for 
creating a separate definition for ``electric heat pump storage water 
heater,'' similar to the definition in the March 2019 ASHRAE Draft 
118.2, or whether the current DOE definitions in 10 CFR 430.2 for 
``electric storage water heater'' and ``water heater,'' which include 
``heat pump type units,'' would adequately cover such products for the 
purpose of performing the DOE test procedure. 85 FR 21104, 21110 (April 
16, 2020). Rheem supported the creation of a separate definition for 
electric heat pump storage water heaters, specifically to clarify power 
rating limits and to include different design types. (Rheem, No. 14 at 
p. 3) Rinnai supported the inclusion of a definition for electric heat 
pump water heaters but not the creation of a separate product category. 
(Rinnai, No. 13 at p. 4) EEI stated that DOE should adopt the March 
2019 ASHRAE Draft 118.2 definition for electric heat pump storage water 
heaters. (EEI, No. 8 at p. 3) On the other hand, BWC stated that the 
definition for ``electric heat pump water heater'' is adequate at this 
time. (BWC, No. 12 at p. 2) A.O. Smith stated that the introduction of 
the electric heat pump water heater definition from the March 2019 
ASHRAE Draft 118.2 is unnecessary and will cause confusion due to the 
difference in scope, and that DOE's definitions for heat pump type 
units with additional clarification regarding maximum amperage and 
input power would be sufficient. (A.O. Smith, No. 20 at p. 2) AHRI 
stated that DOE should carefully review the entire heat pump water 
heater market, consider how each of the various designs should be 
characterized, and consider changes to the definitions, as necessary. 
(AHRI, No. 17 at p. 4) NEEA stated that no change to the definition is 
needed yet as the ``heat pump type units'' definition is adequate as 
written. (NEEA, No. 21 at p. 6) NEEA also requested that DOE clarify 
the boundary between residential and commercial heat pump water heaters 
for testing purposes and further stated that residential is implied to 
include input rates lower than 6 kW,\10\ whereas commercial is implied 
to include input rates greater than 12 kW, such that the 6-12 kW range 
is ambiguous. (Id. at pp. 1-3)
---------------------------------------------------------------------------

    \10\ Power equals amperage times voltage, so the definition of 
consumer heat pump type unit corresponds to a maximum power rating 
of 6,000 W, or 6 kW (24 A times 250 V equals 6,000 W).
---------------------------------------------------------------------------

    DOE's consideration of the March 2019 ASHRAE Draft 118.2 ``electric 
heat pump storage water heater'' definition, the comments received in 
response to the April 2020 RFI, and a review of the market, lead DOE to 
revisit its prior application of the water heater definition in the 
context of heat pump type water heaters. DOE is re-evaluating these 
terms with additional consideration of the distinction between heat 
pump water heater consumer products and commercial products. More 
specifically, DOE proposes to clarify the application of the ``heat 
pump type'' provision in the EPCA definition of ``water heater.'' DOE 
proposes that the ``heat pump type'' provision specifies the criteria 
to distinguish consumer water heaters that incorporate heat pumps from 
commercial water heaters that incorporate heat pumps.
    As noted, EPCA defines water heater to include ``(A) storage type 
units which heat and store water at a thermostatically controlled 
temperature, including . . . electric storage water heaters with an 
input of 12 kilowatts or less; (B) instantaneous type units which heat 
water but contain no more than one gallon of water per 4,000 Btu per 
hour of input, including . . . electric instantaneous water heaters 
with an input of 12 kilowatts or less; and (C) heat pump type units, 
with a maximum current rating of 24 amperes at a voltage no greater 
than 250 volts, which are products designed to transfer thermal energy 
from one temperature level to a higher temperature level for the 
purpose of heating water, including all ancillary equipment such as 
fans, storage tanks, pumps, or controls necessary for the device to 
perform its function.'' (42 U.S.C. 6291(27))
    ``Storage type units'' and ``instantaneous type units'' are not 
exclusive of ``heat pump type units.'' Based on the ``water heater'' 
definition, an electric heat pump type unit could be covered under the 
water heater definition's description of storage type units (if it 
heats and stores water at a thermostatically controlled temperature 
with an input of 12 kilowatts or less) or instantaneous type unit (if 
it heats water and contains no more than one gallon of water per 4,000 
Btu per hour of input and has an input of 12 kilowatts or less). EPCA 
is not explicit as to whether heat pump type units are considered a 
subcategory of storage type units and instantaneous type units.
    The November 2016 final rule treated heat pump type units as a 
subcategory of the other two types of units listed in the definition of 
water heater. Specifically, DOE stated in the November 2016 final rule 
that a heat pump water heater with a total rated input of less than 12 
kW would be a consumer water heater, as EPCA classifies electric water 
heaters with less than 12 kW rated electrical input as consumer water 
heaters. 81 FR 79261, 79301-79302 (Nov. 10, 2016). However, upon a 
review of EPCA and the water heater market, DOE has tentatively 
determined that the interpretation presented in the November 2016 final 
rule is not the best reading of EPCA.
    The structure of the statutory definition of ``water heater'' in 
the Energy Conservation Program for Consumer Products in Part A of 
EPCA, lists each type of water heater at equal subparagraph 
designations. Therefore, when defining ``water heater'' for the purpose 
of determining whether a water heater is a consumer water heater, the 
energy use criteria specified for heat pump type units \11\ is to be 
applied separately and distinctly from the criteria specified for the 
broader categorizations of storage type units \12\ and instantaneous 
type units.\13\
---------------------------------------------------------------------------

    \11\ For heat pump type units EPCA specifies a maximum current 
rating of 24 amperes at a voltage no greater than 250 volts. (42 
U.S.C. 6291(27)(C))
    \12\ For storage type units EPCA specifies gas storage water 
heaters with an input of 75,000 Btu per hour or less, oil storage 
water heaters with an input of 105,000 Btu per hour or less, and 
electric storage water heaters with an input of 12 kilowatts or 
less. (42 U.S.C. 6291(27)(A))
    \13\ For instantaneous type units EPCA specifies gas 
instantaneous water heaters with an input of 200,000 Btu per hour or 
less, oil instantaneous water heaters with an input of 210,000 Btu 
per hour or less, and electric instantaneous water heaters with an 
input of 12 kilowatts or less. (42 U.S.C. 6291(27)(B))
---------------------------------------------------------------------------

    This separate consideration of heat pump type units when defining 
the scope of the consumer water heater definition is further supported 
by

[[Page 1562]]

considering the output capacities associated with the input limits 
specified for each type of unit. The electrical requirements for heat 
pump type water heaters (i.e., less than or equal to 24 amperes (A) at 
250 volts (V) or less) align with common electrical requirements for a 
residential electrical circuit.\14\ EPCA's energy use criteria for heat 
pump type units corresponds to an input rate of 6 kW.\15\ Whereas, 
DOE's interpretation in the November 2016 final rule additionally 
applies the 12 kW input rate limit to heat pump type units. A heat pump 
type unit with an input rate of 12 kW would have a heating capacity 
(i.e., output capacity) of approximately 42 kW, which is 3.6 times the 
output heating capacity provided by the largest possible consumer 
electric storage type water heater (i.e., 11.8 kW).\16\ While a heat 
pump type unit with a 12 kW input capacity could theoretically be 
designed and installed in a residential application, a water heating 
capacity (i.e., output capacity) of 42 kW would far exceed the water 
heating demand of any residential installation.
---------------------------------------------------------------------------

    \14\ In a safely designed home electrical circuit, a circuit 
breaker should only service outlets and/or devices that add up to 80 
percent of the maximum current rating for the circuit breaker (i.e., 
a 30 A circuit breaker should only service up to 24 A across all 
outlets and/or devices connected to that circuit breaker). Further, 
large appliances, such as water heaters, if installed on a dedicated 
circuit, should not exceed 80 percent of the circuit rating. See 
section 550.12(D) of the 2019 California Electrical Code: 
www.nfpa.org/codes-and-standards/all-codes-and-standards/codes-and-standards/free-access?mode=view.
    \15\ Power (in watts) is calculated as current (i.e., amperage) 
multiplied by voltage. The EPCA criteria of 24 A and 250 V 
correspond to a power of 6,000 W (i.e., 24 x 250 = 6,000), or 6 kW.
    \16\ A 12-kW electric resistance water heater with an assumed 
recovery efficiency of 98 percent would have an output heating 
capacity of 11.8 kW (i.e., 12 kW x 0.98 = 11.8 kW). Whereas, an 
electric heat pump type water heater with a 12 kW input capacity, 
with an assumed recovery efficiency of 350 percent, would have an 
output heating capacity of 42 kW (i.e., 12 kW x 3.5 = 42 kW), which 
is 3.6 times greater than the 11.8 kW output heating capacity of an 
electric resistance water heater with equivalent input capacity.
---------------------------------------------------------------------------

    This tentative interpretation is supported by the current market. 
DOE reviewed manufacturers' product literature and found no electric 
heat pump water heaters marketed towards residential use that were 
designed to operate at greater than 24 A at 250 V.
    This proposed interpretation of the ``heat pump type'' provision 
would define the scope of ``water heater'' for the purpose of Part A of 
EPCA. The interpretation would not be applicable in the context of 
determining product classes for water heaters. Any such consideration 
of product classes would be governed by 42 U.S.C. 6295(q). As stated 
previously, ``storage type units'' and ``instantaneous type units'' are 
not exclusive of ``heat pump type units.'' The criteria established in 
the statutory definition of water heater for each of these types of 
units in the definition of ``water heater'' excludes units with 
capacities that would be more appropriately addressed as commercial 
water heaters.
    When considering the unit types included in the water heater 
definition (i.e., ``storage type,'' ``instantaneous type,'' and ``heat 
pump type'') as separate and distinct elements, the statutory 
definition of consumer water heater includes only those heat pump type 
units that have a maximum current rating of 24 A at a voltage no 
greater than 250 V. Heat pump type water heaters with an input capacity 
greater than the 24 A at 250 V do not meet the EPCA definition of a 
covered water heater. Instead, such units would be commercial water 
heaters, i.e., if a heat pump type water heater has either an amperage 
greater than 24 A or a voltage greater than 250 V, under the definition 
it would be a commercial water heater.
    EPCA defines covered equipment as certain types of industrial 
equipment, including storage water heaters and instantaneous water 
heaters. (42 U.S.C. 6311(1)(K)) EPCA defines ``industrial equipment,'' 
in relevant part, as ``any article of equipment [. . .] which is not a 
``covered product'' as defined in 42 U.S.C. 6291(a)(2). (42 U.S.C. 
6311(2)(A)) In the context of covered equipment, EPCA defines ``storage 
water heater'' as a water heater that heats and stores water within the 
appliance at a thermostatically controlled temperature for delivery on 
demand. Such term does not include units with an input rating of 4,000 
Btu per hour or more per gallon of stored water. (42 U.S.C. 
6311(12)(A)) The term ``instantaneous water heater'' is defined in the 
context of covered equipment as a water heater that has an input rating 
of at least 4,000 Btu per hour per gallon of stored water. (42 U.S.C. 
6311(12)(B)) Under these EPCA definitions, a heat pump type water 
heater that was not defined as a consumer water heater would be either 
a commercial storage water heater or a commercial instantaneous water 
heater, depending on the input rating.
    DOE has tentatively determined that heat pump water heaters, which 
operate with a maximum current rating greater than 24 A or at a voltage 
greater than 250 V, are more appropriately covered as commercial water 
heaters than consumer water heaters.
    As discussed in the November 2016 final rule, electric heat pump 
water heaters with greater than 24 A at 250 V and a total input rate 
less than or equal to 12kW would be covered by the energy conservation 
standards for consumer electric storage water heaters. See 81 FR 79261, 
79301-79302. (Nov. 10, 2016). These standards for consumer electric 
storage water heaters effectively require electric resistance 
technology at less than or equal to 55 gallons of rated storage volume 
or baseline \17\ heat pump technology at greater than 55 gallons of 
rated storage volume. However, section 1.12.3 of the DOE test procedure 
at the time \18\ only included heat pump water heaters which have ``a 
maximum current rating of 24 amperes (including the compressor and all 
auxiliary equipment such as fans, pumps, controls, and, if on the same 
circuit, any resistive elements) for an input voltage of 250 volts or 
less.'' Therefore, electric heat pump water heaters with greater than 
24 A at 250 V were not considered in the analysis of the April 2010 
final rule, and, as such, the electric storage water heater standards 
are not applicable to these heat pump water heaters. Under the proposed 
interpretation in this NOPR, electric heat pump water heaters with 
greater than 24 A at 250 V and a total input rate less than or equal to 
12kW would be subject to the commercial water heater standards, which 
specify a maximum standby loss. 10 CFR 431.110(a). DOE notes that it 
has established a test procedure for commercial water heaters (10 CFR 
431.106), and any representation made by a manufacturer as to the 
energy efficiency or energy use of a commercial water heater must be 
based on testing in accordance with the DOE test procedure, and such 
representation must fairly disclose the results of such testing. (42 
U.S.C. 6314(d)(1))
---------------------------------------------------------------------------

    \17\ The electric storage water heater energy conservation 
standards established by the April 2010 final rule set a minimum 
efficiency level that was attainable by all heat pump water heaters 
available at the time. Therefore, the standard did not eliminate any 
heat pump water heaters from the market.
    \18\ At the time of the April 2010 final, rule, the DOE test 
procedure for consumer water heaters was last updated by a final 
rule published on July 20, 1998. 63 FR 38737.
---------------------------------------------------------------------------

    In determining the input rate of a water heater with a heat pump 
component for the purpose of classifying such a water heater as either 
a consumer water heater or a commercial water heater, DOE would 
consider the total input rate, including all heat pump components and 
the resistive elements. As specified in the definition of ``water 
heater'' and ``commercial heat pump water heater,'' determination of 
the rated electric power input includes all ancillary

[[Page 1563]]

equipment. 10 CFR 430.2 and 10 CFR 431.102. Similarly, DOE would 
consider all heat pump components and resistive elements in determining 
voltage and amperage.
    DOE reviewed the electric heat pump water heater market and found 
that several new configurations of heat pump water heaters have either 
become available or will soon become available on the market. Based its 
review of the market, DOE has identified these new configurations as 
electric storage water heaters that are heat pump type units.
    In the present market, a consumer heat pump water heater typically 
consists of an air-source heat pump and a storage tank that are 
integrated together into one assembly. This ``typical'' consumer heat 
pump water heater uses electricity, operates around 240 volts, and has 
two 4,500-watt backup resistance elements within the storage tank that 
operate non-simultaneously. The new configurations that DOE identified 
include split-system heat pump water heaters (which consist of a 
separate heat pump and storage tank that are sold together), heat pump 
only models (which are sold without a storage tank but require being 
paired with one), ``retrofit-ready'' or ``plug-in'' heat pump water 
heaters (which are integrated heat pump and storage tank water heaters 
that can operate on a shared 120V/15A circuit and plugged into a 
standard 120 V receptacle (i.e., wall outlet)), and ground- or water-
source heat pump water heaters.
    Split-system heat pump water heaters are currently available and 
used in residential applications; however, they are relatively uncommon 
when compared to typical integrated heat pump water heaters. Although 
split-system heat pump water heaters are more prevalent outside of the 
United States, they are produced by manufacturers that sell water 
heaters within the United States. As such, split-system water heaters 
may become more prevalent in the U.S. market in the future, and the DOE 
test procedure should adequately test these products. The current DOE 
test procedure covers split-system heat pump water heaters and the 
relevant proposed amendments are discussed in section III.C.8.b of this 
document. DOE has tentatively determined that split-system heat pump 
water heaters are covered by the current definitions of ``electric 
storage water heater'' and ``heat pump type units.''
    DOE has identified heat pump water heaters models that are sold 
with only the heat pump (heat pump only water heaters) and must be 
paired with an external storage tank in the field, with the specific 
tank characteristics depending on the hot water requirements of the 
installation (i.e., the heat pump can be used with storage tanks of 
various storage volumes). Currently, these units are marketed only for 
commercial use. However, some models of these units have rated voltage 
and amperage values below the limits specified in the ``heat pump type 
unit'' consumer water heater definition. Further, DOE has identified 
models that will soon enter the market that are marketed for 
residential and light-commercial use. To the extent that a heat pump 
only water heater is covered by the definition of ``heat pump type 
unit'' consumer water heater, it would be subject to the DOE test 
procedure for consumer water heaters. DOE proposes to add a definition 
to cover heat pump only water heaters to 10 CFR 430.2. This definition 
is presented in section III.A.1.c of this document where products with 
a similar application are discussed. Test procedure amendments proposed 
in this document specific to heat pump only water heaters are discussed 
in section III.C.8.c of this NOPR.
    DOE reviewed the plug-in (or ``retro-fit ready'') heat pump water 
heater market described previously (integrated heat pump and storage 
tank water heaters that can operate on a 120V/15A circuit and plugged 
into a standard 120 V receptacle (i.e., wall outlet)) and has initially 
found that these products are still under development and are not 
commercially available at this time. On December 23, 2019, NEEA 
published version 7.0 of its Advanced Water Heating Specification,\19\ 
which includes an appendix that describes plug-in heat pump water 
heaters. As reported, these products are being designed as an 
integrated heat pump and storage tank for space-constrained 
installations (e.g., small closets) and to operate on a shared 120V/15A 
circuit. Indications are that plug-in heat pump water heaters will be 
marketed for residential use, have input rates at or below the 12 kW 
threshold to be considered a consumer electric storage water heater, 
and have voltage and amperage levels below the 250 V and 24 A limits to 
be considered a ``heat pump type unit.'' Based on the initial 
information available, plug-in heat pump water heaters would be covered 
by either the current definition of ``electric storage water heater'' 
or ``heat pump type units.'' As plug-in heat pump water heaters are not 
currently available on the market, DOE is not proposing any changes to 
the test procedure specific to these products in this NOPR. DOE may 
reevaluate this tentative determination at such time as when these 
models enter the market.
---------------------------------------------------------------------------

    \19\ Version 7.0 of NEEA's Advanced Water Heater Specification 
can be found at: www.neea.org/img/documents/Advanced-Water-Heating-Specification.pdf.
---------------------------------------------------------------------------

    DOE has also identified heat pump water heaters that use 
alternative heat sources (e.g., water- or ground-source) that, although 
more commonly installed in commercial applications, do have residential 
applications and are at or below the 12kW limit to be considered a 
consumer ``water heater.'' Alternative source heat pump water heaters 
were not prevalent in the market at the time DOE established the 
current consumer water heater test procedure and therefore were not 
considered in the development of the current DOE test procedure. 79 FR 
40542, 40566-40567 (July 11, 2014).
    Significant changes and clarifications to the test setup and test 
conditions would be required to appropriately represent the various 
alternative source heat pump water heater components and installation 
requirements. The current test procedure for consumer water heaters 
incorporates draw patterns to represent an average period of use for 
the products subject to the test procedure. Section 5.4.1 of appendix 
E. Alternative source heat pump water heaters were not considered in 
the development of the current draw pattern requirements. Based on a 
current review of the market, these water heaters continue to have a 
small market share and indications are that they are predominantly used 
in commercial applications. DOE currently does not have data as to the 
use of such water heaters as installed. Absent such data, DOE is unable 
to develop and propose test procedure provisions that would be 
representative of such water heaters during an average period of use. 
To the extent there is no test procedure for such covered water 
heaters, they would not be subject to energy conservation standards. 
Because of the limited market share and unavailability of usage data, 
DOE has tentatively determined not to propose test procedures for these 
products.
    Based on the forgoing discussion, DOE has tentatively determined 
that the current definitions of ``heat pump type'' and ``electric 
storage water heaters'' adequately cover the electric heat pump water 
heaters on the market that are representative of residential use, 
including ``plug in'' and alternative source heat pump water heaters, 
and that a separate definition for ``electric heat pump water heaters'' 
is not needed at this time. However, as discussed previously in this 
NOPR, DOE is

[[Page 1564]]

proposing to add a new definition to cover heat pump only water 
heaters.
b. Gas-Fired Heat Pump Storage Water Heater
    In the April 2020 RFI, DOE requested feedback on whether a separate 
definition for ``gas-fired heat pump storage water heater,'' similar to 
the definition in the March 2019 ASHRAE Draft 118.2, was needed or 
whether the current DOE definitions in 10 CFR 430.2 for ``gas-fired 
storage water heater'' and ``water heater,'' which include ``heat pump 
type units,'' would adequately cover such products for the purpose of 
performing the DOE test procedure. 85 FR 21104, 21110 (April 16, 2020). 
AHRI, A.O. Smith, BWC, EEI, Rheem, Rinnai, and SMTI recommended that 
DOE add a separate definition for ``gas-fired heat pump storage water 
heater.'' (AHRI, No. 17 at p. 4; A.O. Smith, No. 20 at p. 2; BWC, No. 
12 at p. 2; EEI, No. 8 at p. 3; Rheem, No. 14 at p. 3; Rinnai, No. 13 
at p. 4; SMTI, No. 19 at p. 2) A.O. Smith further stated that the gas-
fired storage water heater input capacity limit (less than or equal to 
75,000 Btu/h) is not appropriate for defining a gas-fired heat pump 
storage water heater that is representative of residential 
applications. (A.O. Smith, No. 20 at p. 2) AHRI stated that a separate 
definition for ``gas-fired heat pump water heater'' is appropriate and 
that DOE had already established a definition for it as part of the 
July 2014 final rule. (AHRI, No. 17 at p. 4) However, CEC stated there 
is no need to add a definition for ``gas-fired heat pump storage water 
heater'' because the definition currently in 10 CFR 430.2 for ``gas-
fired storage water heater'' and ``water heater'' includes ``heat pump 
type units,'' which adequately covers gas-fired heat pump storage water 
heaters. (CEC, No. 11 at p. 2) CEC argued that introducing the new 
definition as suggested under the March 2019 ASHRAE Draft 118.2 would 
indirectly limit the scope of heat pump water heaters standards by 
limiting the size of the gas-fired heat pump water heaters to be 
tested. (Id.) NEAA agreed that the current definitions for ``gas-fired 
storage water heater'' and ``heat pump units'' are adequate to cover 
gas-fired heat pump storage water heaters for purposes of testing, but 
the commenter noted there is value in creating a definition for market 
clarity. (NEEA, No. 21 at p. 6)
    In the July 2014 final rule, DOE defined a ``gas-fired heat pump 
water heater'' as ``a water heater that uses gas as the main energy 
source, has a nameplate input rating of 75,000 Btu/h (79 MJ/h) or less, 
has a maximum current rating of 24 amperes (including all auxiliary 
equipment such as fans, pumps, controls, and, if on the same circuit, 
any resistive elements) at an input voltage of no greater than 250 
volts, has a rated storage volume not more than 120 gallons (450 
liters), and is designed to transfer thermal energy from one 
temperature level to a higher temperature level to deliver water at a 
thermostatically controlled temperature less than or equal to 180 
[deg]F (82 [deg]C).'' 79 FR 40542, 40567 (July 11, 2014). DOE also 
stated that gas-fired heat pump water heaters are covered by the test 
procedure established in the July 2014 final rule. Id. at 79 FR 40549. 
The November 2016 final rule replaced this definition with the current 
definition of ``gas-fired storage water heater.'' 81 FR 79261, 79320-
79321 (Nov. 10, 2016). The current definition of ``water heater,'' 
which includes ``heat pump type units'' was added in a final rule 
published on February 7, 1989. 54 FR 6062, 6075. DOE reasoned in the 
November 2016 final rule that, because the definition of ``gas-fired 
heat pump water heater'' is not used in DOE's test procedures or energy 
conservation standards for consumer waters, removing this definition 
will have no effect on the implementation of DOE's regulations. 81 FR 
79261, 79287.
    Currently, a water heater that uses gas as the main energy source, 
has a nameplate input rating of 75,000 Btu/h or less, and contains more 
than one gallon of water per 4,000 Btu per hour of input is a gas-fired 
storage water heater. 10 CFR 430.2. If the gas-fired storage water 
heater also has a heat pump with a maximum current rating of 24 amperes 
at a voltage no greater than 250 volts, is designed to transfer thermal 
energy from one temperature level to a higher temperature level for the 
purpose of heating water, including all ancillary equipment such as 
fans, storage tanks, pumps, or controls necessary for the device to 
perform its function, it would be a heat pump type unit. 10 CFR 430.2. 
This definition of heat pump type unit is not exclusive of gas-fired 
units.
    The input rate of models currently in development for residential 
application are less than 20,000 Btu/h, which the March 2019 ASHRAE 
Draft 118.2 defines as the limit for gas-fired heat pump water heaters, 
and which is well below the 75,000 Btu/h limit in DOE's regulations. 
Gas-fired heat pump water heaters currently under design will likely 
have voltage and amperage requirements below the DOE ``heat pump type 
unit'' requirements, as electricity is not the main fuel source. 
Recognizing that the market for heat pump type units that are gas-fired 
is still developing, limiting coverage to less than 20,000 Btu/h 
(consistent with March 2019 ASHRAE Draft 118.2) would not accommodate 
the potential for future products designed for residential applications 
that may have input rates above 20,000 Btu/h. Therefore, DOE has 
tentatively determined that the definitions of ``heat pump type'' and 
``gas-fired storage water heaters'' adequately cover the water heaters 
that are within the ASHRAE definition of ``gas-fired heat pump water 
heaters,'' and a separate DOE regulatory definition is not needed at 
this time. Further, as DOE stated in the July 2014 final rule, gas-
fired heat pump water heaters are covered by the DOE test procedure 
established in that rule. 79 FR 40542, 40549 (July 11, 2014).
c. Gas-Fired Instantaneous Water Heater
    As discussed previously in this document, a gas-fired instantaneous 
water heater is a water heater that uses gas as the main energy source, 
has a nameplate input rating less than 200,000 Btu/h, and contains no 
more than one gallon of water per 4,000 Btu per hour of input. 10 CFR 
430.2. In the April 2020 RFI, DOE requested feedback on the typical 
application of a specific configuration of gas-fired instantaneous 
water heaters, commonly referred to as ``circulating gas-fired 
instantaneous water heaters.'' 85 FR 21104, 21113 (April 16, 2020). As 
explained in the April 2020 RFI, DOE has found that several 
manufacturers produce consumer gas-fired instantaneous water heaters 
that are designed to be used with a volume of stored water (usually in 
a tank, but sometimes in a recirculating hot water system of sufficient 
volume, such as a hydronic space heating or designated hot water 
system) in which the water heater does not provide hot water directly 
to fixtures, such as a faucet or shower head, but rather replenishes 
heat lost from the tank or system through hot water draws or standby 
losses by circulating water to and from the tank or other system. Id. 
These circulating gas-fired instantaneous water heaters are typically 
activated by an aquastat \20\ installed in a storage tank that is sold 
separately or by an inlet water temperature sensor. Id. DOE further 
stated that while the products identified by DOE are within the 
statutory and regulatory definition of a consumer water heater as a 
covered product, the design and application of circulating gas-fired 
instantaneous water heaters makes testing to the consumer water

[[Page 1565]]

heater test procedure difficult, if not impossible, as these products 
are not capable of delivering water at the temperatures and flow rates 
specified in the UEF test method. Id.
---------------------------------------------------------------------------

    \20\ An ``aquastat'' is a temperature measuring device typically 
used to control the water temperature in a separate hot water 
storage tank.
---------------------------------------------------------------------------

    In response to the April 2020 RFI, AHRI, APGA, Rheem, and Rinnai 
recommended generally that DOE amend the regulatory definitions of gas-
fired instantaneous water heaters to exclude models designed 
exclusively for commercial use with input rates below the consumer 
water heater input rate limit (i.e., <=200,000 Btu/h) and provided 
circulating gas-fired instantaneous water heaters as an example. (AHRI, 
No. 17 at p. 2; APGA, No. 16 at pp. 1-2; Rheem, No. 14 at p. 2; Rinnai, 
No. 13 at p. 2) A.O. Smith addressed circulating gas-fired water 
heaters specifically, stating that these models are produced at input 
rates both above and below the consumer water heater input rate cut-off 
for gas-fired instantaneous water heaters, and that all circulating 
water heaters, regardless of input rate, serve commercial applications; 
as such, they should be excluded from the consumer water heater 
regulations. (A.O. Smith, No. 20 at pp. 1-2) AHRI, Rheem, and Rinnai 
stated that these types of water heaters are sold into commercial 
building applications and should not be tested using a residential draw 
profile, which would not be applicable. (AHRI, No. 17 at p. 11; Rheem, 
No. 14 at p. 8; Rinnai, No. 13 at p. 10)
    Currently, an enforcement policy \21\ is in place addressing 
circulating water heaters. As provided in the enforcement policy, DOE 
will not seek civil penalties for the failure to properly certify 
covered products or the distribution in commerce by a manufacturer or 
private labeler of covered products that are not in compliance with an 
applicable energy conservation standard, if the violation occurs on or 
before December 31, 2021, with respect to an individual model of water 
heater that:
---------------------------------------------------------------------------

    \21\ Enforcement policy for circulating water heaters is 
available at: www.energy.gov/sites/prod/files/2019/09/f66/Enforcement%20Policy-CirculatingWH.92019.pdf.
---------------------------------------------------------------------------

     Meets the statutory definition of an instantaneous type of 
consumer water heater per 42 U.S.C. 6291(27);
     Does not have an operational scheme in which the burner or 
heating element initiates and terminates heating based on sensing flow;
     Has a water temperature sensor located at the inlet of the 
water heater or in a separate storage tank that is the primary 
operating temperature means of initiating and terminating heating;
     Must be used in combination with a recirculating pump and 
either a separate storage tank or water circulation loop in order to 
achieve the water flow and temperature conditions recommended in the 
manufacturer's installation and operation instructions;
     Is designed to provide outlet hot water at a 
thermostatically controlled temperature greater than 180 [deg]F; and
     Meets the corresponding energy conservation standards in 
10 CFR 431.110.
    As provided in the enforcement policy, a water heater must first 
meet the statutory definition of an instantaneous type of consumer 
water heater per 42 U.S.C. 6291(27) in order to be a circulating water 
heater. Inherent to being a water heater per 42 U.S.C. 6291(27), a 
product must be a ``consumer product.'' DOE's authority under the 
Energy Conservation Program for Consumer Products Other Than 
Automobiles established by EPCA (42 U.S.C. 6291-6309) applies to 
``consumer products.'' (See 42 U.S.C. 6292)
    In relevant part, 42 U.S.C. 6291(1) states that a ``consumer 
product'' means any article of a type which, to any significant extent, 
is distributed in commerce for personal use or consumption by 
individuals. Through an examination of product literature, DOE has 
found that circulating water heaters are predominately marketed for 
commercial applications. However, the input rates of many of the 
available models are below the maximum input rate of a consumer water 
heater and can therefore be suitable for residential applications. As 
such, DOE has tentatively determined that circulating water heaters are 
covered ``consumer products.'' Further, circulating water heaters 
operate similarly to the heat pump only water heaters discussed in 
section III.A.1.a, which DOE tentatively determined are marketed 
towards consumers and have residential applications (e.g., they extract 
water from a storage tank, heat the water, and return the heated water 
to the storage tank). The circulating water heaters currently on the 
market circulate water at high flow rates (e.g., greater than 10 gpm) 
and are, for the most part, designed to deliver water at a temperature 
greater than 180 [deg]F. These characteristics suggest that the 
circulating water heaters on the market would not be appropriate for 
residential applications. However, when developing the test procedure 
currently in appendix E, DOE is required to develop a test procedure 
that applied, to the maximum extent practicable, to all water heating 
technologies in use and to future water heating technologies. (42 
U.S.C. 6295(e)(5)(H)) As a circulating water heater could be designed 
to operate in a similar manner to other consumer water heaters (i.e., 
heat pump only water heaters) and at conditions appropriate for 
residential applications, DOE is required to amend appendix E to 
address these products.
    DOE proposes to add the definition described below for circulating 
water heaters to 10 CFR 430.2. The proposed definition also covers heat 
pump only water heaters which are discussed in section III.A.1.a in 
this NOPR. Test procedure amendments for circulating water heaters are 
discussed in section III.C.9 of this document.
    DOE proposes to define ``circulating water heater'' at 10 CFR 430.2 
as ``an instantaneous or heat pump type water heater that does not have 
an operational scheme in which the burner, heating element, or 
compressor initiates and terminates heating based on sensing flow; has 
a water temperature sensor located at the inlet of the water heater or 
in a separate storage tank that is the primary means of initiating and 
terminating heating; and must be used in combination with a 
recirculating pump and either a separate storage tank or water 
circulation loop in order to achieve the water flow and temperature 
conditions recommended in the manufacturer's installation and operation 
instructions.''
    With regard to the other gas-fired instantaneous water heaters 
referenced by commenters, DOE has also examined the market for gas-
fired instantaneous water heaters with an emphasis on product lines 
with input rates both above and below the consumer and commercial input 
rate threshold of 200,000 Btu/h. The models with an input rate at or 
below the 200,000 Btu/h threshold could be used in consumer 
applications, are nearly indistinguishable from water heaters marketed 
and used in consumer applications, and are completely self-contained; 
that is, no other components would be required for these products to 
operate within a residence. As such, DOE has tentatively determined 
that these models continue to be considered ``consumer products'' and 
are subject to the test procedures and energy conservation standards 
for consumer gas-fired instantaneous water heaters.
    DOE has also examined gas-fired water heaters with input rates of 
200,000 Btu/h or less, containing less than one gallon of water per 
4,000 Btu/h of input, and with rated storage volumes greater than 2 
gallons. In the July 2014 final rule, storage volume requirements were 
removed from the definition of a ``gas-fired instantaneous water 
heater.'' 79 FR 40542, 40567 (July 11, 2014). In the December 2016 
final

[[Page 1566]]

rule, DOE stated that definitions for consumer water heaters added to 
EPCA under the National Appliance Energy Conservation Act of 1987 
(NAECA; Pub. L. 100-12 (March 17, 1987)), which amended EPCA, do not 
place any limitation on the storage volume of consumer water heaters. 
(42 U.S.C. 6291(27); 81 FR 96204, 96210 (Dec. 29, 2016)) DOE further 
stated that the energy conservation standards established by EPCA for 
consumer water heaters apply to all consumer water heaters regardless 
of storage volume. 81 FR 96204, 96210. DOE also acknowledged that its 
delay in issuing test procedures for such products, as well as 
statements it has made in the past, may have caused confusion about 
whether these products are covered by energy conservation standards for 
consumer water heaters, and that achieving compliance with the 
statutory standards immediately would be quite burdensome for industry. 
Id. at 81 FR 96211. As such, DOE stated that it will not enforce the 
statutory standards applicable to these products until some point after 
DOE finalizes a conversion factor and the converted standards 
applicable to those products. Id. DOE has tentatively determined that 
the interpretation presented in the December 2016 final rule for gas-
fired instantaneous water heaters with storage volume greater than 2 
gallons is still valid.
d. Tabletop Water Heaters
    On January 17, 2001, DOE published a final rule (January 2001 final 
rule) that established definitions and created a separate product class 
for tabletop water heaters. 66 FR 4474. A ``tabletop water heater,'' 
was defined in the January 2001 final rule as a water heater in a 
rectangular box enclosure designed to slide into a kitchen countertop 
space with typical dimensions of 36 inches high, 25 inches deep, and 24 
inches wide. Id. at 66 FR 4497. The definition for ``tabletop water 
heater'' was removed from appendix E as part of the July 2014 final 
rule and was inadvertently not added to 10 CFR 430.2. 79 FR 40542, 
40567-40568 (July 11, 2014). However, energy conservation standards for 
tabletop water heaters are still specified at 10 CFR 430.32(d).
    In the April 2020 RFI, DOE requested feedback on whether the 
previous definition for ``tabletop water heater'' is still appropriate, 
and whether such products should continue to be considered separately 
from other classes of consumer water heaters. 85 FR 21104, 21108 (April 
16, 2020). AHRI, A.O. Smith, BWC, Rheem, and Rinnai commented that the 
definition for ``tabletop water heater'' is still appropriate and 
should remain as a separate product class. (AHRI, No. 17 at p. 3; A.O. 
Smith, No. 20 at p. 2; BWC, No. 12 at p. 2; Rheem, No. 14 at p. 2; 
Rinnai, No. 13 at p. 2) EEI suggested that the definition include a 
rated capacity of at least 20 gallons and exclude the phrases 
``rectangular box'' and ``designed to slide into a kitchen countertop 
space'' to make the definition broader. (EEI, No. 8 at p. 3) Keltech 
stated that point-of-use (POU) units may benefit from being classified 
as a ``tabletop water heater'' and that a category should be created 
for POU water heaters that can be installed under a countertop. 
(Keltech, No. 7 at p. 1)
    In the January 2001 final rule, DOE separated tabletop water 
heaters from the electric storage water heater product class ``due to 
strict size limitations for these products.'' 66 FR 4474, 4478 (Jan. 
17, 2001). Tabletop water heaters are a unique type of water heater 
that are designed to fit into a countertop and provide a working 
surface in the installed location; as such, they are inherently size-
constrained. DOE has tentatively determined that excluding the phrases 
``rectangular box'' and ``designed to slide into a kitchen countertop 
space'' would make the tabletop water heater definition broader but 
would also remove the distinction of the key features that distinguish 
tabletop water heaters from electric storage water heaters (i.e., the 
tabletop water heater product class addresses the very specific size 
limitations and location installations associated with these products). 
Further, the addition of a minimum rated storage volume of 20 gallons 
would define a scope of coverage that might not include the full volume 
range of water heaters in a rectangular box enclosure designed to slide 
into a kitchen countertop space. Therefore, DOE has tentatively 
determined not to add a minimum rated storage volume.
    A POU water heater is, in general terms, a water heater that is 
located where the hot water is needed (e.g., under a sink or counter). 
Water heaters that are installed under sinks or counters are typically 
small electric storage water heaters (30 gallons or less) or electric 
instantaneous water heaters. For small electric storage water heaters, 
these products are currently covered by the definition for electric 
storage water heater, which does not have storage volume requirements. 
See 10 CFR 430.2. The test procedure for electric storage water heaters 
varies slightly depending on the delivery capacity of the water heater, 
which is a result of the first-hour rating test. See section 5.4.1 of 
appendix E. DOE has tentatively determined that POU or small electric 
storage water heaters are adequately covered by the current DOE test 
procedure when tested to the very small or low draw patterns. The same 
can be said for electric instantaneous water heaters, for which the 
test procedure also varies slightly depending on the delivery capacity 
of the water heater, which is a result of the Max GPM test. See section 
5.4.1 of appendix E.
    For the reasons discussed previously, DOE proposes to add the 
``tabletop water heater'' definition that was removed from appendix E 
in the July 2014 final rule to 10 CFR 430.2.
e. Residential-Duty Commercial Water Heaters
    In the April 2020 RFI, DOE requested comment on the definition for 
``residential-duty commercial water heater,'' which defines a category 
of commercial water heaters that are subject to the consumer water 
heater test procedure. 85 FR 21104, 21108 (April 16, 2020). AHRI, A.O. 
Smith, Rheem, and Rinnai supported the current definition of 
``residential-duty commercial water heater'' and had no recommended 
changes. (AHRI, No. 17 at p. 3; A.O. Smith, No. 20 at p. 2; Rinnai, No. 
13 at p. 3; Rheem, No. 14 at p. 2) Keltech recommended adding the 
intended market for the water heater as another criteria for 
determining whether a water heater is a residential-duty commercial 
water heater and stated that if a water heater is not intended for sale 
in a consumer setting, it should not be held to consumer requirements. 
(Keltech, No. 7 at p. 1) DOE acknowledges that some water heaters, 
which are intended for commercial use, are covered by the residential-
duty commercial water heater definition and tested and rated to the 
consumer water heater test procedure and residential-duty commercial 
water heater energy conservation standards. These water heaters have 
characteristics that are similar to water heaters with residential 
applications and, as such, under 42 U.S.C. 6295(e)(5)(F), cannot be 
excluded from being tested and rated using the consumer water heaters 
test procedure and residential-duty commercial water heater energy 
conservation standards. Further, DOE has tentatively determined that 
whether a product is marketed as commercial or residential may not 
always be indicative of the intended installation location. For 
example, water heaters intended for residential use are sometimes 
marketed as ``commercial-grade'' as a means to convey

[[Page 1567]]

reliability.\22\ Therefore, DOE has tentatively determined not to amend 
the definition for ``residential-duty commercial water heater.''
---------------------------------------------------------------------------

    \22\ A water heater designed to be installed in commercial 
applications will typically be used more often and be subjected to 
environments that are harsher than would be experienced by a water 
heater designed to be installed in residential application. 
Therefore, a ``commercial-grade'' water heater could be considered 
more reliable, as it can operate longer in such an environment 
without malfunctioning.
---------------------------------------------------------------------------

B. Updates to Industry Standards

    The current DOE test procedure in appendix E references the 
following industry standards:
     ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for 
Temperature Measurement (ASHRAE 41.1-1986 (RA 2006)); and
     ASTM D2156-09, (ASTM D2156-09), Standard Test Method for 
Smoke Density in Flue Gases from Burning Distillate Fuels.
    ASHRAE 41.1-1986 (RA 2006) was superseded by ASHRAE 41.1-2013 on 
January 30, 2013 (ASHRAE 41.1-2013). ASHRAE 41.1-2013 was superseded by 
ASHRAE 41.1-2020 on June 30, 2020. Updates to ASHRAE 41.1 are discussed 
in section III.B.1.
    ASTM D2156-09 was reapproved without modification in 2018 (ASTM 
D2156-09 (RA 2018)). Therefore, DOE proposes to update the reference of 
ASTM D2156-09 to the most recent industry standard (i.e., ASTM D2156-09 
(RA 2018)). ASTM D2156-09 and ASTM D2156-09 (RA 2018) directly 
reference ASTM E97-1987 (W1991), which is necessary to perform the 
procedures within ASTM D216-09 and ASTM D2156-09 (RA 2018). Therefore, 
DOE also proposes to incorporate by reference ASTM E97-1987 (W1991).
    ASHRAE maintains a published water heater test procedure titled, 
``ANSI/ASHRAE Standard 118.2-2006 (RA 2015), Method of Testing for 
Rating Residential Water Heaters'' (ANSI/ASHRAE 118.2-2006 (RA 2015)). 
The ANSI/ASHRAE 118.2-2006 (RA 2015) test procedure is similar to the 
DOE test procedure that was in effect prior to the July 2014 final 
rule, although neither the former nor the current DOE consumer water 
heater test procedure reference ANSI/ASHRAE Standard 118.2-2006 (RA 
2015). In March 2019, ASHRAE published the March 2019 ASHRAE Draft 
118.2, the second public review draft of Board of Standards Review 
(BSR) ANSI/ASHRAE Standard 118.2-2006R, ``Method of Testing for Rating 
Residential Water Heaters and Residential-Duty Commercial Water 
Heaters,'' which DOE referenced in the April 2020 RFI. 85 FR 21104, 
21109-21111 (April 16, 2020). In April 2021, ASHRAE published 
substantive changes to a previous public review draft \23\ of BSR ANSI/
ASHRAE Standard 118.2-2006R, ``Method of Testing for Rating Residential 
Water Heaters and Residential-Duty Commercial Water Heaters.'' (April 
2021 ASHRAE Draft 118.2) The March 2019 ASHRAE Draft 118.2 and April 
2021 ASHRAE Draft 118.2 are examined together in section III.B.2. Both 
the March 2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 118.2 are 
similar to the current DOE test procedure but include some differences 
throughout, some of which would result in test procedure results 
different from the current DOE test procedure.
---------------------------------------------------------------------------

    \23\ The April 2021 ASHRAE Draft 118.2 shows only the proposed 
substantive changes to the March 2019 ASHRAE Draft 118.2. All 
sections not included in the April 2021 ASHRAE Draft 118.2 are as 
proposed in the March 2019 ASHRAE Draft 118.2 or have not been 
changed in a way that their content affects the results of the test 
procedure proposed in the March 2019 ASHRAE Draft 118.2.
---------------------------------------------------------------------------

    As discussed previously in this document, DOE will adopt industry 
test standards as DOE test procedures for covered products and 
equipment, unless such methodology would be unduly burdensome to 
conduct or would not produce test results that reflect the energy 
efficiency, energy use, water use (as specified in EPCA) or estimated 
operating costs of that equipment during a representative average use 
cycle. 10 CFR part 430, subpart C, appendix A, Section 8(c). While DOE 
would only consider adopting through incorporation by reference (IBR) a 
finalized version of ASHRAE 118.2, DOE is interested in receiving 
comments on the merits of the draft in anticipation of such a 
possibility, or to consider incorporating aspects of the draft into a 
revised DOE test procedure. The differences between the March 2019 
ASHRAE Draft 118.2, the April 2021 ASHRAE Draft 118.2, and the DOE test 
procedure are discussed in section III.B.2 of this NOPR.
1. ASHRAE 41.1
    As stated previously, ASHRAE 41.1-1986 (RA 2006) was superseded by 
ASHRAE 41.1-2013 and ASHRAE 41.1-2013 was superseded by ASHRAE 41.1-
2020. ASHRAE 41.1-2013 removed the aspirated wet bulb psychrometer 
descriptions and stated they would be included in the next revision to 
ASHRAE 41.6, ``Standard Method for Humidity Measurement.'' ASHRAE 41.6 
was updated on July 3, 2014 and included the aspirated wet bulb 
psychrometer descriptions that were removed in ASHRAE 41.1-2013. ASHRAE 
41.1-2013 also added uncertainty analysis for temperature measurements, 
information for thermistor-type devices, descriptions for thermopiles, 
and reorganized the standard to be consistent with other ASHRAE 
standards. ASHRAE 41.1-2020 added conditional steady-state test 
criteria and further updated the standard to meet ASHRAE's mandatory 
language requirements.
    Section 3.2.1 of appendix E requires that temperature measurements 
be made in accordance with ASHRAE 41.1-1986 (RA 2006), and section 
3.2.2 of appendix E provides accuracy and precision requirements for 
air dry bulb, air wet bulb, inlet and outlet water, and storage tank 
temperatures. Sections 5.2.2.1 and 5.3.2 of appendix E effectively 
require steady-state operation in which the flow-activated water heater 
is operating at the maximum input rate, is supplied with water at a 
temperature of 58 [deg]F 2 [deg]F, and delivers water at a 
temperature of 125 [deg]F 5 [deg]F.
    DOE reviewed ASHRAE 41.1-1986 (RA 2006), ASHRAE 41.1-2013, and 
ASHRAE 41.1-2020 and found that the sections most relevant to appendix 
E are the temperature measurement sections (i.e., sections 5 through 11 
of ASHRAE 41.1-1986 (RA 2006), section 7 of ASHRAE 41.1-2013, and 
section 7 of ASHRAE 41.1-2020) \24\ and the steady-state test criteria 
added in ASHRAE 41.1-2020. The information in the temperature 
measurement sections of the three versions of ASHRAE 41.1 examined does 
not vary significantly. The additional steady-state test criteria of 
ASHRAE 41.1-2020 varies significantly from and is more stringent than 
\25\ the criteria specified in sections 5.2.2.1 and 5.3.2 of appendix 
E; however, the appendix E criteria supersedes those in ASHRAE 41.1-
2020. DOE has tentatively determined that updating the reference of 
ASHRAE 41.1-1986 (RA 2006) to the most recent version of the industry 
standard (i.e., ASHRAE 41.1-2020) would not have a significant effect 
on the test results, as the content of the relevant sections of the 
ASHRAE 41.1 standards have not changed significantly and the new

[[Page 1568]]

content published in ASHRAE 41.1-2020 is superseded by appendix E. As 
such, DOE proposes to update the reference of ASHRAE 41.1-1986 (RA 
2006) to ASHRAE 41.1-2020. ASHRAE 41.1-2020 references ASHRAE 41.6-2014 
and requires its use when measuring the wet bulb temperature. The wet 
bulb temperature is required when testing heat pump water heaters to 
appendix E and, therefore, DOE proposes to incorporate by reference 
ASHRAE 41.6-2014.
---------------------------------------------------------------------------

    \24\ Sections 5 through 11 of ASHRAE 41.1-1986 (RA 2006) were 
combined into section 7 of ASHRAE 41.1-2013.
    \25\ If adopted, section 5.5.3 of ASHRAE 41.1-2020 would be used 
to determine steady-state operation within sections 5.2.2.1 and 
5.3.2 of appendix E. Using this criteria, a flow-activated water 
heater delivering water between 120 [deg]F and 121 [deg]F, which is 
within the current delivery temperature range of 125 [deg]F 5 [deg]F, would not be considered in steady-state due to the 
difference in temperature between the average of the sample and the 
set point temperature.
---------------------------------------------------------------------------

2. ASHRAE 118.2
a. Scope
    Section 2 of the March 2019 ASHRAE Draft 118.2 defines the scope of 
products covered by the industry test standard more narrowly than the 
definitions for consumer water heaters and relevant commercial water 
heater definitions contained in EPCA. For example, section 2 of the 
March 2019 ASHRAE Draft 118.2 limits the storage volume for storage-
type water heaters to 120 gallons or less and limits the maximum 
delivery temperature to 180 [deg]F (82 [deg]C), whereas EPCA does not 
define limits on storage volume or maximum delivery temperature (42 
U.S.C. 6291(27); 42 U.S.C. 6311(12)(A)-(B).
    In the April 2020 RFI, DOE requested comment on whether the March 
2019 ASHRAE Draft 118.2 test method could be applied to water heaters 
beyond the scope defined in the March 2019 ASHRAE Draft 118.2 to cover 
all water heaters included within the scope of DOE's definitions for 
consumer water heaters and residential-duty commercial water heaters. 
85 FR 21104, 21110 (April 16, 2020). And if modifications to the March 
2019 ASHRAE Draft 118.2 would be required, DOE requested comment on 
what those modifications should be. Id. CA IOUs and Rinnai expressed 
their understanding that the March 2019 ASHRAE Draft 118.2 applies to 
all water heaters within the current scope of DOE's test procedure. (CA 
IOUs, No. 18 at p. 3; Rinnai, No. 13 at p. 5) A.O. Smith stated that 
most aspects of the March 2019 ASHRAE Draft 118.2 could be applied to 
water heaters beyond the scope defined in section 2 of the March 2019 
ASHRAE Draft 118.2 with similar characteristics. (A.O. Smith, No. 20 at 
p. 3) Rheem supported application of the March 2019 ASHRAE Draft 118.2 
test method to cover a broader scope, including all water heaters 
within DOE's definitions of consumer water heaters. However, Rheem 
commented that modification may be required to address key differences, 
along with validation testing of any changes. (Rheem, No. 14 at pp. 3)
    The April 2021 ASHRAE Draft 118.2 did not propose changes to the 
scope; therefore, section 2 of the April 2021 ASHRAE Draft 118.2 is the 
same as the March 2019 ASHRAE Draft 118.2. DOE has tentatively reached 
a similar conclusion as the commenters that the March 2019 ASHRAE Draft 
118.2 and April 2021 ASHRAE Draft 118.2 could be applied to water 
heaters that are outside of the scope found in section 2 of the March 
2019 ASHRAE Draft 118.2 and within the scope of DOE's current consumer 
water heater test procedure. As noted previously in this section, the 
March 2019 ASHRAE Draft 118.2 scope limits the maximum rated storage 
capacity at 120 gallons and the maximum delivery temperature at 180 
[deg]F; whereas the scope prescribed by EPCA and the relevant 
implementing regulations does not include these limits. Further, DOE 
has found through testing that models with rated storage volumes above 
120 gallons or that can deliver water above 180 [deg]F can be tested to 
DOE's consumer water heater test procedure. Given the similarities 
between the current DOE test procedure and the March 2019 ASHRAE Draft 
118.2 and April 2021 ASHRAE Draft 118.2, such models could also be 
tested using the ASHRAE test standard. Therefore, DOE has tentatively 
determined that the test procedure presented in the March 2019 ASHRAE 
Draft 118.2 and the April 2021 ASHRAE Draft 118.2 could be used to test 
water heaters outside of the scope presented in section 2 of the March 
2019 ASHRAE Draft 118.2.
b. Test Setup
Figures
    Section 6 of the March 2019 ASHRAE Draft 118.2 includes new figures 
that provide greater detail illustrating how to set up a water heater 
for test. For example, a by-pass (purge) loop is added to the inlet 
water line in Figures 1 through 8. Additional figures include: A test 
set-up for a storage water heater with a side inlet water line and top 
outlet water line; a test set-up for an instantaneous water heater with 
connections on the top; the placement of a thermal break in the inlet 
water line (the thermal break is added to the test set-up to prevent 
heat from traveling up the inlet piping into the by-pass loop section, 
as discussed in the next subsection); and two configurations for the 
thermocouple tree if it needs to be installed through the outlet water 
line.
    In the April 2020 RFI, DOE requested feedback on whether the 
figures in appendix E should be updated to include additional detail, 
including the detail provided in the figures in the March 2019 ASHRAE 
Draft 118.2. 85 FR 21104, 21110 (April 16, 2020). If thought to be 
necessary, DOE asked that commenters address whether the additional 
specificity provided in the figures could be too restrictive for the 
purpose of the DOE test procedure, or whether such specificity would be 
justified by improving reproducibility of test results. Id. AHRI, A.O. 
Smith, CA IOUs, CSA, NEEA, Rheem, and Rinnai recommended that the 
figures in appendix E be updated to include additional detail in 
alignment with ASHRAE 118.2. (AHRI, No. 17 at p. 5; A.O. Smith, No. 20 
at p. 3; CA IOUS, No. 18 at p. 3; CSA, No. 10 at p. 3; NEEA, No. 21 at 
p. 6; Rheem, No. 14 at p. 4; Rinnai, No. 13 at p. 5) Rheem stated 
further that the figures in the March 2019 ASHRAE Draft 118.2 represent 
test set-up configurations that have been utilized by the AHRI contract 
laboratories and were also developed through a best practices effort to 
improve test consistency and repeatability across different labs. 
(Rheem, No. 14 at p. 4) However, A.O. Smith suggested that any updates 
to the figures in appendix E be used for reference only and not be 
required, in order to avoid being overly restrictive. (A.O. Smith, No. 
20 at p. 3)
    Upon further comparison of the figures within the March 2019 ASHRAE 
Draft 118.2 and appendix E, DOE found that the location in which the 
inlet temperature is measured in figures 2A, 2B, and 3 of the March 
2019 ASHRAE Draft 118.2 is different than in the corresponding figures 
2 and 3 within appendix E. In the March 2019 ASHRAE Draft 118.2, the 
inlet temperature is measured on the upstream side of the heat trap 
formed by the U-bend in the required piping, while in appendix E the 
inlet temperature measurement location is on the downstream side of the 
U-bend. All figures in the March 2019 ASHRAE Draft 118.2 have the inlet 
temperature location on the upstream side of the U-bend, while the 
figures in appendix E vary depending on the type of water heater being 
tested. Maintaining the same inlet temperature location for all water 
heater types would simplify the test setup as compared to the current 
requirements of appendix E. Further, given the short pipe distance 
between the upstream and downstream side of the U-bend (on the order of 
a few inches), it is unlikely that changing the location from the 
downstream side to the upstream side would result in a measurable 
difference in temperature.

[[Page 1569]]

However, DOE does not have adequate test data to fully understand the 
effect that changing the location of the inlet temperature measurement 
will have on test results and therefore is not proposing the use of the 
inlet temperature locations specified in the March 2019 ASHRAE Draft 
118.2. DOE welcomes information or data that may demonstrate any impact 
of inlet temperature measurement location on energy efficiency results.
Thermal Break
    Section 6 of the March 2019 ASHRAE Draft 118.2 includes new figures 
that provide greater detail illustrating how to set up a water heater 
for test. These additional figures include the installation location of 
a thermal break in the inlet water line. Figure 9 of the March 2019 
ASHRAE Draft 118.2 shows the thermal break installed in greater detail 
than the other figures and provides more detail on the material 
properties of the thermal break. The thermal break is added to the test 
set-up to prevent heat from traveling up the inlet piping into the by-
pass loop section. When purging before a draw, any heat that is 
transferred from the water heater through the inlet piping to the by-
pass loop section would be lost, as the by-pass loop is replenished 
with cold supply water. The thermal break helps to prevent this heat 
loss.
    In the April 2020 RFI, DOE requested feedback on whether a 
definition of ``thermal break'' \26\ should be added to its consumer 
water heater test procedure. 85 FR 21104, 21110 (April 16, 2020). AHRI, 
A.O. Smith, BWC, CSA, Keltech, NEEA, Rheem, and Rinnai supported the 
addition of a definition for ``thermal break'' to the test procedure. 
(AHRI, No. 17 at p. 5; A.O. Smith, No. 20 at p. 3; BWC, No. 12 at p. 2; 
CSA, No. 10 at pp. 3; Keltech, No. 7 at p. 1; NEEA, No. 21 at p. 6; 
Rheem, No. 14 at p. 4; Rinnai, No. 13 at p. 5) However, CEC argued that 
there is no need to add the definition to the test procedure since the 
definition can be incorporated by referencing a finalized version of 
ASHRAE 118.2. (CEC, No. 11 at p. 2)
---------------------------------------------------------------------------

    \26\ A ``thermal break'' is defined in the March 2019 ASHRAE 
Draft 118.2 as a nipple made of material that has thermal insulation 
properties (e.g., plastics) to insulate the by-pass loop from the 
inlet piping. It should be able to withstand a pressure of 150 psi 
and a temperature of 150 [deg]F.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on the necessity of a 
thermal break if no by-pass or purge loop is included in the test set-
up. 85 FR 21104, 21110 (April 16, 2020). AHRI, A.O. Smith, and Rinnai 
stated that a thermal break should be included in the test set-up 
regardless of whether there is a by-pass or purge loop. (AHRI, No. 17 
at p. 5; A.O. Smith, No. 20 at p. 3; Rinnai, No. 13 at p. 5) CSA, NEEA, 
and Rheem stated that a thermal break is not needed if no by-pass or 
purge loop is present. (CSA, No. 10 at p. 4; NEEA, No. 21 at p. 6; 
Rheem, No. 14 at p. 4)
    Thermal breaks are not typically installed in the field. Therefore, 
installation of a thermal break is not representative of an actual 
installation configuration. The purpose of a thermal break is to 
minimize unrepresentative effects of other parts of the test setup. A 
by-pass loop is a method test labs use to ensure inlet water 
temperatures are within the bounds of the test procedure (i.e., within 
58 [deg]F 2 [deg]F by the first measurement of the draw, 
which occurs at either 15 or 5 seconds from the start of draw when 
testing to the first-hour rating or 24-hour simulated-use test, 
respectively), but its inclusion in the test setup can create a 
condition whereby a constant low temperature can remove energy from the 
water heater at a higher rate than would be removed in the field. Heat 
naturally travels through the inlet piping during standby, and the flow 
rates and inlet temperatures required by the test procedure do not 
always counteract this heating of the inlet piping before the required 
inlet temperature measurements are taken. The addition of a thermal 
break can help prevent these unrepresentative tank losses due to the 
by-pass loop by creating a barrier between the highly conductive piping 
materials. The inclusion of a thermal break in test setups that use a 
by-pass loop would likely result in test results that are more 
representative than a test setup with a by-pass loop and no thermal 
break. However, use of a by-pass loop is not the only possible test 
setup for meeting the test conditions within appendix E and it is 
unclear the effect that requiring a thermal break in test setups would 
have on the results from testing using a setup other than one employing 
a by-pass loop. Absent such information DOE is not proposing to require 
the use of a thermal break at this time. Therefore, DOE has tentatively 
determined that a definition for ``thermal break'' is not necessary to 
include, and DOE is not proposing one in this NOPR.
    In the April 2020 RFI, DOE requested feedback on whether the 
maximum temperature the thermal break must be able to withstand would 
appropriately be set at 150 [deg]F, as is set in the March 2019 ASHRAE 
Draft 118.2. 85 FR 21104, 21110 (April 16, 2020). AHRI, A.O. Smith, 
BWC, CSA, Rheem, and Rinnai commented that a temperature of at least 
150 [deg]F is an appropriate temperature for a thermal break to be able 
to withstand. (AHRI, No. 17 at p. 5; A.O. Smith, No. 20 at p. 3; BWC, 
No. 12 at p. 2; CSA, No. 10 at pp. 3-4; Rheem, No. 14 at p. 4; Rinnai, 
No. 13 at p. 5-6) AHRI and BWC further commented that a thermal break 
should be made of plastic or another material that is not thermally 
conductive. (AHRI, No. 17 at p. 5; BWC, No. 12 at p. 2) Keltech stated 
that thermal breaks should be able to withstand a maximum temperature 
of at least 200 [deg]F, stating that 150 [deg]F might pose a problem 
for water heaters capable of producing more than 125 [deg]F. (Keltech, 
No. 7 at p. 1)
    The thermal break is installed on the inlet water line, upstream of 
the thermocouple measuring the inlet water temperature. DOE examined 
its test data and found that, when water was not being drawn off, the 
maximum temperature measured by the thermocouple measuring the inlet 
water temperature never exceeded 100 [deg]F. Therefore, a thermal break 
that is installed upstream of the thermocouple measuring the inlet 
water temperature would not experience water temperatures exceeding 100 
[deg]F. However, as stated previously, DOE is not proposing to require 
the use of a thermal break and, as such, does not need to propose the 
maximum temperature the thermal break must be able to withstand.
c. First-Hour Rating
Flow Rate
    The April 2021 ASHRAE Draft 118.2 indicates that the flow rate for 
water heaters with rated storage volumes less than 20 gallons would be 
1.5 0.25 gpm (5.7 0.95 L/min). DOE has 
identified consumer water heaters with storage volumes less than 20 
gallons and with input rates near or at the maximum input rate 
specified at 10 CFR 430.2 (i.e., water heaters with low volume and high 
input rate). Section 5.3.3, ``First-Hour Rating Test'' of appendix E 
requires that water heaters with a storage volume less than 20 gallons 
be tested at 1.0 0.25 gallons per minute (gpm) (3.8 0.95 liters (L)/minute (min)), as opposed to 3.0 0.25 
gpm (11.4 0.95 L/min) required for water heaters with rated 
storage volumes greater than or equal to 20 gallons. Water heaters with 
low volume and high input rates can potentially operate indefinitely at 
the 3.0 0.25 gpm (11.4 0.95 L/min) flow rate. 
When tested as currently required by appendix E, such products would 
have a measured FHR around 60 gallons (227 L) and, therefore, would be 
required to use the medium draw pattern, although such models could be

[[Page 1570]]

used in applications similar to water heaters that are required to test 
using the high draw pattern (e.g., flow-activated instantaneous water 
heaters with high input rates and storage water heaters with greater 
than 20 gallons stored water and high input rates and/or volumes). As 
such, the current method of testing these products may not best 
represent how they are used in the field.
    In the April 2020 RFI, DOE requested feedback on the consumer water 
heater test procedure with respect to testing the delivery capacity of 
non-flow activated water heaters with low volume and high input rate. 
85 FR 21104, 21114 (April 16, 2020). If amendments were thought to be 
warranted, DOE requested comment on what method(s) would be appropriate 
for determining the delivery capacity of such models and what 
attributes can be used to distinguish these water heaters from non-flow 
activated water heaters more appropriately tested by the FHR test. Id. 
Rheem stated that there is a need to update the test procedure for 
testing delivery capacity of non-flow activated water heaters with low 
volume and high input rate. (Rheem, No. 14 at p. 9) DOE submitted a 
comment on this issue to the March 2019 ASHRAE Draft 118.2, and a 
solution was proposed in the April 2021 ASHRAE Draft 118.2 in which the 
flow rate for water heaters with rated storage volumes less than 20 
gallons would be 1.5 0.25 gpm (5.7 0.95 L/min) 
instead of the 1.0 0.25 gpm (3.8 0.95 L/min) 
currently specified in the consumer water heater test procedure. This 
change would allow a water heater that can run continuously (i.e., low 
volume and high input rate) to have a FHR that would correspond to the 
high draw pattern. Further, lower capacity water heaters would not be 
able to continuously deliver hot water at 1.5 gpm, which would result 
in them continuing to be rated in a lower draw pattern.
    DOE tested three electric storage water heaters with rated storage 
volumes below 20 gallons to the current DOE FHR test (i.e., 1.0 0.25 gpm (3.8 0.95 L/min)) and a FHR test at a flow 
rate of 1.5 0.25 gpm (5.7 0.95 L/min). All 
three electric storage water heaters are rated in the very small draw 
pattern (i.e., they have low input rates). The three electric storage 
water heaters were tested 4 times to each version of the FHR test 
(i.e., 8 tests per unit and 24 tests total). The results of the tests 
are shown in Table III.1.

 Table III.1--Average First-Hour Rating Based on a Flow Rate of 1.0 gpm
                               and 1.5 gpm
------------------------------------------------------------------------
                          Average FHR at  Average FHR at
        Unit No.          1.0 gpm (3.8 L/ 1.5 gpm (5.7 L/   Change (%)
                          min) (gallons)  min) (gallons)
------------------------------------------------------------------------
1.......................             7.3             7.5            +3.4
2.......................             6.4             6.2            -2.2
3.......................             6.9             7.2            +4.7
------------------------------------------------------------------------

    As shown in Table III.1, changing the flow rate from 1.0 gpm to 1.5 
gpm resulted in an average change in FHR between -2.2 percent and +4.7 
percent. As the FHR rating did not increase above 10 gallons (i.e., the 
threshold for determining whether to test to the very small or low draw 
patterns during the 24-hour simulated-use test) when tested at 1.5 gpm, 
the water heaters would continue to be tested to the very small draw 
pattern when tested to the 24-hour simulated-use test.
    Based on the testing of the three models, changing the flow rate 
during the FHR test for water heaters with a rated storage volume less 
than 20 gallons from 1.0 0.25 gpm (3.8 0.95 L/
min) to 1.5 0.25 gpm (5.7 0.95 L/min) would 
have a relatively minimal impact on the FHR for water heaters with low 
input rates, and the resultant FHR and associated draw pattern for the 
24-hour simulated-use test would still be representative of the 
expected use in the field. However, for water heaters with high input 
rates the change in flow rate could significantly increase the FHR and 
result in some models being tested and rated for UEF using a higher 
draw pattern, which would provide ratings that are more representative 
of their actual use. For these reasons, DOE is proposing to change the 
flow rate during the FHR test for water heaters with a rated storage 
volume less than 20 gallons from 1.0 0.25 gpm (3.8 0.95 L/min) to 1.5 0.25 gpm (5.7 0.95 L/
min). This proposed change is also consistent with the April 2021 
ASHRAE Draft 118.2, and, in development of the final rule, DOE will 
consider the flow rate as finalized in the update to ASHRAE 118.2.
Initiation Criteria
    The April 2021 ASHRAE Draft 118.2 includes additional criteria 
defining the start of the FHR test, as compared to DOE's test 
procedure. Section 5.3.3.3 of appendix E of the current DOE test 
procedure states that prior to the start of the FHR test, if the water 
heater is not operating (i.e., heating water), initiate a draw until 
cut-in \27\ (i.e., when the water heater begins heating water). The 
draw is then terminated any time after cut-in, and the water heater is 
operated until cut-out.\28\ Once the maximum mean tank temperature is 
observed after cut-out, the initial draw of the FHR test begins. 
Section 7.3.3.3 of the April 2021 ASHRAE Draft 118.2 specifies that the 
draw preceding the initial draw of the FHR test must proceed until the 
outlet temperature drops 15 [deg]F below the maximum outlet temperature 
observed, or until the draw time limit \29\ is reached. If the draw 
time limit is reached before the outlet temperature drops 15 [deg]F 
below the maximum outlet temperature observed, then the main heating 
source of the water heater is shut off and the draw is continued until 
the outlet temperature has dropped 15 [deg]F below the maximum outlet 
temperature. Requiring the outlet temperature to drop 15 [deg]F below 
the maximum outlet temperature may provide a more consistent starting 
condition for the FHR test compared to the pre-conditioning method 
specified in the current DOE test procedure because draws of varying 
lengths can create different internal tank temperature profiles. Thus, 
the additional requirement to tie the length

[[Page 1571]]

of the initial draw to a specific outlet temperature, which in some 
cases would extend the draw length as compared to the current DOE test 
procedure, could increase the repeatability of the FHR test.
---------------------------------------------------------------------------

    \27\ ``Cut-in'' is defined in section 1 of appendix E as ``the 
time when or water temperature at which a water heater control or 
thermostat acts to increase the energy or fuel input to the heating 
elements, compressor, or burner.''
    \28\ ``Cut-out'' is defined in section 1 of appendix E as ``the 
time when or water temperature at which a water heater control or 
thermostat acts to reduce to a minimum the energy or fuel input to 
the heating elements, compressor, or burner.''
    \29\ The draw time limit is the rated storage capacity divided 
by the flow rate times 1.2 (i.e., for a 75-gallon water heater the 
draw time limit would be 30 minutes, or 75 gallons divided by 3 gpm 
times 1.2).
---------------------------------------------------------------------------

    The March 2019 ASHRAE Draft 118.2 specified two criteria for 
terminating the water draw prior to the start of the FHR test: A 15 
[deg]F drop in outlet temperature from the maximum outlet temperature 
observed and a cut-in. The draft requirement for a cut-in was replaced 
with the draw time limit in the April 2021 ASHRAE Draft 118.2.
    In the April 2020 RFI, DOE requested feedback on whether the 
addition of an outlet temperature drop criterion for terminating the 
water draw prior to the start of the FHR test within the March 2019 
ASHRAE Draft 118.2 is appropriate and/or necessary. 85 FR 21104, 21109 
(April 16, 2020). If an outlet temperature drop criterion is 
appropriate, DOE requested comment and data on whether 15 [deg]F is 
sufficiently representative, given consumer expectation, or whether a 
different threshold should be considered. Id. DOE also requested 
information on any potential impact to the testing burden that would 
result from an outlet temperature drop criterion. Id. Further, DOE 
requested comment on how to address water heaters that would not meet 
both initiation criteria (i.e., both a cut-in and an outlet temperature 
drop) due to the ability to continuously deliver hot water at the 
prescribed test conditions. Id. AHRI generally agreed that the 15 
[deg]F drop is sufficiently representative. However, AHRI stated there 
are oil-fired water heaters available that cannot achieve this 
temperature drop. AHRI recommended that additional review and testing 
be done to determine how to address water heaters that would not meet 
both initiation criteria (i.e., the 15 [deg]F drop in outlet water 
temperature and a cut-in). (AHRI, No. 17 at p. 4) A.O. Smith, BWC, 
NEEA, Keltech, Rheem, and Rinnai agreed with AHRI's statements. (A.O. 
Smith, No. 20 at p. 2; BWC, No. 12 at p. 3; Keltech, No. 7 at p. 1; 
NEEA, No. 21 at p. 5; Rheem, No. 14 at p. 2; Rinnai, No. 13 at p. 3) 
CSA stated that it is part of a working group for ASHRAE Draft 118.2 to 
address this issue. (CSA, No. 10 at p. 2) NEEA stated that for water 
heaters with enough output capacity to never drop 15 [deg]F, the FHR 
test is not necessary, and the water heater should be tested to the Max 
GPM test, even if the water heater is not technically flow-activated. 
(NEEA, No. 21 at p. 5)
    The combination of the 15 [deg]F drop in outlet water temperature 
and the draw time limit criteria to the start of the FHR test would 
provide a more repeatable pre-FHR draw, as the criteria to end the draw 
would be explicitly stated (in contrast to the current test procedure, 
which allows for any length of pre-FHR test draw, as long as a cut-in 
occurs before the end of the draw). Because the pre-FHR test draw would 
be more repeatable, the available energy content of the tank at the 
start of the FHR test would be more consistent among different test 
runs. In both the current DOE test procedure and the procedure in the 
April 2021 ASHRAE Draft 118.2, the FHR test is initiated after a cut-
out from the recovery that occurs due to the pre-FHR test draw. 
Therefore, in both cases, the water heater can be considered ``fully 
heated'' and to have similar internal energy content, although 
differences may be present due to the internal water temperature 
gradient throughout the tank. However, it is unclear how these 
differences in internal tank temperature will affect the test results. 
Absent information as to the impact of the differences in internal tank 
temperature on the test results, DOE is not proposing to amend appendix 
E to include the pre-FHR test conditioning proposed in the April 2021 
ASHRAE Draft 118.2.
    Additionally, in the April 2020 RFI, DOE raised concerns over high 
input rate water heaters that can heat water quicker than it is being 
drawn off. 85 FR 21104, 21113-21114 (April 16, 2020). The solution \30\ 
presented in the April 2021 ASHRAE Draft 118.2 was the addition of a 
draw time limit, which eliminates the chances of an indefinite water 
draw. The procedure currently in appendix E \31\ also would not allow 
an indefinite draw and, as stated previously, it is unclear the effect 
the draw time limit proposal would have on test results. Therefore, DOE 
is not proposing to include the draw time limit within appendix E.
---------------------------------------------------------------------------

    \30\ The draw time limit solution was the result of the working 
group in which CSA stated it was a part of. (CSA, No. 10 at p. 2)
    \31\ Appendix E requires that the pre-FHR test draw be 
terminated after the water heater initiates a recovery.
---------------------------------------------------------------------------

    DOE agrees in principle with NEEA that the Max GPM test may provide 
a representative value of delivery capacity and could be used to 
determine the appropriate draw pattern of a water heater with a 
sufficiently high input rate and low storage volume, despite not being 
flow-activated. However, it is unclear at this time how these types of 
non-flow activated water heaters could be separated from other non-flow 
activated water heaters that are appropriately tested with the FHR test 
and would be inappropriately tested with the Max GPM test.
Minimum Outlet Temperature
    Section 7.3.3.3 of the March 2019 ASHRAE Draft 118.2 and section 
7.3.3.4 of the April 2021 ASHRAE Draft 118.2 include additional 
criteria regarding water draws during the FHR test, as compared to the 
current DOE test procedure. The FHR test required in section 5.3.3 of 
appendix E specifies a series of water draws over the course of one 
hour. After each water draw is initiated, the draw is terminated when 
the outlet water temperature decreases 15 [deg]F from the maximum 
outlet water temperature measured during the draw. For example, if 
after initiating a water draw, the outlet water temperature reaches a 
maximum temperature of 125 [deg]F, the water draw would continue until 
the outlet water temperature drops to 110 [deg]F, at which time the 
water draw would be terminated. Section 7.3.3.4 of the April 2021 
ASHRAE Draft 118.2 specifies that water draws during the FHR test 
terminate if either: (1) The outlet water temperature decreases 15 
[deg]F from the maximum outlet water temperature measured during the 
draw, or (2) the outlet water temperature decreases to 105 [deg]F, 
regardless of the maximum outlet water temperature measured during the 
draw. Setting a minimum temperature threshold of 105 [deg]F would 
reflect that in practice because consumers would likely stop drawing 
water when it gets below 105 [deg]F, as the water would no longer be 
considered ``hot.''
    In the April 2020 RFI, DOE requested feedback on whether the 
addition of a minimum outlet temperature as a criterion for terminating 
draws during the FHR test is appropriate and/or necessary. 85 FR 21104, 
21109 (April 16, 2020). If a minimum outlet temperature criterion is 
appropriate, DOE requested comment and data on whether 105 [deg]F would 
be sufficiently representative given consumer expectation, or whether a 
different threshold should be considered. Id. DOE also requested 
information on any potential impact this minimum outlet temperature may 
have on testing burden. Id. BWC and NEEA supported the minimum outlet 
temperature of 105 [deg]F for terminating draws of the FHR test. (BWC, 
No. 12 at p. 2; NEEA, No. 21 at p. 5) Rheem supported a minimum outlet 
temperature, but suggested a 100 [deg]F limit would be more appropriate 
and would better represent usable hot water temperatures, especially 
when considering electric water heaters used for point-of-use, such as 
handwashing applications. (Rheem, No. 14 at p. 3)

[[Page 1572]]

AHRI and Rinnai stated that a 15 [deg]F drop in outlet temperature or 
105 [deg]F minimum outlet temperature, whichever is higher, would be 
sufficiently representative. (AHRI, No. 17 at p. 4; Rinnai, No. 13 at 
p. 4) A.O. Smith and Rheem suggested more testing and investigation are 
necessary before any decisions are made. (A.O. Smith, No. 20 at p. 2; 
Rheem, No. 14 at p. 3) CSA stated that, when testing to the March 2019 
ASHRAE Draft 118.2, all draws would be terminated at 105 [deg]F 
regardless of outlet temperature, but stated that this can potentially 
create a bias for conducting the procedure at the higher end of 125 
5 [deg]F tolerance. CSA further stated that some water 
heaters start stacking \32\ after the first draw, resulting in the 
outlet temperature going above 130 [deg]F during the FHR test, and 
questioned how that would affect the overall FHR and draw pattern bin. 
(CSA, No. 10 at p. 2)
---------------------------------------------------------------------------

    \32\ ``Stacking'' refers to when a storage water heater has hot 
water within the storage tank that is well above the temperature 
that is typically stored, which can result from successive short 
duration draws in a short amount of time. During typical operation, 
a draw removes hot water from the top of the storage tank, and the 
removed water is replaced with cold water that enters near the 
bottom the tank. The thermostat that controls the burner or element 
operation is also located near the bottom of the tank. Repeated 
short-duration draws result in multiple ``bursts'' of cold water 
entering the bottom of the tank; however, because the draws are 
short-duration, the total amount of water drawn is relatively small, 
and the temperature at the top of the tank may remain ``hot'' at the 
target setpoint. These short bursts of cold water entering near the 
thermostat may trigger a cut-in, and the water heater will begin 
heating despite the temperature at the top of the tank still being 
hot at the target setpoint. As the already-hot tank is being heated 
further, the temperature within the tank increases above the 
temperature that the water heater typical operates.
---------------------------------------------------------------------------

    Based on a review of existing test data, the 105 [deg]F outlet 
temperature criteria would affect only a small number of tests, if any. 
The test currently requires that the draw be terminated after a 15 
[deg]F drop in outlet temperature, and the outlet temperature is 
required to be between 120 [deg]F and 130 [deg]F when setting the 
thermostat. Therefore, the outlet temperature is unlikely to be below 
105 [deg]F during the test, as most draws should terminate before that 
point. The maximum outlet temperature of the draw would have to be 
below 120 [deg]F for the 105 [deg]F criteria to be triggered. As a 
result, DOE understands CSA's comment that all draws will be terminated 
at 105 [deg]F, if tested to ASHRAE Draft 118.2, to be incorrect. 
Section 7.3.3.4 of the April 2021 ASHRAE Draft 118.2 includes a 
statement that requires the draw be terminated at 105 [deg]F or when 
the outlet temperature is 15 [deg]F below the maximum outlet 
temperature measured during the draw, ``whichever is higher.'' 
Therefore, if the maximum outlet temperature of a draw was 125 [deg]F, 
for example, then the draw would end after a 15 [deg]F drop, or once 
the outlet water temperature is 110 [deg]F, which is higher than 105 
[deg]F. Also, Rheem's suggestion of a 100 [deg]F limit to address 
handwashing water heaters would not be appropriate for water heaters 
generally and would be more appropriately addressed as part of 
development of a method to appropriately test such water heaters (see 
section III.C.7). DOE is not proposing to add the 105 [deg]F minimum 
outlet temperature criteria to the FHR test draw termination criteria, 
as further test data is needed to assess the effect on the FHR test 
results.
Scaling of the Last Draw Volume
    Section 5.3.3.3 of appendix E includes a provision for the FHR test 
requiring that if the final draw is not initiated prior to one hour 
from the start of the test, then a final draw is imposed at the elapsed 
time of one hour. In this situation, calculations presented in section 
6.1 of appendix E are used to determine the volume drawn during the 
final draw for purposes of calculating FHR. The volume of the final 
draw is scaled based on the temperature of the water delivered during 
the final draw as compared to the temperature of the water delivered 
during the previous draw. The calculated final draw volume is added to 
the total volume drawn during the prior draws to determine the FHR. The 
April 2021 ASHRAE Draft 118.2 does not include a final draw volume 
scaling calculation for the case in which a draw is not in progress at 
one hour from the start of the test and a final draw is imposed at the 
elapsed time of one hour. Instead, the April 2021 ASHRAE Draft 118.2 
method calculates FHR as the sum of the volume of hot water delivered 
without any scaling of the final draw.
    The methodology for conducting the FHR test, and in particular the 
issue of whether to scale the final draw, was considered by DOE in a 
final rule that was published on May 11, 1998 (May 1998 final rule). In 
the May 1998 final rule, DOE determined that scaling the final draw 
volume based on the outlet water temperature was appropriate and was 
included to adjust the volume of the last draw to account for the lower 
heat content of the last draw compared to the earlier draws with fully 
heated water. 63 FR 25996, 26004-26005 (May 11, 1998).
    In the April 2020 RFI, DOE requested comment on whether the scaling 
of final draw volume should be maintained as part of the FHR 
calculation, in the case that a draw is not initiated prior to one hour 
from the start of the test but is imposed at that time before the water 
has been heated to the specified temperature to initiate the draw. 85 
FR 21104, 21111 (April 16, 2020). DOE further requested feedback on the 
effect that removing the scaling of the final draw volume would have on 
the rated FHR, draw pattern, and rated UEF values of the various types 
of non-flow activated water heaters that are tested to the FHR test. 
Id. In response, AHRI, A.O. Smith, BWC, Rheem, Rinnai, and SMTI 
suggested that DOE remove the final draw volume scaling calculation, 
which would be consistent with the March 2019 ASHRAE Draft 118.2. 
(AHRI, No. 17 at p. 6; A.O. Smith, No. 20 at p. 3; BWC, No. 12 at p. 3; 
Rheem, No. 14 at p. 5; Rinnai, No. 13 at p. 6; SMTI, No. 19 at p. 3) 
AHRI, A.O. Smith, Rinnai, and Rheem further stated that removing the 
final draw volume scaling would have minimal impact on the rated FHR, 
draw pattern, and rated UEF values. (AHRI, No. 17 at p. 6; A.O. Smith, 
No. 20 at p. 3; Rinnai, No. 13 at p. 6; Rheem, No. 14 at p. 5) CSA 
stated that the current final draw volume scaling method should be 
maintained and that a water heater delivering water at 106 [deg]F 
should not be equal to a water heater delivering water at 110 [deg]F. 
According to CSA, the outlet water temperatures would most likely be 
tempered by the end user, and the water heater delivering 110 [deg]F 
water would supply more tempered water than a water heater delivering 
106 [deg]F, even though the volume of the last draw, as measured, would 
be roughly the same. CSA stated further that removing the scaling of 
the final draw volume could possibly move water heaters to the next 
highest draw pattern. (CSA, No. 10 at p. 5)
    The scaling of the final draw accounts for the possible lower heat 
content of the last draw as compared to earlier draws. The test 
procedure specifies a constant flow rate throughout testing. The flow 
rate is fixed, and, as water is drawn, the water temperature decreases. 
In practice, water used by the consumer is typically at a lower 
temperature than is delivered by the water heater (i.e., water drawn 
from the water heater is mixed with water from the cold tap). The flow 
rate of water delivered to the consumer by a faucet or showerhead is 
fixed by the faucet or showerhead. As the heat content of the water 
delivered by the water heater decreases, the flow rate of water from 
the water heater is increased to maintain the temperature of the mixed 
water delivered by the faucet

[[Page 1573]]

or showerhead (i.e., in practice, as water temperature decreases, the 
flow rate of water from the water heater is increased). Thus, DOE has 
tentatively determined that scaling the final draw volume based on 
outlet temperature is more representative of the actual use in the 
field.
    Further, removing the scaling of the final draw volume would result 
in many FHR values having to be recertified as many models have the 
final draw imposed at the one-hour mark (only those models that 
initiated their final draw prior to 1 hour would not be affected). 
Because the change is to the calculation of FHR only, retesting would 
not be needed unless the resulting FHR value required a new 24-hour 
simulated-use test due to a change in the applicable draw pattern bin 
(e.g., if the FHR increases such that a model moves from the medium to 
the high draw pattern). DOE agrees with commenters that most models 
would not require a new 24-hour simulated-use test. However, any 
retesting would be a burden on manufacturers and, as stated previously, 
removing the scaling provisions would result in a less representative 
test.
    Removing or amending the scaling of the final draw volume would 
change the FHR value, which could change the required draw pattern to 
use for the simulated-use test, as defined in section 5.4.1 of appendix 
E. The current draw pattern thresholds were determined based on the 
current final draw scaling methodology, and are therefore 
representative of actual use only when used with FHR values based on 
the current final draw scaling methodology. Removing or amending the 
scaling of the final draw volume could require adjusting the draw 
pattern thresholds to ensure that the applicable draw patterns (based 
on FHR value thresholds) remain representative of actual use.
    The FHR metric is a method to compare the amount of usable water 
that a water heater can produce in a given amount of time. As long as 
the metric is applied consistently throughout the market, the consumer 
can use it to make comparisons among different models. Removing the 
scaling of the final draw volume may increase test burden on some 
manufacturers while resulting in a less representative test, and could 
require an update to the draw pattern thresholds. As described, changes 
to the draw pattern threshold could result in water heaters being 
classified in a lower draw pattern than they are currently, and it is 
uncertain as to the extent the reclassification would result in a test 
procedure that is representative for such models. Therefore, DOE has 
tentatively determined not to remove or amend the scaling of the final 
draw volume.
    In response to the April 2020 RFI, SMTI stated that, if the scaling 
of the final draw volume was maintained, the equation should be amended 
to use the inlet water temperature as opposed to the minimum outlet 
temperature of the previous draw. According to SMTI, this change would 
make the overall calculation more representative of the energy 
availability in the final draw. (SMTI, No. 19 at p. 3-4) However, while 
basing the scaling calculation on inlet water temperature as opposed to 
outlet water temperature would be more representative of the energy 
availability in the tank, it would not be more representative of the 
energy availability in the final draw. The energy that is useful to the 
consumer is based on the energy of water delivered at a temperature at 
or above the consumer's desired temperature. The consumer's desired 
temperature is approximated in the FHR test by the minimum delivery 
temperature of the draw and not the inlet water temperature. Therefore, 
DOE has tentatively determined that scaling the final draw volume based 
on the inlet water temperature would result in a less representative 
test and a metric that could mislead the consumer as to how much hot 
water they actually have available. Further, the change suggested by 
SMTI to base the scaling of the final draw volume on inlet water 
temperature would result in a FHR value that is higher than under the 
current DOE test procedure, but to a lesser degree than if the 
temperature scaling were removed. As stated, DOE has tentatively 
determined that amending scaling of the final draw volume to use the 
inlet water temperature as opposed to the minimum outlet water 
temperature would result in a less representative test and, therefore, 
DOE is not proposing this change.
d. 24-Hour Simulated-Use Test
Initiation Criteria
    Similar to the initiation criteria discussed in section III.B.2.c 
for the FHR test, section 7.4.2 of the April 2021 ASHRAE Draft 118.2 
includes criteria for a pre-24-hour simulated-use test draw, which ends 
after either the outlet temperature drops by 15 [deg]F or the draw time 
limit is reached. Section 5.4.2 of appendix E currently requires that 
the water heater sit idle for 1 hour prior to the start of the 24-hour 
simulated-use test; during which time no water is drawn from the unit 
and no energy is input to the main heating elements, heat pump 
compressor, and/or burners. Appendix E provides no instruction on how 
to condition the tank prior to this one hour. However, as discussed in 
section III.B.2.c, it is unclear how the outlet temperature drop 
criteria and the draw time limit will affect the internal tank 
temperature at the start of the 24-hour simulated-use test and how this 
difference in internal tank temperatures will affect the test results. 
Therefore, DOE is not proposing to amend appendix E to include the 
preconditioning proposed in the April 2021 ASHRAE Draft 118.2. DOE 
welcomes data that provide information regarding the impact of the 
preconditioning provisions in the April 2021 ASHRAE Draft 118.2 on the 
UEF result.
Recovery Efficiency
    Section 8.3.2 of the March 2019 ASHRAE Draft 118.2 includes 
language specifying that, when the first recovery of the 24-hour 
simulated-use test ends during a draw, the first recovery period 
extends until the end of that draw. The first recovery period is used 
in section 8.3.2 of the March 2019 ASHRAE Draft 118.2 and section 6.3.2 
of appendix E to calculate recovery efficiency. DOE's test procedure 
does not explicitly address how to calculate recovery efficiency if the 
first recovery period ends during a draw. A recovery period is defined 
in section 1 of appendix E as ``the time when the main burner of a 
storage water heater is raising the temperature of the stored water.'' 
Each of the parameters in the recovery efficiency equation are recorded 
from the ``beginning of the test to the end of the first recovery 
period following the first draw.'' The DOE test procedure does not 
explicitly state whether values are recorded at the end of the recovery 
period that ends after the initiation of the first draw, or at the end 
of a recovery period that occurs after the end of the first draw.
    In the April 2020 RFI, DOE requested feedback on whether additional 
specification should be added to appendix E addressing the first 
recovery period ending during a draw. 85 FR 21104, 21111 (April 16, 
2020). DOE further requested that if extending the first recovery 
period to the end of the draw is thought to be appropriate, whether the 
test procedure should also address the situation where a second 
recovery is initiated prior to the ending of the draw. Id. DOE also 
requested how to appropriately find the maximum mean tank temperature 
after cut-out following the recovery period. Id. AHRI, A.O. Smith, CSA, 
Rheem, and Rinnai generally supported adding a specification in 
appendix E to address the first recovery period ending during a draw. 
(AHRI, No. 17 at p. 7; A.O.

[[Page 1574]]

Smith, No. 20 at p. 3; CSA, No. 10 at p. 5; Rheem, No. 14 at p. 5; 
Rinnai, No. 13 at p. 7) AHRI, A.O. Smith, Rheem, and Rinnai supported 
extending the first recovery period to the end of the draw to include 
all water heater activity up to and including the end of the draw. 
(AHRI, No. 17 at p. 7; A.O. Smith, No. 20 at p. 3; Rheem, No. 14 at p. 
5; Rinnai, No. 13 at p. 7) AHRI and Rheem recommended that the maximum 
mean tank temperature just after the first cut-out be used. (AHRI, No. 
17 at p. 7; Rheem, No. 14 at p. 5) CSA recommended that for the other 
scenarios outlined by DOE, testing should be conducted to determine the 
proper procedure. (CSA, No. 10 at p. 5) No comments were received 
directly addressing the issue of when a second recovery starts prior to 
the end of the draw in which the first recovery ended.
    The situation in which a recovery ends during a draw likely occurs 
during draws with a low enough flow rate that the water heater can heat 
water more quickly than the draw is removing. The energy used for the 
recovery efficiency calculation includes energy used to heat water and 
auxiliary energy; therefore, the energy associated with the first 
recovery period should represent the entire draw to capture all energy 
use. Commenters generally agreed that the maximum mean tank temperature 
measured after the recovery should be right after cut-out (i.e., in the 
middle of the draw). After cut-out, as the draw continues, the mean 
tank temperature will drop as heated water is replaced by cold inlet 
water; therefore, the mean tank temperature immediately after cut-out 
will be the maximum observed. As such, DOE proposes to explicitly 
provide that when the first recovery ends during a draw, the first 
recovery period is extended to the end of the draw and the mean tank 
temperature measured immediately after cut-out is used as the maximum 
mean tank temperature value in the recovery efficiency calculation.
    On January 31, 2020, DOE published a Notice of Decision and Order 
\33\ (Decision and Order) by which a test procedure waiver for certain 
basic models was granted to address the issue of a second recovery 
initiating during the draw during which the first recovery ended. 85 FR 
5648. The Decision and Order prescribes an alternate test procedure 
that extends the first recovery period to include both the first and 
second recoveries. Id. at 85 FR 5652. In the context of the Decision 
and Order, DOE determined that the consideration of delivered water 
mass and inlet and outlet temperatures until the end of the draw is 
appropriately representative, and, therefore, the entire energy used 
from both recoveries is included. Id. at 85 FR 5651-5652.
---------------------------------------------------------------------------

    \33\ Notice of Decision and Order in response to BWC petition 
for waiver is available at: www.regulations.gov/document?D=EERE-2019-BT-WAV-0020-0008.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on whether the 
equation for recovery efficiency for water heaters with a rated storage 
volume greater than or equal to 2 gallons (7.6 L) should be updated to 
address when the recovery period lasts for more than one draw. 85 FR 
21104, 21111 (April 16, 2020). CSA, EEI, NEEA, Rheem, and Rinnai 
recommended that DOE update the recovery efficiency calculation to 
account for the period extending beyond one draw to increase clarity. 
(CSA, No. 10 at p. 5; EEI, No. 8 at p. 4; NEEA, No. 21 at p. 6; Rheem, 
No. 14 at p. 6; Rinnai, No. 13 at p. 7) This change was presented in 
the March 2019 ASHRAE Draft 118.2 and is in the Notice of Decision and 
Order. 85 FR 5648, 5652 (Jan. 31, 2020). Consistent with the published 
Notice of Decision and Order and as supported by commenters, DOE 
proposes to update the recovery efficiency equation to specify 
accounting for the mass of water drawn for all draws initiated during 
the recovery period. As such, DOE is proposing to amend appendix E 
consistent with the alternate test procedure in the Decision and Order.
Standby Period
    Appendix E includes a standby \34\ period measured between the 
first and second draw clusters,\35\ during which data is recorded that 
is used to calculate the standby heat loss coefficient. See section 
5.4.2 of appendix E. Sections 7.4.2.1 and 7.4.2.2 of the March 2019 
ASHRAE Draft 118.2 and sections 7.4.3.1 and 7.4.3.2 of the April 2021 
ASHRAE Draft 118.2 add a condition that the standby period data can be 
recorded between the first and second draw clusters only if the time 
between the observed maximum mean tank temperatures after cut-out 
following the first draw cluster to the start of the second draw 
cluster is greater than or equal to 6 hours. Otherwise, the standby 
period data would be recorded after the last draw of the test. This 
condition would provide a sufficiently long standby period to determine 
standby loss, which might make this calculation more repeatable and the 
results more representative of standby losses experienced in an average 
period of use. However, this might also cause the test to extend beyond 
a 24-hour duration.
---------------------------------------------------------------------------

    \34\ ``Standby'' is defined in section 1.12 of appendix E as 
``the time, in hours, during which water is not being withdrawn from 
the water heater.''
    \35\ A ``draw cluster'' is defined in section 1 of appendix E as 
``a collection of water draws initiated during the 24-hour 
simulated-use test during which no successive draws are separated by 
more than 2 hours.'' There are two draw clusters in the very small 
draw pattern and three draw clusters in the low, medium, and high 
draw patterns.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on whether it should 
consider the addition of a minimum standby period length of 6 hours for 
use in the standby loss calculations, and on the appropriateness of 
recording this data after the final draw cluster when less than 6 hours 
of standby time occur between the first and second draw clusters. 85 FR 
21104, 21110 (April 16, 2020). BWC stated that DOE should adopt a 
minimum standby period length of 6 hours for use in the standby loss 
calculation. (BWC, No. 12 at p. 3) NEEA stated that DOE should reduce 
the standby period to 4 hours, as it believed the increased burden to 
require a 6-hour standby period would be unwarranted. (NEEA, No. 21 at 
p. 4) AHRI and Rheem stated they do not support the addition of a 
minimum standby period length of 6 hours because it would extend the 
total test period time to over 24 hours. (AHRI, No. 17 at p. 6; Rheem, 
No. 14 at p. 4) A.O. Smith stated that adding 6 hours to the test would 
be significant and recommended that DOE investigate whether the 
addition is truly necessary, or if a less burdensome method could 
achieve the same goal. (A.O. Smith, No. 20 at p. 3) CSA referenced its 
test data, which included units with a standby period ranging from 5 
minutes to over 7 hours, to demonstrate that standby time has very 
little effect on the overall UEF value. (CSA, No. 10 at p. 4)
    The standby heat loss coefficient (i.e., UA) is calculated from 
data recorded during the standby period. DOE reviewed its available 
test data and found that for the models reviewed, UA has very little 
effect on UEF, which is consistent with CSA's comment. UA is used only 
to adjust the daily water heating energy consumption to the nominal 
ambient temperature of 67.5 [deg]F (19.7 [deg]C). Given that the 
ambient temperature range is relatively narrow (i.e., 65 [deg]F to 70 
[deg]F (18.3 [deg]C to 21.1 [deg]C)), the adjustment has only a minimal 
impact on the daily water heating energy consumption. Further, DOE 
found that the length of the recovery period has little effect on the 
resulting UA value. Therefore, DOE has tentatively determined that 
requiring a 6-hour standby period would not affect UA and UEF enough to 
justify the increased test burden associated with a

[[Page 1575]]

test that already could last longer than 24 hours.
Last Hour
    In the April 2020 RFI, DOE requested feedback on whether it should 
consider an alternate procedure, like that in section 7.4.2.2 of the 
March 2019 ASHRAE Draft 118.2 (and section 7.4.3.2 of the April 2021 
ASHRAE Draft 118.2), for the last hour of the 24-hour simulated-use 
test. 85 FR 21104, 21111 (April 16, 2020). DOE further requested 
feedback on whether the addition of standby loss in the total energy 
use calculation adequately represents the auxiliary energy use that is 
not measured between the minute prior to the start of the recovery 
occurring between hours 23 and 24, and hour 24 of the 24-hour 
simulated-use test. Id.
    CSA requested that DOE revisit the procedure for the last hour of 
the 24-hour simulated-use test. CSA raised a number of questions with 
how the test procedure in section 5.4.2, Test Sequence for Water 
Heaters with Rated Storage Volumes Greater Than or Equal to 2 Gallons, 
is implemented, specifically with regard to when power is to be turned 
off and on. (CSA, No. 10 at p. 4)
    Although not stated explicitly in section 5.4.2 of appendix E, in 
the case that the standby period is between the first and second draw 
clusters, power to the main burner, heating element, or compressor is 
disabled during the last hour of the 24-hour simulated-use test. In the 
case that the standby period is after the last draw of the 24-hour 
simulated-use test, power to the main burner, heating element, or 
compressor is not disabled.
    Section 5.4.2 of appendix E states that during the last hour of the 
24-hour simulated-use test, power to the main burner, heating element, 
or compressor shall be disabled; at 24 hours, record the reading given 
by the gas meter, oil meter, and/or the electrical energy meter as 
appropriate; and determine the fossil fuel and/or electrical energy 
consumed during the entire 24-hour simulated-use test and designate the 
quantity as Q.
    Section 5.4.2 of appendix E also provides that in the case that the 
standby period is after the last draw of the 24-hour simulated-use 
test, an 8-hour standby period is required, and this period may extend 
past hour 24. The procedures for the standby period after the last draw 
of the 24-hour simulated-use test allow for a recovery to occur at the 
end of the 8-hour standby period, which indicates that the power to the 
main burner, heating element, or compressor is not disabled. DOE's 
procedure as described may result in some confusion. Further, the 
method of determining the total energy use during the 24-hour 
simulated-use test, Q, and total test time are not explicitly stated 
for when a standby period occurs after the last draw of the 24-hour 
simulated-use test. As discussed in the following paragraphs, DOE is 
proposing to amend the procedures for the last hour of the 24-hour 
simulated-use test to explain how to end the test for both standby 
period scenarios.
    CSA and NEEA stated that DOE should adopt the March 2019 ASHRAE 
Draft 118.2 approach. (CSA, No. 10 at p. 4; NEEA, No. 21 at p. 6)
    In the March 2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 
118.2, power is not disabled when the standby period occurs after the 
last draw of the test. But, if a recovery occurs between an elapsed 
time of 23 hours following the start of the test (hour 23) and 24 hours 
following the start of the test (hour 24), the following alternate 
approach is applied to determine the energy consumed during the 24-hour 
simulated-use test: The time, total energy used, and mean tank 
temperature are recorded at 1 minute prior to the start of the recovery 
occurring between hour 23 and hour 24, along with the average ambient 
temperature from 1 minute prior to the start of the recovery occurring 
between hour 23 and hour 24 to hour 24 of the 24-hour simulated-use 
test. These values are used to determine the total energy used by the 
water heater during the 24-hour simulated-use test. This alternate 
calculation combines the total energy used 1 minute prior to the start 
of the recovery occurring between hours 23 and 24 and the standby loss 
experienced by the tank during the time between the minute prior to the 
recovery start and hour 24. This provision in section 7.4.2.2 of the 
March 2019 ASHRAE Draft 118.2 and section 7.4.3.2 of the April 2021 
ASHRAE Draft 118.2 does not require the water heater to be de-energized 
during the standby period. Disabling power to the water heater is 
typically a manual operation that requires the presence of a 
technician. In cases where the technician does not disable power at the 
correct time, a retest of the 24-hour simulated-use test may be 
necessary. To the extent this draft provision would eliminate the need 
to ensure that a unit is switched off for the last hour of the 24-hour 
simulated-use test, it could reduce test burden.
    In response to the April 2020 RFI, CSA further stated that not 
including the pilot energy does not adequately represent auxiliary 
energy usage for water heaters with continuously burning pilot lights. 
(CSA, No. 10 at p. 5) DOE notes that in the last hour of the 24-hour 
simulated-use test, the power to the main burner is disabled. In 
practice, cutting off the gas flow to the main burner disables the 
pilot light as well. However, disabling power to the main burner could 
also be accomplished by reducing the thermostat setting to the minimum 
setting available, which would result in the water heater under test 
not initiating a recovery during the last hour and gas continuing to be 
supplied to the pilot light. Reducing the thermostat setting would be a 
manual operation performed by a technician, not an automated action, 
which increases the chances of an invalid test. CSA also stated that 
water heaters without standing pilots will have minimal energy 
consumption in the last hour compared to the overall energy 
consumption, and that the total energy use calculation adequately 
represents the auxiliary energy use for these water heaters. Id. AHRI 
and A.O. Smith stated that they are in the process of evaluating the 
March 2019 ASHRAE Draft 118.2 test procedure for the last hour of the 
24-hour simulated-use test and will provide additional information 
after their evaluation is completed. (AHRI, No. 17 at p. 6; A.O. Smith, 
No. 20 at p. 3) Rheem stated that given the limited time for evaluation 
and testing of an alternate procedure, the current procedure for the 
last hour of the 24-hour simulated-use test in appendix E should be 
maintained. (Rheem, No. 14 at p. 5)
    At this time, DOE has not been provided with the additional 
information from AHRI or A.O. Smith regarding the procedure for the 
last hour of the 24-hour simulated-use test, and agrees with Rheem that 
further evaluation of the alternate procedure presented in the March 
2019 ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 118.2 should be 
conducted before a determination is made. As stated previously, the 
procedure for the last hour of the 24-hour simulated-use test may 
benefit from further, more explicit instruction, and DOE proposes to 
explicitly state how to end the test depending on whether the standby 
period is between draw clusters 1 and 2 or after the last draw of the 
test.

C. Test Procedure Requirements

1. Commercial Water Heater Draw Pattern
    In response to the April 2020 RFI, EEI suggested DOE consider a 
definition and test procedure for consumer water heaters used in 
commercial settings. EEI suggested that the test procedure would

[[Page 1576]]

include a daily water draw (i.e., draw pattern) that is greater than 
the ``high'' draw pattern, which is the draw pattern with the largest 
amount of delivered water in the test procedure for consumer water 
heaters. (EEI, No. 8 at p. 3)
    DOE has tentatively determined not to add a draw pattern with a 
delivered volume greater than the high draw pattern in appendix E, 
which would represent consumer water heaters installed in commercial 
applications. Under 42 U.S.C. 6293(b)(3), in relevant part, any test 
procedures prescribed or amended shall be reasonably designed to 
produce test results which measure energy efficiency of a covered 
product during a representative average use cycle or period of use. 
Consumer water heaters are designed for use in residential applications 
and, as such, a draw pattern representative of a commercial 
installation would not be representative of the product's average use 
cycle or period of use.
2. Terminology
    In sections 5.3.3.1 and 5.3.3.2 of appendix E, which describe 
general requirements and draw initiation criteria, respectively, for 
the FHR test, the term ``storage-type water heaters'' is used. However, 
the FHR test applies to all water heaters that are not flow-activated, 
which includes non-flow activated instantaneous water heaters. In the 
April 2020 RFI, DOE requested feedback on whether to update the phrase 
``storage-type water heaters'' in section 5.3.3 to ``non-flow activated 
water heaters.'' 85 FR 21104, 21112 (April 16, 2020). AHRI, Keltech, 
Rheem, and Rinnai stated that there is no need to change the phrase 
``storage-type water heaters'' in section 5.3.3. (AHRI, No. 17 at p. 9; 
Keltech, No. 7 at p. 1; Rheem, No. 14 at p. 7; Rinnai, No. 13 at p. 9) 
AHRI stated that if instantaneous water heaters are properly 
classified, this issue would be resolved (AHRI, No. 17 at p. 9).
    DOE submitted a comment to the March 2019 ASHRAE Draft 118.2 that 
suggested changing the language within sections 7.3.3.1 and 7.3.3.2 
from ``storage-type'' to ``non-flow activated.'' This proposed change 
was accepted by the ASHRAE 118.2 committee and is present in section 
7.3.3.1 of the April 2021 ASHRAE Draft 118.2. Section 7.3.3.2 was not 
included in the April 2021 ASHRAE Draft 118.2. In an effort to align 
terminology with that recognized by industry in proceedings subsequent 
to the April 2020 RFI, DOE proposes to change the phrase ``storage-
type'' to ``non-flow activated'' within sections 5.3.3.1 and 5.3.3.2 of 
appendix E and further proposes to change ``storage-type'' and 
``instantaneous-type'' to ``non-flow activated'' and ``flow-
activated,'' respectively, throughout appendix E. This change would be 
a clarification only and would not change the current application of 
sections 5.3.3.1 and 5.3.3.2 of appendix E.
    In section 6.3.3 of appendix E, titled ``Hourly Standby Losses,'' 
the descriptions for cumulative energy consumption (Qsu,0 
and Qsu,f) \36\ and mean tank temperature 
(Tsu,0 and Tsu,f,) at the start and 
end of the standby period, along with the elapsed time, average storage 
tank temperature, and average ambient temperature over the standby 
period ([tau]stby,1, Tt,stby,1, and 
Ta,stby,1, respectively) \37\ specifically refer to the 
standby period that would occur after the first draw cluster, but do 
not explicitly address the case where the standby period occurs after 
the last draw of the test.
---------------------------------------------------------------------------

    \36\ The subscript ``su,0'' refers to the start of the standby 
period in which the standby loss coefficient is determined, and the 
subscript ``su,f'' refers to the end of this standby period.
    \37\ The subscript ``stby,1'' refers to the standby period in 
which the standby loss coefficient is determined. The subscripts 
``t'' and ``a'' refer to the mean tank temperature and ambient 
temperature, respectively.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on whether it should 
revise the descriptions of Qsu,0, Qsu,f, 
Tsu,0, Tsu,f, [tau]stby,1, 
Tt,stby,1, and Ta,stby,1 to explicitly 
include cases where the standby period occurs after the last draw of 
the test, in addition to cases where the standby period occurs after 
the first draw cluster. 85 FR 21104, 21113 (April 16, 2020). AHRI, A.O. 
Smith, CSA, and Rheem recommended not changing the descriptions. (AHRI, 
No. 17 at p. 10; A.O. Smith, No. 20 at p. 5; CSA, No. 10 at p. 8; 
Rheem, No. 14 at p. 8) BWC observed inconsistences in definitions of 
the variables in the current test procedure in sections 1.13 and 6.3.3 
and stated further that many of these can be addressed by adopting the 
descriptions in the March 2019 ASHRAE Draft 118.2. (BWC, No. 12 at p. 
6)
    Within appendix E, the standby loss period could occur at multiple 
points in the test, depending on the operation of the water heater 
under test, but, as described previously, the descriptions of these 
variables (Qsu,0, Qsu,f, 
Tsu,0, Tsu,f, [tau]stby,1, 
Tt,stby,1, and Ta,stby,1) reference 
only one of the possible time periods. Therefore, DOE proposes to 
remove references to specific time periods to reduce the possibility of 
confusion and to align with the April 2021 ASHRAE Draft 118.2.
3. Test Conditions
a. Supply Water Temperature
    Section 2.3 of appendix E specifies maintaining the supply water 
temperature at 58 [deg]F 2 [deg]F (14.4 [deg]C 1.1 [deg]C). During the 24-hour simulated-use test, maintaining 
the supply water temperature within this range can be difficult at the 
immediate start of a draw due to the short time between draw initiation 
and the first measurement at 5 seconds (with subsequent measurements 
every 3 seconds thereafter), as required by sections 5.4.2 and 5.4.3 of 
appendix E. In some test configurations, particularly during the lower 
flow rate water draws, the inlet water and piping may retain heat from 
a previous draw, causing the water entering the unit during the initial 
measurements to be slightly outside of tolerance. Any supply water 
temperature reading outside of the test tolerances would invalidate a 
test. However, due to the small percentage of total water use that 
would be affected, supply water temperatures that are slightly out of 
tolerance for the first one or two data points would have a negligible 
effect on the overall test result.\38\ This issue is less evident 
during the FHR test, which specifies an initial temperature measurement 
15 seconds after the start of the water draw. This is not an issue 
during the Max GPM test due to the system being in steady state during 
the entire test.
---------------------------------------------------------------------------

    \38\ For example, the first two temperature readings would 
reflect 8 seconds of water flow, in comparison to total water draw 
durations ranging from 1 minute to over 8 minutes, according to the 
water draw patterns defined in Tables III.1, III.2, III.3, and III.4 
of appendix E.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on whether one or two 
supply water temperature data points outside of the test tolerance at 
the beginning of a draw would have a measurable effect on the results 
of the test. 85 FR 21104, 21111 (April 16, 2020). DOE further requested 
feedback on whether it should consider relaxing the requirement for 
supply water temperature tolerances at the start of a draw, and if so, 
which methods are most appropriate for doing so while maintaining 
accuracy and repeatability. Id. at 85 FR 21111-21112. A.O. Smith stated 
there would be no measurable effect on test results by allowing one or 
two supply water temperature data points outside of the test tolerance 
at the beginning of a draw. (A.O. Smith, No. 20 at p. 4) NEEA 
recommended DOE conduct a sensitivity analysis to determine a 
reasonable range and encouraged relaxing the requirements to ease test 
burden. (NEEA, No. 21 at p. 7) A.O.

[[Page 1577]]

Smith, NEEA, and Rheem recommended that DOE allow the first one or two 
measurements of the supply water temperature to be outside of test 
tolerance to ease test burden. (A.O. Smith, No. 20 at p. 4; NEEA, No. 
21 at p. 7; Rheem, No. 14 at p. 6) AHRI, A.O. Smith, BWC, CSA, Rheem, 
and Rinnai recommended that DOE increase the time between initiating a 
draw and the first data measurement from 5 seconds to 15 seconds within 
section 5.4.2 of appendix E. (AHRI, No. 17 at p. 7; A.O. Smith, No. 20 
at p. 4; BWC, No. 12 at p. 3; CSA, No. 10 at p. 6; Rheem, No. 14 at p. 
6; Rinnai, No. 13 at p. 8) SMTI recommended that the supply water 
temperature requirement be changed to: the average supply water 
temperature during draws shall be 58 [deg]F 2 [deg]F, with 
all data points being 58 [deg]F 5 [deg]F. (SMTI, No. 19 at 
p. 4) NEEA encouraged DOE to relax the tolerances at the start of the 
draw and suggested allowing a given maximum percentage deviation in 
mass-weighted temperature over the course of a single draw or to set a 
corresponding absolute number. (NEEA, No. 21 at p. 7) CSA recommended 
that DOE adopt the March 2019 ASHRAE Draft 118.2 piping diagrams, with 
the by-pass loop, to alleviate inlet temperature problems. (CSA, No. 10 
at p. 6) DOE notes this supply water temperature issue has been 
observed in testing with the test setup described in the March 2019 
ASHRAE Draft 118.2. Therefore, adopting the March 2019 ASHRAE Draft 
118.2 test setup alone would not alleviate this issue.
    As explained previously, DOE agrees with commenters that one or two 
supply water temperature measurements outside of tolerance at the start 
of the draw will likely have no measurable effect on test results. 
These outside of tolerance measurements typically occur during draws 
with lower flow rates, where the inlet water line (which has been 
heated slightly due to heat transferring from the water heater) is not 
cleared by the first data measurement. DOE notes that during its own 
testing, multiple retests were sometimes needed before a valid test was 
performed. To alleviate this issue, DOE proposes to increase the time 
between initiating the draw and first measurement from 5 seconds to 15 
seconds in sections 5.4.2 and 5.4.3 of appendix E, as recommended by 
the commenters. This proposed change may reduce test burden by reducing 
the occurrence of a test being invalidated (which would require re-
testing) due to the first one or two water temperature readings 
exceeding the defined temperature tolerance. Further, this proposed 
change would eliminate the need to amend the supply water temperature 
tolerances, which, outside of the time period at the start of a draw, 
are relatively easy to maintain.
b. Test Tolerances
    Section 2.2 of appendix E specifies maintaining the ambient air 
temperature between 65.0 [deg]F and 70.0 [deg]F (18.3 [deg]C and 21.1 
[deg]C) on a continuous basis for all types of consumer water heaters 
(and residential-duty commercial water heaters) other than heat pump 
water heaters. For heat pump water heaters, the dry bulb (ambient air) 
temperature must be maintained between 67.5 [deg]F 1 [deg]F 
(19.7 [deg]C 0.6 [deg]C), and the relative humidity must be 
maintained at 50% 2% throughout the test. Appendix E does 
not specify a relative humidity tolerance for non-heat pump water 
heaters. For all water heaters, section 2.7.1 of appendix E specifies 
maintaining the electrical supply voltage within 1% of the 
center of the voltage range specified by the manufacturer. Similar to 
the supply water temperature discussed previously, a brief measurement 
of air temperature, relative humidity, or electrical supply voltage 
that is only minimally outside of the test tolerance would invalidate a 
test, but likely would have a negligible effect on the results of the 
test, as the total time out of tolerance would be insignificant 
compared to the total time of the test. In the April 2020 RFI, DOE 
requested feedback on whether the tolerances for ambient air 
temperature, relative humidity, and electrical supply voltage are 
difficult to maintain at the start of a draw, and if so, whether DOE 
should consider relaxing these requirements at the start of a draw and 
to what extent. 85 FR 21104, 21112 (April 16, 2020).
    AHRI recommended that the tolerances for the electric supply 
voltage be made less stringent and noted that the current electric 
supply voltage requirements require specialized equipment that is very 
costly and has little effect on the UEF results. (AHRI, No. 17 at p. 8) 
CSA, NEEA, Rheem, and Rinnai proposed increasing the electrical supply 
voltage tolerance to 2 percent of the rated voltage, while 
BWC proposed a tolerance of 5% of the rated voltage. (CSA, 
No. 10 at p. 6; NEEA, No. 21 at p. 3; Rheem, No. 14 at p. 6; Rinnai, 
No. 13 at p. 8; BWC, No. 12 at p. 4) CSA further stated that the 
electric supply voltage tolerance should apply only when the main heat 
source is on, as there are spikes in voltage when heating is turned on/
off. (CSA, No. 10 at p. 6) Keltech stated that it might be difficult to 
maintain 1 percent voltage tolerance, as there might be 
considerable voltage sag \39\ for really high amperage units, and that 
the test procedure should be clearer about what is acceptable for a 
power supply source to recover. (Keltech, No. 7 at p. 1)
---------------------------------------------------------------------------

    \39\ A voltage sag (or swell) is a short duration change in 
voltage which can be caused by sudden load changes or excessive 
loads (e.g., a water heater starting or ending a recovery).
---------------------------------------------------------------------------

    DOE agrees with commenters that maintaining the electric supply 
voltage within 1 percent of the rated voltage is difficult 
and requires expensive equipment, and that maintaining this narrow 
tolerance range is likely not necessary to achieve repeatable and 
reproducible test results. DOE further agrees with CSA and Keltech that 
short spikes in the measured voltage that occur around the start and 
end of a recovery, when heating components are turning on or off, have 
little to no effect on UEF, but can invalidate a test. Therefore, to 
reduce the potential need to re-run tests and thereby potentially 
reduce test burden, DOE proposes to increase the electrical supply 
voltage tolerance from 1 percent on a continuous basis to 
2 percent on a continuous basis and to add clarification 
that this tolerance is only applicable beginning 5 seconds after the 
start of a recovery to 5 seconds before the end of a recovery (i.e., 
only when the water heaters is undergoing a recovery). These proposed 
changes may reduce test burden by reducing the need to re-run tests 
while maintaining the representativeness of the test procedure.
    SMTI stated that for heat pump water heaters the average dry bulb 
temperature during recoveries should be 67.5 [deg]F 1 
[deg]F, with all data points being 67.5 [deg]F 5 [deg]F, 
and that the average dry bulb temperature during standby period should 
be 67.5 [deg]F 2.5 [deg]F, with all data points being 67.5 
[deg]F 5 [deg]F. (SMTI, No. 19 at p. 4) Rheem recommended a 
dry bulb temperature tolerance between 65.0 [deg]F and 70.0 [deg]F for 
heat pump water heaters. (Rheem, No. 14 at p. 6) Rinnai stated that the 
average ambient air temperature for non-heat pump water heaters should 
be 67.5 [deg]F 2.5 [deg]F, and that a single data point 
outside of the range should not invalidate a test. (Rinnai, No. 13 at 
p. 8) A.O. Smith stated that relaxing ambient air tolerance for the 
first 15 minutes during the test will not have a measurable effect on 
the overall test results and that DOE should investigate whether 
relaxing this tolerance for the entirety of the test still provides 
results that are repeatable and representative of an average use cycle. 
(A.O. Smith, No. 20 at p. 4)

[[Page 1578]]

    Through a review of its available test data, DOE has found that 
short fluctuations in ambient temperature have little to no effect on 
the test results of non-heat pump water heaters. Therefore, in an 
effort to reduce the need to re-run tests in instances in which the 
results of the invalid test and the valid test would not differ 
significantly, and therefore reduce test burden, DOE proposes to change 
the ambient temperature requirement for non-heat pump water heaters to 
an average of 67.5 [deg]F 2.5 [deg]F, with a maximum 
deviation of 67.5 [deg]F 5 [deg]F, as opposed to only a 
maximum deviation of 67.5 [deg]F 2.5 [deg]F as currently 
specified in the test procedure.
    For heat pump water heaters, DOE agrees with SMTI that the dry bulb 
temperature tolerances are important to maintain during recoveries but 
are less important during standby periods when the air is not being 
used to heat water. Further, through its own testing, DOE has observed 
that short deviations outside of the dry bulb temperature tolerances 
have little to no effect on the test results. Therefore, in an effort 
to reduce the need to re-run tests in instances in which the results of 
the invalid test and the valid test would not differ significantly, DOE 
proposes to change the dry bulb temperature requirement for heat pump 
water heaters to an average of 67.5 [deg]F 1 [deg]F during 
recoveries and an average of 67.5 [deg]F 2.5 [deg]F when 
not recovering, with a maximum deviation of 67.5 [deg]F 5 
[deg]F, as opposed to only a maximum deviation of 67.5 [deg]F 1 [deg]F as currently specified in the test procedure. This 
proposed change would maintain the stringency of the dry bulb 
temperature requirement while allowing for short deviations from the 
targeted dry bulb temperature range, which would reduce the need to re-
run tests in instances in which the results of the invalid test and the 
valid test would not differ significantly, and therefore reduce test 
burden.
    In response to the April 2020 RFI, SMTI stated that for heat pump 
water heaters, the relative humidity tolerance is only relevant during 
recoveries and suggested changing the relative humidity requirements to 
an average of 50% 2%, with a maximum deviation of 50% 
10%. (SMTI, No. 19 at p. 4) A.O. Smith stated that relaxing 
relative humidity tolerance for the first 15 minutes during the test 
will not have a measurable effect on the overall test results and that 
DOE should investigate whether relaxing this tolerance for the entirety 
of the test still provides results that are repeatable and 
representative of an average use cycle. (A.O. Smith, No. 20 at p. 4) 
BWC and Rinnai supported relaxing the relative humidity tolerance, and 
NEEA stated that the relative humidity tolerance should be increased 
from 2 percent to 5 percent. (BWC, No. 12 at p. 
4; Rinnai, No. 13 at p. 8; NEEA, No. 21 at p. 4)
    For heat pump water heaters, DOE is proposing to increase the 
absolute relative humidity tolerance from 2 percent to 
5 percent across the entire test, with the average relative 
humidity between 50% 2% during recoveries. This change 
would reduce test burden by reducing the need to re-run tests in 
instances in which the results of the invalid test and the valid test 
would not differ significantly.
    As noted, appendix E does not currently specify a relative humidity 
tolerance for non-heat pump water heaters. As described in the April 
2020 RFI, DOE has conducted exploratory testing to investigate the 
effect of relative humidity on the measured UEF values of two consumer 
gas-fired instantaneous water heaters that are flow activated and have 
less than 2 gallons of storage volume. 85 FR 21104, 21112 (April 16, 
2020). Of the two models tested, one used non-condensing technology and 
the other used condensing technology. For each model, two tests were 
performed at a relative humidity of 50 percent, and two tests were 
performed at a relative humidity of 80 percent (i.e., a total of four 
tests for each model). Id. Increasing in relative humidity from 50 
percent to 80 percent resulted in a maximum change in UEF for the non-
condensing and condensing models of 0.011 and 0.015, respectively. Id. 
Given that DOE requires reporting UEF to the nearest 0.01 (see 10 CFR 
429.17(b)(2)), a change in UEF on the order of 0.01-0.02 as suggested 
by DOE's test results could be considered as substantively impacting 
the test results. DOE is still examining this issue and requests 
comment and test data on whether a relative humidity requirement should 
be added to appendix E for non-heat pump water heaters.
    DOE is also proposing a clarification regarding the correction of 
the heating value to a standard temperature and pressure. Section 3.7 
of appendix E states that the heating values of natural gas and propane 
must be corrected from those reported at standard temperature and 
pressure conditions to provide the heating value at the temperature and 
pressure measured at the fuel meter, but does not specify standard 
temperature and pressure conditions.
    AHRI maintains an Operations Manual for Residential Water Heater 
Certification Program (AHRI Operations Manual),\40\ which addresses how 
testing will be done in the AHRI certification program. The procedures 
outlined in the AHRI Operations Manual are similar to appendix E and 
provide instruction for AHRI certification program testing that is not 
included within the DOE test procedure. In section A1.4.1 of the AHRI 
Operations Manual, an equation is provided that corrects the measured 
heating value, when using a dry gas \41\ and a wet test meter,\42\ to 
the heating value at the standard temperature and pressure of 60 [deg]F 
(15.6 [deg]C) and 30 inches of mercury column (101.6 kPa), 
respectively. Annex B of the March 2019 ASHRAE Draft 118.2 also 
provides a method for correcting the heating value from measured to 
standard conditions, which allows for the use of either dry or 
saturated gas \43\ and either a dry \44\ or wet test meter. Sections 
2.4.1 and 3.1.1 of appendix O to part 430 correct the input rate to the 
standard conditions of 60 [deg]F (15.6 [deg]C) and 30 inches of mercury 
column (101.6 kPa). Therefore, to align with the AHRI Operations Manual 
and the current practice in other appendices with part 430 of the CFR, 
DOE is proposing to explicitly state that the standard temperature and 
pressure conditions for gas measurements be 60 [deg]F (15.6 [deg]C) and 
30 inches of mercury column (101.6 kPa), respectively. Further, to 
detail the method in which the heating value must be corrected to 
standard conditions and to align with the consensus industry standard, 
DOE proposes to reference Annex B of a finalized ASHRAE 118.2.
---------------------------------------------------------------------------

    \40\ The AHRI Operations Manual for Residential Water Heater 
Certification Program is available at: www.ahrinet.org/App_Content/ahri/files/Certification/OM%20pdfs/RWH_OM.pdf.
    \41\ Dry gas refers to non-saturated test gas that does not 
contain water vapor.
    \42\ A wet test meter measures the heating value of saturated 
test gas that contains water vapor.
    \43\ Saturated gas refers to test gas that contains water vapor.
    \44\ A dry test meter measures the heating value of dry test 
gas.
---------------------------------------------------------------------------

c. Gas Pressure
    For gas-fired water heaters, sections 2.7.2 and 2.7.3 of appendix E 
require maintaining the gas supply pressure in accordance with the 
manufacturer's specifications; or if the supply pressure is not 
specified, maintaining a supply pressure of 7 to 10 inches of water 
column (1.7 to 2.5 kPa) for natural gas and 11 to 13 inches of water 
column (2.7 to 3.2 kPa) for propane gas. In addition, for gas-fired 
water heaters with a pressure regulator, sections 2.7.2 and 2.7.3 
require the regulator outlet pressure to be within 10 
percent of the manufacturer's specified manifold pressure. From a 
review of product

[[Page 1579]]

literature, DOE has found that many gas-fired water heaters with 
modulating input rate burners have a factory preset manifold pressure 
that is computer-controlled and cannot be adjusted directly. Further, 
the manufacturer-specified manifold pressure typically refers to when 
the water heater is operating at the maximum firing rate.
    In the April 2020 RFI, DOE requested comment on whether sections 
2.7.2 and 2.7.3 (Test Conditions for Natural and Propane Gas, 
respectively) should be amended to account for models where the 
manifold pressure cannot be adjusted directly and whether the 10% tolerance on the manufacturer's specified manifold pressure 
should apply only when firing at the manufacturer specified maximum 
input rate. 85 FR 21104, 21112 (April 16, 2020). AHRI, CSA, Rheem, and 
Rinnai recommended that an alternate tolerance based on percentages be 
used when a ``zero-governor'' valve \45\ is used. (AHRI, No. 17 at p. 
8; CSA, No. 10 at p. 7; Rheem, No. 14 at p. 7; Rinnai, No. 13 at p. 9) 
Rheem commented that the 10 percent tolerance should apply 
when operating at the manufacturer's specified firing rate, and that 
for modulating water heaters the 10 percent tolerance 
should be applied to the maximum firing rate. (Rheem, No. 14 at p. 7) 
A.O. Smith and CSA suggested that sections 2.7.2 and 2.7.3 be amended 
to account for manifold pressure that cannot be adjusted directly, and 
specifically recommended that if the target manifold pressure cannot be 
achieved through manifold adjustment, then modifying the orifice should 
be required. (A.O. Smith, No. 20 at p. 4; CSA, No. 10 at p. 7)
---------------------------------------------------------------------------

    \45\ A zero-governor valve controls the outlet pressure of the 
valve to a target of near-zero inches of water column (i.e., zero 
pressure).
---------------------------------------------------------------------------

    Recognizing that certain gas-fired water heaters do not provide the 
capability to adjust the manifold pressure, DOE proposes to remove the 
10 percent manifold pressure tolerance for these products. 
DOE is proposing to add an absolute manifold pressure tolerance of 
0.2 inches water column, which would be used for gas-fired 
water heaters with a zero-governor valve for which the 10 
percent tolerance would be overly restrictive. For example, applying 
the 10 percent to a manufacturer recommended gas pressure 
of 0.1 inches water column would result in a tolerance of 0.01 inches of water column, which is less than both the accuracy 
and precision tolerances required for gas pressure instrumentation 
within section 3.1 of appendix E. Further, DOE proposes that the 
required gas pressures within appendix E apply when operating at the 
manufacturer's specified input rate or, for modulating input rate water 
heaters, the maximum input rate. Section III.C.3.d of this document 
provides further discussion on modifying the orifice of gas-fired water 
heaters that are not operating at the manufacturer specified input 
rate.
d. Input rate
    In addition to the gas pressure requirements, section 5.2.3 
requires maintaining an hourly Btu rating (i.e., input rate) that is 
within 2 percent of the value specified by the manufacturer 
(i.e., the nameplate value). DOE has observed during testing that an 
input rate cannot be achieved that is within 2 percent of 
the nameplate value while maintaining the gas supply pressure and 
manifold pressure within the required ranges for some gas-fired water 
heaters. In such instances, it is common practice for the testing 
laboratory to modify the size of the orifice that is shipped with the 
water heater; for example, the testing laboratory may enlarge the 
orifice to allow enough gas flow to achieve the nameplate input rating 
within the specified tolerance, if the input rate is too low with the 
orifice as supplied. For commercial water heating equipment, DOE 
addressed this issue by specifying in the product-specific enforcement 
provisions that, if the fuel input rate is still not within 2 percent of the rated input after adjusting the manifold and 
supply pressures to their specified limits, DOE will attempt to modify 
the gas inlet orifice. 10 CFR 429.134(n)(ii).
    In the April 2020 RFI, DOE requested comment on whether provisions 
should be added to the test procedure at appendix E to address water 
heaters that cannot operate within 2 percent of the 
nameplate rated input as shipped from the factory. 85 FR 21104, 21112 
(April 16, 2020). If so, DOE requested comment on how to address this 
issue, and whether it is appropriate to physically modify the orifice, 
similar to the direction for commercial water heaters. Id. AHRI, Rheem, 
and Rinnai recommended using the test procedure in the AHRI Operations 
Manual for Residential Water Heater Certification Program, which 
specifies procedures to adjust the test setup when the appliance's 
input rate is not within the 2 percent of the specified 
input rate either by adjusting the manifold pressure, modifying the 
orifice of the unit, or checking/fixing any leaks. (AHRI, No. 17 at p. 
8; Rheem, No. 14 at p. 7; Rinnai, No. 13 at p. 9) BWC stated that DOE 
should add provisions to address products that cannot operate within 
2 percent of the nameplate input rate, potentially by 
allowing manufacturers to provide testing facilities with alternate 
means to achieve the rated input, such as modifying the orifice(s) 
while the regulator outlet pressure is within 10 percent of 
the manufacturer's specified manifold pressure. (BWC, No. 12 at p. 4) 
CEC recommended that DOE review, study, and provide results to 
stakeholders before allowing laboratories to make any physical 
modification to the size of the gas flow orifice to increase or 
decrease gas flow to achieve the nameplate input rating within the 
specified tolerance, further stating that this modification should be 
made by the manufacturer prior to testing, since this will lead to 
false efficiency readings that are not representative of actual use and 
could negatively impact the consumers ability to choose an efficient 
water heater. (CEC, No. 11 at p. 4)
    After considering these comments, DOE proposes to add provisions to 
appendix E to provide further direction for achieving an input rate 
that is  2 percent of the nameplate value specified by the 
manufacturer. Specifically, DOE proposes to modify section 5.2.3 of 
appendix E to require that the following steps be taken to achieve an 
input rate that is  2 percent of the nameplate value 
specified by the manufacturer. First, attempt to increase or decrease 
the gas outlet pressure within  10 percent of the value 
specified on the nameplate to achieve the nameplate input (within 
2 percent). If the fuel input rate is still not within 
2 percent of the nameplate input, increase or decrease the 
gas supply pressure within the range specified on the nameplate. If the 
measured fuel input rate is still not within 2 percent of 
the certified rated input, modify the gas inlet orifice as required to 
achieve a fuel input rate that is  2 percent of the 
nameplate input rate. Regarding commenters' suggestion to check for 
leaks as an additional step in the process, DOE notes that gas leak 
detection should be part of a test laboratory's normal operating 
procedures and, therefore, detection does not require specification 
within DOE's test procedures. In response to CEC's concern regarding 
representativeness, the purpose of adjusting the orifice during testing 
is to ensure that the performance of the water heater is representative 
of performance at the Btu rating specified by the manufacturer on the 
product's nameplate, which informs the field installation conditions. 
Allowing for

[[Page 1580]]

adjustment of the orifice reduces test burden and improves 
repeatability by providing test laboratories with a last resort to 
maintain the hourly Btu rating as specified by the manufacturer. 
Further, DOE is proposing that modification of the orifice be done only 
after other options have been exhausted.
    DOE seeks further comment on its proposed amendments to clarify the 
procedure for achieving an input rate within 2 percent of 
the nameplate input rating.
    DOE also proposes to add enforcement specific provisions to 10 CFR 
429.134 to require that if the fuel input rate still cannot be achieved 
within 2 percent of the nameplate input rate after 
adjusting the burner as described above, the fuel input rate found via 
testing will be used for the purpose of determining compliance. DOE 
proposes similar provisions for oil-fired water heaters that cannot be 
adjusted to within 2 percent of the nameplate value. DOE 
requests comment on this proposal.
e. Optional Test Conditions
    In response to the April 2020 RFI, NEEA requested that DOE allow 
for optional reporting of additional efficiency ratings at two 
different ambient and inlet water temperature conditions within the 
Compliance Certification Management System (CCMS) database, 
specifically for heat pump water heaters. NEEA further recommended that 
testing and reporting of the lower compressor cut off temperature in 
the CCMS database, similar to NEEA's Advanced Water Heating 
Specification, be required. (NEEA, No. 21 at pp. 1-3) The Joint 
Advocates requested that DOE explore the usage of NEEA's Advanced Water 
Heating Specification and allowing for voluntary testing needed to 
calculate climate-specific efficiency. (Joint Advocates, No. 15 at pp. 
1-2)
    DOE recognizes that regional differences in ambient temperature, 
inlet water temperature, and relative humidity exist and that these 
differences can have an effect on the efficiency of heat pump water 
heaters. However, as required under EPCA, the DOE test procedure must 
be reasonably designed to produce test results which measure energy 
efficiency during a representative average use cycle or period of use. 
(42 U.S.C. 6293(b)(3)) Compliance with the applicable energy 
conservation standard, which was developed based on an analysis of 
water heaters nationally, must be determined using the current DOE test 
procedure. (42 U.S.C. 6295(s)). The conditions in appendix E are 
representative of the nation as a whole. Moreover, DOE does not have 
data to indicate what conditions would be representative for regional 
representations. As the test procedure must be representative of the 
nation as a whole, and as DOE has no data to indicate what conditions 
would be representative for regional representations, DOE has 
tentatively determined not to allow for optional reporting of 
additional efficiency ratings at test conditions other than those found 
in the DOE test procedure.
4. Mixing Valve
    Through a review of product literature, DOE has found consumer 
water heaters on the market that are designed to, or have operational 
modes that, raise the temperature of the stored water significantly 
above the outlet water temperature requirements specified in section 
2.4 of appendix E (i.e., 125 [deg]F 5 [deg]F (51.7 [deg]C 
2.8 [deg]C)). These water heaters are meant to be installed 
with a mixing valve, which may or may not be provided with, or built 
into, the unit, to temper the outlet water to a typical outlet water 
temperature. Generally, raising the temperature of the water in the 
storage tank significantly above the target output temperature (i.e., 
``over-heating'' the water) without the presence of a mixing valve 
would effectively increase the amount of hot water that a given size 
water heater can deliver (e.g., a 50 gallon water heater with an over-
heated storage tank temperature could provide the same amount of hot 
water as an 80 gallon water heater with a more typical storage tank 
temperature). An FHR test performed at an over-heated storage tank 
temperature would result in a higher FHR than a test performed at a 
lower, more typical storage tank temperature. The installation 
instructions in section 4 of appendix E do not address when a separate 
mixing valve should be installed, and the operational mode selection 
instructions in section 5.1 of appendix E do not specifically address 
when the water heater has an operational mode that can over-heat the 
water in the storage tank. However, section 5.1 of appendix E requires 
that the water heater be tested in its default mode, and where a 
default mode is not specified, to test the unit in all modes and rate 
the unit using the results of the most energy-intensive mode.
    The ENERGY STAR program published a Test Method to Validate Demand 
Response \46\ for connected residential water heaters on April 5, 2021 
(ENERGY STAR Connected Test Method). Section 4.1 of the ENERGY STAR 
Connected Test Method, which was developed with input from industry, 
addresses the test setup in which a separate mixing valve is required. 
This setup requires the installing the mixing valve in accordance with 
the water heater and mixing valve manufacturer's instructions. Absent 
instruction from the water heater or mixing valve manufacturer, the 
mixing valve is to be installed in the outlet water line, upstream of 
the outlet water temperature measurement location, with the cold water 
supplied from a tee installed in the inlet water line, downstream of 
the inlet water temperature measurement location (i.e., the mixing 
valve and cold water tee are installed within the inlet and outlet 
water temperature measurement locations). Section 4.1 of the ENERGY 
STAR Connected Test Method further clarifies that if the liquid flow 
rate and/or mass measuring instrumentation is installed on the outlet 
side of the water heater, that it shall be installed after the mixing 
valve.
---------------------------------------------------------------------------

    \46\ The Energy Star Test Method to Validate Demand Response for 
Connected Residential Water Heaters is available at: 
www.energystar.gov/sites/default/files/ENERGY%20STAR%20Connected%20Residential%20Water%20Heaters%20Test%20Method%20to%20Validate%20Demand%20Response_0.pdf.
---------------------------------------------------------------------------

    To accommodate water heaters that are designed to, or have 
operational modes that, raise the temperature of the stored water 
significantly above the outlet water temperature requirements specified 
in section 2.4 of appendix E, DOE proposes to add instructions for the 
installation of a mixing valve similar to what is published in section 
4.1 of the ENERGY STAR Connected Test Method.
5. Mass Measurements
    In appendix E, both section 6.3.2, which provides for the 
computation of the recovery efficiency for gas, oil, and heat pump 
storage-type water heaters, and section 6.4.1, which provides for 
computation of the recovery efficiency for water heaters with rated 
storage volume less than 2 gallons, specify that the total mass of 
water removed (i.e., mass of water that flows through the outlet) from 
the start of the 24-hour simulated-use test to the end of the first 
recovery period (M1) is used to calculate recovery 
efficiency. The test procedure accommodates determining the total mass 
either directly (e.g., through the use of a weighing scale), or 
indirectly by multiplying the total volume removed (V1) 
(i.e., total volume of hot water flow through the outlet) by the 
density of

[[Page 1581]]

water ([rho]1) as determined based on the water temperature 
at the point where the flow volume is measured.\47\
---------------------------------------------------------------------------

    \47\ Although the DOE test procedure does not specify how to 
measure and/or calculate density, it is typically calculated using 
either a regression equation or density tables based on a specific 
temperature and pressure.
---------------------------------------------------------------------------

a. Flow Meter Location
    The current test procedure does not specify where in the flow path 
the flow volume and density must be measured, which allows for 
laboratory test setups that measure the flow volume either on the cold 
inlet side of the water heater or on the hot outlet side. Allowing the 
flow meter to be located on either the inlet or outlet side, and 
calculating the mass of the water that is heated during the test based 
on the density of the water where the flow meter is located, could 
result in differences in the mass of water that is calculated depending 
on whether the flow meter is in the inlet water line or the outlet 
water line. Because the inlet water is colder than at the outlet, it is 
also denser, meaning that the same volume of water has more mass at the 
inlet than the outlet. In addition, some of the mass of inlet water 
could, after being heated, expand out of the water heater into the 
expansion tank and be purged prior to a draw.\48\ Any ``expanded'' 
volume of water that is lost through the by-pass (purge) line could be 
included in a volume measurement taken at the inlet, but not be 
included in a volume measurement taken at the outlet.
---------------------------------------------------------------------------

    \48\ The change in volume occurs because water expands and 
increases in volume as it is heated.
---------------------------------------------------------------------------

    In the April 2020 RFI, DOE requested feedback on whether the 
consumer water heater test procedure should require measurement of flow 
in the outlet water line to ensure that the mass of water removed from 
the tank is accurate. 85 FR 21104, 21113 (April 16, 2020). DOE further 
requested comment on whether requiring the density, [rho]1, 
to be determined based on the outlet temperature, rather than the 
temperature where the flow volume is measured, would alleviate this 
issue. Id. AHRI disagreed with requiring measurement of flow in the 
outlet water line and recommended that measurements be allowed on the 
inlet to ensure greater long-term reliability of the volume or mass 
flow measurement device used. (AHRI, No. 17 at p. 9) Rheem and Rinnai 
opposed requiring measurement of flow in the outlet water line, as they 
believe it is more consistent to measure the inlet. (Rheem, No. 14 at 
pp. 7-8; Rinnai, No. 13 at p. 10) BWC stated that DOE should continue 
to allow manufacturers and laboratories to maintain the option of 
placing a water meter as part of the inlet water piping. (BWC, No. 12 
at p. 5) CSA and Keltech stated that flow rate should be measured at 
the outlet, not the inlet of a water heater. (CSA, No. 10 at p. 7; 
Keltech, No. 7 at p. 1) CSA also stated that measuring water based on 
mass would work and would give the best results since mass is measured 
directly and temperature measurements are not needed; however, CSA 
noted this would require the use of a mass flow meter. CSA stated that 
for labs that do not have a mass flow meter and instead use volume flow 
meters like a magnetic flow meter, the location of the temperature 
sensor to determine the density needs to be specified. (CSA, No. 10 at 
p. 7)
    DOE conducted exploratory testing to evaluate the effect on the 
test results due to differences in recording the water delivered using 
a flow meter at the inlet and outlet of the water heater, compared to 
the mass delivered as measured with a scale. The mass delivered was 
measured directly using Coriolis flow meters and these values were 
compared to the mass measured by the scale. The three different mass 
values were used to determine the UEF and the results are shown in 
Table III.2. Table III.2 shows the measured mass of each draw of the 
24-hour simulated-use test, the root-mean-square deviation \49\ (RMSD) 
of the mass measurements, and the resulting UEF values for each mass 
measurement method used in the calculations. DOE's preliminary testing 
indicates that more accurate measurements of the mass of water 
delivered are obtained at the outlet flow meter as compared to the 
inlet flow meter. The difference in UEF between the outlet flow meter 
and the scale method was 0.002 and 0.016 for gas-fired storage and 
instantaneous water heaters, respectively; whereas the difference in 
UEF between the inlet flow meter and the scale method was 0.023 and 
0.029 for gas-fired storage and instantaneous water heaters, 
respectively.
---------------------------------------------------------------------------

    \49\ RMSD is the square root of the average of squared 
deviations, or differences, between the mass measured by the inlet 
or outlet flow meter and the outlet scale. By using RMSD, any 
``negative'' differences are converted to ``positive,'' which 
provides a more meaningful basis for calculating the average 
deviation from the reference.

        Table III.2--Test Results Using Mass Measured by Inlet and Outlet Flow Meters and an Outlet Scale
----------------------------------------------------------------------------------------------------------------
     Water heater description           Gas-fired storage water heater      Gas-fired instantaneous water heater
----------------------------------------------------------------------------------------------------------------
                                     Inlet flow  Outlet flow     Outlet     Inlet flow  Outlet flow     Outlet
     Mass determination method         meter        meter        scale        meter        meter        scale
----------------------------------------------------------------------------------------------------------------
Resulting UEF.....................        0.641        0.620        0.618        0.820        0.807        0.791
RMSD, lbs.........................         1.97         0.39          N/A         2.67         2.10          N/A
----------------------------------------------------------------------------------------------------------------
Draw                                        lbs          lbs          Lbs          Lbs          lbs          lbs
----------------------------------------------------------------------------------------------------------------
1.................................        222.5        218.7        218.3        223.2        222.0        214.5
----------------------------------------------------------------------------------------------------------------
2.................................         16.3         15.6         15.0         16.1         15.6         13.9
3.................................          8.2          7.7          7.1          7.9          7.7          7.1
4.................................         74.1         72.2         72.3         74.5         73.0         72.8
5.................................        124.9        122.2        121.7        123.4        122.2        121.5
6.................................         41.0         39.6         39.9         41.2         40.8         40.3
7.................................          8.0          7.1          7.1          8.0          7.1          6.6
8.................................          8.1          7.4          7.3          7.7          7.4          6.6
9.................................          8.1          7.3          7.1          8.4          8.0          7.5
10................................         16.3         15.7         15.7         16.4         16.0         15.2
11................................         16.4         15.3         15.2         16.7         16.2         16.1
12................................         16.4         14.7         15.0         16.3         15.5         15.7
13................................         16.7         15.3         15.4         17.1         16.3         16.3
14................................        115.5        111.5        112.2        115.8        113.8        113.5
----------------------------------------------------------------------------------------------------------------


[[Page 1582]]

    The trend from DOE's preliminary test results is consistent with 
CSA and Keltech's comments. However, at this time, the preliminary 
testing is not sufficient for DOE to propose requiring the measurement 
of the mass or volume water at the outlet or at the inlet of the water 
heater. DOE's preliminary results are based on testing only one unit 
each of a gas-fired storage water heater and a gas-fired instantaneous 
water heater. It is not clear that measurements for all water heaters 
would demonstrate a similar impact based on the location of the 
measurement at the outlet versus inlet of the water heater. From DOE's 
testing using third party laboratories, most, if not all, tests are 
conducted with a flow meter installed on the inlet side of the water 
heater. To require water flow to be measured at the outlet may require 
consumer water heaters on the market to be retested without a complete 
understanding of the impact of the change in measurement location. 
Therefore, DOE requests test data comparing the results of testing with 
flow meters installed at the inlet or outlet of the water heater.
b. Mass Calculation
    In sections 6.3.5 and 6.4.2 of appendix E, the mass withdrawn from 
each draw (Mi) is used to calculate the daily energy 
consumption of the heated water at the measured average temperature 
rise across the water heater (QHW). However, neither section 
includes a description of how to calculate the mass withdrawn for tests 
in which the mass is indirectly determined using density and volume 
measurements.
    In the April 2020 RFI, DOE requested feedback on whether to update 
the consumer water heater test procedure to include a description of 
how to calculate the mass withdrawn from each draw in cases where mass 
is indirectly determined using density and volume measurements. 85 FR 
21104, 21113 (April 16, 2020). AHRI recommended including a description 
of how to calculate the mass withdrawn from each draw where mass is 
indirectly determined by using one of the calculations from the AHRI 
Operations Manual for Residential Water Heater Certification Program. 
(AHRI, No. 17 at p. 9) A.O. Smith, Rheem, and Rinnai supported the use 
of the method recommended by AHRI. (A.O. Smith, No. 20 at p. 4; Rheem, 
No. 14 at p. 8; Rinnai, No. 13 at p. 10) BWC stated that DOE should 
update the federal test procedure to include a means to calculate the 
mass withdrawn from each draw in cases where mass removed is determined 
using ratio of the inlet and outlet densities and volume measured on 
the inlet. (BWC, No. 12 at p. 5) Keltech stated that DOE does not need 
to specify the means to collect mass or volume measurements and that 
DOE should only specify the accuracy and tolerance of mass, volume, or 
temperature measurements. (Keltech, No. 7 at p. 1)
    DOE is proposing to specify how mass calculations are made when the 
mass is indirectly determined using density and volume measurements. 
Specifically, DOE proposes that the volume at the outlet would be 
multiplied by the density, which would be based on the average outlet 
temperature measured during the draw. DOE is also proposing to add 
procedures similar to those in the AHRI Operations Manual for 
Residential Water Heater Certification Program; in particular, a method 
of converting inlet water volume to outlet water volume using the ratio 
of the water densities at the inlet and outlet.\50\ In response to 
Keltech's comment, DOE is not proposing to specify the means to collect 
mass or volume measurements. Rather, DOE is specifying how to calculate 
outlet water volume and mass regardless of the means used to collect 
mass or volume measurements.
---------------------------------------------------------------------------

    \50\ The AHRI Operations Manual for Residential Water Heater 
Certification Program specifies that the outlet water volume is 
equal to the inlet water volume times the inlet water density 
divided by the outlet water density.
---------------------------------------------------------------------------

6. Very Small Draw Pattern Flow Rate
    Section 5.4.1 of appendix E states that if the Max GPM is less than 
1.7 gpm (6.4 L/min) that the very small draw pattern be used during the 
24-hour simulated-use test. Section 5.5 of appendix E states that, for 
the very small draw pattern, if the water heater has a Max GPM rating 
less than 1 gpm (3.8 L/min), then all draws shall be implemented at a 
flow rate equal to the rated Max GPM. DOE has identified flow-activated 
water heaters that are designed to deliver water at the set point 
temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C) that is required by section 2.5 of appendix E at a 
flow rate well below 1 gpm (3.8 L/min). For these products, draw 2 of 
the very small draw pattern requires 1 gallon to be removed at the 
rated Max GPM and the pattern requires draw 3 to start five minutes 
after draw 2 initiation. However, any rated Max GPM less than or equal 
to 0.2 gpm (0.76 L/min) will result in draw 2 lasting more than five 
minutes and past the start time of draw 3. To clarify the appropriate 
method of testing these products, DOE proposes to amend the very small 
draw pattern description to state that when a draw extends beyond the 
start time of a subsequent draw, that the subsequent draw will start 
after the required volume of the previous draw has been delivered.
7. Low Temperature Water Heaters
    DOE has identified flow-activated water heaters that are designed 
to deliver water at a temperature below the set point temperature of 
125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C) 
that is required by section 2.5 of appendix E. These water heating 
products are typically marketed as ``handwashing'' or ``POU water'' 
heaters. These units typically have low heating rates, which requires 
the testing agency to reduce the flow rate in order to be able to 
achieve the outlet temperature within the set point temperature range. 
However, these units have a minimum activation flow rate below which 
the unit shuts off. To the extent that a unit would stop heating water 
when the flow rate is too low, there may be no flow rate at which the 
unit would operate and deliver water at the outlet temperature required 
under section 2.5 of appendix E.
    In the April 2020 RFI, DOE requested feedback on whether language 
should be added to section 5.2.2.1 of appendix E, titled, ``Flow-
Activated Water Heaters, including certain instantaneous water heaters 
and certain storage-type water heaters,'' to allow for water heaters 
not designed to deliver water at 125 [deg]F 5 [deg]F (51.7 
[deg]C 2.8 [deg]C) to be tested at a lower set point 
temperature, or whether other changes to the test method need to be 
made to accommodate these types of models (e.g., an additional draw 
pattern, product definition). 85 FR 21104, 21113 (Apr. 16, 2020). AHRI, 
A.O. Smith, CSA, EEI, Keltech, and Rheem recommended that the test 
procedure be modified to include a lower set point temperature to 
accommodate products that are not designed to deliver water at 125 
[deg]F 5 [deg]F. (AHRI, No. 17 at p. 11; A.O. Smith, No. 20 
at p. 5; CSA, No. 10 at p. 8; EEI, No. 8 at p. 4; Keltech, No. 7 at p. 
1; Rheem, No. 14 at p. 9) A.O. Smith further recommended that any 
alternative provisions require testing at the maximum water temperature 
delivery that the model is capable of delivering. (A.O. Smith, No. 20 
at p. 5) CSA and Rheem added that most of these heaters are 
specialized, as some are only used for handwashing or point-of-use 
applications, so they do not need to go through a typical DOE draw 
pattern. (CSA, No. 10 at p. 8; Rheem, No. 14 at p. 9)
    Water heaters that provide water at a maximum temperature lower 
than 125 [deg]F (i.e., ``low temperature'' water heaters) are consumer 
water heaters. To the extent that a ``low temperature'' water heater 
uses electricity as the

[[Page 1583]]

energy source, has a nameplate input rating of 12 kW or less, and 
contains no more than one gallon of water per 4,000 Btu per hour of 
input, it would be an electric instantaneous water heater. 10 CFR 
430.2. The definition of water heater or electric instantaneous water 
heater does not include a minimum water delivery temperature. As 
stated, ``low temperature'' water heaters cannot be tested under the 
current DOE test procedure. To the extent that a consumer water heater 
is not able to heat water to the required set point temperature, the 
manufacturer would be required to petition DOE for a waiver from the 
DOE test procedure and request use of an alternate test procedure 
pursuant to the procedure at 10 CFR 430.27.
    Although DOE has not received any such petitions, to minimize the 
potential need for manufacturers to petition for a test procedure 
waiver, DOE is proposing to define ``low temperature'' water heaters 
and to establish test procedure provisions that specify a lower set 
point temperature for such products. DOE is proposing to define a ``low 
temperature water heater'' as ``an electric instantaneous water heater 
that, is not a circulating water heater and, cannot deliver water at a 
temperature greater than or equal to the set point temperature 
specified in section 2.5 of appendix E to subpart B of this part when 
supplied with water at the supply water temperature specified in 
section 2.3 of appendix E to subpart B of this part.''
    DOE has tentatively determined that lowering the set point 
temperature for ``low temperature'' water heaters to their maximum 
possible delivery temperature would permit these water heaters to be 
tested appropriately and in a manner that would produce representative 
test results. Therefore, DOE proposes to require low temperature water 
heaters to be tested to their maximum possible delivery temperature.
    As stated previously, if a consumer water heater exists that is not 
able to heat water to the required set point temperature, the 
manufacturer would be required to petition DOE for a waiver from the 
DOE test procedure and request use of an alternate test procedure 
pursuant to the procedure at 10 CFR 430.27. If a manufacturer produces 
a consumer water heater that is not able to heat water to the required 
set point temperature but does not meet the definition of a ``low 
temperature water heater'' as proposed in this document, the 
manufacturer should petition DOE for a waiver for that model.
8. Heat Pump Water Heater Heaters
a. Controls
    As discussed in section III.A.1.a, in the present market, a 
consumer heat pump water heater typically consists of an air-source 
heat pump and a storage tank that are integrated together into one 
assembly. This ``typical'' consumer heat pump water heater uses 
electricity and has backup resistance elements within the storage tank. 
Heating water with the heat pump components is more efficient than 
heating water with the backup resistance elements. Therefore, water 
heaters with controls that prioritize heat pump water heating over 
resistance element water heating will operate more efficiently than 
water heaters that do not prioritize heat pump water heating or that do 
not prioritize heat pump water heating to the same extent.
    In response to the April 2020 RFI, the Joint Advocates suggested 
modifying the test procedure to reflect the effectiveness of controls 
in minimizing use of the resistance element in heat pump water heaters, 
stating this modification would improve the representativeness of the 
test procedure and create new incentives for manufacturers to develop 
products that provide increased savings for consumers. (Joint 
Advocates, No. 15 at p. 2) No suggestion was provided on how to better 
reflect the use of controls to minimize element usage.
    DOE's test data shows that for most (or possibly all) heat pump 
water heater models available on the market currently, electric 
elements do not turn on during the 24-hour simulated-use test. Although 
element usage during the test could be forced through a more aggressive 
draw pattern (i.e., longer or more frequent draws designed to deplete 
the water heater and require more hot water than the heat pump alone 
could keep up with), the draw patterns are required to be 
representative of actual use. Therefore, designing the draw pattern 
with the goal of forcing resistance element use would not be 
representative of typical use, and DOE has tentatively determined not 
to modify the test procedure to activate the use of electric resistance 
elements in heat pump water heaters during testing.
b. Split-System Heat Pump Water Heaters
    In response to the April 2020 RFI, the Joint Advocates and NEEA 
recommended that DOE investigate the inclusion of niche products, such 
as split system heat pumps, within appendix E. (Joint Advocates, No. 15 
at p. 3; NEEA, No. 21 at p. 3) In a split system heat pump, the heat 
pump part of the system is typically installed outdoors. The storage 
tank part of the system is typically installed indoors and does not use 
the ambient air for water heating directly. As discussed in section 
III.C.3.b, different ambient conditions are specified in appendix E for 
heat pump water heaters and non-heat pump water heaters. For split 
system heat pump water heaters, DOE is proposing to specify that the 
heat pump part of the system shall be tested using the heat pump water 
heater dry bulb temperature and relative humidity requirements, while 
the storage tank part of the system shall be tested using the non-heat 
pump water heater ambient temperature and relative humidity 
requirements. DOE notes that the required non-heat pump water heater 
ambient conditions can be met by keeping the entire system within the 
dry bulb temperature and relative humidity requirements for heat pump 
water heaters (i.e., both parts of the system can be tested in the same 
psychrometric chamber).
c. Heat Pump Only Water Heaters
    As discussed in section III.A.1.a, certain heat pump water heaters 
are sold that consist of only a heat pump (i.e., heat pump only water 
heater). These heat pump only water heaters require the use of a 
separate storage tank to properly operate. The current DOE test 
procedure does not have procedures in place to appropriately test these 
water heaters.
    In a final rule published October 17, 1990, DOE established test 
procedures that included a description of how to test heat pump water 
heaters sold without a storage tank. 55 FR 42162, 42173. These 
procedures were updated in the May 1998 final rule and included testing 
the heat pump water heater with an electric storage water heater having 
a measured volume of 47 gallons 1.0 gallons (178 liters 
3.8 liters); two 4.5 kW heating elements controlled in such 
a manner as to prevent both elements from operating simultaneously; and 
a rated efficiency at or near the minimum energy conservation standard. 
63 FR 25996, 26011 (May 11, 1998).
    DOE published the April 2010 final rule based on an evaluation of 
heat pump only water heaters available on the market. 75 FR 20112 
(April 16, 2010). DOE determined such water heaters do not meet EPCA's 
definition of a ``water heater'' and are not covered products. Id. at 
75 FR 20127. The products that provided the basis for DOE's 
determination were characterized as add-on heat pump water heaters. Id. 
In a NOPR that preceded the April 2010 final rule, DOE stated that add-
on heat pump water heaters are typically

[[Page 1584]]

marketed and used as an add-on component to a separately manufactured, 
fully functioning electric storage water heater. 74 FR 65852, 65865 
(Dec. 11, 2009). DOE further stated that the add-on unit consists of a 
small pump and a heat pump system. Id. In the products considered by 
DOE, the pump circulates refrigerant from the water heater storage tank 
through the heat pump system and back into the tank, while the heat 
pump extracts heat from the surrounding air and transfers it to the 
refrigerant. Id. The add-on units evaluated for DOE's determination 
cannot by themselves provide hot water on demand, but rather heat water 
only when operated in conjunction with a storage water heater. Id. DOE 
also stated that manufacturers do not ship add-on heat pump water 
heaters as self-contained, fully functioning water heaters or paired 
with a storage tank, and that the add-on device, by itself, is not 
capable of heating water and lacks much of the equipment necessary to 
operate as a water heater. Id. The test procedures addressing heat pump 
water heaters that are sold without a storage tank were removed in the 
July 2014 final rule, due to the previous determination that add-on 
heat pump water heaters are not covered products. 79 FR 40542, 40547 
(July 11, 2014).
    A review of the current market has identified certain heat pump 
only water heaters that operate differently than the add-on heat pump 
water heaters that were examined during the April 2010 final rule. 
Certain heat pump only water heaters are used in conjunction with a 
separately sold unfired hot water storage tank or backup storage water 
heater and extract ``cold'' water from the tank, heat the water 
directly using the ambient air as the heat source, and return water at 
a slightly higher temperature to the storage tank or backup heater. In 
contrast to the add-on heat pump water heaters previously examined in 
the April 2010 Final Rule, these heat pump only water heaters heat 
water directly. Currently, testing these heat pump only water heaters 
to appendix E is not possible because they are unable to heat water to 
the required set point temperature on demand. These products require 
the use of a separately sold storage tank and gradually increase the 
temperature of the stored water to the required outlet temperature.
    Because of the differences with certain heat pump only water 
heaters currently on the market as compared to the add-on heat pump 
water heaters that provided the basis for DOE's prior determination, 
DOE has tentatively determined that certain heat pump only water 
heaters are covered products. As discussed in section III.A.1.a, DOE is 
proposing a definition for ``circulating water heater,'' which covers 
heat pump only water heaters, and that procedures to test these 
products should be included in appendix E.
    As stated previously, a 47-gallon electric storage water heater 
that uses electric resistance elements and that has a rated efficiency 
at or near the minimum energy conservation standard was previously 
required when testing the test procedures prior to the July 2014 final 
rule. Consistent with DOE's prior approach to testing heat pump only 
water heaters, DOE is proposing testing with a standard storage tank. 
Through testing of integrated heat pump water heaters,\51\ DOE has 
observed that the electric resistance elements do not turn on during 
the 24-hour simulated-use test. Therefore, DOE is not proposing to 
require backup heating (i.e., electric resistance elements) within the 
standard storage tank, as the backup heating would likely not operate 
during the test. DOE reviewed the CCMS database for unfired hot water 
storage tanks \52\ and found that several manufacturers produce 80-
gallon unfired hot water storage tanks, while no manufacturers produce 
a 47-gallon unfired hot water storage tank. DOE is proposing that the 
storage tank to be used with a heat pump only water heater would be an 
80 gallon 1 gallon unfired hot water storage tank that 
meets the energy conservation standards for an unfired hot water 
storage tank at 10 CFR 431.110(a).\53\ DOE requests comment on the 
approach of using a standard storage tank for testing heat pump only 
water heaters and whether there are other procedures that are not 
burdensome to conduct and that are representative of actual use.
---------------------------------------------------------------------------

    \51\ Integrated heat pump water heaters are discussed in section 
III.C.8.a and represent the ``typical'' heat pump water heater 
available on the market, in which the storage tank and heat pump are 
combined (integrated) into one assembly. The integrated heat pump 
water heaters on the market typically have electric resistance 
elements installed in the tank for supplementary heating when the 
heat pump alone cannot provide enough hot water. The residential 
application of an integrated heat pump water heater and a heat pump 
only water heater combined with a separately sold storage tank are 
similar.
    \52\ The CCMS database for unfired hot water storage tanks is 
available at: www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A*.
    \53\ Currently unfired hot water storage tanks must have a 
minimum thermal insulation of R-12.5.
---------------------------------------------------------------------------

    Were DOE to establish a test procedure for heat pump only water 
heaters, such water heaters would not be subject to energy conservation 
standards until such a time that DOE addressed such products in an 
energy conservation standard rulemaking.
9. Circulating Gas-Fired Water Heaters
    As described in section III.A.1.c, several manufacturers produce 
``circulating'' consumer gas-fired instantaneous water heaters that are 
designed to be used with a volume of stored water (usually in a tank, 
but sometimes within a recirculating hot water system of sufficient 
volume, such as a hydronic space heating or designated hot water 
system) in which the water heater does not directly provide hot water 
to fixtures, such as a faucet or shower head, but rather replenishes 
heat lost from the tank or system through hot water draws or standby 
losses. In section III.A.1.c, DOE tentatively determined that these 
water heaters are ``covered products'' under the ``water heater'' 
definition and proposed a definition for ``circulating water heaters'' 
to be included at 10 CFR 430.2.
    In the April 2020 RFI, DOE requested feedback on what changes to 
the consumer water heater test procedure may be necessary to 
appropriately test circulating gas-fired instantaneous water heaters. 
DOE also requested feedback on whether there is an industry standard 
that would allow for testing of circulating gas-fired instantaneous 
water heaters that would provide results representative of the energy 
use of these products for an average use cycle or period of use. 85 FR 
21104, 21113 (April 16, 2020). AHRI, Rinnai, and Rheem recommended 
using DOE's commercial water heater test procedure, which references 
parts of ANSI Z21.10.3-2015/CSA 4.3-2015 (ANSI Z21.10.3-2015), ``Gas-
fired water heaters, volume III, storage water heaters with input 
ratings above 75,000 Btu per hour, circulating and instantaneous.'' 
(AHRI, No. 17 at p. 11; Rheem, No. 14 at p. 8; Rinnai, No. 13 at p. 10-
11) Additionally, AHRI suggested that if DOE declines to modify the 
definition and retains circulating gas-fired instantaneous water 
heaters within scope of this test procedure, then DOE should consider 
adopting the thermal efficiency commercial test procedure and metric 
for these products. (AHRI, No. 17 at p. 11)
    As stated previously in section III.A.1.c, DOE has tentatively 
determined that circulating water heaters are consumer water heaters 
and would be covered by DOE's test procedures for consumer water 
heaters. Congress, through 42 U.S.C. 6295(e)(5)(B), directed DOE to 
establish a ``uniform efficiency descriptor'' as the required metric 
for consumer water heaters. This ``uniform efficiency

[[Page 1585]]

descriptor'' was established during the July 2014 final rule and is the 
UEF metric. DOE may exclude a specific category of covered water 
heaters from the uniform energy descriptor established by DOE if DOE 
determines that the category of water heaters does not have a 
residential use and can be clearly described in the final rule, and is 
effectively rated using the thermal efficiency and standby loss 
descriptors applied to the category as of December 18, 2012, as a 
commercial water heater. 42 U.S.C. 6295(e)(5)(F) As stated previously, 
DOE has tentatively determined that circulating water heaters have a 
residential use. As such, to the extent that circulating water heaters 
are consumer water heaters, they would be subject to an energy 
conservation standard using the UEF metric.
    Similar to heat pump only water heaters described in section 
III.C.8.c, circulating water heaters operate with a separate storage 
tank. Therefore, DOE has tentatively determined that, as proposed for 
heat pump only water heaters, circulating water heaters would be tested 
with an 80 gallon  1 gallon unfired hot water storage tank 
that meets the energy conservation standards for an unfired hot water 
storage tank at 10 CFR 431.110(a). DOE requests comment on the approach 
of using a standard storage tank for testing circulating water heaters 
and whether there are other procedures that are not unduly burdensome 
to conduct and that are representative of actual use.
10. Solar Water Heaters
    In response to an RFI published on May 21, 2020 (May 2020 RFI), 
regarding the energy conservation standards for consumer water heaters 
(85 FR 30853), the Solar Rating & Certification Corporation 
(``(SRCC'')) recommended that solar water heating technologies be 
considered for inclusion in the DOE energy conservation standards and 
test procedures for consumer water heaters. SRCC stated that without 
the involvement of DOE, the industry metrics struggle to gain 
acceptance with policymakers and consumers. SRCC also stated that DOE 
rulemakings to include solar-equipped water heaters in regulations 
would serve to establish a single performance metric and signal the 
legitimacy of solar water heating technologies. (Docket: EERE-2017-BT-
STD-0019, SRCC, No. 11 at pp. 3-4) On October 7, 2020, SRCC published a 
draft test procedure titled, ``Solar Uniform Energy Factor Procedure 
for Solar Water Heating Systems.'' \54\ The draft SRCC test procedure 
addresses methods to test different types of solar water heaters.
---------------------------------------------------------------------------

    \54\ SRCC's draft Solar Uniform Energy Factor Procedure for 
Solar Water Heating Systems is available at: www.iccsafe.org/wp-content/uploads/is_stsc/Solar-UEF-Specification-for-Rating-Solar-Water-Heating-Systems-20201012.pdf.
---------------------------------------------------------------------------

    On April 8, 2015, DOE published an energy conservation standards 
NOPR addressing definitions for consumer water heaters. 80 FR 18784. In 
particular, DOE proposed definitions for ``solar-assisted fossil fuel 
storage water heater'' and ``solar-assisted electric storage water 
heater'' and clarified that water heaters meeting these definitions are 
not subject to the amended energy conservation standards for consumer 
water heaters established by the April 2010 final rule. Id. at 80 FR 
18789. DOE has tentatively determined to address solar water heaters in 
a separate rulemaking.
11. Connected Water Heaters
    On September 17, 2018, DOE published an RFI seeking information on 
the emerging smart technology appliance and equipment market. 83 FR 
46886 (September 2018 RFI). In the September 2018 RFI, DOE sought 
information to better understand market trends and issues in the 
emerging market for appliances and commercial equipment that 
incorporate smart technology. Id. at 83 FR 46887. DOE's intent in 
issuing the September 2018 RFI was to ensure that DOE did not 
inadvertently impede such innovation in fulfilling its statutory 
obligations in setting efficiency standards for covered products and 
equipment. Id. In the April 2020 RFI, DOE sought comment on the same 
issues presented in the September 2018 RFI as they may be applicable to 
consumer water heaters.
    EEI stated that DOE should update the test procedure to better 
capture the performance difference between traditional and ``smart'' 
water heaters by including subcategories for non-connected,\55\ 
connected,\56\ and disconnected water heaters; \57\ and provided 
recommended definitions for these categories. EEI further stated that 
during testing, ``connected'' water heaters should be disconnected from 
their external networks so that their UEF values can be compared on an 
equivalent basis with ``non-connected'' water heaters. (EEI, No. 8 at 
p. 2) NEEA commented that DOE should allow optional reporting of demand 
response \58\ capability in CCMS. (NEEA, No. 21 at pp. 2-3) Similarly, 
in the May 2020 RFI, SRCC recommended that DOE consider adding a 
thermal energy storage \59\ metric to the current test method. SRCC 
stated that in its simplest form, the metric could simply involve the 
calculation of the energy contained in water heated from the entering 
water temperature to the maximum operating temperature for the tank. 
According to SRCC, the metric could be accomplished using no additional 
testing and could help to spur the use of thermal energy storage and 
demand response in the context of consumer and commercial storage water 
heaters and unfired tanks. (Docket: EERE-2017-BT-STD-0019, SRCC, No. 11 
at p. 5-6)
---------------------------------------------------------------------------

    \55\ EEI proposed to define non-connected water heaters as 
traditional water heaters that do not have ``smart'' features and 
cannot connect to any external network or device.
    \56\ EEI proposed to define connected water heaters as ``smart'' 
water heaters (that are not already categorized as grid-enabled 
water heaters) that connect to smart home networks and/or smart 
devices (home assistant speakers, smart phones, etc.) and/or 
external networks such as those provided by a local energy company.
    \57\ EEI proposed to define disconnected water heaters (for test 
procedures only) as ``smart'' water heaters (that are not already 
categorized as grid-enabled water heaters) that have the ability to 
disconnect from smart home networks and/or smart devices (home 
assistant speakers, smart phones, etc.) and/or external networks 
based on user command or as a ``default'' mode if it detects 
problems with the communication network.
    \58\ Demand response refers to changes in electric or gas usage 
from the normal consumption patterns in response to changes in the 
price of electricity or gas over time, or to incentive payments 
designed to induce lower electricity or gas use at times of high 
wholesale market prices or when system reliability is jeopardized.
    \59\ Thermal energy storage is important to demand response 
programs, as the water that is heated during off-peak times must be 
kept heated and ready for use when the consumer desires hot water.
---------------------------------------------------------------------------

    Section 5.1 of appendix E specifies the operational mode selection 
for water heaters, but does not explicitly address ``smart'' or 
``connected'' modes of operation. For water heaters that allow for 
multiple user-selected operational modes, all procedures specified in 
appendix E must be carried out with the water heater in the same 
operational mode (i.e., only one mode). Section 5.1 of appendix E. This 
operational mode must be the default mode (or similarly named, 
suggested mode for normal operation) as defined by the manufacturer in 
its product literature for giving selection guidance to the consumer. 
Id.
    DOE is proposing to explicitly state that any connection to an 
external network or control would be disconnected during testing. While 
DOE recognizes that connected water heaters are on the market with 
varying implementations of connected features, DOE is not aware of any 
data available, nor did interested parties provide any such data, 
regarding the consumer use of connected features. Absent such data,

[[Page 1586]]

DOE is unable to develop a representative test configuration for 
assessing the energy consumption of connected functionality for water 
heaters.
    Furthermore, while acknowledging the potential benefits that could 
be provided by connected capability, such as providing energy saving 
benefits to consumers and enabling peak load shifting on the grid, DOE 
believes that requiring measurement of the energy consumed by connected 
features at this time may prematurely hinder the development and 
incorporation of such features in water heaters. While grid management 
programs have existed for many years, demand response capability is 
rapidly evolving. Therefore, DOE has tentatively determined that, at 
this time, any regulation on its part to address these products may 
harm the evolution of this market.
    DOE acknowledges that storage-type water heaters are useful thermal 
energy storage devices that can help save consumers money and help 
utilities manage the grid by heating up the water in the tank during 
non-peak times. However, the technology required to operate within a 
demand response program is not available on most consumer water heaters 
and the available thermal energy of the tank can be determined using 
the already available rated storage volume metric. Further, DOE notes 
that a thermal energy storage metric would be most useful to utilities 
operating demand response programs. These utilities are regionally 
located and can therefore make better assumptions about water heating 
conditions, such as supply water temperature and ambient temperature, 
as compared to a national average of these conditions, which are used 
in the DOE test procedure. Therefore, DOE has tentatively determined 
not to add a thermal energy storage metric to the DOE test procedure at 
this time.
    As DOE is not proposing test procedures specific to connected water 
heaters, separate definitions would not be needed to identify non-
connected, connected, and disconnected water heaters.
12. Drain Down Test Method
    Section 4.5 of appendix E provides the procedure for measuring the 
internal storage tank temperature for water heaters with a rated 
storage volume at or above 2 gallons. Section 4.5 of appendix E 
specifies that the thermocouples be inserted into the storage tank of a 
water heater through either the anodic device opening, the temperature 
and pressure relief valve, or the outlet water line. DOE has identified 
consumer water heaters with physical attributes that make measuring 
internal storage tank temperature difficult, such as water heaters that 
have a built-in mixing valve and no anodic device, or have a large heat 
exchanger that does not accommodate insertion of a thermocouple tree.
    In the April 2020 RFI, DOE requested comment on whether amendments 
to the water heater test procedure are needed to address water heaters 
that cannot have their internal storage tank temperatures measured as 
required by the test procedure. 85 FR 21104, 21114 (April 16, 2020). In 
response, CA IOUs recommended that DOE not amend the test procedure to 
address water heaters for which it is impossible to measure internal 
storage tank temperatures. (CA IOUs, No. 18 at p. 4) Rheem stated its 
support of such amendments and recommended a drain down method, whereby 
the entire volume would be removed and the temperature measured at the 
end of the 24-hour test. (Rheem, No. 14 at p. 9) BWC agreed such 
amendments were necessary and suggested a framework for a procedure to 
address water heaters that cannot have their internal storage tank 
temperatures measured that would involve: (1) After the FHR test, 
purging the water heater with inlet water at 58 [deg]F 2 
[deg]F to establish the mean tank temperature at the beginning of the 
24-hour simulated-use test; (2) allowing the water heater to heat up to 
the original thermostat setting and recording the energy used to do so; 
(3) running the appropriate draw pattern, then fully draining the water 
heater by gravity, while measuring the mass and temperature of the 
water; and (4) calculating the energy change as: energy change = mass x 
specific heat x the difference between the average end temperature and 
the beginning temperature just after the 58 [deg]F purge. (BWC, No. 12 
at p. 5)
    Throughout the 24-hour simulated-use test, internal tank 
thermocouples are used to determine the mean tank temperature. Mean 
tank temperatures are required at the start and end of the test, the 
start and end of the standby period, and the after the first recovery 
period (i.e., T0, T24, Tsu,0, 
Tsu,f, and Tmax,1, respectively). Also, an 
average mean tank temperature throughout the standby period is required 
(i.e., Tt,stby,1). The procedures recommended by BWC and 
Rheem could provide an estimate of the mean tank temperature at the 
start and end of the 24-hour simulated-use test but would not provide 
an estimate at the end of the first recovery period, the start and end 
of the standby period, or an average over the standby period. To 
provide for determining the mean tank temperature at each required 
stage, DOE proposes an amended version of the procedure suggested by 
BWC. DOE is proposing the following procedure for water heaters that 
cannot accommodate a thermocouple tree:

    1. Allow the water heater to finish any recovery it is 
undergoing.
    2. Wait 1 hour, during which time the water heater sits idle 
without any water draws or energy used for heating water.
    3. Begin the first draw of the appropriate draw pattern. Record 
the inlet and outlet water temperatures 5 seconds after the 
initiation of the first draw. The mean tank temperature at the start 
of the test, T0, is the average of the inlet and outlet temperature 
measurements.
    4. At the end of the first draw, record the inlet and outlet 
water temperatures. The maximum mean tank temperature after the 
first recovery period, Tmax,1, is the average of the inlet and 
outlet temperature measurements.
    5. Continue with the appropriate draw pattern.
    6. At the end of the last draw of the first draw cluster, record 
the inlet and outlet water temperatures. The mean tank temperature 
after the start of the standby period, Tsu,0, is the average of the 
inlet and outlet temperature measurements.
    7. Continue with the appropriate draw pattern.
    8. Begin the first draw of the second draw cluster. Record the 
inlet and outlet water temperatures 5 seconds after the initiation 
of the first draw. The mean tank temperature at the end of the 
standby period, Tsu,f, is the average of the inlet and outlet 
temperature measurements.
    9. The average mean tank temperature over the standby period, 
Tt,stby,1, is the average of mean tank temperatures at the start and 
end of the standby period.
    10. Continue with the appropriate draw pattern.
    11. At hour 24, initiate a draw at the flow rate of the first 
draw of the draw pattern that the water heater was tested. The mean 
tank temperature at hour 24 (T24) is the average of the inlet and 
outlet water temperatures measured 5 seconds after the start of the 
draw.

    The proposed drain down test would estimate the mean tank 
temperature based on the inlet and outlet water temperature at the 
start or end of the draw. This assumes that the temperature of the 
stored water gradually (i.e., linearly) increases in temperature either 
from the bottom of the tank to the top, or the further the water is 
into the heat exchanger from the water inlet, depending on the design 
of the water heater being tested. As the exact internal dimensions of 
the storage tank or heat exchanger in relation to the location of the 
heat source cannot be known for every water heater, the linear

[[Page 1587]]

assumption is the most representative of the water heater market as a 
whole.
13. Alternate Order 24-Hour Simulated-Use Test
    In response to the April 2020 RFI, SMTI recommended that DOE move 
the standby loss period of the test to the beginning of the 24-hour 
simulated-use test and to start the first draw at the 6-hour mark, 
asserting that doing so would increase the accuracy and repeatability 
of the test, and would decrease burden by eliminating the possibility 
of having to extend the 24-hour simulated-use test. (SMTI, No. 19 at p. 
2) SMTI further asserted that the calculation for recovery efficiency 
can provide an artificially low value for water heaters with high 
storage volume and low input rates such as heat pump water heaters. For 
these water heaters, SMTI stated that the first recovery period could 
be delayed well past the start of the test, during which time the water 
heater would use a significant amount of energy in standby (e.g., 
controls and auxiliary components) and would lose a signification 
amount of energy through standby losses. SMTI asserted that when 
initiating the 24-hour simulated-use test with a 6-hour standby period, 
the energy use and tank temperatures for the recovery efficiency 
calculation would occur at 6 hours into the test (after completion of 
the standby period), and the recovery efficiency calculation error 
would be somewhat reduced based on the assumption that the first 
recovery would begin closer to the first draw, given that 6 hours of 
standby losses would have already accrued. (Id. at pp. 4-5)
    As stated in section III.B.2.d, UA (the result of the standby 
period) has a negligible effect on UEF. Therefore, moving the standby 
period to the start of test would have a negligible effect on UEF in 
terms of improving the accuracy of the standby loss calculations. 
However, moving the standby period to the start of the test may have an 
effect on the recovery efficiency of large volume low input rate water 
heaters described by SMTI, and a large change in recovery efficiency 
can have a significant effect on UEF. From a review of DOE's available 
test data, the first recovery is rarely delayed past the first draw. If 
DOE were to adopt this alternate order 24-hour simulated-use test, all 
water heaters on the market would need to be retested. Therefore, DOE 
is not proposing to move the standby period to the start of the 24-hour 
simulated-use test, as the resulting burden to manufacturers to retest 
would result in a potential increase in accuracy for only a small 
subset of the consumer water heaters available on the market.
14. Untested Provisions
    At 10 CFR 429.70, DOE specifies alternative methods for determining 
energy efficiency and energy use for certain covered products and 
equipment, including consumer water heaters.\60\ In general, these 
provisions allow a manufacturer to determine the energy efficiency or 
energy use of a basic model using an alternative efficiency 
determination method (AEDM) in lieu of actually testing the basic 
model. Specific to each product or equipment type covered by these AEDM 
provisions, DOE defines the criteria for using an AEDM and, for some 
products and equipment, procedures to be used to validate an AEDM and 
to perform verification testing on units certified using an AEDM.
---------------------------------------------------------------------------

    \60\ Section 429.71 uses the term ``residential'', which is 
synonymous with the use of the term ``consumer'' in this document.
---------------------------------------------------------------------------

    The provisions at 10 CFR 429.70(g) provide alternative methods for 
determining ratings for ``untested'' basic models of residential water 
heaters and residential-duty commercial water heaters. For models of 
water heaters that differ only in fuel type or power input, these 
provisions allow manufacturers to establish ratings for untested basic 
models based on the ratings of tested basic models if certain 
prescribed requirements are met. (Simulations or other modeling 
predictions or ratings of UEF, volume, first-hour rating, or maximum 
gallons per minute are not permitted (10 CFR 429.70(g))).
    Specifically, for gas water heaters, the provisions at 10 CFR 
429.70(g)(1) specify that for untested basic models of gas-fired water 
heaters that differ from tested basic models only in whether the basic 
models use natural gas or propane gas, the represented value of UEF, 
FHR, and maximum gallons per minute for an untested basic model can be 
the same as those for a tested basic model, as long as the input 
ratings of the tested and untested basic models are within 10 percent.
    For electric storage water heaters, the provisions at 10 CFR 
429.70(g)(2) specify rating an untested basic model using the FHR and 
the UEF obtained from a tested basic model as a basis for ratings of 
basic models with other input ratings, provided that certain conditions 
are met: (1) Each heating element of the untested basic model is rated 
at or above the input rating for the corresponding heating element of 
the tested basic model; and (2) for an untested basic model having any 
heating element with an input rating that is lower than that of the 
corresponding heating element in the tested basic model, the FHR for 
the untested basic model must result in the same draw pattern specified 
in Table I of appendix E for the simulated-use test as was applied to 
the tested basic model.\61\ 10 CFR 429.70(g)(2)(i)-(ii)
---------------------------------------------------------------------------

    \61\ To establish whether this condition is met, the provisions 
at 10 CFR 429.70(g)(2)(ii) specify determining the FHR for the 
tested and the untested basic models in accordance with the 
procedure described in section 5.3.3 of 10 CFR part 430, subpart B, 
appendix E, and then comparing the appropriate draw pattern 
specified in Table I of appendix E for the FHR of the tested basic 
model with that for the untested basic model. If this condition is 
not met, then the untested basic model must be tested and the 
appropriate sampling provisions applied to determine its UEF in 
accordance with appendix E.
---------------------------------------------------------------------------

    As discussed previously, for certain products or equipment types 
for which the use of an AEDM is authorized, DOE prescribes procedures 
to be used to validate the AEDM and/or to perform verification testing 
on units certified using an AEDM. For consumer water heaters, however, 
DOE does not currently prescribe procedures to validate the alternative 
rating method or to perform verification testing of untested basic 
models that are certified using the provisions at 10 CFR 429.70(g).
    The following sections discuss representations of the FHR value of 
certain untested models; consideration of extending the alternative 
rating method to electric instantaneous type water heaters; and 
proposed methods for verifying the ratings of untested models of water 
heaters.
a. Representations of FHR
    As discussed previously, the provisions at 10 CFR 429.70(g) allow 
for an untested electric storage water heater basic model with element 
wattages less than a tested basic model to use the FHR of the tested 
basic model, provided that the untested basic model's FHR is in the 
same draw pattern as the tested basic model. For an untested basic 
model with an element wattage that is lower than the tested basic 
model's, the tested FHR of the untested basic model will generally be 
less than the FHR of the tested basic model. In such cases, using the 
tested basic model's FHR to represent the untested model's FHR may not 
be as representative as using the FHR value directly determined from 
the untested model (the FHR of the untested basic model is determined 
pursuant to the procedures in appendix E specifically for the purpose 
of allowing use of the tested basic model's UEF rating). Instead, using 
the untested basic model's measured FHR for

[[Page 1588]]

representation purposes, rather than the tested model's FHR (as 
currently required), could increase the representativeness of the 
certified FHR, while potentially not increasing burden on the 
manufacturer. DOE, therefore, is requesting comment on the potential to 
revise the existing provisions at 10 CFR 429.70(g)(2)(ii) for electric 
storage water heaters with element wattages less than the tested basic 
model to require that the represented FHR of the untested model be the 
untested basic model's FHR as determined according to the procedures at 
appendix E. Specifically, DOE is seeking information on whether 
manufacturers collect sufficient data to establish a rated value of FHR 
based on FHR testing for untested basic models, subject to the sampling 
plan requirements at 10 CFR 429.17 (i.e., whether manufacturers 
currently measure the FHR of at least two units of an untested basic 
model to ensure it is in the same draw pattern bin as the tested 
model).
    As discussed in section III.C.14.b, DOE is proposing to adopt 
provisions for rating untested electric instantaneous water heaters in 
a manner similar to that currently allowed for electric storage water 
heaters. Correspondingly, DOE is also requesting comment on a proposal 
to require, for untested models of electric instantaneous water heaters 
with an input rating less than the tested model, that the represented 
maximum GPM value for the untested model be the actual value as 
determined for the untested model according to appendix E and the 
sampling plan requirements at 10 CFR 429.17. The represented UEF of the 
untested model still would match that of the tested basic model.
    Should DOE amend the method for determining the represented value 
of FHR or maximum GPM for certain untested basic models of electric 
water heaters, such a change could be required beginning with the 
annual filing of certification reports following the effective date of 
any change. Manufacturers of consumer water heaters are required to 
submit an annual filing for covered basic models by May 1 of each year. 
10 CFR 429.12(d).
b. Alternative Rating Method for Instantaneous Water Heaters
    As described previously, the provisions at 10 CFR 429.70(g) allow 
manufacturers to apply ratings for a tested basic model to untested 
basic models of gas water heaters and electric storage water heaters if 
certain prescribed requirements are met. In response to the April 2020 
RFI, A.O. Smith suggested that DOE consider extending the untested 
provisions in 10 CFR 429.70(g) to consumer and residential[hyphen]duty 
electric instantaneous water heaters. (A.O. Smith, No. 20 at p. 5)
    As discussed, untested electric storage water heater basic models 
are currently allowed to use the same FHR and UEF rating as a tested 
basic model, provided that one of the following two criteria are met: 
(1) Each heating element of the untested basic model is rated at or 
above the input rating for the corresponding heating element of the 
tested basic model; or (2) a tested FHR for the untested basic model 
with a lower input rating must result in the same draw pattern as the 
tested basic model. 10 CFR 429.70(g)(2).
    Regarding the first criteria, the untested provisions for electric 
storage water heaters at 10 CFR 429.70(g)(2) allow an untested basic 
model to be rated the same as a tested basic model if each heating 
element of the untested basic model is rated at or above the input 
rating for the corresponding heating element of the tested basic model. 
DOE notes that as the input rate of a water heater increases, so too 
does the amount of hot water that it can deliver; and the more hot 
water the water heater can deliver, the higher the draw pattern that is 
required during the 24-hour simulated-use test. In general, for a given 
water heater, a higher draw pattern correlates with higher UEF results; 
conversely, a smaller draw pattern corresponds with lower UEF results. 
(DOE has found through its own testing that this trend holds for 
electric instantaneous water heaters in addition to storage water 
heaters.) As a result, higher input rates generally correlate with 
higher UEF values. Because higher input rates generally correlate with 
higher UEF values (due to a change in draw pattern, as described), an 
untested basic model with an input rate higher than the tested basic 
model is generally considered to be conservatively rated.
    Regarding the second criteria, the untested provisions for electric 
storage water heaters at 10 CFR 429.70(g)(2) allow an untested basic 
model to be rated the same as a tested basic model if any heating 
element has in input rating lower than that of the corresponding 
heating element in the tested basic model and the tested FHR for the 
untested basic model results in the same draw pattern as that of the 
tested basic model.\62\ This requirement ensures that the UEF rating 
applied to the untested basic model is representative.
---------------------------------------------------------------------------

    \62\ Determining the applicable draw pattern for an untested 
model in this case requires performing the FHR test on the untested 
model and determining the draw pattern using Table I in section 
5.4.1 of appendix E.
---------------------------------------------------------------------------

    Because instantaneous water heaters exhibit the same trends in 
performance that justify the use of an alternative rating determination 
method for electric storage water heaters, DOE has tentatively 
determined that extending the use of the untested provisions to 
electric instantaneous water heaters in 10 CFR 429.70(g) would maintain 
a representative rating of these products' energy efficiency, while 
reducing manufacturer burden. Therefore, DOE is proposing to permit use 
of the untested provisions for electric instantaneous water heaters 
through newly proposed provisions at 10 CFR 429.70(g)(3). DOE is 
proposing that the criteria that currently apply to electric storage 
water heaters at 10 CFR 429.70(g)(2) would apply to electric 
instantaneous type water heaters at 10 CFR 429.70(g)(3), with the 
exceptions that: (1) The criteria for electric instantaneous water 
heaters would reference the maximum GPM rather than the FHR, as FHR 
applies only to storage water heaters; and (2) the criteria for 
electric instantaneous water heaters would reference the ``input rate'' 
rather than the ``heating element'' or ``input rating for the 
corresponding heating element''.
    DOE has tentatively determined that extending the untested 
provisions in 10 CFR 429.70(g) to electric instantaneous water heaters 
would reduce manufacturer burden, as many basic models would not 
require testing, while maintaining an accurate representation of these 
products actual efficiency. Therefore, DOE is proposing to permit use 
of the untested provisions for electric instantaneous water heaters. 
DOE seeks comment on the proposal to establish provisions for rating 
untested basic models of electric instantaneous water heaters at 10 CFR 
420.70(g)(3) that are analogous to the existing provisions for rating 
untested basic models of electric storage water heaters at 10 CFR 
429.70(g)(2).

D. Reporting

    Manufacturers, including importers, must use product-specific 
certification templates \63\ to certify compliance to DOE. For consumer 
water heaters, the certification template reflects the general 
certification requirements specified at 10 CFR 429.12 and the product-
specific requirements specified at 10 CFR 429.17. As discussed in the 
previous paragraphs, DOE is not proposing to amend the product-specific

[[Page 1589]]

certification requirements for these products.
---------------------------------------------------------------------------

    \63\ DOE's product-specific certification templates are 
available at: www.regulations.doe.gov/ccms/templates.
---------------------------------------------------------------------------

E. Test Procedure Costs and Harmonization

1. Test Procedure Costs and Impact
    In this NOPR, DOE proposes to amend the existing test procedure for 
consumer and residential-duty commercial water heaters by adding 
procedures to test water heaters designed to be used with a separately 
sold hot water storage tank, to test the newly defined low temperature 
water heaters, and to estimate the internal stored water temperature 
for water heater designs in which the internal tank temperature cannot 
be directly measured. DOE also proposes to amend the existing test 
procedure for consumer and residential-duty commercial water heaters by 
modifying the flow rate requirements during the FHR test for water 
heaters with a rated storage volume less than 20 gallons; the timing of 
the first measurement in each draw of the 24-hour simulated-use test; 
and the test condition specifications and tolerances, including 
electric supply voltage tolerance, ambient temperature, ambient dry 
bulb temperature, ambient relative humidity, standard temperature and 
pressure definition, gas supply pressure, and manifold pressure. DOE 
has tentatively determined that these proposed amendments would impact 
testing costs as discussed in the following paragraphs.
a. Water Heaters Requiring a Separately Sold Hot Water Storage Tank
    DOE proposes to add procedures to test water heaters that are 
designed to be used with a separately sold hot water storage tank. 
These products raise the temperature of inlet water by less than the 
required temperature rise specified in sections 2.3 through 2.5 of 
appendix E and therefore require a storage volume (either a tank or 
circulation loop of sufficient size) to raise the temperature of the 
water to levels required by appendix E. Under the proposed procedures, 
the manufacturer, or third-party testing facility, would need to 
install the water heater with an 80-gallon unfired hot water storage 
tank which meets the energy conservation standard requirements at 10 
CFR 431.110(a). DOE estimates that the cost of running the test 
procedure should be the same as testing a comparable water heater with 
storage volume (i.e., testing a fossil fuel-fired or electric storage 
water heater would cost approximately $3,000 and testing an electric 
storage water heater which uses heat pump technology would cost 
approximately $4,500). In addition to the test cost, the manufacturer, 
or third-party testing facility, would have a one-time purchase of an 
unfired hot water storage tank which are commercially available for 
approximately $900.
    DOE has tentatively determined that the proposed amendment 
regarding water heaters that are designed to be used with a separately 
sold hot water storage tank allow for these products to be tested to 
the DOE test procedure for consumer and residential-duty commercial 
water heaters. Such testing would be required should the proposed 
amendments be finalized.
    DOE requests comment on the impact and associated costs of this 
proposed amendment.
b. Water Heaters That Cannot Have Their Internal Tank Temperature 
Measured
    DOE proposes to add procedures to appendix E to estimate the 
internal stored water temperature for water heater designs in which the 
internal tank temperature cannot be directly measured. These products 
have a rated storage volume greater than or equal to 2 gallons and are 
required to have the internal tank temperature measured as specified in 
section 4.5 of appendix E. However, these products are designed in such 
a way that instruments for measuring the internal water temperature 
cannot be installed. These products cannot be tested to the current 
version of appendix E. DOE estimates that the cost of running the test 
procedure should be the same as testing a comparable water heater with 
storage volume (i.e., testing a fossil fuel-fired or electric storage 
water heater would cost approximately $3,000).
    DOE requests comment on the impact and associated costs of this 
proposed amendment.
c. Additional Amendments
    DOE does not anticipate that the remainder of the amendments 
proposed in this NOPR would impact test costs.
    DOE proposes to amend section 2.5 of appendix E to allow low 
temperature water heaters to deliver water at their maximum outlet 
temperature that they are capable of. This proposal aligns with DOE's 
understanding of how these products are tested currently. As discussed 
in section III.C.7, manufacturers already should have requested a 
waiver for these products as the current test procedure cannot be used 
as written to test low temperature water heaters. As these products are 
currently tested and rated to the procedures which DOE is proposing, 
there should be no additional cost associated with this proposed 
change.
    DOE also proposes to amend the existing test procedure for consumer 
and residential-duty commercial water heaters by modifying the flow 
rate requirements during the FHR test for water heaters with a rated 
storage volume less than 20 gallons. This change does not significantly 
affect the test results of the FHR test, thus DOE expects that 
manufacturers may rely on existing test data where available. Further, 
water heaters with less than 20 gallons of rated storage volume 
currently do not have energy conservation standards codified at 10 CFR 
430.32(d) and are therefore not rated and certified to DOE.
    DOE also proposes to amend the timing of the first measurement in 
each draw of the 24-hour simulated-use test and the test condition 
specifications and tolerances, including electric supply voltage 
tolerance, ambient temperature, ambient dry bulb temperature, ambient 
relative humidity, standard temperature and pressure definition, gas 
supply pressure, and manifold pressure. These changes are intended to 
reduce retesting associated with having a single measurement out of 
tolerance, while maintaining the current representativeness of the test 
conditions and the stringency of the tolerances for the test 
conditions.
    DOE has tentatively determined that manufacturers would be able to 
rely on data generated under the current test procedure should any of 
these additional proposed amendments be finalized.
2. Harmonization With Industry Standards
    DOE's established practice is to adopt relevant industry standards 
as DOE test procedures unless such methodology would be unduly 
burdensome to conduct or would not produce test results that reflect 
the energy efficiency, energy use, water use (as specified in EPCA) or 
estimated operating costs of that product during a representative 
average use cycle or period of use. Section 8(c) of appendix A of part 
430 subpart C. In cases where the industry standard does not meet EPCA 
statutory criteria for test procedures, DOE will make modifications to 
these standards and adopt the modified standard as the DOE test 
procedure through the rulemaking process.
    The test procedures for consumer water heaters at appendix E 
incorporate by reference ASHRAE 41.1-1986 (RA 2006), which describes 
the standard methods for temperature measurement, and ASTM D2156-09, 
which describes

[[Page 1590]]

a test method for measuring the smoke density in flue gasses for 
burning distillate fuels. The industry standards DOE proposes to 
incorporate by reference via amendments described in this NOPR are 
discussed in further detail in section III.B. DOE requests comments on 
the benefits and burdens of the proposed updates and additions to 
industry standards referenced in the test procedure for consumer water 
heaters.
    DOE notes that ASHRAE 41.1-1986 (RA 2006) and ASTM D2156-09 are 
incorporated by reference without modification.
    In the April 2020 RFI, DOE discussed the possibility of adopting a 
finalized draft of ASHRAE 118.2, which in its drafted state is similar 
to appendix E. 85 FR 21104, 21109 (Apr. 16, 2020). A detailed 
discussion of the differences between the March 2019 ASHRAE Draft 
118.2, the April 2021 ASHRAE Draft 118.2, and appendix E can be found 
in section III.B.2. In response to the April 2020 RFI, AHRI recommended 
adopting ASHRAE 118.2 once it is finalized and stated that as a user of 
the standard, DOE would define the specific test conditions. (AHRI, No. 
17 at p. 3) The CA IOUs, CEC, CSA, Keltech, and NEEA supported adoption 
of ASHRAE 118.2 once updated. (CA IOUs, No. 18 at p. 3; CEC, No. 11 at 
pp. 2-3; CSA, No. 10 at p. 2; Keltech, No. 7 at p. 1; NEEA, No. 21 at 
p. 5) As discussed throughout section III.B.2, DOE has proposed certain 
changes to appendix E that have been presented in the March 2019 ASHRAE 
Draft 118.2 and April 2021 ASHRAE Draft 118.2. However, several changes 
presented in the March 2019 ASHRAE Draft 118.2 and January 2021 ASHRAE 
Draft 118.2 are either not proposed by DOE or are proposed by DOE with 
modification. In particular, DOE does not propose to scale the last 
draw of the FHR test (section III.B.2.c), to require a 6 hour standby 
period (section III.B.2.d), or to use the draft ASHRAE method for the 
last hour of the test regardless of whether the standby period occurred 
between draw clusters 1 and 2 or at the end of the test (section 
III.B.2.d). Further, DOE proposes the following amendments to appendix 
E, which are not included in either the March 2019 ASHRAE Draft 118.2 
or the April 2021 ASHRAE Draft 118.2: Updated test conditions and 
tolerances (section III.C.3); new definitions and test procedures for 
low temperature water heaters (section III.C.7); test procedures for 
heat pump only water heaters (section III.C.8.c), test procedures for 
circulating water heaters (section III.C.9); and test procedures for a 
drain down test method (section III.C.12). To reduce confusion due to 
the differences between the proposed appendix E and the March 2019 
ASHRAE Draft 118.2 and April 2021 ASHRAE Draft 118.2, DOE has 
tentatively determined not to incorporate by reference a finalized 
version of ASHRAE 118.2 without modification. Rather, DOE proposes to 
incorporate by reference a finalized ASHRAE 118.2 (contingent on the 
finalized update being substantively the same as the current draft made 
available for review) but only reference specific parts of the 
finalized ASHRAE 118.2 within appendix E (e.g., Annex B as discussed in 
section III.C.3.b).

F. Compliance Date and Waivers

    EPCA prescribes that, if DOE amends a test procedure, all 
representations of energy efficiency and energy use, including those 
made on marketing materials and product labels, must be made in 
accordance with that amended test procedure beginning 180 days after 
publication of such a test procedure final rule in the Federal 
Register. (42 U.S.C. 6293(c)(2); 42 U.S.C. 6314(d)(1)) To the extent 
the modified test procedure proposed in this document is required only 
for the evaluation and issuance of updated efficiency standards, use of 
the modified test procedure, if finalized, would not be required until 
the implementation date of updated standards. Section 8(d) of appendix 
A part 430 subpart C.
    If DOE were to publish an amended test procedure, EPCA provides an 
allowance for individual manufacturers to petition DOE for an extension 
of the 180-day period if the manufacturer may experience undue hardship 
in meeting the deadline. (42 U.S.C. 6293(c)(3); 42 U.S.C. 6314(d)(2)) 
To receive such an extension, petitions must be filed with DOE no later 
than 60 days before the end of the 180-day period and must detail how 
the manufacturer will experience undue hardship. (Id.)
    Upon the compliance date of test procedure provisions of an amended 
test procedure, should DOE issue a such an amendment, any waivers that 
had been previously issued and are in effect that pertain to issues 
addressed by such provisions are terminated. 10 CFR 430.27(h)(3); 10 
CFR 431.401(h)(3). Recipients of any such waivers would be required to 
test the products subject to the waiver according to the amended test 
procedure as of the compliance date of the amended test procedure. The 
amendments proposed in this document pertain to issues addressed by 
waivers granted to Bradford White Corporation (Case No. 2019-006).
    On January 31, 2020, DOE published a Notice of Decision and Order 
in the Federal Register granting Bradford White Corporation a waiver 
for a specified basic model that experiences the first cut-out of the 
24-hour simulated-use test during a draw. 85 FR 5648. The Decision and 
Order requires Bradford White Corporation to use an alternate test 
procedure that DOE determined more accurately calculates the recovery 
efficiency when the first cut-out occurs during a draw. Id. at 85 FR 
5651. DOE has tentatively determined that the alternate test procedure 
is representative of real-world use conditions for the basic model 
specified in the Decision and Order. In the April 2020 RFI, DOE 
requested feedback on whether the test procedure waiver approach is 
generally appropriate for testing basic models with these features. 85 
FR 21104, 21114 (April 16, 2020). AHRI, A.O. Smith, and BWC commented 
that the test procedure waiver approach is appropriate for testing 
basic models with the specified features and that the waiver test 
procedure should be incorporated into the current rule making so that 
it may be utilized more broadly. (AHRI, No. 17 at p. 12; A.O. Smith, 
No. 20 at p. 5; BWC, No. 12 at pp. 5-6) AHRI pointed out that the 
Bradford White Corporation test procedure waiver is implemented in 
ASHRAE 118.2 and must be adopted by DOE. (AHRI, No. 17 at p. 12)
    As a result, and as also discussed in section III.B.2.d, DOE is 
proposing to adopt the alternate test procedure prescribed in the 
Decision and Order granted to Bradford White Corporation into the test 
procedure at appendix E.

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Order 12866

    The Office of Management and Budget (OMB) has determined that this 
test procedure rulemaking does not constitute a ``significant 
regulatory action'' under section 3(f) of Executive Order (E.O.) 12866, 
Regulatory Planning and Review, 58 FR 51735 (Oct. 4, 1993). 
Accordingly, this action was not subject to review under the Executive 
order by the Office of Information and Regulatory Affairs (OIRA) in 
OMB.

B. Review Under the Regulatory Flexibility Act

    The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires 
preparation of an initial regulatory flexibility analysis (IRFA) for 
any rule that by law must be proposed for public comment, unless the 
agency certifies that the rule, if promulgated, will not have a 
significant economic impact on a substantial number of small entities. 
As

[[Page 1591]]

required by Executive Order 13272, ``Proper Consideration of Small 
Entities in Agency Rulemaking,'' 67 FR 53461 (August 16, 2002), DOE 
published procedures and policies on February 19, 2003, to ensure that 
the potential impacts of its rules on small entities are properly 
considered during the DOE rulemaking process. 68 FR 7990. DOE has made 
its procedures and policies available on the Office of the General 
Counsel's website: www.energy.gov/gc/office-general-counsel. DOE 
reviewed this proposed rule under the provisions of the Regulatory 
Flexibility Act and the policies and procedures published on February 
19, 2003.
    The following sections detail DOE's IRFA for this test procedure 
rulemaking.
1. Description of Reasons Why Action Is Being Considered
    DOE is proposing to amend test procedures for consumer water 
heaters and residential-duty commercial water heaters. DOE is 
publishing this NOPR in satisfaction of the 7-year review requirement 
specified in EPCA. (42 U.S.C. 6293(b)(1)(A); 6314(a)(1)) Further, 
amending test procedures for consumer and residential-duty commercial 
water heaters assists DOE in fulfilling its statutory deadline for 
amending energy conservation standards for products and equipment that 
achieve the maximum improvement in energy efficiency that is 
technologically feasible and economically justified. (42 U.S.C. 
6295(o)(2)(A); 42 U.S.C. 6313(a)(6)) Additionally, amending test 
procedures for consumer and residential-duty commercial water heaters 
allows manufacturers to produce measurements of energy efficiency that 
are representative of an average use cycle and uniform for all 
manufacturers.
2. Objectives of, and Legal Basis for, Rule
    DOE has undertaken this proposed rulemaking pursuant to 42 U.S.C. 
6292(a)(4) and 42 U.S.C. 6312(a), which authorizes DOE to regulate the 
energy efficiency of a number of consumer products and certain 
industrial equipment, including the consumer and residential-duty 
commercial water heaters that are the subject of this proposed 
rulemaking.
3. Description and Estimate of Small Entities Regulated
    For manufacturers of consumer water heaters and residential-duty 
commercial water heaters, the SBA has set a size threshold, which 
defines those entities classified as ``small businesses'' for the 
purposes of the statute. DOE used the SBA's small business size 
standards to determine whether any small entities would be subject to 
the requirements of the rule. (See 13 CFR part 121.) The size standards 
are listed by North American Industry Classification System (``NAICS'') 
code and industry description and are available at: www.sba.gov/
document/support--table-size-standards. Manufacturing of consumer water 
heaters and residential-duty commercial water heaters is classified 
under NAICS 335220, ``Major Household Appliance Manufacturing.'' The 
SBA sets a threshold of 1,500 employees or fewer for an entity to be 
considered as a small business for this category. DOE used available 
public information to identify potential small manufacturers. DOE 
accessed CCMS,\64\ the certified product directory of the AHRI \65\, 
company websites, and manufacturer literature to identify companies 
that import, private label, or produce the consumer water heaters and 
residential-duty commercial water heaters covered by this proposal. 
Using these sources, DOE identified a total of 31 manufacturers of 
consumer water heaters and residential-duty commercial water heaters.
---------------------------------------------------------------------------

    \64\ U.S. Department of Energy Compliance Certification 
Management System, available at: www.regulations.doe.gov/ccms.
    \65\ AHRI Directory of Certified Product Performance, available 
at: www.ahridirectory.org/Search/SearchHome.
---------------------------------------------------------------------------

    Of the proposals in this NOPR, two amendments could potentially 
lead to additional costs for manufacturers:
     Defining the use of a separate unfired hot water storage 
tank for testing water heaters designed to operate with a separately 
sold hot water storage tank.
     Adding procedures for estimating internal stored water 
temperature for water heater designs in which the internal tank 
temperature cannot be directly measured.
    After reviewing models in the CCMS and AHRI Directory for the 31 
manufacturers, DOE identified six companies that could incur additional 
testing costs as result of the proposed test procedures amendments. Of 
the six companies, one is a small domestic manufacturer that could 
incur costs as a result of the proposed test procedure amendments. The 
small domestic manufacturer offers one model in which the internal tank 
temperature cannot be directly measured.
4. Description and Estimate of Compliance Requirements
    In this NOPR, DOE evaluates a range of potential test procedure 
amendments. One amendment could lead to additional testing costs for 
small business. The existing DOE test procedure does not accommodate 
testing of water heaters that require a separately sold hot water 
storage tank to properly operate. Such products are currently available 
on the market.
    DOE proposes to add procedures to test such water heaters to 
improve the representativeness of the test procedure. Under the 
proposed amendments, the testing facility would need to install the 
water heater with a commonly available 80-gallon unfired hot water 
storage tank which meets the energy conservation standard requirements 
at 10 CFR 431.110(a). DOE estimates that the cost of running the 
amended test procedure should be the same as testing a comparable water 
heater with storage volume (i.e., third-party testing of a fossil fuel-
fired or electric storage water heater would cost approximately $3,000 
and third-party testing of an electric storage water heater which uses 
heat pump technology would cost approximately $4,500). If a small 
manufacturer chose to perform in-house testing rather than use a third-
party, the unfired hot water storage tank is commercially available for 
approximately $900.
    The one domestic small manufacturer has a single model that would 
be affected by this amendment. DOE expects the cost to re-test that 
model to be $4,500. This is less than 0.01% of company revenue.
    DOE requests comment of the cost impacts to small business of the 
test procedure change to accommodate testing of water heaters that 
require a separately sold hot water storage tank.
5. Duplication, Overlap, and Conflict With Other Rules and Regulations
    DOE is not aware of any rules or regulations that duplicate, 
overlap, or conflict with the rule being considered today.
6. Significant Alternatives to the Rule
    The discussion in the previous section analyzes impacts on small 
businesses that would result from DOE's proposed test procedure, if 
finalized. In reviewing alternatives to the proposed test procedure, 
DOE examined not establishing a performance-based test procedure for 
consumer and residential-duty commercial water heaters or establishing 
prescriptive-based test procedures. While not establishing performance-
based test procedures or establishing prescriptive-based test 
procedures for consumer and residential-duty commercial water heaters 
would reduce the burden on small businesses, DOE must use test 
procedures to determine whether the

[[Page 1592]]

products comply with relevant standards promulgated under EPCA. (42 
U.S.C. 6295(s)) Because establishing performance-based test procedures 
for consumer and residential-duty commercial water heaters is necessary 
prior to establishing performance-based energy conservation standards, 
DOE tentatively concludes that establishing performance-based test 
procedures, as proposed in this NOPR, supports DOE's authority to 
achieve the maximum improvement in energy efficiency that is 
technologically feasible and economically justified. (42 U.S.C. 
6295(o)(2)(A); 42 U.S.C. 6313(a)(6)(A)(ii)(II))
    The Department has tentatively determined that there are no better 
alternatives than the test procedures amendments proposed in this NOPR, 
in terms of both meeting the agency's objectives and reducing burden. 
Additionally, manufacturers subject to DOE's test procedures may apply 
to DOE's Office of Hearings and Appeals for exception relief under 
certain circumstances. Manufacturers should refer to 10 CFR part 430, 
subpart E, and 10 CFR part 1003 for additional details.
    DOE seeks comments on these findings related to significant 
alternative related to small entities.

C. Review Under the Paperwork Reduction Act of 1995

    Manufacturers of consumer and commercial water heaters must certify 
to DOE that their products comply with any applicable energy 
conservation standards. To certify compliance, manufacturers must first 
obtain test data for their products according to the DOE test 
procedures, including any amendments adopted for those test procedures. 
DOE has established regulations for the certification and recordkeeping 
requirements for all covered consumer products and commercial 
equipment, including consumer and commercial water heaters. (See 
generally 10 CFR part 429.) The collection-of-information requirement 
for the certification and recordkeeping is subject to review and 
approval by OMB under the Paperwork Reduction Act (PRA). This 
requirement has been approved by OMB under OMB control number 1910-
1400. Public reporting burden for the certification is estimated to 
average 35 hours per response, including the time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information.
    Notwithstanding any other provision of the law, no person is 
required to respond to, nor shall any person be subject to a penalty 
for failure to comply with, a collection of information subject to the 
requirements of the PRA, unless that collection of information displays 
a currently valid OMB Control Number.

D. Review Under the National Environmental Policy Act of 1969

    In this NOPR, DOE proposes test procedure amendments that DOE 
expects will be used to develop and implement future energy 
conservation standards for consumer water heaters. DOE has determined 
that this rule falls into a class of actions that are categorically 
excluded from review under the National Environmental Policy Act of 
1969 (42 U.S.C. 4321 et seq.) and DOE's implementing regulations at 10 
CFR part 1021. Specifically, DOE has determined that adopting test 
procedures for measuring energy efficiency of consumer products and 
industrial equipment is consistent with activities identified in 10 CFR 
part 1021, appendix A to subpart D, A5 and A6. Accordingly, neither an 
environmental assessment nor an environmental impact statement is 
required.

E. Review Under Executive Order 13132

    Executive Order 13132, ``Federalism,'' 64 FR 43255 (Aug. 4, 1999) 
imposes certain requirements on agencies formulating and implementing 
policies or regulations that preempt State law or that have federalism 
implications. The E.O. requires agencies to examine the constitutional 
and statutory authority supporting any action that would limit the 
policymaking discretion of the States and to carefully assess the 
necessity for such actions. The E.O. also requires agencies to have an 
accountable process to ensure meaningful and timely input by State and 
local officials in the development of regulatory policies that have 
federalism implications. On March 14, 2000, DOE published a statement 
of policy describing the intergovernmental consultation process it will 
follow in the development of such regulations. 65 FR 13735. DOE has 
examined this proposed rule and has determined that it would not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government. EPCA 
governs and prescribes Federal preemption of State regulations as to 
energy conservation for the products that are the subject of this 
proposed rule. States can petition DOE for exemption from such 
preemption to the extent, and based on criteria, set forth in EPCA. (42 
U.S.C. 6297(d)) No further action is required by E.O. 13132.

F. Review Under Executive Order 12988

    Regarding the review of existing regulations and the promulgation 
of new regulations, section 3(a) of E.O. 12988, ``Civil Justice 
Reform,'' 61 FR 4729 (Feb. 7, 1996), imposes on Federal agencies the 
general duty to adhere to the following requirements: (1) Eliminate 
drafting errors and ambiguity, (2) write regulations to minimize 
litigation, (3) provide a clear legal standard for affected conduct 
rather than a general standard, and (4) promote simplification and 
burden reduction. Section 3(b) of E.O. 12988 specifically requires that 
executive agencies make every reasonable effort to ensure that the 
regulation (1) Clearly specifies the preemptive effect, if any, (2) 
clearly specifies any effect on existing Federal law or regulation, (3) 
provides a clear legal standard for affected conduct while promoting 
simplification and burden reduction, (4) specifies the retroactive 
effect, if any, (5) adequately defines key terms, and (6) addresses 
other important issues affecting clarity and general draftsmanship 
under any guidelines issued by the Attorney General. Section 3(c) of 
E.O. 12988 requires executive agencies to review regulations in light 
of applicable standards in sections 3(a) and 3(b) to determine whether 
they are met or it is unreasonable to meet one or more of them. DOE has 
completed the required review and determined that, to the extent 
permitted by law, the proposed rule meets the relevant standards of 
E.O. 12988.

G. Review Under the Unfunded Mandates Reform Act of 1995

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA) 
requires each Federal agency to assess the effects of Federal 
regulatory actions on State, local, and Tribal governments and the 
private sector. Public Law 104-4, sec. 201 (codified at 2 U.S.C. 1531). 
For a proposed regulatory action likely to result in a rule that may 
cause the expenditure by State, local, and Tribal governments, in the 
aggregate, or by the private sector of $100 million or more in any one 
year (adjusted annually for inflation), section 202 of UMRA requires a 
Federal agency to publish a written statement that estimates the 
resulting costs, benefits, and other effects on the national economy. 
(2 U.S.C. 1532(a), (b)) The UMRA also requires a Federal agency to 
develop an effective process to permit timely input by elected officers 
of State, local, and Tribal governments on a proposed ``significant

[[Page 1593]]

intergovernmental mandate,'' and requires an agency plan for giving 
notice and opportunity for timely input to potentially affected small 
governments before establishing any requirements that might 
significantly or uniquely affect small governments. On March 18, 1997, 
DOE published a statement of policy on its process for 
intergovernmental consultation under UMRA. 62 FR 12820; also available 
at www.energy.gov/gc/office-general-counsel. DOE examined this proposed 
rule according to UMRA and its statement of policy and determined that 
the rule contains neither an intergovernmental mandate, nor a mandate 
that may result in the expenditure of $100 million or more in any year, 
so these requirements do not apply.

H. Review Under the Treasury and General Government Appropriations Act, 
1999

    Section 654 of the Treasury and General Government Appropriations 
Act, 1999 (Pub. L. 105-277) requires Federal agencies to issue a Family 
Policymaking Assessment for any rule that may affect family well-being. 
This proposed rule would not have any impact on the autonomy or 
integrity of the family as an institution. Accordingly, DOE has 
concluded that it is not necessary to prepare a Family Policymaking 
Assessment.

I. Review Under Executive Order 12630

    DOE has determined, under E.O. 12630, ``Governmental Actions and 
Interference with Constitutionally Protected Property Rights,'' 53 FR 
8859 (March 18, 1988), that this proposed regulation would not result 
in any takings that might require compensation under the Fifth 
Amendment to the U.S. Constitution.

J. Review Under Treasury and General Government Appropriations Act, 
2001

    Section 515 of the Treasury and General Government Appropriations 
Act, 2001 (44 U.S.C. 3516 note) provides for agencies to review most 
disseminations of information to the public under guidelines 
established by each agency pursuant to general guidelines issued by 
OMB. OMB's guidelines were published at 67 FR 8452 (Feb. 22, 2002), and 
DOE's guidelines were published at 67 FR 62446 (Oct. 7, 2002). Pursuant 
to OMB Memorandum M-19-15, Improving Implementation of the Information 
Quality Act (April 24, 2019), DOE published updated guidelines which 
are available at: www.energy.gov/sites/prod/files/2019/12/f70/DOE%20Final%20Updated%20IQA%20Guidelines%20Dec%202019.pdf. DOE has 
reviewed this proposed rule under the OMB and DOE guidelines and has 
concluded that it is consistent with applicable policies in those 
guidelines.

K. Review Under Executive Order 13211

    E.O. 13211, ``Actions Concerning Regulations That Significantly 
Affect Energy Supply, Distribution, or Use,'' 66 FR 28355 (May 22, 
2001), requires Federal agencies to prepare and submit to OMB, a 
Statement of Energy Effects for any proposed significant energy action. 
A ``significant energy action'' is defined as any action by an agency 
that promulgated or is expected to lead to promulgation of a final 
rule, and that (1) is a significant regulatory action under E.O. 12866, 
or any successor order; and (2) is likely to have a significant adverse 
effect on the supply, distribution, or use of energy; or (3) is 
designated by the Administrator of OIRA as a significant energy action. 
For any proposed significant energy action, the agency must give a 
detailed statement of any adverse effects on energy supply, 
distribution, or use should the proposal be implemented, and of 
reasonable alternatives to the action and their expected benefits on 
energy supply, distribution, and use.
    The proposed regulatory action to amend the test procedure for 
measuring the energy efficiency of consumer and commercial water 
heaters is not a significant regulatory action under E.O. 12866. 
Moreover, it would not have a significant adverse effect on the supply, 
distribution, or use of energy, nor has it been designated as a 
significant energy action by the Administrator of OIRA. Therefore, it 
is not a significant energy action, and, accordingly, DOE has not 
prepared a Statement of Energy Effects.

L. Review Under Section 32 of the Federal Energy Administration Act of 
1974

    Under section 301 of the Department of Energy Organization Act 
(Pub. L. 95-91; 42 U.S.C. 7101), DOE must comply with section 32 of the 
Federal Energy Administration Act of 1974, as amended by the Federal 
Energy Administration Authorization Act of 1977. (15 U.S.C. 788; FEAA) 
Section 32 essentially provides in relevant part that, where a proposed 
rule authorizes or requires use of commercial standards, the notice of 
proposed rulemaking must inform the public of the use and background of 
such standards. In addition, section 32(c) requires DOE to consult with 
the Attorney General and the Chairman of the Federal Trade Commission 
(FTC) concerning the impact of the commercial or industry standards on 
competition.
    The proposed modifications to the test procedure for consumer and 
commercial water heaters would incorporate testing methods contained in 
certain sections of the following commercial standards: ASHRAE 41.1-
2020, ASTM D2156-09 (RA 2018), and a finalized version of ASHRAE 118.2. 
DOE has evaluated these standards and is unable to conclude whether it 
fully complies with the requirements of section 32(b) of the FEAA 
(i.e., whether it was developed in a manner that fully provides for 
public participation, comment, and review.) DOE will consult with both 
the Attorney General and the Chairman of the FTC concerning the impact 
of these test procedures on competition, prior to prescribing a final 
rule.

M. Description of Materials Incorporated by Reference

    In this NOPR, DOE proposes to incorporate by reference the test 
standard published by ASHRAE, titled ``Standard Methods for Temperature 
Measurement,'' ASHRAE 41.1-2020; the test standard published by ANSI/
ASHRAE, titled ``Standard Method for Humidity Measurement,'' Standard 
41.6-2014; the test standard published by ASHRAE, titled ``Method of 
Testing for Rating Residential Water Heaters and Residential-Duty 
Commercial Water Heaters,'' ASHRAE 118.2-[year finalized]; the test 
standard published by ASTM, titled ``Standard Test Method for Smoke 
Density in Flue Gases from Burning Distillate Fuels,'' ASTM D2156-09 
(RA 2018); and, the test standard published by ASTM, titled ``Standard 
Test Methods for Directional Reflectance Factor, 45-Deg 0-Deg, of 
Opaque Specimens by Broad-Band Filter Reflectometry,'' ASTM E97-1987 
(W1991).
    ASHRAE 41.1-2020 prescribes methods for measuring temperature under 
laboratory and field conditions which are required for system 
performance tests and for testing heating, ventilating, air-
conditioning, and refrigerating components. ASHRAE 41.6-2014 prescribes 
methods for measuring the humidity of moist air with instruments. 
ASHRAE 118.2-[year finalized] provides test procedures for rating the 
efficiency and hot water delivery capabilities of directly heated 
residential water heaters and residential-duty commercial water 
heaters. ASTM D2156-09 (RA 2018) provides a test method to evaluate the 
density of smoke in the flue gases from burning distillate fuels, is 
intended primarily for use with home heating

[[Page 1594]]

equipment burning kerosene or heating oils, and can be used in the 
laboratory or in the field to compare fuels for clean burning or to 
compare heating equipment. ASTM E97-1987 (W1991) provides a method to 
determinate of the 45-deg, 0-deg directional reflectance factor of 
nonfluorescent opaque specimens by means of filter photometers.
    Copies of ASHRAE 41.1-2020, ASHRAE 41.6-2014, and ASHRAE 118.2-
[year finalized] can be obtained from the American Society of Heating, 
Refrigerating, and Air-Conditioning Engineers, Inc., 1791 Tullie Circle 
NE, Atlanta, GA 30329, (800) 527-4723 or (404) 636-8400, or online at: 
www.ashrae.org.
    Copies of ASTM D2156-09 (RA 2018) and ASTM E97-1987 (W1991) can be 
obtained from the American Society for Testing and Materials 
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, 
PA 19428-2959 or online at: www.astm.org.

V. Public Participation

A. Participation in the Webinar

    The time and date of the webinar are listed in the DATES section at 
the beginning of this document. If no participants register for the 
webinar, it will be cancelled. Webinar registration information, 
participant instructions, and information about the capabilities 
available to webinar participants will be published on DOE's website: 
www1.eere.energy.gov/buildings/appliance_standards/standards.aspx?productid=32. Participants are responsible for ensuring 
their systems are compatible with the webinar software.

B. Submission of Comments

    DOE will accept comments, data, and information regarding this 
proposed rule no later than the date provided in the DATES section at 
the beginning of this proposed rule. Interested parties may submit 
comments using any of the methods described in the ADDRESSES section at 
the beginning of this document.
    Submitting comments via www.regulations.gov. The 
www.regulations.gov web page will require you to provide your name and 
contact information. Your contact information will be viewable to DOE 
Building Technologies staff only. Your contact information will not be 
publicly viewable except for your first and last names, organization 
name (if any), and submitter representative name (if any). If your 
comment is not processed properly because of technical difficulties, 
DOE will use this information to contact you. If DOE cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, DOE may not be able to consider your comment.
    However, your contact information will be publicly viewable if you 
include it in the comment or in any documents attached to your comment. 
Any information that you do not want to be publicly viewable should not 
be included in your comment, nor in any document attached to your 
comment. Persons viewing comments will see only first and last names, 
organization names, correspondence containing comments, and any 
documents submitted with the comments.
    Do not submit to www.regulations.gov information for which 
disclosure is restricted by statute, such as trade secrets and 
commercial or financial information (hereinafter referred to as 
Confidential Business Information (CBI)). Comments submitted through 
www.regulations.gov cannot be claimed as CBI. Comments received through 
the website will waive any CBI claims for the information submitted. 
For information on submitting CBI, see the Confidential Business 
Information section.
    DOE processes submissions made through www.regulations.gov before 
posting. Normally, comments will be posted within a few days of being 
submitted. However, if large volumes of comments are being processed 
simultaneously, your comment may not be viewable for up to several 
weeks. Please keep the comment tracking number that www.regulations.gov 
provides after you have successfully uploaded your comment.
    Submitting comments via email. Comments and documents submitted via 
email also will be posted to www.regulations.gov. If you do not want 
your personal contact information to be publicly viewable, do not 
include it in your comment or any accompanying documents. Instead, 
provide your contact information on a cover letter. Include your first 
and last names, email address, telephone number, and optional mailing 
address. The cover letter will not be publicly viewable as long as it 
does not include any comments.
    Include contact information each time you submit comments, data, 
documents, and other information to DOE. No faxes will be accepted.
    Comments, data, and other information submitted to DOE 
electronically should be provided in PDF (preferred), Microsoft Word or 
Excel, WordPerfect, or text (ASCII) file format. Provide documents that 
are not secured, written in English and free of any defects or viruses. 
Documents should not contain special characters or any form of 
encryption and, if possible, they should carry the electronic signature 
of the author.
    Campaign form letters. Please submit campaign form letters by the 
originating organization in batches of between 50 to 500 form letters 
per PDF or as one form letter with a list of supporters' names compiled 
into one or more PDFs. This reduces comment processing and posting 
time.
    Confidential Business Information. Pursuant to 10 CFR 1004.11, any 
person submitting information that he or she believes to be 
confidential and exempt by law from public disclosure should submit via 
email two well-marked copies: One copy of the document marked 
confidential including all the information believed to be confidential, 
and one copy of the document marked non-confidential with the 
information believed to be confidential deleted. DOE will make its own 
determination about the confidential status of the information and 
treat it according to its determination.
    It is DOE's policy that all comments may be included in the public 
docket, without change and as received, including any personal 
information provided in the comments (except information deemed to be 
exempt from public disclosure).

VI. Approval of the Office of the Secretary

    The Secretary of Energy has approved publication of this notice of 
proposed rulemaking and request for comment.

List of Subjects

10 CFR Part 429

    Administrative practice and procedure, Confidential business 
information, Energy conservation, Household appliances, Reporting and 
recordkeeping requirements.

10 CFR Part 430

    Administrative practice and procedure, Confidential business 
information, Energy conservation, Household appliances, Imports, 
Incorporation by reference, Intergovernmental relations, Small 
businesses.

10 CFR Part 431

    Administrative practice and procedure, Confidential business 
information, Energy conservation test procedures, Incorporation by 
reference, Reporting and recordkeeping requirements.

[[Page 1595]]

Signing Authority

    This document of the Department of Energy was signed on December 9, 
2021, by Kelly J. Speakes-Backman, Principal Deputy Assistant Secretary 
for Energy Efficiency and Renewable Energy, pursuant to delegated 
authority from the Secretary of Energy. That document with the original 
signature and date is maintained by DOE. For administrative purposes 
only, and in compliance with requirements of the Office of the Federal 
Register, the undersigned DOE Federal Register Liaison Officer has been 
authorized to sign and submit the document in electronic format for 
publication, as an official document of the Department of Energy. This 
administrative process in no way alters the legal effect of this 
document upon publication in the Federal Register.

    Signed in Washington, DC, on December 9, 2021.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.

    For the reasons stated in the preamble, DOE is proposing to amend 
parts 429, 430, and 431 of Chapter II of Title 10, Code of Federal 
Regulations, as set forth below:

PART 429--CERTIFICATION, COMPLIANCE, AND ENFORCEMENT FOR CONSUMER 
PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT

0
1. The authority citation for part 429 continues to read as follows:

    Authority:  42 U.S.C. 6291-6317; 28 U.S.C. 2461 note.

0
2. Amend Sec.  429.70 by adding paragraph (g)(3) to read as follows:


Sec.  429.70  Alternative methods for determining energy efficiency and 
energy use.

* * * * *
    (g) * * *
    (3) Electric Instantaneous Water Heaters. Rate an untested basic 
model of an electric instantaneous type water heater using the maximum 
GPM and the uniform energy factor obtained from a tested basic model as 
a basis for ratings of basic models with other input ratings, provided 
that certain conditions are met:
    (i) For an untested basic model, the represented value of the 
maximum GPM and the uniform energy factor is the same as that of a 
tested basic model, provided that the untested basic model's input is 
rated at or above the input rating for the corresponding tested basic 
model.
    (ii) For an untested basic model having any input rating that is 
lower than that of the corresponding tested basic model, the 
represented value of the maximum GPM and the uniform energy factor is 
the same as that of a tested basic model, provided that the maximum GPM 
for the untested basic model results in the same draw pattern specified 
in Table II of appendix E for the 24-hour simulated-use test as was 
applied to the tested basic model. To establish whether this condition 
is met, determine the maximum GPM for the tested and the untested basic 
models in accordance with the procedure described in section 5.3.2 of 
10 CFR part 430, subpart B, appendix E, then compare the appropriate 
draw pattern specified in Table II of appendix E for the maximum GPM of 
the tested basic model with that for the untested basic model. If this 
condition is not met, then the untested basic model must be tested and 
the appropriate sampling provisions applied to determine its uniform 
energy factor in accordance with appendix E and this part.
* * * * *
0
3. Amend Sec.  429.134 by adding paragraph (d)(3) to read as follows:


Sec.  429.134  Product-specific enforcement provisions.

* * * * *
    (d) * * *
    (3) Verification of fuel input rate. The fuel input rate of each 
tested unit of the basic model will be measured pursuant to the test 
requirements of section 5.2.3 of 10 CFR part 430, subpart B, appendix 
E. The measured fuel input rate (either the measured fuel input rate 
for a single unit sample or the average of the measured fuel input 
rates for a multiple unit sample) will be compared to the rated input 
certified by the manufacturer. The certified rated input will be 
considered valid only if the measured fuel input rate is within 2 percent of the certified rated input.
    (i) If the certified rated input is found to be valid, then the 
certified rated input will be used to determine compliance with the 
associated energy conservation standard.
    (ii) If the measured fuel input rate is not within 2 
percent of the certified rated input, the measured fuel input rate will 
be used to determine compliance with the associated energy conservation 
standard.
    (iii) If the measured fuel input rate for oil-fired water heating 
products is not within 2 percent of the certified rated 
input, the measured fuel input rate will be used to determine 
compliance with the associated energy conservation standard.
* * * * *

PART 430--ENERGY CONSERVATION PROGRAM FOR CONSUMER PRODUCTS

0
4. The authority citation for part 430 continues to read as follows:

    Authority:  42 U.S.C. 6291-6309; 28 U.S.C. 2461 note.

0
5. Amend Sec.  430.2 by adding, in alphabetical order, the definitions 
of ``Circulating water heater'', ``Low temperature water heater'', and 
``Tabletop water heater'' to read as follows:


Sec.  430.2   Definitions.

* * * * *
    Circulating water heater means an instantaneous or heat pump type 
water heater that does not have an operational scheme in which the 
burner, heating element, or compressor initiates and/or terminates 
heating based on sensing flow; has a water temperature sensor located 
at the inlet of the water heater or in a separate storage tank that is 
the primary means of initiating and terminating heating; and must be 
used in combination with a recirculating pump and either a separate 
storage tank or water circulation loop in order to achieve the water 
flow and temperature conditions recommended in the manufacturer's 
installation and operation instructions.
* * * * *
    Low temperature water heater means an electric instantaneous water 
heater that is not a circulating water heater and cannot deliver water 
at a temperature greater than or equal to the set point temperature 
specified in section 2.5 of appendix E to subpart B of this part when 
supplied with water at the supply water temperature specified in 
section 2.3 of appendix E to subpart B of this part.
* * * * *
    Tabletop water heater means a heater in a rectangular box enclosure 
designed to slide into a kitchen countertop space with typical 
dimensions of 36 inches high, 25 inches deep and 24 inches wide.
* * * * *
0
6. Section 430.3 is amended by:
0
a. Revising paragraph (g)(5);
0
b. Redesignating paragraphs (g)(8) as (9);
0
c. Adding new paragraph (g)(8);
0
d. Redesignating paragraphs (g)(10) and (11), as (g)(11) and (12);
0
e. Revising newly designated paragraph (g)(12);

[[Page 1596]]

0
f. Redesignating paragraphs (g)(13) through (17), as (g)(14) through 
(18);
0
g. Redesignating paragraph (g)(19) as (20);
0
h. Adding new paragraph (g)(19);
0
i. Revising paragraph (j)(1); and
0
j. Adding paragraphs (j)(3) and (4);
    The revisions and additions read as follows:


Sec.  430.3  Materials incorporated by reference.

* * * * *
    (g) * * *
    (5) ASHRAE 41.1-1986 (Reaffirmed 2006), Standard Method for 
Temperature Measurement, approved February 18, 1987, IBR approved for 
appendix AA to subpart B.
* * * * *
    (8) ANSI/ASHRAE Standard 41.1-2020, (``ANSI/ASHRAE 41.1-2020''), 
Standard Method for Temperature Measurement, ANSI approved June 30, 
2020, IBR approved for appendix E to subpart B.
* * * * *
    (12) ANSI/ASHRAE Standard 41.6-2014, (``ASHRAE 41.6-2014''), 
Standard Method for Humidity Measurement, ANSI approved July 3, 2014, 
IBR approved for appendices E and F to subpart B.
* * * * *
    (19) ANSI/ASHRAE Standard 118.2-[year finalized], (``[ASHRAE 118.2-
TBD]''), Method of Testing for Rating Residential Water Heaters and 
Residential-Duty Commercial Water Heaters, ANSI approved [date 
finalized], IBR approved for appendix E to subpart B.
* * * * *
    (j) * * *
    (1) ASTM D2156-09, (``ASTM D2156''), Standard Test Method for Smoke 
Density in Flue Gases from Burning Distillate Fuels, ASTM approved 
December 1, 2009, IBR approved for appendix O to subpart B.
* * * * *
    (3) ASTM D2156-09 (Reapproved 2018), (``ASTM D2156 (RA 2018)''), 
Standard Test Method for Smoke Density in Flue Gases from Burning 
Distillate Fuels, ASTM approved October 1, 2018, IBR approved for 
appendix E to subpart B.
    (4) ASTM E97-1987 (Withdrawn 1991) (``ASTM E97-1987 (W1991)''), 
Standard Test Methods for Directional Reflectance Factor, 45-Deg 0-Deg, 
of Opaque Specimens by Broad-Band Filter Reflectometry, approved 
January 1987, IBR approved for appendix E to subpart B.
* * * * *
0
7. Appendix E to subpart B of part 430 is revised to read as follows:

APPENDIX E TO SUBPART B OF PART 430--UNIFORM TEST METHOD FOR MEASURING 
THE ENERGY CONSUMPTION OF WATER HEATERS

    Note: Prior to [date 180 days after publication of the final 
rule in the Federal Register], representations with respect to the 
energy use or efficiency of consumer water heaters and commercial 
water heaters covered by this test method, including compliance 
certifications, must be based on testing conducted in accordance 
with either this appendix as it now appears or appendix E as it 
appeared at 10 CFR part 430, subpart B revised as of January 1, 
2021.
    On and after [date 180 days after date of publication of the 
final rule in the Federal Register], representations with respect to 
energy use or efficiency of consumer water heaters and commercial 
water heaters covered by this test method, including compliance 
certifications, must be based on testing conducted in accordance 
with this appendix.

0. Incorporation by Reference

    DOE incorporated by reference in Sec.  430.3 the entire standard 
for: ANSI/ASHRAE 41.1-2020; ASHRAE 41.6-2014; [ASHRAE 118.2-TBD]; 
ASTM D2156 (RA 2018); and ASTM E97-1987 (W1991). However, only 
enumerated provisions of [ASHRAE 118.2-TBD] are applicable to this 
appendix, as follows:
    (1) [ASHRAE 118.2-TBD]
    (i) Annex B--Gas Heating Value Correction Factor;
    (ii) Reserved.

1. Definitions

    1.1. Cut-in means the time when or water temperature at which a 
water heater control or thermostat acts to increase the energy or 
fuel input to the heating elements, compressor, or burner.
    1.2. Cut-out means the time when or water temperature at which a 
water heater control or thermostat acts to reduce to a minimum the 
energy or fuel input to the heating elements, compressor, or burner.
    1.3. Design Power Rating means the power rating or input rate 
that a water heater manufacturer assigns to a particular design of 
water heater and that is included on the nameplate of the water 
heater, expressed in kilowatts or Btu (kJ) per hour as appropriate. 
For modulating water heaters, the design power rating is the maximum 
power rating or input rate that is specified by the manufacturer on 
the nameplate of the water heater.
    1.4. Draw Cluster means a collection of water draws initiated 
during the 24-hour simulated-use test during which no successive 
draws are separated by more than 2 hours.
    1.5. First-Hour Rating means an estimate of the maximum volume 
of ``hot'' water that a non-flow activated water heater can supply 
within an hour that begins with the water heater fully heated (i.e., 
with all thermostats satisfied).
    1.6. Flow-Activated describes an operational scheme in which a 
water heater initiates and terminates heating based on sensing flow.
    1.7. Heat Trap means a device that can be integrally connected 
or independently attached to the hot and/or cold water pipe 
connections of a water heater such that the device will develop a 
thermal or mechanical seal to minimize the recirculation of water 
due to thermal convection between the water heater tank and its 
connecting pipes.
    1.8. Maximum GPM (L/min) Rating means the maximum gallons per 
minute (liters per minute) of hot water that can be supplied by 
flow-activated water heater when tested in accordance with section 
5.3.2 of this appendix.
    1.9. Modulating Water Heater means a water heater that can 
automatically vary its power or input rate from the minimum to the 
maximum power or input rate specified on the nameplate of the water 
heater by the manufacturer.
    1.10. Rated Storage Volume means the water storage capacity of a 
water heater, in gallons (liters), as certified by the manufacturer 
pursuant to 10 CFR part 429.
    1.11. Recovery Efficiency means the ratio of energy delivered to 
the water to the energy content of the fuel consumed by the water 
heater.
    1.12. Recovery Period means the time when the main burner of a 
water heater with a rated storage volume greater than or equal to 2 
gallons is raising the temperature of the stored water.
    1.13. Standby means the time, in hours, during which water is 
not being withdrawn from the water heater.
    1.14. Symbol Usage. The following identity relationships are 
provided to help clarify the symbology used throughout this 
procedure:

Cp--specific heat of water
Eannual--annual energy consumption of a water heater
Eannual,e--annual electrical energy consumption of a water heater
Eannual,f--annual fossil-fuel energy consumption of a water heater
Fhr--first-hour rating of a non-flow activated water heater
Fmax--maximum GPM (L/min) rating of a flow-activated water heater
i--a subscript to indicate the draw number during a test
Mdel,i--mass of water removed during the ith draw of the 24-hour 
simulated-use test
Min,i--mass of water entering the water heater during the ith draw 
of the 24-hour simulated-use test
M*del,i--for non-flow activated water heaters, mass of water removed 
during the ith draw during the first-hour rating test
M*in,i--for non-flow activated water heaters, mass of water entering 
the water heater during the ith draw during the first-hour rating 
test
Mdel,10m--for flow-activated water heaters, mass of water removed 
continuously during the maximum GPM (L/min) rating test
Min,10m--for flow-activated water heaters, mass of water entering 
the water heater continuously during the maximum GPM (L/min) rating 
test
n--for non-flow activated water heaters, total number of draws 
during the first-hour rating test

[[Page 1597]]

N--total number of draws during the 24-hour simulated-use test
Nr-- number of draws from the start of the 24-hour simulated-use 
test to the end to the first recovery period as described in section 
5.4.2
Q--total fossil fuel and/or electric energy consumed during the 
entire 24-hour simulated-use test
Qd--daily water heating energy consumption adjusted for net change 
in internal energy
Qda--Qd with adjustment for variation of tank to ambient air 
temperature difference from nominal value
Qdm--overall adjusted daily water heating energy consumption 
including Qda and QHWD
Qe--total electrical energy used during the 24-hour simulated-use 
test
Qf--total fossil fuel energy used by the water heater during the 24-
hour simulated-use test
Qhr--hourly standby losses of a water heater with a rated storage 
volume greater than or equal to 2 gallons
QHW--daily energy consumption to heat water at the measured average 
temperature rise across the water heater
QHW,67 [deg]F--daily energy consumption to heat quantity of water 
removed during test over a temperature rise of 67 [deg]F (37.3 
[deg]C)
QHWD--adjustment to daily energy consumption, QHW, due to 
variation of the temperature rise across the water heater not equal 
to the nominal value of 67 [deg]F (37.3 [deg]C)
Qr--energy consumption of water heater from the beginning of the 
test to the end of the first recovery period
Qstby--total energy consumed during the standby time interval 
[tau]stby,1, as determined in section 5.4.2 of this 
appendix
Qsu,0-- cumulative energy consumption, including all fossil fuel and 
electrical energy use, of the water heater from the start of the 24-
hour simulated-use test to the start of the standby period as 
determined in section 5.4.2 of this appendix
Qsu,f--cumulative energy consumption, including all fossil fuel and 
electrical energy use, of the water heater from the start of the 24-
hour simulated-use test to the end of the standby period as 
determined in section 5.4.2 of this appendix
T0--mean tank temperature at the beginning of the 24-hour simulated-
use test as determined in section 5.4.2 of this appendix
T24--mean tank temperature at the end of the 24-hour simulated-use 
test as determined in section 5.4.2 of this appendix
Ta,stby--average ambient air temperature during all standby periods 
of the 24-hour simulated-use test as determined in section 5.4.2 of 
this appendix
Ta,stby,1--overall average ambient temperature between the start and 
end of the standby period as determined in section 5.4.2 of this 
appendix
Tt,stby,1-- overall average mean tank temperature between the start 
and end of the standby period as determined in section 5.4.2 of this 
appendix
Tdel--for flow-activated water heaters, average outlet water 
temperature during the maximum GPM (L/min) rating test
Tdel,i--average outlet water temperature during the ith draw of the 
24-hour simulated-use test
Tin--for flow-activated water heaters, average inlet water 
temperature during the maximum GPM (L/min) rating test
Tin,i--average inlet water temperature during the ith draw of the 
24-hour simulated-use test
Tmax,1--maximum measured mean tank temperature after the first 
recovery period of the 24-hour simulated-use test as determined in 
section 5.4.2 of this appendix
Tsu,0--maximum measured mean tank temperature at the beginning of 
the standby period as determined in section 5.4.2 of this appendix
Tsu,f--measured mean tank temperature at the end of the standby 
period as determined in section 5.4.2 of this appendix
T*del,i--for non-flow activated water heaters, average outlet water 
temperature during the ith draw (i = 1 to n) of the first-hour 
rating test
T*max,i--for non-flow activated water heaters, maximum outlet water 
temperature observed during the ith draw (i = 1 to n) of the first-
hour rating test
T*min,i--for non-flow activated water heaters, minimum outlet water 
temperature to terminate the ith draw (i = 1 to n) of the first-hour 
rating test
UA--standby loss coefficient of a water heater with a rated storage 
volume greater than or equal to 2 gallons
UEF--uniform energy factor of a water heater
V--the volume of hot water drawn during the applicable draw pattern
Vdel,i--volume of water removed during the ith draw (i = 1 to N) of 
the 24-hour simulated-use test
Vin,i--volume of water entering the water heater during the ith draw 
(i = 1 to N) of the 24-hour simulated-use test
V*del,i--for non-flow activated water heaters, volume of water 
removed during the ith draw (i = 1 to n) of the first-hour rating 
test
V*in,i--for non-flow activated water heaters, volume of water 
entering the water heater during the ith draw (i = 1 to n) of the 
first-hour rating test
Vdel,10m--for flow-activated water heaters, volume of water removed 
during the maximum GPM (L/min) rating test
Vin,10m--for flow-activated water heaters, volume of water entering 
the water heater during the maximum GPM (L/min) rating test
Vst--measured storage volume of the storage tank for water heaters 
with a rated storage volume greater than or equal to 2 gallons
Wf--weight of storage tank when completely filled with water for 
water heaters with a rated storage volume greater than or equal to 2 
gallons
Wt--tare weight of storage tank when completely empty of water for 
water heaters with a rated storage volume greater than or equal to 2 
gallons
[eta]r--recovery efficiency
[rho]--density of water
[tau]stby,1--elapsed time between the start and end of the standby 
period as determined in section 5.4.2 of this appendix
[tau]stby,2--overall time of standby periods when no water is 
withdrawn during the 24-hour simulated-use test as determined in 
section 5.4.2 of this appendix

    1.15. Temperature controller means a device that is available to 
the user to adjust the temperature of the water inside a water 
heater that stores heated water or the outlet water temperature.
    1.16. Uniform Energy Factor means the measure of water heater 
overall efficiency.
    1.17. Water Heater Requiring a Storage Tank means a water heater 
without a storage tank specified or supplied by the manufacturer 
that cannot meet the requirements of sections 2 and 5 of this 
appendix without the use of a storage water heater or unfired hot 
water storage tank.

2. Test Conditions

    2.1 Installation Requirements. Tests shall be performed with the 
water heater and instrumentation installed in accordance with 
section 4 of this appendix.
    2.2 Ambient Air Temperature and Relative Humidity.
    2.2.1 Non-Heat Pump Water Heaters. The ambient air temperature 
shall be maintained between 65.0 [deg]F and 70.0 [deg]F (18.3 [deg]C 
and 21.1 [deg]C) on a continuous basis.
    2.2.2 Heat Pump Water Heaters. The dry bulb temperature shall be 
maintained at an average of 67.5 [deg]F 1 [deg]F (19.7 
[deg]C 0.6 [deg]C) after a cut-in and before the next 
cut-out, an average of 67.5 [deg]F 2.5 [deg]F (19.7 
[deg]C 1.4 [deg]C) after a cut-out and before the next 
cut-in, and at 67.5 [deg]F 5 [deg]F (19.7 [deg]C 2.8 [deg]C) on a continuous basis throughout the test. The 
relative humidity shall be maintained within a range of 50% 5% throughout the test, and at an average of 50% 2% after a cut-in and before the next cut-out.
    When testing a split-system heat pump water heater or heat pump 
water heater requiring a storage tank, the heat pump portion of the 
system shall be tested at the conditions within this section and the 
separate water heater or unfired hot water storage tank shall be 
tested at either the conditions within this section or the 
conditions specified in section 2.2.1 of this appendix.
    2.3 Supply Water Temperature. The temperature of the water being 
supplied to the water heater shall be maintained at 58 [deg]F 2 [deg]F (14.4 [deg]C 1.1 [deg]C) throughout the 
test.
    2.4 Outlet Water Temperature. The temperature controllers of a 
non-flow activated water heater shall be set so that water is 
delivered at a temperature of 125 [deg]F 5 [deg]F (51.7 
[deg]C 2.8 [deg]C).
    2.5 Set Point Temperature. The temperature controller of a flow-
activated water heater shall be set to deliver water at a 
temperature of 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 [deg]C). If the flow-activated water heater is not capable 
of delivering water at a temperature of 125 [deg]F 5 
[deg]F (51.7 [deg]C 2.8 [deg]C) when supplied with water 
at the supply water temperature specified in section 2.3 of this 
appendix, then the flow-activated water

[[Page 1598]]

heater shall be set to deliver water at its maximum water 
temperature.
    2.6 Supply Water Pressure. During the test when water is not 
being withdrawn, the supply pressure shall be maintained between 40 
psig (275 kPa) and the maximum allowable pressure specified by the 
water heater manufacturer.
    2.7 Electrical and/or Fossil Fuel Supply.
    2.7.1 Electrical. Maintain the electrical supply voltage to 
within 2% of the center of the voltage range specified 
on the nameplate of the water heater by the water heater and/or heat 
pump manufacturer, from 5 seconds after a cut-in to 5 seconds before 
next cut-out.
    2.7.2 Natural Gas. Maintain the supply pressure in accordance 
with the supply pressure specified on the nameplate of the water 
heater by the manufacturer. If the supply pressure is not specified, 
maintain a supply pressure of 7-10 inches of water column (1.7-2.5 
kPa). If the water heater is equipped with a gas appliance pressure 
regulator and the gas appliance pressure regulator can be adjusted, 
the regulator outlet pressure shall be within the greater of 10% of the manufacturer's specified manifold pressure, found 
on the nameplate of the water heater, or 0.2 inches 
water column (0.05 kPa). Maintain the gas supply pressure and 
manifold pressure only when operating at the design power rating. 
For all tests, use natural gas having a heating value of 
approximately 1,025 Btu per standard cubic foot (38,190 kJ per 
standard cubic meter).
    2.7.3 Propane Gas. Maintain the supply pressure in accordance 
with the supply pressure specified on the nameplate of the water 
heater by the manufacturer. If the supply pressure is not specified, 
maintain a supply pressure of 11-13 inches of water column (2.7-3.2 
kPa). If the water heater is equipped with a gas appliance pressure 
regulator and the gas appliance pressure regulator can be adjusted, 
the regulator outlet pressure shall be within the greater of 10% of the manufacturer's specified manifold pressure, found 
on the nameplate of the water heater, or 0.2 inches 
water column (0.05 kPa). Maintain the gas supply pressure and 
manifold pressure only when operating at the design power rating. 
For all tests, use propane gas with a heating value of approximately 
2,500 Btu per standard cubic foot (93,147 kJ per standard cubic 
meter).
    2.7.4 Fuel Oil Supply. Maintain an uninterrupted supply of fuel 
oil. The fuel pump pressure shall be within 10% of the 
pump pressure specified on the nameplate of the water heater or the 
installation and operations (I&O) manual by the manufacturer. Use 
fuel oil having a heating value of approximately 138,700 Btu per 
gallon (38,660 kJ per liter).

3. Instrumentation.

    3.1 Pressure Measurements. Pressure-measuring instruments shall 
have an error no greater than the following values:

------------------------------------------------------------------------
        Item measured          Instrument accuracy  Instrument precision
------------------------------------------------------------------------
Gas pressure................  0.1 inch  0.05
                               of water column       inch of water
                               (0.025    column (0.012 kPa).
Atmospheric pressure........  0.1 inch  0.05
                               of mercury column     inch of mercury
                               (0.34     column (0.17 kPa).
Water pressure..............  1.0       0.50
                               pounds per square     pounds per square
                               inch (6.9 kPa).       minus>3.45 kPa).
------------------------------------------------------------------------

    3.2 Temperature Measurement
    3.2.1 Measurement. Temperature measurements shall be made in 
accordance with the Standard Method for Temperature Measurement, 
ASHRAE 41.1-2020, including the conditions as specified in ASHRAE 
41.6-2014 as referenced in ASHRAE 41.1-2020, and excluding the 
steady-state temperature criteria in section 5.5 of ASHRAE 41.1-
2020.
    3.2.2 Accuracy and Precision. The accuracy and precision of the 
instruments, including their associated readout devices, shall be 
within the following limits:

----------------------------------------------------------------------------------------------------------------
             Item measured                      Instrument accuracy                  Instrument precision
----------------------------------------------------------------------------------------------------------------
Air dry bulb temperature..............  0.2 [deg]F (0.1 [deg]F (0.1 [deg]C).                   minus>0.06 [deg]C).
Air wet bulb temperature..............  0.2 [deg]F (0.1 [deg]F (0.1 [deg]C).                   minus>0.06 [deg]C).
Inlet and outlet water temperatures...  0.2 [deg]F (0.1 [deg]F (0.1 [deg]C).                   minus>0.06 [deg]C).
Storage tank temperatures.............  0.5 [deg]F (0.25 [deg]F (0.3 [deg]C).                   minus>0.14 [deg]C).
----------------------------------------------------------------------------------------------------------------

    3.2.3 Scale Division. In no case shall the smallest scale 
division of the instrument or instrument system exceed 2 times the 
specified precision.
    3.2.4 Temperature Difference. Temperature difference between the 
entering and leaving water may be measured with any of the 
following:
    (a) A thermopile
    (b) Calibrated resistance thermometers
    (c) Precision thermometers
    (d) Calibrated thermistors
    (e) Calibrated thermocouples
    (f) Quartz thermometers
    3.2.5 Thermopile Construction. If a thermopile is used, it shall 
be made from calibrated thermocouple wire taken from a single spool. 
Extension wires to the recording device shall also be made from that 
same spool.
    3.2.6 Time Constant. The time constant of the instruments used 
to measure the inlet and outlet water temperatures shall be no 
greater than 2 seconds.
    3.3 Liquid Flow Rate Measurement. The accuracy of the liquid 
flow rate measurement, using the calibration if furnished, shall be 
equal to or less than 1% of the measured value in mass 
units per unit time.
    3.4 Electrical Energy. The electrical energy used shall be 
measured with an instrument and associated readout device that is 
accurate within 0.5% of the reading.
    3.5 Fossil Fuels. The quantity of fuel used by the water heater 
shall be measured with an instrument and associated readout device 
that is accurate within 1% of the reading.
    3.6 Mass Measurements. For mass measurements greater than or 
equal to 10 pounds (4.5 kg), a scale that is accurate within 0.5% of the reading shall be used to make the measurement. For 
mass measurements less than 10 pounds (4.5 kg), the scale shall 
provide a measurement that is accurate within 0.1 pound 
(0.045 kg).
    3.7 Heating Value. The higher heating value of the natural gas, 
propane, or fuel oil shall be measured with an instrument and 
associated readout device that is accurate within 1% of 
the reading. The heating values of natural gas and propane must be 
corrected from those measured to the standard temperature of 60.0 
[deg]F (15.6 [deg]C) and standard pressure of 30 inches of mercury 
column (101.6 kPa) using the method described in Annex B of [ASHRAE 
118.2-TBD].
    3.8 Time. The elapsed time measurements shall be measured with 
an instrument that is accurate within 0.5 seconds per 
hour.
    3.9 Volume. Volume measurements shall be measured with an 
accuracy of 2% of the total volume.
    3.10 Relative Humidity. If a relative humidity (RH) transducer 
is used to measure the relative humidity of the surrounding air 
while testing heat pump water heaters, the relative humidity shall 
be measured with an accuracy of 1.5% RH.

4. Installation

    4.1 Water Heater Mounting. A water heater designed to be 
freestanding shall be placed on a \3/4\ inch (2 cm) thick plywood 
platform supported by three 2 x 4 inch (5 cm x 10 cm) runners. If 
the water heater is not approved for installation on combustible 
flooring, suitable non-combustible material shall be placed between 
the water heater and the platform. Water heaters designed to be 
installed into a kitchen countertop space shall be placed against a 
simulated wall section. Wall-mounted water heaters shall be 
supported on a simulated wall in accordance

[[Page 1599]]

with the manufacturer-published installation instructions. When a 
simulated wall is used, the construction shall be 2 x 4 inch (5 cm x 
10 cm) studs, faced with \3/4\ inch (2 cm) plywood. For heat pump 
water heaters not delivered as a single package, the units shall be 
connected in accordance with the manufacturer-published installation 
instructions and the overall system shall be placed on the above-
described plywood platform. If installation instructions are not 
provided by the heat pump manufacturer, uninsulated 8 foot (2.4 m) 
long connecting hoses having an inside diameter of \5/8\ inch (1.6 
cm) shall be used to connect the storage tank and the heat pump 
water heater. With the exception of using the storage tank described 
in 4.10, the same requirements shall apply for water heaters 
requiring a storage tank. The testing of the water heater shall 
occur in an area that is protected from drafts of more than 50 ft/
min (0.25 m/s) from room ventilation registers, windows, or other 
external sources of air movement.
    4.2 Water Supply. Connect the water heater to a water supply 
capable of delivering water at conditions as specified in sections 
2.3 and 2.6 of this appendix.
    4.3 Water Inlet and Outlet Configuration. For freestanding water 
heaters that are taller than 36 inches (91.4 cm), inlet and outlet 
piping connections shall be configured in a manner consistent with 
Figures 1 and 2 of section 6.4.7 of this appendix. Inlet and outlet 
piping connections for wall-mounted water heaters shall be 
consistent with Figure 3 of section 6.4.7 of this appendix. For 
freestanding water heaters that are 36 inches or less in height and 
not supplied as part of a counter-top enclosure (commonly referred 
to as an under-the-counter model), inlet and outlet piping shall be 
installed in a manner consistent with Figures 4, 5, or 6 of section 
6.4.7 of this appendix. For water heaters that are supplied with a 
counter-top enclosure, inlet and outlet piping shall be made in a 
manner consistent with Figures 7a and 7b of section 6.4.7 of this 
appendix, respectively. The vertical piping noted in Figures 7a and 
7b shall be located (whether inside the enclosure or along the 
outside in a recessed channel) in accordance with the manufacturer-
published installation instructions.
    All dimensions noted in Figures 1 through 7 of section 6.4.7 of 
this appendix must be achieved. All piping between the water heater 
and inlet and outlet temperature sensors, noted as TIN 
and TOUT in the figures, shall be Type ``L'' hard copper 
having the same diameter as the connections on the water heater. 
Unions may be used to facilitate installation and removal of the 
piping arrangements. Install a pressure gauge and diaphragm 
expansion tank in the supply water piping at a location upstream of 
the inlet temperature sensor. Install an appropriately rated 
pressure and temperature relief valve on all water heaters at the 
port specified by the manufacturer. Discharge piping for the relief 
valve must be non-metallic. If heat traps, piping insulation, or 
pressure relief valve insulation are supplied with the water heater, 
they must be installed for testing. Except when using a simulated 
wall, provide sufficient clearance such that none of the piping 
contacts other surfaces in the test room.
    At the discretion of the test lab, the mass or water delivered 
may be measured on either the inlet or outlet of the water heater.
    For water heaters designed to be used with a mixing valve and 
that do not have a self-contained mixing valve, a mixing valve shall 
be installed according to the water heater and/or mixing valve 
manufacturer's installation instructions. If permitted by the water 
heater and mixing valve manufacturer's instructions, the mixing 
valve and cold water junction may be installed where the elbows are 
located in the outlet and inlet line, respectively. If there are no 
installation instructions for the mixing valve in the water heater 
or mixing valve manufacturer's instructions, then the mixing valve 
shall be installed on the outlet line and the cold water shall be 
supplied from the inlet line from a junction installed downstream 
from the location where the inlet water temperature is measured. The 
outlet water temperature, water flow rate, and/or mass measuring 
instrumentation, if installed on the outlet side of the water 
heater, shall be installed downstream from the mixing valve.
    4.4 Fuel and/or Electrical Power and Energy Consumption. Install 
one or more instruments that measure, as appropriate, the quantity 
and rate of electrical energy and/or fossil fuel consumption in 
accordance with section 3 of this appendix.
    4.5 Internal Storage Tank Temperature Measurements. For water 
heaters with rated storage volumes greater than or equal to 20 
gallons, install six temperature measurement sensors inside the 
water heater tank with a vertical distance of at least 4 inches (100 
mm) between successive sensors. For water heaters with rated storage 
volumes between 2 and 20 gallons, install three temperature 
measurement sensors inside the water heater tank. Position a 
temperature sensor at the vertical midpoint of each of the six equal 
volume nodes within a tank larger than 20 gallons or the three equal 
volume nodes within a tank between 2 and 20 gallons. Nodes designate 
the equal volumes used to evenly partition the total volume of the 
tank. As much as is possible, the temperature sensor should be 
positioned away from any heating elements, anodic protective 
devices, tank walls, and flue pipe walls. If the tank cannot 
accommodate six temperature sensors and meet the installation 
requirements specified in this section, install the maximum number 
of sensors that comply with the installation requirements. Install 
the temperature sensors through:
    (a) The anodic device opening;
    (b) The relief valve opening; or
    (c) The hot water outlet.
    If installed through the relief valve opening or the hot water 
outlet, a tee fitting or outlet piping, as applicable, must be 
installed as close as possible to its original location. If the 
relief valve temperature sensor is relocated, and it no longer 
extends into the top of the tank, install a substitute relief valve 
that has a sensing element that can reach into the tank. If the hot 
water outlet includes a heat trap, install the heat trap on top of 
the tee fitting. Cover any added fittings with thermal insulation 
having an R value between 4 and 8 h[middot]ft\2\[middot] [deg]F/Btu 
(0.7 and 1.4 m\2\[middot] [deg]C/W). If temperature measurement 
sensors cannot be installed within the water heater, follow the 
alternate procedures in section 5.4.2 of this appendix.
    4.6 Ambient Air Temperature Measurement. Install an ambient air 
temperature sensor at the vertical midpoint of the water heater and 
approximately 2 feet (610 mm) from the surface of the water heater. 
Shield the sensor against radiation.
    4.7 Inlet and Outlet Water Temperature Measurements. Install 
temperature sensors in the cold-water inlet pipe and hot-water 
outlet pipe as shown in Figures 1, 2, 3, 4, 5, 6, 7a, and 7b of 
section 6.4.7 of this appendix, as applicable.
    4.8 Flow Control. Install a valve or valves to provide flow as 
specified in sections 5.3 and 5.4 of this appendix.
    4.9 Flue Requirements.
    4.9.1 Gas-Fired Water Heaters. Establish a natural draft in the 
following manner. For gas-fired water heaters with a vertically 
discharging draft hood outlet, connect to the draft hood outlet a 5-
foot (1.5-meter) vertical vent pipe extension with a diameter equal 
to the largest flue collar size of the draft hood. For gas-fired 
water heaters with a horizontally discharging draft hood outlet, 
connect to the draft hood outlet a 90-degree elbow with a diameter 
equal to the largest flue collar size of the draft hood, connect a 
5-foot (1.5-meter) length of vent pipe to that elbow, and orient the 
vent pipe to discharge vertically upward. Install direct-vent gas-
fired water heaters with venting equipment specified by the 
manufacturer in the I&O manual using the minimum vertical and 
horizontal lengths of vent pipe recommended by the manufacturer.
    4.9.2 Oil-Fired Water Heaters. Establish a draft at the flue 
collar at the value specified by the manufacturer in the I&O manual. 
Establish the draft by using a sufficient length of vent pipe 
connected to the water heater flue outlet, and directed vertically 
upward. For an oil-fired water heater with a horizontally 
discharging draft hood outlet, connect to the draft hood outlet a 
90-degree elbow with a diameter equal to the largest flue collar 
size of the draft hood, connect to the elbow fitting a length of 
vent pipe sufficient to establish the draft, and orient the vent 
pipe to discharge vertically upward. Direct-vent oil-fired water 
heaters should be installed with venting equipment as specified by 
the manufacturer in the I&O manual, using the minimum vertical and 
horizontal lengths of vent pipe recommended by the manufacturer.
    4.10 Additional Storage Tank. When testing a water heater 
requiring a storage tank, the tank to be used for testing shall be 
an unfired hot water storage tank having a measured volume of 80.0 
gallons 1.0 gallon (178 liters 3.8 liters) 
which meets the energy conservation standards for an unfired hot 
water storage tank at 10 CFR 431.110(a).
    4.11 External Communication. If the water heater can connect to 
an external network or controller, this communication shall be 
disabled for the duration of testing.

[[Page 1600]]

5. Test Procedures

    5.1 Operational Mode Selection. For water heaters that allow for 
multiple user-selected operational modes, all procedures specified 
in this appendix shall be carried out with the water heater in the 
same operational mode (i.e., only one mode). This operational mode 
shall be the default mode (or similarly named, suggested mode for 
normal operation) as defined by the manufacturer in the I&O manual 
for giving selection guidance to the consumer. For heat pump water 
heaters, if a default mode is not defined in the product literature, 
each test shall be conducted under an operational mode in which both 
the heat pump and any electric resistance backup heating element(s) 
are activated by the unit's control scheme, and which can achieve 
the internal storage tank temperature specified in this test 
procedure; if multiple operational modes meet these criteria, the 
water heater shall be tested under the most energy-intensive mode. 
If no default mode is specified and the unit does not offer an 
operational mode that utilizes both the heat pump and the electric 
resistance backup heating element(s), the first-hour rating test and 
the 24-hour simulated-use test shall be tested in heat-pump-only 
mode. For other types of water heaters where a default mode is not 
specified, test the unit in all modes and rate the unit using the 
results of the most energy-intensive mode.
    5.2 Water Heater Preparation.
    5.2.1 Determination of Storage Tank Volume. For water heaters 
with a rated storage volume greater than or equal to 2 gallons, 
determine the storage capacity, Vst, of the water heater 
under test, in gallons (liters), by subtracting the tare weight, 
Wt, (measured while the tank is empty) from the gross 
weight of the storage tank when completely filled with water at the 
supply water temperature specified in section 2.3 of this appendix, 
Wf, (with all air eliminated and line pressure applied as 
described in section 2.6 of this appendix) and dividing the 
resulting net weight by the density of water at the measured 
temperature.
    5.2.2 Setting the Outlet Discharge Temperature.
    5.2.2.1 Flow-Activated Water Heaters, including certain 
instantaneous water heaters and certain storage-type water heaters. 
Initiate normal operation of the water heater at the design power 
rating. Monitor the discharge water temperature and set to the value 
specified in section 2.5 of this appendix in accordance with the 
manufacturer's I&O manual. If the water heater is not capable of 
providing this discharge temperature when the flow rate is 1.7 
gallons 0.25 gallons per minute (6.4 liters 0.95 liters per minute), then adjust the flow rate as 
necessary to achieve the specified discharge water temperature. Once 
the proper temperature control setting is achieved, the setting must 
remain fixed for the duration of the maximum GPM test and the 24-
hour simulated-use test.
    5.2.2.2 Non-Flow Activated Water Heaters, including certain 
instantaneous water heaters and certain storage-type water heaters.
    5.2.2.2.1 Tanks with a Single Temperature Controller.
    5.2.2.2.1.1 Water Heaters with Rated Volumes Less than 20 
Gallons. Starting with a tank at the supply water temperature as 
specified in section 2.3 of this appendix, initiate normal operation 
of the water heater. After cut-out, initiate a draw from the water 
heater at a flow rate of 1.0 gallon 0.25 gallons per 
minute (3.8 liters 0.95 liters per minute) for 2 
minutes. Starting 15 seconds after commencement of the draw, record 
the outlet temperature at 15-second intervals until the end of the 
2-minute period. Determine whether the maximum outlet temperature is 
within the range specified in section 2.4 of this appendix. If not, 
turn off the water heater, adjust the temperature controller, and 
then drain and refill the tank with supply water at the temperature 
specified in section 2.3 of this appendix. Then, once again, 
initiate normal operation of the water heater, and repeat the 2-
minute outlet temperature test following cut-out. Repeat this 
sequence until the maximum outlet temperature during the 2-minute 
test is within the range specified in section 2.4 of this appendix. 
Once the proper temperature control setting is achieved, the setting 
must remain fixed for the duration of the first-hour rating test and 
the 24-hour simulated-use test such that a second identical 24-hour 
simulated-use test run immediately following the one specified in 
section 5.4 of this appendix would result in average delivered water 
temperatures that are within the bounds specified in section 2.4 of 
this appendix.
    5.2.2.2.1.2 Water Heaters with Rated Volumes Greater than or 
Equal to 20 Gallons. Starting with a tank at the supply water 
temperature specified in section 2.3 of this appendix, initiate 
normal operation of the water heater. After cut-out, initiate a draw 
from the water heater at a flow rate of 1.7 gallons 0.25 
gallons per minute (6.4 liters 0.95 liters per minute) 
for 5 minutes. Starting 15 seconds after commencement of the draw, 
record the outlet temperature at 15-second intervals until the end 
of the 5-minute period. Determine whether the maximum outlet 
temperature is within the range specified in section 2.4 of this 
appendix. If not, turn off the water heater, adjust the temperature 
controller, and then drain and refill the tank with supply water at 
the temperature specified in section 2.3 of this appendix. Then, 
once again, initiate normal operation of the water heater, and 
repeat the 5-minute outlet temperature test following cut-out. 
Repeat this sequence until the maximum outlet temperature during the 
5-minute test is within the range specified in section 2.4 of this 
appendix. Once the proper temperature control setting is achieved, 
the setting must remain fixed for the duration of the first-hour 
rating test and the 24-hour simulated-use test such that a second 
identical 24-hour simulated-use test run immediately following the 
one specified in section 5.4 of this appendix would result in 
average delivered water temperatures that are within the bounds 
specified in section 2.4 of this appendix.
    5.2.2.2.2 Tanks with Two or More Temperature Controllers. Verify 
the temperature controller set-point while removing water in 
accordance with the procedure set forth for the first-hour rating 
test in section 5.3.3 of this appendix. The following criteria must 
be met to ensure that all temperature controllers are set to deliver 
water in the range specified in section 2.4 of this appendix:
    (a) At least 50 percent of the water drawn during the first draw 
of the first-hour rating test procedure shall be delivered at a 
temperature within the range specified in section 2.4 of this 
appendix.
    (b) No water is delivered above the range specified in section 
2.4 of this appendix during first-hour rating test.
    (c) The delivery temperature measured 15 seconds after 
commencement of each draw begun prior to an elapsed time of 60 
minutes from the start of the test shall be within the range 
specified in section 2.4 of this appendix.
    (i) If these conditions are not met, turn off the water heater, 
adjust the temperature controllers, and then drain and refill the 
tank with supply water at the temperature specified in section 2.3 
of this appendix. Repeat the procedure described at the start of 
section 5.2.2.2.2 of this appendix until the criteria for setting 
the temperature controllers is met.
    (ii) If the conditions stated above are met, the data obtained 
during the process of verifying the temperature control set-points 
may be used in determining the first-hour rating provided that all 
other conditions and methods required in sections 2 and 5.2.4 of 
this appendix in preparing the water heater were followed.
    5.2.3 Power Input Determination. For all water heaters except 
electric types, initiate normal operation (as described in section 
5.1 of this appendix) and determine the power input, P, to the main 
burners (including pilot light power, if any) after 15 minutes of 
operation. Adjust all burners to achieve an hourly Btu (kJ) rating 
that is within 2% of the maximum input rate value 
specified by the manufacturer. For an oil-fired water heater, adjust 
the burner to give a CO2 reading recommended by the 
manufacturer and an hourly Btu (kJ) rating that is within 2% of the maximum input rate specified by the manufacturer. 
Smoke in the flue may not exceed No. 1 smoke as measured by the 
procedure in ASTM D2156 (RA 2018), including the conditions as 
specified in ASTM E97-1987 (W1991) as referenced in ASTM D2156 (RA 
2018) . If the input rating is not within 2%, first 
increase or decrease the fuel pressure within the tolerances 
specified in section 2.7.2, 2.7.3 or 2.7.4 (as applicable) of this 
appendix until it is 2% of the maximum input rate value 
specified by the manufacturer. If, after adjusting the fuel 
pressure, the fuel input rate cannot be achieved within 2 percent of the maximum input rate value specified by the 
manufacturer, for gas-fired models increase or decrease the gas 
supply pressure within the range specified by the manufacturer. 
Finally, if the measured fuel input rate is still not within 2 percent of the maximum input rate value specified by the 
manufacturer, modify the gas inlet orifice, if so equipped, as 
necessary to achieve a fuel input rate that is within 2 
percent of the maximum input rate value specified by the 
manufacturer.

[[Page 1601]]

    5.2.4 Soak-In Period for Water Heaters with Rated Storage 
Volumes Greater than or Equal to 2 Gallons. For water heaters with a 
rated storage volume greater than or equal to 2 gallons (7.6 
liters), the water heater must sit filled with water, connected to a 
power source, and without any draws taking place for at least 12 
hours after initially being energized so as to achieve the nominal 
temperature set-point within the tank and with the unit connected to 
a power source.
    5.3 Delivery Capacity Tests.
    5.3.1 General. For flow-activated water heaters, conduct the 
maximum GPM test, as described in section 5.3.2, Maximum GPM Rating 
Test for Flow-Activated Water Heaters, of this appendix. For all 
other water heaters, conduct the first-hour rating test as described 
in section 5.3.3 of this appendix.
    5.3.2 Maximum GPM Rating Test for Flow-Activated Water Heaters. 
Establish normal water heater operation at the design power rating 
with the discharge water temperature set in accordance with section 
5.2.2.1 of this appendix.
    For this 10-minute test, either collect the withdrawn water for 
later measurement of the total mass removed or use a water meter to 
directly measure the water mass of volume removed. Initiate water 
flow through the water heater and record the inlet and outlet water 
temperatures beginning 15 seconds after the start of the test and at 
subsequent 5-second intervals throughout the duration of the test. 
At the end of 10 minutes, turn off the water. Determine and record 
the mass of water collected, M10m, in pounds (kilograms), 
or the volume of water, V10m, in gallons (liters).
    5.3.3 First-Hour Rating Test.
    5.3.3.1 General. During hot water draws for non-flow activated 
water heaters with rated storage volumes greater than or equal to 20 
gallons, remove water at a rate of 3.0 0.25 gallons per 
minute (11.4 0.95 liters per minute). During hot water 
draws for non-flow activated water heaters with rated storage 
volumes below 20 gallons, remove water at a rate of 1.5 0.25 gallon per minute (5.7 0.95 liters per 
minute). Collect the water in a container that is large enough to 
hold the volume removed during an individual draw and is suitable 
for weighing at the termination of each draw to determine the total 
volume of water withdrawn. As an alternative to collecting the 
water, a water meter may be used to directly measure the water mass 
or volume withdrawn during each draw.
    5.3.3.2 Draw Initiation Criteria. Begin the first-hour rating 
test by starting a draw on the non-flow activated water heater. 
After completion of this first draw, initiate successive draws based 
on the following criteria. For gas-fired and oil-fired water 
heaters, initiate successive draws when the temperature controller 
acts to reduce the supply of fuel to the main burner. For electric 
water heaters having a single element or multiple elements that all 
operate simultaneously, initiate successive draws when the 
temperature controller acts to reduce the electrical input supplied 
to the element(s). For electric water heaters having two or more 
elements that do not operate simultaneously, initiate successive 
draws when the applicable temperature controller acts to reduce the 
electrical input to the energized element located vertically highest 
in the storage tank. For heat pump water heaters that do not use 
supplemental, resistive heating, initiate successive draws 
immediately after the electrical input to the compressor is reduced 
by the action of the water heater's temperature controller. For heat 
pump water heaters that use supplemental resistive heating, initiate 
successive draws immediately after the electrical input to the first 
of either the compressor or the vertically highest resistive element 
is reduced by the action of the applicable water heater temperature 
controller. This draw initiation criterion for heat pump water 
heaters that use supplemental resistive heating, however, shall only 
apply when the water located above the thermostat at cut-out is 
heated to within the range specified in section 2.4 of this 
appendix. If this criterion is not met, then the next draw should be 
initiated once the heat pump compressor cuts out.
    5.3.3.3 Test Sequence. Establish normal water heater operation. 
If the water heater is not presently operating, initiate a draw. The 
draw may be terminated any time after cut-in occurs. After cut-out 
occurs (i.e., all temperature controllers are satisfied), if the 
water heater can have its internal tank temperatures measured, 
record the internal storage tank temperature at each sensor 
described in section 4.5 of this appendix every one minute, and 
determine the mean tank temperature by averaging the values from 
these sensors.
    (a) Initiate a draw after a maximum mean tank temperature (the 
maximum of the mean temperatures of the individual sensors) has been 
observed following a cut-out. If the water heater cannot have its 
internal tank temperatures measured, wait 5 minutes after cut-out. 
Record the time when the draw is initiated and designate it as an 
elapsed time of zero ([tau]* = 0). (The superscript * is used to 
denote variables pertaining to the first-hour rating test). Record 
the outlet water temperature beginning 15 seconds after the draw is 
initiated and at 5-second intervals thereafter until the draw is 
terminated. Determine the maximum outlet temperature that occurs 
during this first draw and record it as T*max,1. For the 
duration of this first draw and all successive draws, in addition, 
monitor the inlet temperature to the water heater to ensure that the 
required supply water temperature test condition specified in 
section 2.3 of this appendix is met. Terminate the hot water draw 
when the outlet temperature decreases to T*max,1-15 
[deg]F (T*max,1-8.3 [deg]C). (Note, if the outlet 
temperature does not decrease to T*max,1-15 [deg]F 
(T*max,1-8.3 [deg]C) during the draw, then hot water 
would be drawn continuously for the duration of the test. In this 
instance, the test would end when the temperature decreases to 
T*max,1-15 [deg]F (T*max,1-8.3 [deg]C) after 
the electrical power and/or fuel supplied to the water heater is 
shut off, as described in the following paragraphs.) Record this 
temperature as T*min,1. Following draw termination, 
determine the average outlet water temperature and the mass or 
volume removed during this first draw and record them as 
T*del,i and M*1 or V*1, 
respectively.
    (b) Initiate a second and, if applicable, successive draw(s) 
each time the applicable draw initiation criteria described in 
section 5.3.3.2 of this appendix are satisfied. As required for the 
first draw, record the outlet water temperature 15 seconds after 
initiating each draw and at 5-second intervals thereafter until the 
draw is terminated. Determine the maximum outlet temperature that 
occurs during each draw and record it as T*max,i, where 
the subscript i refers to the draw number. Terminate each hot water 
draw when the outlet temperature decreases to T*max,i-15 
[deg]F (T*max,i-8.3 [deg]C). Record this temperature as 
T*min,i. Calculate and record the average outlet 
temperature and the mass or volume removed during each draw 
(T*del,i and M*i or V*i, 
respectively). Continue this sequence of draw and recovery until one 
hour after the start of the test, then shut off the electrical power 
and/or fuel supplied to the water heater.
    (c) If a draw is occurring at one hour from the start of the 
test, continue this draw until the outlet temperature decreases to 
T*max,n-15 [deg]F (T*max,n-8.3 [deg]C), at 
which time the draw shall be immediately terminated. (The subscript 
n shall be used to denote measurements associated with the final 
draw.) If a draw is not occurring one hour after the start of the 
test, initiate a final draw at one hour, regardless of whether the 
criteria described in section 5.3.3.2 of this appendix are 
satisfied. This draw shall proceed for a minimum of 30 seconds and 
shall terminate when the outlet temperature first indicates a value 
less than or equal to the cut-off temperature used for the previous 
draw (T*min,n-1). If an outlet temperature greater than 
T*min,n-1 is not measured within 30 seconds of initiation 
of the draw, zero additional credit shall be given towards first-
hour rating (i.e., M*n = 0 or V*n = 0) based 
on the final draw. After the final draw is terminated, calculate and 
record the average outlet temperature and the mass or volume removed 
during the final draw (T*del,n and M*n or 
V*n, respectively).
    5.4 24-Hour Simulated-Use Test.
    5.4.1 Selection of Draw Pattern. The water heater will be tested 
under a draw profile that depends upon the first-hour rating 
obtained following the test prescribed in section 5.3.3 of this 
appendix, or the maximum GPM rating obtained following the test 
prescribed in section 5.3.2 of this appendix, whichever is 
applicable. For water heaters that have been tested according to the 
first-hour rating procedure, one of four different patterns shall be 
applied based on the measured first-hour rating, as shown in Table I 
of this section. For water heater that have been tested according to 
the maximum GPM rating procedure, one of four different patterns 
shall be applied based on the maximum GPM, as shown in Table II of 
this section.

[[Page 1602]]



                           Table I--Draw Pattern To Be Used Based on First-Hour Rating
----------------------------------------------------------------------------------------------------------------
 First-hour rating greater than or    . . . and first-hour  Draw pattern to be used in the 24-hour simulated-use
             equal to:                 rating less than:                            test
----------------------------------------------------------------------------------------------------------------
0 gallons..........................  18 gallons...........  Very-Small-Usage (Table III.1).
18 gallons.........................  51 gallons...........  Low-Usage (Table III.2).
51 gallons.........................  75 gallons...........  Medium-Usage (Table III.3).
75 gallons.........................  No upper limit.......  High-Usage (Table III.4).
----------------------------------------------------------------------------------------------------------------


                          Table II--Draw Pattern To Be Used Based on Maximum GPM Rating
----------------------------------------------------------------------------------------------------------------
 Maximum GPM rating greater than or     and maximum GPM     Draw pattern to be used in the 24-hour simulated-use
             equal to:                 rating less than:                            test
----------------------------------------------------------------------------------------------------------------
0 gallons/minute...................  1.7 gallons/minute...  Very-Small-Usage (Table III.1).
1.7 gallons/minute.................  2.8 gallons/minute...  Low-Usage (Table III.2).
2.8 gallons/minute.................  4 gallons/minute.....  Medium-Usage (Table III.3).
4 gallons/minute...................  No upper limit.......  High-Usage (Table III.4).
----------------------------------------------------------------------------------------------------------------

    The draw patterns are provided in Tables III.1 through III.4 in 
section 5.5 of this appendix. Use the appropriate draw pattern when 
conducting the test sequence provided in section 5.4.2 of this 
appendix for water heaters with rated storage volumes greater than 
or equal to 2 gallons or section 5.4.3 of this appendix for water 
heaters with rated storage volumes less than 2 gallons.
    5.4.2 Test Sequence for Water Heaters with Rated Storage Volumes 
Greater Than or Equal to 2 Gallons.
    If the water heater is turned off, fill the water heater with 
supply water at the temperature specified in section 2.3 of this 
appendix and maintain supply water pressure as described in section 
2.6 of this appendix. Turn on the water heater and associated heat 
pump unit, if present. If turned on in this fashion, the soak-in 
period described in section 5.2.4 of this appendix shall be 
implemented. If the water heater has undergone a first-hour rating 
test prior to conduct of the 24-hour simulated-use test, allow the 
water heater to fully recover after completion of that test such 
that the main burner, heating elements, or heat pump compressor of 
the water heater are no longer raising the temperature of the stored 
water. In all cases, the water heater shall sit idle for 1 hour 
prior to the start of the 24-hour test; during which time no water 
is drawn from the unit and there is no energy input to the main 
heating elements, heat pump compressor, and/or burners. At the end 
of this period, the 24-hour simulated-use test will begin.
    For water heaters that can have their internal storage tank 
temperature measured, one minute prior to the start of the 24-hour 
test simulated-use test, record the mean tank temperature 
(T0). For water heaters that cannot have their internal 
tank temperatures measured, the mean tank temperature at the start 
of the 24-hour simulated-use test (T0) is the average of 
the supply and outlet water temperatures measured 5 seconds after 
the start of the first draw of the test.
    At the start of the 24-hour simulated-use test, record the 
electrical and/or fuel measurement readings, as appropriate. Begin 
the 24-hour simulated-use test by withdrawing the volume specified 
in the appropriate table in section 5.5 of this appendix (i.e., 
Table III.1, Table III.2, Table III.3, or Table III.4, depending on 
the first-hour rating or maximum GPM rating) for the first draw at 
the flow rate specified in the applicable table. Record the time 
when this first draw is initiated and assign it as the test elapsed 
time ([tau]) of zero (0). Record the average storage tank and 
ambient temperature every minute throughout the 24-hour simulated-
use test. At the elapsed times specified in the applicable draw 
pattern table in section 5.5 of this appendix for a particular draw 
pattern, initiate additional draws pursuant to the draw pattern, 
removing the volume of hot water at the prescribed flow rate 
specified by the table. The maximum allowable deviation from the 
specified volume of water removed for any single draw taken at a 
nominal flow rate of 1 GPM or 1.7 GPM is 0.1 gallons 
(0.4 liters). The maximum allowable deviation from the 
specified volume of water removed for any single draw taken at a 
nominal flow rate of 3 GPM is 0.25 gallons (0.9 liters). 
The quantity of water withdrawn during the last draw shall be 
increased or decreased as necessary such that the total volume of 
water withdrawn equals the prescribed daily amount for that draw 
pattern 1.0 gallon (3.8 liters). If this 
adjustment to the volume drawn during the last draw results in no 
draw taking place, the test is considered invalid.
    All draws during the 24-hour simulated-use test shall be made at 
the flow rates specified in the applicable draw pattern table in 
section 5.5 of this appendix, within a tolerance of 0.25 
gallons per minute (0.9 liters per minute). Measurements 
of the inlet and outlet temperatures shall be made 15 seconds after 
the draw is initiated and at every subsequent 3-second interval 
throughout the duration of each draw. Calculate and record the mean 
of the hot water discharge temperature and the cold water inlet 
temperature for each draw Tdel,i and Tin,i). 
Determine and record the net mass or volume removed (Mi 
or Vi), as appropriate, after each draw.
    The first recovery period is the time from the start of the 24-
hour simulated-use test and continues during the temperature rise of 
the stored water until the first cut-out; if the cut-out occurs 
during a subsequent draw, the first recovery period includes the 
time until the draw of water from the tank stops. If, after the 
first cut-out occurs but during a subsequent draw, a subsequent cut-
in occurs prior to the draw completion, the first recovery period 
includes the time until the subsequent cut-out occurs, prior to 
another draw. The first recovery period may continue until a cut-out 
occurs when water is not being removed from the water heater or a 
cut-out occurs during a draw and the water heater does not cut-in 
prior to the end of the draw.
    At the end of the first recovery period, record the maximum mean 
tank temperature observed after cut-out (Tmax,1). For 
water heaters that cannot have their internal storage tank 
temperatures measured, the maximum mean tank temperature after the 
first recovery period (Tmax,1) is the average of the 
final inlet and outlet water temperature measurements of the first 
draw. At the end of the first recovery period, record the total 
energy consumed by the water heater from the beginning of the test 
(Qr), including all fossil fuel and/or electrical energy 
use, from the main heat source and auxiliary equipment including, 
but not limited to, burner(s), resistive elements(s), compressor, 
fan, controls, pump, etc., as applicable.
    The start of the portion of the test during which the standby 
loss coefficient is determined depends upon whether the unit has 
fully recovered from the first draw cluster. For water heaters than 
can have their internal storage tank temperatures measured, if a 
recovery is occurring at or within five minutes after the end of the 
final draw in the first draw cluster, as identified in the 
applicable draw pattern table in section 5.5 of this appendix, then 
the standby period starts when a maximum mean tank temperature is 
observed starting five minutes after the end of the recovery period 
that follows that draw. If a recovery does not occur at or within 
five minutes after the end of the final draw in the first draw 
cluster, as identified in the applicable draw pattern table in 
section 5.5 of this appendix, then the standby period starts five 
minutes after the end of that draw. For water heaters that cannot 
have their internal storage tank temperatures measured, the start of 
the standby period is at the final measurement of

[[Page 1603]]

the last draw of the first draw cluster. Determine and record the 
total electrical energy and/or fossil fuel consumed from the 
beginning of the test to the start of the standby period 
(Qsu,0).
    In preparation for determining the energy consumed during 
standby, record the reading given on the electrical energy (watt-
hour) meter, the gas meter, and/or the scale used to determine oil 
consumption, as appropriate. Record the mean tank temperature at the 
start of the standby period (Tsu,0). For water heaters 
that cannot have their internal storage tank temperatures measured, 
the mean tank temperature at the start of the standby period 
(Tsu,0) is the average of the final measured inlet and 
outlet water temperature from the last draw of the first draw 
cluster. At 1-minute intervals, record ambient temperature, the 
electric and/or fuel instrument readings, and, for water heaters 
that can have their internal storage tank temperatures measured, the 
mean tank temperature until the next draw is initiated. The end of 
the standby period is when the final mean tank temperature is 
recorded, as described. For water heaters that can have their 
internal storage tank temperatures measured, just prior to 
initiation of the next draw, record the mean tank temperature 
(Tsu,f). If the water heater is undergoing recovery when 
the next draw is initiated, record the mean tank temperature 
(Tsu,f) at the minute prior to the start of the recovery. 
For water heaters that cannot have their internal storage tank 
temperatures measured, the mean tank temperature at the end of the 
standby period (Tsu,f) is the average of the inlet and 
outlet water temperatures measured 5 seconds after the start of the 
next draw. Determine the total electrical energy and/or fossil fuel 
energy consumption from the beginning of the test to the end of the 
standby period (Qsu,f). Record the time interval between 
the start of the standby period and the end of the standby period 
([tau]stby,1).
    Following the final draw of the prescribed draw pattern and 
subsequent recovery, allow the water heater to remain in the standby 
mode until exactly 24 hours have elapsed since the start of the 24-
hour simulated-use test (i.e., since [tau] = 0). During the last 
hour of the 24-hour simulated-use test (i.e., hour 23 of the 24-hour 
simulated-use test), power to the main burner, heating element, or 
compressor shall be disabled. At 24 hours, record the reading given 
by the gas meter, oil meter, and/or the electrical energy meter as 
appropriate. Determine the fossil fuel and/or electrical energy 
consumed during the entire 24-hour simulated-use test and designate 
the quantity as Q. For water heaters that cannot have their internal 
storage tank temperatures measured, at hour 24 initiate a draw at 
the flow rate of the first draw of the draw pattern determined as 
described in section 5.4.1 of this appendix. The mean tank 
temperature at hour 24 (T24) is the average of the inlet 
and outlet water temperatures measured 5 seconds after the start of 
the draw.
    In the event that the recovery period continues from the end of 
the last draw of the first draw cluster until the subsequent draw, 
the standby period will start after the end of the first recovery 
period after the last draw of the 24-hour simulated-use test, when 
the temperature reaches the maximum mean tank temperature, though no 
sooner than five minutes after the end of this recovery period. The 
standby period shall last eight hours, so testing may extend beyond 
the 24-hour duration of the 24-hour simulated-use test. Determine 
and record the total electrical energy and/or fossil fuel consumed 
from the beginning of the 24-hour simulated-use test to the start of 
the 8-hour standby period (Qsu,0). In preparation for 
determining the energy consumed during standby, record the 
reading(s) given on the electrical energy (watt-hour) meter, the gas 
meter, and/or the scale used to determine oil consumption, as 
appropriate. Record the mean tank temperature at the start of the 
standby period (Tsu,0). Record the mean tank temperature, 
the ambient temperature, and the electric and/or fuel instrument 
readings at 1-minute intervals until the end of the 8-hour period. 
Record the mean tank temperature at the end of the 8-hour standby 
period (Tsu,f). If the water heater is undergoing 
recovery at the end of the standby period, record the mean tank 
temperature (Tsu,f) at the minute prior to the start of 
the recovery, which will mark the end of the standby period. 
Determine the total electrical energy and/or fossil fuel energy 
consumption from the beginning of the test to the end of the standby 
period (Qsu,f). Record the time interval between the 
start of the standby period and the end of the standby period as 
[tau]stby,1. Record the average ambient temperature from 
the start of the standby period to the end of the standby period 
(Ta,stby,1). Record the average mean tank temperature 
from the start of the standby period to the end of the standby 
period (Tt,stby,1).
    If the standby period occurred at the end of the first recovery 
period after the last draw of the 24-hour simulated-use test, allow 
the water heater to remain in the standby mode until exactly 24 
hours have elapsed since the start of the 24-hour simulated-use test 
(i.e., since [tau] = 0) or the end of the standby period, whichever 
is longer. At 24 hours, record the mean tank temperature 
(T24) and the reading given by the gas meter, oil meter, 
and/or the electrical energy meter as appropriate. If the water 
heater is undergoing a recovery at 24 hours, record the reading 
given by the gas meter, oil meter, and/or electrical energy meter, 
as appropriate, and the mean tank temperature (T24) at 
the minute prior to the start of the recovery. Determine the fossil 
fuel and/or electrical energy consumed during the 24 hours and 
designate the quantity as Q.
    Record the time during which water is not being withdrawn from 
the water heater during the entire 24-hour period 
([tau]stby,2). When the standby period occurs after the 
last draw of the 24-hour simulated-use test, the test may extend 
past hour 24. When this occurs, the measurements taken after hour 24 
apply only to the calculations of the standby loss coefficient. All 
other measurements during the time between hour 23 and hour 24 
remain the same.
    5.4.3 Test Sequence for Water Heaters with Rated Storage Volume 
Less Than 2 Gallons.
    Establish normal operation with the discharge water temperature 
at 125 [deg]F 5 [deg]F (51.7 [deg]C 2.8 
[deg]C) and set the flow rate as determined in section 5.2 of this 
appendix. Prior to commencement of the 24-hour simulated-use test, 
the unit shall remain in an idle state in which controls are active 
but no water is drawn through the unit for a period of one hour. 
With no draw occurring, record the reading given by the gas meter 
and/or the electrical energy meter as appropriate. Begin the 24-hour 
simulated-use test by withdrawing the volume specified in Tables 
III.1 through III.4 of section 5.5 of this appendix for the first 
draw at the flow rate specified. Record the time when this first 
draw is initiated and designate it as an elapsed time, [tau], of 0. 
At the elapsed times specified in Tables III.1 through III.4 for a 
particular draw pattern, initiate additional draws, removing the 
volume of hot water at the prescribed flow rate specified in Tables 
III.1 through III.4. The maximum allowable deviation from the 
specified volume of water removed for any single draw taken at a 
nominal flow rate less than or equal to 1.7 GPM (6.4 L/min) is 
0.1 gallons (0.4 liters). The maximum 
allowable deviation from the specified volume of water removed for 
any single draw taken at a nominal flow rate of 3 GPM (11.4 L/min) 
is 0.25 gallons (0.9 liters). The quantity of water 
drawn during the final draw shall be increased or decreased as 
necessary such that the total volume of water withdrawn equals the 
prescribed daily amount for that draw pattern 1.0 gallon 
(3.8 liters). If this adjustment to the volume drawn in 
the last draw results in no draw taking place, the test is 
considered invalid.
    All draws during the 24-hour simulated-use test shall be made at 
the flow rates specified in the applicable draw pattern table in 
section 5.5 of this appendix, within a tolerance of 0.25 
gallons per minute (0.9 liters per minute). Measurements 
of the inlet and outlet water temperatures shall be made 15 seconds 
after the draw is initiated and at every 3-second interval 
thereafter throughout the duration of the draw. Calculate the mean 
of the hot water discharge temperature and the cold water inlet 
temperature for each draw. Record the mass of the withdrawn water or 
the water meter reading, as appropriate, after each draw. At the end 
of the first recovery period following the first draw, determine and 
record the fossil fuel and/or electrical energy consumed, 
Qr. Following the final draw and subsequent recovery, 
allow the water heater to remain in the standby mode until exactly 
24 hours have elapsed since the start of the test (i.e., since [tau] 
= 0). At 24 hours, record the reading given by the gas meter, oil 
meter, and/or the electrical energy meter, as appropriate. Determine 
the fossil fuel and/or electrical energy consumed during the entire 
24-hour simulated-use test and designate the quantity as Q.
    5.5 Draw Patterns.
    The draw patterns to be imposed during 24-hour simulated-use 
tests are provided in Tables III.1 through III.4. Subject each water 
heater under test to one of these draw patterns based on its first-
hour rating or maximum GPM rating, as discussed in section 5.4.1 of 
this appendix. Each draw pattern specifies the elapsed time in hours 
and minutes during the 24-hour test when a draw is to commence, the 
total volume of

[[Page 1604]]

water in gallons (liters) that is to be removed during each draw, 
and the flow rate at which each draw is to be taken, in gallons 
(liters) per minute.

                                   Table III.1--Very-Small-Usage Draw Pattern
----------------------------------------------------------------------------------------------------------------
                                                          Time during test   Volume [gallons     Flow rate ***
                        Draw No.                             ** [hh:mm]            (L)]          [GPM (L/min)]
----------------------------------------------------------------------------------------------------------------
1 *....................................................               0:00          2.0 (7.6)            1 (3.8)
2 *....................................................               1:00          1.0 (3.8)            1 (3.8)
3 *....................................................               1:05          0.5 (1.9)            1 (3.8)
4 *....................................................               1:10          0.5 (1.9)            1 (3.8)
5 *....................................................               1:15          0.5 (1.9)            1 (3.8)
6......................................................               8:00          1.0 (3.8)            1 (3.8)
7......................................................               8:15          2.0 (7.6)            1 (3.8)
8......................................................               9:00          1.5 (5.7)            1 (3.8)
9......................................................               9:15          1.0 (3.8)            1 (3.8)
----------------------------------------------------------------------------------------------------------------
                                  Total Volume Drawn Per Day: 10 gallons (38 L)
----------------------------------------------------------------------------------------------------------------
* Denotes draws in first draw cluster.
** If a draw extends to the start of the subsequent draw, then the subsequent draw shall start when the required
  volume of the previous draw has been delivered.
*** Should the water heater have a maximum GPM rating less than 1 GPM (3.8 L/min), then all draws shall be
  implemented at a flow rate equal to the rated maximum GPM.


                                       Table III.2--Low-Usage Draw Pattern
----------------------------------------------------------------------------------------------------------------
                                                          Time during test   Volume [gallons   Flow rate [GPM (L/
                        Draw No.                              [hh:mm]              (L)]              min)]
----------------------------------------------------------------------------------------------------------------
1 *....................................................               0:00        15.0 (56.8)          1.7 (6.4)
2 *....................................................               0:30          2.0 (7.6)            1 (3.8)
3 *....................................................               1:00          1.0 (3.8)            1 (3.8)
4......................................................              10:30         6.0 (22.7)          1.7 (6.4)
5......................................................              11:30         4.0 (15.1)          1.7 (6.4)
6......................................................              12:00          1.0 (3.8)            1 (3.8)
7......................................................              12:45          1.0 (3.8)            1 (3.8)
8......................................................              12:50          1.0 (3.8)            1 (3.8)
9......................................................              16:15          2.0 (7.6)            1 (3.8)
10.....................................................              16:45          2.0 (7.6)          1.7 (6.4)
11.....................................................              17:00         3.0 (11.4)          1.7 (6.4)
----------------------------------------------------------------------------------------------------------------
                                 Total Volume Drawn Per Day: 38 gallons (144 L)
----------------------------------------------------------------------------------------------------------------
* Denotes draws in first draw cluster.


                                     Table III.3--Medium-Usage Draw Pattern
----------------------------------------------------------------------------------------------------------------
                                                          Time during test   Volume [gallons   Flow rate [GPM (L/
                        Draw No.                              [hh:mm]              (L)]              min)]
----------------------------------------------------------------------------------------------------------------
1 *....................................................               0:00        15.0 (56.8)          1.7 (6.4)
2 *....................................................               0:30          2.0 (7.6)            1 (3.8)
3 *....................................................               1:40         9.0 (34.1)          1.7 (6.4)
4......................................................              10:30         9.0 (34.1)          1.7 (6.4)
5......................................................              11:30         5.0 (18.9)          1.7 (6.4)
6......................................................              12:00          1.0 (3.8)            1 (3.8)
7......................................................              12:45          1.0 (3.8)            1 (3.8)
8......................................................              12:50          1.0 (3.8)            1 (3.8)
9......................................................              16:00          1.0 (3.8)            1 (3.8)
10.....................................................              16:15          2.0 (7.6)            1 (3.8)
11.....................................................              16:45          2.0 (7.6)          1.7 (6.4)
12.....................................................              17:00         7.0 (26.5)          1.7 (6.4)
----------------------------------------------------------------------------------------------------------------
                                 Total Volume Drawn Per Day: 55 gallons (208 L)
----------------------------------------------------------------------------------------------------------------
* Denotes draws in first draw cluster.


                                      Table III.4--High-Usage Draw Pattern
----------------------------------------------------------------------------------------------------------------
                                                          Time during test   Volume [gallons   Flow rate [GPM (L/
                        Draw No.                              [hh:mm]              (L)]              min)]
----------------------------------------------------------------------------------------------------------------
1 *....................................................               0:00         27.0 (102)           3 (11.4)
2 *....................................................               0:30          2.0 (7.6)            1 (3.8)
3 *....................................................               0:40          1.0 (3.8)            1 (3.8)

[[Page 1605]]

 
4 *....................................................               1:40         9.0 (34.1)          1.7 (6.4)
5......................................................              10:30        15.0 (56.8)           3 (11.4)
6......................................................              11:30         5.0 (18.9)          1.7 (6.4)
7......................................................              12:00          1.0 (3.8)            1 (3.8)
8......................................................              12:45          1.0 (3.8)            1 (3.8)
9......................................................              12:50          1.0 (3.8)            1 (3.8)
10.....................................................              16:00          2.0 (7.6)            1 (3.8)
11.....................................................              16:15          2.0 (7.6)            1 (3.8)
12.....................................................              16:30          2.0 (7.6)          1.7 (6.4)
13.....................................................              16:45          2.0 (7.6)          1.7 (6.4)
14.....................................................              17:00        14.0 (53.0)           3 (11.4)
----------------------------------------------------------------------------------------------------------------
                                 Total Volume Drawn Per Day: 84 gallons (318 L)
----------------------------------------------------------------------------------------------------------------
* Denotes draws in first draw cluster.

6. Computations

    6.1 First-Hour Rating Computation. For the case in which the 
final draw is initiated at or prior to one hour from the start of 
the test, the first-hour rating, Fhr, shall be computed 
using,
BILLING CODE 6450-01-P
[GRAPHIC] [TIFF OMITTED] TP11JA22.002

Where:

n = the number of draws that are completed during the first-hour 
rating test.
V*del,i = the volume of water removed during the ith draw 
of the first-hour rating test, gal (L) or, if the mass of water 
removed is being measured,
[GRAPHIC] [TIFF OMITTED] TP11JA22.003

Where:

M*del,i = the mass of water removed during the ith draw 
of the first-hour rating test, lb (kg).
[rho]del,i = the density of water removed, evaluated at 
the average outlet water temperature measured during the ith draw of 
the first-hour rating test, (T*del,i), lb/gal (kg/L).
or, if the volume of the water entering the water heater is being 
measured,
[GRAPHIC] [TIFF OMITTED] TP11JA22.004

Where:

V*in,i = the volume of water entering the water heater 
during the ith draw of the first-hour rating test, gal (L).
[rho]in,i = the density of water entering the water 
heater, evaluated at the average inlet water temperature measured 
during the ith draw of the first-hour rating test, 
(T*in,i), lb/gal (kg/L).
or, if the mass of water entering the water heater is being 
measured,
[GRAPHIC] [TIFF OMITTED] TP11JA22.005

Where:

M*in,i = the mass of water entering the water heater 
during the ith draw of the first-hour rating test, lb (kg).

    For the case in which a draw is not in progress at one hour from 
the start of the test and a final draw is imposed at the elapsed 
time of one hour, the first-hour rating shall be calculated using,
[GRAPHIC] [TIFF OMITTED] TP11JA22.006

Where:

n and V*del,i are the same quantities as defined above, 
and
V*del,n = the volume of water removed during the nth 
(final) draw of the first-hour rating test, gal (L).
T*del,n-1 = the average water outlet temperature measured 
during the (n-1)th draw of the first-hour rating test, [deg]F 
([deg]C).
T*del,n = the average water outlet temperature measured 
during the nth (final) draw of the first-hour rating test, [deg]F 
([deg]C).
T*min,n-1 = the minimum water outlet temperature measured 
during the (n-1)th draw of the first-hour rating test, [deg]F 
([deg]C).

    6.2 Maximum GPM (L/min) Rating Computation. Compute the maximum 
GPM (L/min) rating, Fmax, as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.007

Where:

Vdel,10m = the volume of water removed during the maximum 
GPM (L/min) rating test, gal (L).
Tdel = the average delivery temperature, [deg]F ([deg]C).
Tin = the average inlet temperature, [deg]F ([deg]C).
10 = the number of minutes in the maximum GPM (L/min) rating test, 
min.
or, if the mass of water removed is measured,
[GRAPHIC] [TIFF OMITTED] TP11JA22.008

Where:

Mdel,10m = the mass of water removed during the maximum 
GPM (L/min) rating test, lb (kg).
[rho]del = the density of water removed, evaluated at the 
average delivery water temperature of the maximum GPM (L/min) rating 
test (Tdel), lb/gal (kg/L).

    or, if the volume of water entering the water heater is 
measured,
[GRAPHIC] [TIFF OMITTED] TP11JA22.009

Where:


[[Page 1606]]


Vin,10m = the volume of water entering the water heater 
during the maximum GPM (L/min) rating test, gal (L).
[rho]in = the density of water entering the water heater, 
evaluated at the average inlet water temperature of the maximum GPM 
(L/min) rating test (Tdel), lb/gal (kg/L).

    or, if the mass of water entering the water heater is measured,
    [GRAPHIC] [TIFF OMITTED] TP11JA22.010
    
Where:

Min,10m = the mass of water entering the water heater 
during the maximum GPM (L/min) rating test, lb (kg).

    6.3 Computations for Water Heaters with a Rated Storage Volume 
Greater Than or Equal to 2 Gallons.
    6.3.1 Storage Tank Capacity. The storage tank capacity, 
Vst, is computed as follows:
[GRAPHIC] [TIFF OMITTED] TP11JA22.011

Where:

Vst = the storage capacity of the water heater, gal (L).
Wf = the weight of the storage tank when completely 
filled with water, lb (kg).
Wt = the (tare) weight of the storage tank when 
completely empty, lb (kg).
[rho] = the density of water used to fill the tank measured at the 
temperature of the water, lb/gal (kg/L).

    6.3.2 Mass of Water Removed. Determine the mass of water removed 
during each draw of the 24-hour simulated-use test 
(Mdel,i) as:
    If the mass of water removed is measured, use the measured 
value, or, if the volume of water removed is being measured,

Mdel,i = Vdel,i * [rho]del,i

Where:

Vdel,i = volume of water removed during draw ith draw of 
the 24-hour simulated-use test, gal (L).
[rho]del,i = density of the water removed, evaluated at 
the average outlet water temperature measured during the ith draw of 
the 24-hour simulated-use test, (Tdel,i), lb/gal (kg/L).

    or, if the volume of water entering the water heater is 
measured,

Mdel,i = Vin,i * [rho]in,i

Where:

Vin,i = volume of water entering the water heater during 
draw ith draw of the 24-hour simulated-use test, gal (L).
[rho]in,i = density of the water entering the water 
heater, evaluated at the average inlet water temperature measured 
during the ith draw of the 24-hour simulated-use test, 
(Tin,i), lb/gal (kg/L).

    or, if the mass of water entering the water heater is measured,

Mdel,i = Min,i

Where:

Min,i = mass of water entering the water heater during 
draw ith draw of the 24-hour simulated-use test, lb (kg).

    6.3.3 Recovery Efficiency. The recovery efficiency for gas, oil, 
and heat pump water heaters with a rated storage volume greater than 
or equal to 2 gallons, [eta]r, is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.012

Where:

Vst = as defined in section 6.3.1 of this appendix.
[rho]1 = density of stored hot water evaluated at 
(Tmax,1 + T0)/2, lb/gal (kg/L).
Cp1 = specific heat of the stored hot water, evaluated at 
(Tmax,1 + T0)/2, Btu/(lb[middot][deg]F) (kJ/
(kg[middot][deg]C).
Tmax,1 = maximum mean tank temperature recorded after the 
first recovery period as defined in section 5.4.2 of this appendix, 
[deg]F ([deg]C).
T0 = mean tank temperature recorded at the beginning of 
the 24-hour simulated-use test as determined in section 5.4.2 of 
this appendix, [deg]F ([deg]C).
Qr = the total energy used by the water heater during the 
first recovery period as defined in section 5.4.2 of this appendix, 
including auxiliary energy such as pilot lights, pumps, fans, etc., 
Btu (kJ). (Electrical auxiliary energy shall be converted to thermal 
energy using the following conversion: 1 kWh = 3,412 Btu).
Nr = number of draws from the start of the 24-hour simulated-use 
test to the end to the first recovery period as described in section 
5.4.2.
Mdel,i = mass of water removed as calculated in section 
6.3.2 of this appendix during draw ith draw of the first recovery 
period as described in section 5.4.2, lb (kg).
Cpi = specific heat of the withdrawn water during the ith 
draw of the first recovery period as described in section 5.4.2, 
evaluated at (Tdel,i + Tin,i)/2, Btu/
(lb[middot] [deg]F) (kJ/(kg[middot] [deg]C)).
Tdel,i = average water outlet temperature measured during 
the ith draw of the first recovery period as described in section 
5.4.2, [deg]F ([deg]C).
Tin,i = average water inlet temperature measured during 
the ith draw of the first recovery period as described in section 
5.4.2, [deg]F ([deg]C).

    The recovery efficiency for electric water heaters with immersed 
heating elements, not including heat pump water heaters with 
immersed heating elements, is assumed to be 98 percent.
    6.3.4 Hourly Standby Losses. The energy consumed as part of the 
standby loss test of the 24-hour simulated-use test, 
Qstby, is computed as:

Qstby = Qsu,f-Qsu,0

Where:

Qsu,0 = cumulative energy consumption, including all 
fossil fuel and electrical energy use, of the water heater from the 
start of the 24-hour simulated-use test to the start of the standby 
period as determined in section 5.4.2 of this appendix, Btu (kJ).
Qsu,f = cumulative energy consumption, including all 
fossil fuel and electrical energy use, of the water heater from the 
start of the 24-hour simulated-use test to the end of the standby 
period as determined in section 5.4.2 of this appendix, Btu (kJ).

    The hourly standby energy losses are computed as:
    [GRAPHIC] [TIFF OMITTED] TP11JA22.013
    
Where:

Qhr = the hourly standby energy losses of the water 
heater, Btu/h (kJ/h).
Vst = as defined in section 6.3.1 of this appendix.
[rho] = density of the stored hot water, evaluated at 
(Tsu,f + Tsu,0)/2, lb/gal (kg/L).
Cp = specific heat of the stored water, evaluated at 
(Tsu,f + Tsu,0)/2, Btu/(lb[middot]F), (kJ/
(kg[middot]K)).
Tsu,f = the mean tank temperature measured at the end of 
the standby period as determined in section 5.4.2 of this appendix, 
[deg]F ([deg]C).
Tsu,0 = the maximum mean tank temperature measured at the 
beginning of the standby

[[Page 1607]]

period as determined in section 5.4.2 of this appendix, [deg]F 
([deg]C).
[eta]r = as defined in section 6.3.3 of this appendix.
[tau]stby,1 = elapsed time between the start and end of 
the standby period as determined in section 5.4.2 of this appendix, 
h.

    The standby heat loss coefficient for the tank is computed as:
    [GRAPHIC] [TIFF OMITTED] TP11JA22.014
    
Where:

UA = standby heat loss coefficient of the storage tank, Btu/
(h[middot] [deg]F), (kJ/(h[middot] [deg]C).
Tt,stby,1 = overall average mean tank temperature between 
the start and end of the standby period as determined in section 
5.4.2 of this appendix, [deg]F ([deg]C).
Ta,stby,1 = overall average ambient temperature between 
the start and end of the standby period as determined in section 
5.4.2 of this appendix, [deg]F ([deg]C).

    6.3.5 Daily Water Heating Energy Consumption. The total energy 
used by the water heater during the 24-hour simulated-use test (Q) 
is as measured in section 5.4.2 of this appendix, or,

Q = Qf + Qe = total energy used by the water 
heater during the 24-hour simulated-use test, including auxiliary 
energy such as pilot lights, pumps, fans, etc., Btu (kJ).
Qf = total fossil fuel energy used by the water heater 
during the 24-hour simulated-use test, Btu (kJ).
Qe = total electrical energy used during the 24-hour 
simulated-use test, Btu (kJ). (Electrical energy shall be converted 
to thermal energy using the following conversion: 1kWh = 3,412 Btu.)
    The daily water heating energy consumption, Qd, is 
computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.015

Where:

Vst = as defined in section 6.3.1 of this appendix.
[rho] = density of the stored hot water, evaluated at 
(T24 + T0)/2, lb/gal (kg/L).
Cp = specific heat of the stored water, evaluated at 
(T24 + T0)/2, Btu/(lb[middot]F), (kJ/
(kg[middot]K)).
T24 = mean tank temperature at the end of the 24-hour 
simulated-use test as determined in section 5.4.2 of this appendix, 
[deg]F ([deg]C).
T0 = mean tank temperature recorded at the beginning of 
the 24-hour simulated-use test as determined in section 5.4.2 of 
this appendix, [deg]F ([deg]C).
[eta]r = as defined in section 6.3.3 of this appendix.

    6.3.6 Adjusted Daily Water Heating Energy Consumption. The 
adjusted daily water heating energy consumption, Qda, 
takes into account that the ambient temperature may differ from the 
nominal value of 67.5 [deg]F (19.7 [deg]C) due to the allowable 
variation in surrounding ambient temperature of 65 [deg]F (18.3 
[deg]C) to 70 [deg]C (21.1 [deg]C). The adjusted daily water heating 
energy consumption is computed as:

Qda = Qd - (67.5[deg]F - Ta,stby,2)UA [tau]stby,2

    or,

Qda = Qd - (19.7[deg]C - Ta,stby,2)UA [tau]stby,2

Where:

Qda = the adjusted daily water heating energy 
consumption, Btu (kJ).
Qd = as defined in section 6.3.4 of this appendix.
Ta,stby,2 = the average ambient temperature during the 
total standby portion, [tau]stby,2, of the 24-hour 
simulated-use test, [deg]F ([deg]C).
UA = as defined in section 6.3.4 of this appendix.
[tau]stby,2 = the number of hours during the 24-hour 
simulated-use test when water is not being withdrawn from the water 
heater.

    A modification is also needed to take into account that the 
temperature difference between the outlet water temperature and 
supply water temperature may not be equivalent to the nominal value 
of 67 [deg]F (125 [deg]F-58 [deg]F) or 37.3 [deg]C (51.7 [deg]C-14.4 
[deg]C). The following equations adjust the experimental data to a 
nominal 67 [deg]F (37.3 [deg]C) temperature rise.
    The energy used to heat water, Btu/day (kJ/day), may be computed 
as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.016

Where:

N = total number of draws in the 24-hour simulated-use test.
Mdel,i = the mass of water removed during the ith draw (i 
= 1 to N) as calculated in section 6.3.2 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn during the 
ith draw of the 24-hour simulated-use test, evaluated at (
Tdel,i +
Tin,i)/2, Btu/(lb[middot] [deg]F) (kJ/
(kg[middot][deg]C)).
Tdel,i = the average water outlet temperature measured 
during the ith draw (i = 1 to N), [deg]F ([deg]C).
Tin,i = the average water inlet temperature measured 
during the ith draw (i = 1 to N), [deg]F ([deg]C).
[eta]r = as defined in section 6.3.3 of this appendix.

    The energy required to heat the same quantity of water over a 67 
[deg]F (37.3 [deg]C) temperature rise, Btu/day (kJ/day), is:
[GRAPHIC] [TIFF OMITTED] TP11JA22.017


[[Page 1608]]


    The difference between these two values is:

QHWD = QHW,67[deg]F - QHW

    or,

QHWD = QHW,37.3[deg]C - QHW

    This difference (QHWD) must be added to the adjusted 
daily water heating energy consumption value. Thus, the daily energy 
consumption value, which takes into account that the ambient 
temperature may not be 67.5 [deg]F (19.7 [deg]C) and that the 
temperature rise across the storage tank may not be 67 [deg]F (37.3 
[deg]C) is:

Qdm = Qda + QHWD

    6.3.7 Uniform Energy Factor. The uniform energy factor, UEF, is 
computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.018

Where:

N = total number of draws in the 24-hour simulated-use test.
Qdm = the modified daily water heating energy consumption 
as computed in accordance with section 6.3.6 of this appendix, Btu 
(kJ).
Mdel,i = the mass of water removed during the ith draw (i 
= 1 to N) as calculated in section 6.3.2 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn during the 
ith draw of the 24-hour simulated-use test, evaluated at (125 [deg]F 
+ 58 [deg]F)/2 = 91.5 [deg]F ((51.7 [deg]C + 14.4 [deg]C)/2 = 33 
[deg]C), Btu/(lb[middot][deg]F) (kJ/(kg[middot][deg]C)).
    6.3.8 Annual Energy Consumption. The annual energy consumption 
for water heaters with rated storage volumes greater than or equal 
to 2 gallons is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.019

Where:

UEF = the uniform energy factor as computed in accordance with 
section 6.3.7 of this appendix.
365 = the number of days in a year.
V = the volume of hot water drawn during the applicable draw 
pattern, gallons
    = 10 for the very-small-usage draw pattern.
    = 38 for the low-usage draw pattern.
    = 55 for the medium-usage draw pattern.
    = 84 for high-usage draw pattern.
[rho] = 8.24 lb/gallon, the density of water at 125 [deg]F.
Cp = 1.00 Btu/(lb [deg]F), the specific heat of water at 
91.5 [deg]F.
67 = the nominal temperature difference between inlet and outlet 
water.

    6.3.9 Annual Electrical Energy Consumption. The annual 
electrical energy consumption in kilowatt-hours for water heaters 
with rated storage volumes greater than or equal to 2 gallons, 
Eannual,e, is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.020

    Where:

Eannual = the annual energy consumption as determined in 
accordance with section 6.3.8 of this appendix, Btu (kJ).
Qe = the daily electrical energy consumption as defined 
in section 6.3.5 of this appendix, Btu (kJ).
Q = total energy used by the water heater during the 24-hour 
simulated-use test in accordance with section 6.3.5 of this 
appendix, Btu (kJ).
3412 = conversion factor from Btu to kWh.

    6.3.10 Annual Fossil Fuel Energy Consumption. The annual fossil 
fuel energy consumption for water heaters with rated storage volumes 
greater than or equal to 2 gallons, Eannual,f, is 
computed as:

Eannual,f = Eannual - (Eannual,e * 3412)

Where:

Eannual = the annual energy consumption as determined in 
accordance with section 6.3.8 of this appendix, Btu (kJ).
Eannual,e = the annual electrical energy consumption as 
determined in accordance with section 6.3.9 of this appendix, kWh.
3412 = conversion factor from kWh to Btu.

    6.4 Computations for Water Heaters With a Rated Storage Volume 
Less Than 2 Gallons.
    6.4.1 Mass of Water Removed
    Calculate the mass of water removed using the calculations in 
section 6.3.2 of this appendix.
    6.4.2 Recovery Efficiency. The recovery efficiency, 
[eta]r, is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.021

Where:

M1 = mass of water removed during the first draw of the 
24-hour simulated-use test, lb (kg).
Cp1 = specific heat of the withdrawn water during the 
first draw of the 24-hour simulated-use test, evaluated at 
(Tdel,i + Tin,i =)/2, Btu/(lb [middot][deg]F) 
(kJ/(kg [middot][deg]C)).
Tdel,i = average water outlet temperature measured during 
the first draw of the 24-hour simulated-use test, [deg]F ([deg]C).
Tin,i = average water inlet temperature measured during 
the first draw of the 24-hour simulated-use test, [deg]F ([deg]C).

Qr = the total energy used by the water heater during the 
first recovery period as defined in section 5.4.3 of this appendix, 
including auxiliary energy such as pilot lights, pumps, fans, etc., 
Btu (kJ). (Electrical auxiliary energy shall be converted to thermal 
energy using the following conversion: 1 kWh = 3412 Btu.)

    6.4.3 Daily Water Heating Energy Consumption. The daily water 
heating energy consumption, Qd, is computed as:

Qd = Q
Where:

Q = Qf + Qe = the energy used by the water 
heater during the 24-hour simulated-use test.

[[Page 1609]]

Qf = total fossil fuel energy used by the water heater 
during the 24-hour simulated-use test, Btu (kJ).
Qe = total electrical energy used during the 24-hour 
simulated-use test, Btu (kJ). (Electrical auxiliary energy shall be 
converted to thermal energy using the following conversion: 1 kWh = 
3412 Btu.)

    A modification is needed to take into account that the 
temperature difference between the outlet water temperature and 
supply water temperature may not be equivalent to the nominal value 
of 67 [deg]F (125 [deg]F-58 [deg]F) or 37.3 [deg]C (51.7 [deg]C-14.4 
[deg]C). The following equations adjust the experimental data to a 
nominal 67 [deg]F (37.3 [deg]C) temperature rise.
    The energy used to heat water may be computed as:
    [GRAPHIC] [TIFF OMITTED] TP11JA22.022
    
Where:

N = total number of draws in the 24-hour simulated-use test.
Mdel,i = the mass of water removed during the ith draw (i 
= 1 to N) as calculated in section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn during the 
ith draw of the 24-hour simulated-use test, evaluated at 
(Tdel,i + Tin,i)/2, Btu/(lb[middot][deg]F) 
(kJ/(kg[middot][deg]C)).
Tdel,i = the average water outlet temperature measured 
during the ith draw (i = 1 to N), [deg]F ([deg]C).
Tin,i = the average water inlet temperature measured 
during the ith draw (i = 1 to N), [deg]F ([deg]C).
[eta]r = as defined in section 6.4.2 of this appendix.

    The energy required to heat the same quantity of water over a 67 
[deg]F (37.3 [deg]C) temperature rise is:
[GRAPHIC] [TIFF OMITTED] TP11JA22.023

Where:

N = total number of draws in the 24-hour simulated-use test.
Mdel,i = the mass of water removed during the ith draw (i 
= 1 to N) as calculated in section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn during the 
ith draw of the 24-hour simulated-use test, evaluated at 
(Tdel,i + Tin,i)/2, Btu/(lb[middot][deg]F) 
(kJ/(kg[middot][deg]C)).
[eta]r = as defined in section 6.4.2 of this appendix.

    The difference between these two values is:
QHWD = QHW,67[deg]F - QHW

    or,

QHWD = QHW,37.3[deg]C - QHW

    This difference (QHWD) must be added to the daily 
water heating energy consumption value. Thus, the daily energy 
consumption value, which takes into account that the temperature 
rise across the water heater may not be 67 [deg]F (37.3 [deg]C), is:

Qdm = Qda + QHWD

    6.4.4 Uniform Energy Factor. The uniform energy factor, UEF, is 
computed as:

[[Page 1610]]

[GRAPHIC] [TIFF OMITTED] TP11JA22.024

Where:

N = total number of draws in the 24-hour simulated-use test.
Qdm = the modified daily water heating energy consumption 
as computed in accordance with section 6.4.3 of this appendix, Btu 
(kJ).
Mdel,i = the mass of water removed during the ith draw (i 
= 1 to N) as calculated in section 6.4.1 of this appendix, lb (kg).
Cpi = the specific heat of the water withdrawn during the 
ith draw of the 24-hour simulated-use test, evaluated at (125 [deg]F 
+ 58 [deg]F)/2 = 91.5 [deg]F ((51.7 [deg]C + 14.4 [deg]C)/2 = 33.1 
[deg]C), Btu/(lb[middot][deg]F) (kJ/(kg[middot][deg]C)).

    6.4.5 Annual Energy Consumption. The annual energy consumption 
for water heaters with rated storage volumes less than 2 gallons, 
Eannual, is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.025

Where:

UEF = the uniform energy factor as computed in accordance with 
section 6.4.4 of this appendix.
365 = the number of days in a year.
V = the volume of hot water drawn during the applicable draw 
pattern, gallons
    = 10 for the very-small-usage draw pattern.
    = 38 for the low-usage draw pattern.
    = 55 for the medium-usage draw pattern.
    = 84 for high-usage draw pattern.
[rho] = 8.24 lb/gallon, the density of water at 125 [deg]F.
Cp = 1.00 Btu/(lb [deg]F), the specific heat of water at 
91.5 [deg]F.
67 = the nominal temperature difference between inlet and outlet 
water.

    6.4.6 Annual Electrical Energy Consumption. The annual 
electrical energy consumption in kilowatt-hours for water heaters 
with rated storage volumes less than 2 gallons, 
Eannual,e, is computed as:
[GRAPHIC] [TIFF OMITTED] TP11JA22.026

Where:

Qe = the daily electrical energy consumption as defined 
in section 6.4.3 of this appendix, Btu (kJ).
Eannual = the annual energy consumption as determined in 
accordance with section 6.4.5 of this appendix, Btu (kJ).
Q = total energy used by the water heater during the 24-hour 
simulated-use test in accordance with section 6.4.3 of this 
appendix, Btu (kJ).
Qdm = the modified daily water heating energy consumption 
as computed in accordance with section 6.4.3 of this appendix, Btu 
(kJ).
3412 = conversion factor from Btu to kWh.

    6.4.7 Annual Fossil Fuel Energy Consumption. The annual fossil 
fuel energy consumption for water heaters with rated storage volumes 
less than 2 gallons, Eannual,f, is computed as:

Eannual,f = Eannual - (Eannual,e * 3412)

Where:

Eannual = the annual energy consumption as defined in 
section 6.4.5 of this appendix, Btu (kJ).
Eannual,e = the annual electrical energy consumption as 
defined in section 6.4.6 of this appendix, kWh.
3412 = conversion factor from kWh to Btu.

[[Page 1611]]

[GRAPHIC] [TIFF OMITTED] TP11JA22.027


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[GRAPHIC] [TIFF OMITTED] TP11JA22.028


[[Page 1613]]


[GRAPHIC] [TIFF OMITTED] TP11JA22.029


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[GRAPHIC] [TIFF OMITTED] TP11JA22.030

PART 431--ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND 
INDUSTRIAL EQUIPMENT

0
8. The authority citation for part 431 continues to read as follows:

    Authority:  42 U.S.C. 6291-6317; 28 U.S.C. 2461 note.

0
9. Amend Sec.  431.102 by adding in alphabetical order the definition 
of ``Commercial heat pump water heater (CHPWH)'' to read as follows:


Sec.  431.102  Definitions concerning commercial water heaters, hot 
water supply boilers, unfired hot water storage tanks, and commercial 
heat pump water heaters.

* * * * *
    Commercial heat pump water heater (CHPWH) means a water heater 
(including all ancillary equipment such as fans, blowers, pumps, 
storage tanks, piping, and controls, as applicable) that uses a 
refrigeration cycle, such as vapor compression, to transfer heat from a 
low-temperature source to a higher-temperature sink for the purpose of 
heating potable water, and operates with a current rating greater than 
24 amperes or a voltage greater than 250 volts. Such equipment 
includes, but is not limited to, air-source heat pump water heaters, 
water-source heat pump water heaters, and direct geo-exchange heat pump 
water heaters.
* * * * *
[FR Doc. 2021-27004 Filed 1-10-22; 8:45 am]
BILLING CODE 6450-01-P