[Federal Register Volume 87, Number 134 (Thursday, July 14, 2022)]
[Proposed Rules]
[Pages 42270-42295]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-14687]



[[Page 42269]]

Vol. 87

Thursday,

No. 134

July 14, 2022

Part II





 Department of Energy





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10 CFR Part 430





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

  Federal Register / Vol. 87 , No. 134 / Thursday, July 14, 2022 / 
Proposed Rules  

[[Page 42270]]


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DEPARTMENT OF ENERGY

10 CFR Part 430

[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: Supplemental notice of proposed rulemaking and request for 
comment.

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SUMMARY: The U.S. Department of Energy (``DOE'') is publishing this 
supplemental notice of proposed rulemaking (``SNOPR'') to amend the 
test procedure for consumer water heaters and residential-duty 
commercial water heaters. This SNOPR updates the proposals presented in 
a notice of proposed rulemaking published in the Federal Register on 
January 11, 2022. In this SNOPR, DOE proposes additional amendments 
that would provide additional specificity regarding flow rate 
tolerances for water heaters with a rated storage volume of less than 2 
gallons; allow for voluntary representations at certain additionally 
specified test conditions for heat pump water heaters; revise the 
proposed specifications regarding separate storage tank requirements 
for certain types of water heaters; provide instructions for testing 
certain water heaters that store water at a temperature higher than the 
delivery setpoint; establish a metric and method for determining the 
effective storage volume of certain storage-type water heaters; and 
update the proposed methodology for estimating the internal tank 
temperature of water heaters which cannot be directly measured. DOE is 
seeking comment from interested parties on these proposals.

DATES: DOE will accept comments, data, and information regarding this 
SNOPR no later than August 4, 2022. See section IV, ``Public 
Participation,'' for details.

ADDRESSES: Comments: Interested persons are encouraged to submit 
comments using the Federal eRulemaking Portal at www.regulations.gov, 
under docket number EERE-2019-BT-TP-0032. Follow the instructions for 
submitting comments. Alternatively, interested persons may submit 
comments, identified by docket number EERE-2019-BT-TP-0032 and/or RIN 
1904-AE77, by any of the following methods:
    (1) Email: [email protected]. Include docket number 
EERE-2019-BT-TP-0032 in the subject line of the message.
    (2) Postal Mail: Appliance and Equipment Standards Program, U.S. 
Department of Energy, Building Technologies Office, Mailstop EE-5B, 
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: 
(202) 287-1445. If possible, please submit all items on a compact disc 
(``CD''), in which case it is not necessary to include printed copies.
    (3) Hand Delivery/Courier: Appliance and Equipment Standards 
Program, U.S. Department of Energy, Building Technologies Office, 950 
L'Enfant Plaza SW, 6th Floor, Washington, DC 20024. Telephone: (202) 
287-1445. If possible, please submit all items on a CD, in which case 
it is not necessary to include printed copies.
    No telefacsimiles (``faxes'') will be accepted. For detailed 
instructions on submitting comments and additional information on this 
process, see section V of this document (Public Participation).
    Docket: The docket for this activity, which includes Federal 
Register notices, public meeting/webinar attendee lists and 
transcripts, 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, not all 
documents listed in the index may be publicly available, such as 
information that is exempt from public disclosure.
    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 (Public Participation) 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].
    Mr. Eric Stas, U.S. Department of Energy, Office of the General 
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. 
Telephone: (202) 586-5827. Email: [email protected].
    For further information on how to submit a comment, review other 
public comments and the docket, contact the Appliance and Equipment 
Standards Program staff at (202) 287-1445 or by email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Authority and Background
    A. Authority
    B. Background
II. Synopsis of Proposed Amendments
III. Discussion
    A. Flow Rate Tolerance Requirements
    B. Optional Test Conditions
    C. Storage Tank Over-Heating
    1. Testing in Over-Heated Mode
    2. Effective Storage Volume
    D. Separate Storage Tank Requirements
    E. Method for Determining Internal Tank Temperature for Certain 
Water Heaters
IV. Procedural Issues and Regulatory Review
    A. Review Under Executive Orders 12866 and 13563
    B. Review Under the Regulatory Flexibility Act
    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
V. Public Participation
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 procedures for consumer 
water heaters are currently prescribed respectively 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''), Uniform Test 
Method for Measuring the Energy Consumption of Water Heaters. 
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

[[Page 42271]]

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, one of the subjects 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 residential-duty 
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, Pub. L. 116-260 (Dec. 27, 
2020), which reflect the last statutory amendments that impact Parts 
A and A-1 of EPCA.
    \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) 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/equipment 
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 other representations about the efficiency of 
those consumer 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 
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)) DOE may, 
however, 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, EPCA 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 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 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), Pub. L. 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

[[Page 42272]]

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 American National Standards 
Institute (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 or equipment, 
including consumer water heaters and residential-duty commercial water 
heaters, 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); 42 U.S.C. 6314(a)(1)(A))
    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) and 42 U.S.C. 
6314(a)(1)(A)(ii))
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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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    DOE is conducting this rulemaking in satisfaction of the 7-year-
lookback review requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A) 
and 42 U.S.C. 6314(a)(1)(A))

B. Background

    On January 11, 2022, DOE published in the Federal Register a notice 
of proposed rulemaking (``January 2022 NOPR'') in which the Department 
proposed 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: American Society of Heating, Refrigerating, and Air-
Conditioning Engineers (ASHRAE) Standard 41.1,\8\ ASHRAE Standard 
41.6,\9\ the pending update to ASHRAE Standard 118.2 \10\ 
(contingent on it being substantively the same as the draft which 
was under review), ASTM International (ASTM) D2156,\11\ and ASTM 
E97.\12\
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    \8\ ASHRAE Standard 41.1-2020, ``Standard Methods for 
Temperature Measurement,'' approved June 30, 2020.
    \9\ ASHRAE Standard 41.6-2014, ``Standard Method for Humidity 
Measurement,'' ANSI approved July 3, 2014.
    \10\ ASHRAE Standard 118.2-2022, ``Method of Testing for Rating 
Residential Water Heaters and Residential-Duty Commercial Water 
Heaters,'' ANSI approved March 1, 2022.
    \11\ ASTM Standard D2156-09 (RA 2018), ``Standard Test Method 
for Smoke Density in Flue Gases from Burning Distillate Fuels,'' 
reapproved October 1, 2018.
    \12\ ASTM Standard E97-1987 (W 1991), ``Standard Test Methods 
for Directional Reflectance Factor, 45-Deg 0-Deg, of Opaque 
Specimens by Broad-Band Filter Reflectometry,'' approved January 
1987, withdrawn 1991. Referenced by ASTM Standard D2156-09 (RA 
2018).
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    (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.

87 FR 1554, 1558.\13\
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    \13\ A correction was published in the Federal Register on 
January 19, 2022, to properly reflect the date of the public meeting 
to discuss the test procedure NOPR. 87 FR 2731.
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    DOE received written comments in response to the January 2022 NOPR 
pertinent to the issues discussed in this SNOPR from the interested 
parties listed in Table III.1 of this document. In this SNOPR, DOE is 
maintaining the proposals from the January 2022 NOPR with modifications 
as discussed in this SNOPR and will address comments on any remaining 
topics in a future test procedure final rule.

Table III.1--List of Commenters With Written Submissions in Response to the January 2022 NOPR Relevant to Topics
                                              Covered in This SNOPR
----------------------------------------------------------------------------------------------------------------
                                                                         Comment No. in
             Commenter(s)                   Reference in this SNOPR          Docket           Commenter type
----------------------------------------------------------------------------------------------------------------
A.O. Smith Corporation...............  A.O. Smith......................              37  Manufacturer.
Air Conditioning, Heating, and         AHRI............................              40  Trade Association.
 Refrigeration Institute.
Appliance Standards Awareness          Joint Advocates.................              34  Efficiency Advocacy
 Project, American Council for and                                                        Organizations.
 Energy-Efficient Economy, National
 Consumer Law Center.
Bradford White Corporation...........  BWC.............................              33  Manufacturer.

[[Page 42273]]

 
Pacific Gas and Electric Company, San  CA IOUs.........................              36  Utilities.
 Diego Gas and Electric, and Southern
 California Edison; collectively, the
 California Investor-Owned Utilities.
Jim Lutz.............................  Lutz............................              35  Individual.
New York State Energy Research and     NYSERDA.........................              32  State Agency.
 Development Authority.
Northwest Energy Efficiency Alliance.  NEEA............................              30  Efficiency Advocacy
                                                                                          Organization.
Rheem Manufacturing Company..........  Rheem...........................              31  Manufacturer.
----------------------------------------------------------------------------------------------------------------

    As discussed, this SNOPR addresses only those comments related to 
the proposals laid out in this document; all other relevant comments 
will be addressed in a future stage of the rulemaking. A parenthetical 
reference at the end of a comment quotation or paraphrase provides the 
location of the item in the public record.\14\
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    \14\ 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). The references are arranged as 
follows: (commenter name, comment docket ID number, page of that 
document).
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II. Synopsis of Proposed Amendments

    DOE's proposed actions in this SNOPR are summarized in Table II.1 
of this document as compared to the January 2022 TP NOPR. Reasons for 
each proposed change are also explained in summary.

     Table II.1--Summary of Proposed Changes Addressed in This SNOPR
------------------------------------------------------------------------
 January 2022 NOPR proposal           SNOPR              Attribution
------------------------------------------------------------------------
Proposed that flow rates for  Additionally          Improve
 all water heaters with        proposes that for     repeatability and
 rated storage volume less     water heaters with    reproducibility of
 than 2 gallons must be        rated storage         the test procedure.
 maintained within a           volume less than 2
 tolerance of 0.25 gallons per        Max GPM of less
 minute.                       than 1 gallon per
                               minute, the flow
                               rate tolerance
                               shall be 25 percent of
                               the rated Max GPM.
Did not propose to allow for  Proposes to allow     Harmonize with
 optional efficiency           for optional          current industry
 representations at            efficiency            testing practices.
 alternative test conditions   representations at
 for heat pump water heaters.  alternative test
                               conditions for heat
                               pump water heaters.
Did not propose a definition  Proposes a            Provide additional
 for split-system heat pump    definition for        clarity to
 water heaters.                split-system heat     application of test
                               pump water heaters    conditions for heat
                               to distinguish        pump water heaters.
                               these from heat
                               pump-only water
                               heaters.
Proposed to define            Proposes that gas-    Improve
 ``circulating water           fired circulating     representativeness
 heaters'' and require that    water heaters be      of test methodology
 such products be tested       tested using a        for circulating
 using an 80 gallon (1 gallon) unfired hot   storage volume
 water storage tank            between 80 and 120
 (``UFHWST'') that meets the   gallons and an R-
 energy conservation           value exactly at
 standards for an unfired      the minimum R-value
 hot water storage tank at     required at 10 CFR
 10 CFR 431110(a).             431110(a), and that
                               heat pump
                               circulating water
                               heaters be tested
                               using a 40-gallon
                               electric resistance
                               water heater at the
                               minimum UEF
                               standard required
                               at 10 CFR 43032(d).
Proposed to continue to       Proposes that water   Improve
 specify that water heaters    heaters (with the     representativeness
 with multiple modes of        exception of demand-  of test methodology
 operation be tested in the    response water        for water heaters
 ``default'' or other          heaters) with user-   with user-
 similarly named mode as       selectable modes to   selectable
 currently required by         ``over-heat'' the     overheated storage
 Appendix E.                   water stored in the   tank modes.
                               tank to increase
                               effective capacity
                               be tested at the
                               highest internal
                               tank temperature
                               that can be
                               achieved while
                               maintaining the
                               outlet water
                               temperature at 125
                                5
                               [deg]F If no such
                               over-heated mode
                               exists, the unit is
                               to be tested in a
                               default mode.
Did not include a definition  Proposes to define    Clarify the test
 for ``demand-response water   ``demand-response     methods for
 heater''.                     water heater''        products with
                               based on the ENERGY   demand-response
                               STAR specification    utility,
                               v5.0 definition for
                               connected water
                               heating product,
                               with the additional
                               requirement that
                               demand-response
                               water heaters
                               cannot over-heat as
                               a result of user-
                               initiated operation.
Did not include any proposal  Proposes to           Adopt a metric to
 related to the effective      establish a metric    provide additional
 storage volume of storage-    and method for        information to
 type water heaters.           determining the       consumers on
                               effective storage     product
                               volume of storage-    performance.
                               type water heaters.

[[Page 42274]]

 
Proposed a method of          Proposes a method of  Adopt a test method
 determining the internal      determining the       for certain water
 storage tank temperature      internal storage      heaters which
 (for water heaters with       tank temperature      cannot be directly
 rated storage volume          using draws at the    measured.
 greater than or equal to 2    beginning and end
 gallons which cannot be       of the 24-hour
 directly measured) based on   simulated use test.
 an assumption that the mean
 tank temperature is
 approximately the average
 of the inlet water
 temperature and the outlet
 water temperature.
------------------------------------------------------------------------

III. Discussion

A. Flow Rate Tolerance Requirements

    In this SNOPR, DOE proposes to supplement the proposal presented in 
the January 2022 NOPR regarding specified flow rate tolerances for 
water heaters with a rated storage volume under 2 gallons.
    Section 5.4 of appendix E provides instructions for conducting the 
24-hour simulated-use test for the determination of the uniform energy 
factor (``UEF''). Section 5.4.1 of appendix E specifies directions for 
determination of the draw pattern of the water heater under test; 
section 5.4.2 of appendix E specifies the test sequence for water 
heaters with rated storage volume greater than or equal to 2 gallons; 
and section 5.4.3 of appendix E specifies the test sequence for water 
heaters with rated storage volume less than 2 gallons. These test 
sequences specify the timings of each water draw during the 24-hour 
simulated-use test, the flow rates at which the draws must occur, and 
condition tolerances for these draws.
    In particular, section 5.4.2 of appendix E, Test Sequence for Water 
Heaters with Rated Storage Volumes Greater Than or Equal to 2 Gallons, 
provides that all draws during the 24-hour simulated-use test must 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). Section 5.4.3 
of appendix E, Test Sequence for Water Heaters with Rated Storage 
Volume Less Than 2 Gallons, currently does not provide explicit 
instruction for the tolerance on the flow rate.
    Within the proposed amendments to the regulatory text provided in 
the January 2022 NOPR, DOE included a proposed amendment to section 
5.4.3 of appendix E to specify that flow rates for water heaters with 
rated storage volume less than 2 gallons must be maintained within a 
tolerance of 0.25 gallons per minute. 87 FR 1554, 1603 
(Jan. 11, 2022). The preamble to the January 2022 NOPR did not include 
discussion of this topic, nor did DOE specifically request for comment 
on this topic.
    Adopting these proposed tolerances at section 5.4.3 of appendix E 
would ensure repeatability and reproducibility of test results for 
water heaters with rated storage volume less than 2 gallons. Most water 
heaters with storage volume less than 2 gallons are flow-activated 
devices, meaning that burner or heating element activation is 
controlled based on sensing the flow rate when hot water is called for. 
As such, significant variations in the flow rate from test to test 
could affect the measured efficiency of these products.
    In this SNOPR, DOE is updating its proposal to include additional 
specificity for water heaters with flow rates less than 1 gallon per 
minute. In section III.C.6 of the January 2022 NOPR, DOE discussed 
water heaters on the market with maximum gallon per minute (``Max 
GPM'') delivery capacities below 1 gallon per minute. 87 FR 1554, 1582 
(Jan. 11, 2022). For these models, the ``very small'' draw pattern for 
the 24-hour simulated-use test would be applicable. 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 gallon per minute (3.8 L/min), 
then all draws shall be implemented at a flow rate equal to the rated 
Max GPM. For products with Max GPM less than 1 gallon per minute, an 
allowable flow rate tolerance of 0.25 gallon per minute 
would represent a significant variation of flow rate in comparison to 
the rated Max GPM. For example, for a water heater with Max GPM of 0.5 
gallon per minute, a tolerance of 0.25 gallon per minute 
would represent a 50 percent difference from the rated flow 
rate. Furthermore, in its review of publicly certified water heater 
ratings,\15\ DOE identified models with rated Max GPM delivery 
capacities as low as 0.20 gallon per minute. For such products, a flow 
rate tolerance of 0.25 gallon per minute would allow for 
either flow rates close to zero or flow rates that are more than twice 
the rated Max GPM; either case would lead to results unrepresentative 
of actual product usage. Therefore, in this SNOPR, DOE proposes further 
amending section 5.4.3 of appendix E to specify that for water heaters 
with a rated Max GPM of less than 1 gallon per minute, the flow rate 
tolerance shall be 25 percent of the rated Max GPM. For 
such products, a flow rate tolerance of 25 percent would 
represent the same level of variation (on a percentage basis) as for 
products rated at 1.0 gallon per minute and subject to a tolerance of 
0.25 gallon per minute.
---------------------------------------------------------------------------

    \15\ DOE consulted its public Certification Compliance Database 
(Available at: www.regulations.doe.gov/certification-data/CCMS-4-Water_Heaters.html#q=Product_Group_s%3A%22Water%20Heaters%22).
---------------------------------------------------------------------------

    By way of example, under the proposal, for a water heater with a 
rated Max GPM flow rate of 0.5 gallon per minute, the required 
tolerance would be 0.125 gallon per minute. For a water 
heater with a rated Max GPM flow rate of 0.20 gallon per minute, the 
required tolerance would thus be 0.05 gallon per minute.
    As discussed, EPCA requires that test procedures 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 not be 
unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) DOE expects that 
laboratories may require high-precision water flow rate instrumentation 
(e.g., Coriolis flow meters) in order to maintain the tolerances 
discussed, in particular for water heaters with rated Max GPM flow 
rates less than 1 gallon per minute. DOE is aware through its testing 
activities that multiple third-party laboratories already use Coriolis 
flow meters. In reviewing water heater test data previously collected, 
DOE has observed third-party laboratories maintaining flow rate 
condition tolerances as low as 0.05 gallon per minute. For 
these reasons, DOE has initially determined that the proposed 
tolerances would generally not require additional capital investments 
for test

[[Page 42275]]

laboratories and, therefore, would not be unduly burdensome to conduct.
    DOE also has tentatively determined that the proposed amendment 
would not alter the measured efficiency of consumer water heaters and 
residential-duty commercial water heaters, nor require retesting or 
recertification solely as a result of DOE's adoption of the proposed 
amendments to the test procedure, if made final. In the absence of an 
explicit instruction for the flow rate tolerance applicable to water 
heaters with rated storage volume under 2 gallons, DOE expects that 
general industry best practice is to apply the flow rate tolerances 
being proposed for section 5.4.3 of appendix E for water heaters with 
rated storage volume less than 2 gallons (based on DOE's review of 
third-party laboratory test data), such that this proposal is expected 
to be consistent with current methodology.
    With the addition of these proposed amendments to section 5.4.3 of 
appendix E, DOE maintains the proposals set forth in the January 2022 
NOPR.
    DOE seeks comment on the proposed amendment to specify flow rate 
tolerances for the 24-hour simulated use test for water heaters with 
rated storage volume under 2 gallons, and in particular to specify the 
tolerance as 25 percent for water heaters with a rated 
maximum flow rate of less than 1 gallon per minute. DOE is particularly 
interested in test data or information that would indicate the 
technical feasibility of maintaining the tolerances proposed with 
instrumentation that is used in general practice, as well as the 
potential impacts on test burden.

B. Optional Test Conditions

    Section 2.2 of appendix E specifies that 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 during the test. 
Additionally, for heat pump water heaters, that test procedure 
provision provides that the dry-bulb temperature shall be maintained at 
67.5 [deg]F 1 [deg]F (19.7 [deg]C 0.6 [deg]C) 
and that the relative humidity shall be maintained at 50 percent 2 percent throughout the test.\16\
---------------------------------------------------------------------------

    \16\ DOE proposed amendments to the ambient air tolerance 
requirements in the January 2022 NOPR. 87 FR 1554, 1577-1578 (Jan. 
11, 2022).
---------------------------------------------------------------------------

    In the January 2022 NOPR, DOE discussed comments previously 
received on the April 2020 RFI suggesting that DOE explore the usage of 
NEEA's Advanced Water Heating Specification for voluntary climate-
specific efficiency representations of heat pump water heaters. 87 FR 
1554, 1580 (Jan. 11, 2022). In response to those comments, DOE stated 
that it did not have data to indicate what conditions would be 
representative for regional representations, and, thus, DOE tentatively 
decided not to allow optional representations of additional efficiency 
ratings at test conditions other than those found in the DOE test 
procedure, such as those made in accordance with NEEA's Advanced Water 
Heating Specification. Id.
    In response to the January 2022 NOPR, DOE received additional 
comments regarding optional representations that have led the 
Department to reconsider its tentative decision not to allow optional 
representations.
    The CA IOUs stated that water heater installation practices vary 
regionally, and that similar units installed in the same region can 
experience different ambient conditions. The CA IOUs further stated 
that the direct relationship between the diverse ambient conditions and 
efficiency make it impossible to choose a single representative value 
for ambient conditions for the consumer water heaters test procedure 
that will yield useful energy consumption estimates for heat pump water 
heaters. The CA IOUs asserted that in the case of a split-system heat 
pump water heater, the condenser is almost always located in an 
unconditioned space (e.g., outdoors), such that the ambient conditions 
specified in the current DOE test procedure are not representative. The 
CA IOUs recommended that DOE clarify whether manufacturers may provide 
information on the performance of heat pump water heaters at ambient 
temperatures other than 67.5 [deg]F 1 [deg]F. The CA IOUs 
reiterated their recommendation to allow manufacturers to provide 
representations for more than one ambient condition, stating that 
allowing manufacturers to state performance under different conditions 
would allow them to introduce heat pump water heater models optimized 
for different applications, would help keep performance claims 
consistent, and would help consumers select the most appropriate 
products. (CA IOUs, No. 36 at p. 2)
    The Joint Advocates stated that the value of having test data at 
both colder and warmer conditions than those specified in the current 
test procedure is that they would allow for calculating UEFs for any 
climate regardless of whether the specific optional test conditions are 
representative of any region. The Joint Advocates reiterated its 
recommendation that DOE allow voluntary reporting of ratings at two 
additional test conditions. The Joint Advocates asserted that allowing 
optional reporting would help provide a better understanding of the 
differences in heat pump water heater performance at various conditions 
without increasing test burden for manufacturers who do not wish to 
report these additional rating. (Joint Advocates, No. 34 at p. 1)
    NYSERDA requested that DOE require heat pump water heater 
performance data at a range of operating conditions. NYSERDA stated 
that demonstrating performance at different ambient temperatures is a 
commonly applied approach for heat pumps that serve HVAC loads, and 
that similar treatment for heat pump water heaters is appropriate. 
NYSERDA stated that in order for heat pump water heaters to provide 
utility in all climates, including the colder temperatures in New York, 
consumers and installers will need to understand the expected 
performance at a range of operating conditions. NYSERDA encouraged DOE 
to allow manufacturers to provide performance data at conditions 
representative of where heat pump water heaters will be installed 
throughout the country. NYSERDA specifically referenced NEEA's Advanced 
Water Heating Specification as an example resource. (NYSERDA, No. 32 at 
p. 3)
    BWC stated that voluntary representations would potentially 
increase burden and not increase representativeness for performance on 
a national basis. BWC expressed its support for DOE's tentative 
determination not to allow additional voluntary representations. (BWC, 
No. 33 at p. 8)
    After considering these comments, the Department once again notes 
that EPCA requires that 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)) While the test conditions in the current appendix E test 
procedure must remain representative for the nation as a whole, 
comments from interested parties have demonstrated that allowing 
additional representations of efficiency at alternative ambient 
conditions could provide consumers with additional information about 
the expected performance of heat pump water heaters at conditions that 
are representative of their specific installation circumstances. For 
other types of covered products and equipment, DOE has adopted optional 
metrics for voluntary representations where it was determined that the 
primary efficiency metric would not be representative for certain 
installation

[[Page 42276]]

conditions common for the product or equipment. For heat pump water 
heaters, both the efficiency and the heating capacity of the product 
are sensitive to the ambient conditions, and in general will be lower 
at colder ambient temperatures and higher at warmer ambient 
temperatures. For example, at lower ambient temperatures, the reduction 
in heating capacity of the heat pump could result in back-up electric 
resistance heating elements operating more frequently than at the 
current DOE rating conditions. Differences in ambient conditions also 
would affect integrated heat pump water heaters installed in 
unconditioned spaces (e.g., garage or attic) and split-system heat pump 
water heaters for which the heat pump components are located outdoors. 
Depending on the installation location, the ambient conditions may vary 
significantly from the conditions in the DOE test method, thereby 
resulting in significantly different performance for such products. For 
these reasons, in this SNOPR, DOE has tentatively determined to allow 
for certain optional representations for additional ambient conditions, 
as described further in the following paragraphs. DOE understands this 
to be the intent in NYSERDA's request (however, NYSERDA's comment 
discusses both a requirement for optional representations as well as an 
allowance for optional representations). In response to BWC's concerns 
regarding a potential increase in test burden, DOE proposes that any 
testing at multiple ambient conditions would be optional, and DOE is 
not proposing to require testing at the alternative ambient conditions. 
In summary, DOE is proposing to define new metrics for optional 
representations based primarily upon the test conditions provided in 
NEEA's Advanced Water Heating Specification version 8.0 (``AWHS 
v8.0'').
    AWHS v8.0 was published by NEEA on March 1, 2022. Though early 
editions of the AWHS focused primarily on providing more representative 
performance metrics for heat pump water heaters in cold climates, the 
latest editions are now more broadly focused on providing 
representative performance metrics for heat pump water heaters across 
all climates. Performance metrics in the AWHS are generally calculated 
by measuring energy efficiency at multiple (two or more) ambient test 
conditions, linearly interpolating between the test results, and 
finally calculating an ambient temperature-weighted efficiency metric 
using temperature bin data. The metric is a cold climate efficiency 
(``CCE'') rating for integrated heat pump water heaters installed in 
semi-conditioned (i.e., garage, basement) spaces and a seasonal 
coefficient of performance (``SCOP'') for split-system heat pump water 
heaters (where the heat pump is separated from the storage tank and 
located outdoors).
    NEEA maintains a Qualified Products List for heat pump water 
heaters tested by manufacturers to the AWHS.\17\ As of February 2022, 
the Qualified Products List contains CCE and SCOP representations from 
seventeen heat pump water heater brands. As such, DOE notes that 
manufacturers are already conducting testing per the AWHS and are 
providing representations in accordance with its test methods. On this 
basis, DOE has tentatively determined that adopting these test points 
for voluntary testing and representations would not significantly 
increase test burden for manufacturers who choose to provide these 
ratings.
---------------------------------------------------------------------------

    \17\ Available at: neea.org/img/documents/residential-unitary-HPWH-qualified-products-list.pdf (Last accessed on May 11, 2022).
---------------------------------------------------------------------------

    In its review of the AWHS v8.0, DOE determined that there are 
several differences between the test conditions provided and those 
present in the appendix E test procedure. These differences include 
ambient dry bulb temperatures, relative humidity conditions, and supply 
water temperatures.
    For integrated heat pump water heaters, AWHS v8.0 determines 
CCE50 at ambient air conditions of 50 [deg]F dry bulb 
temperature and 58 percent relative humidity, with a supply water 
temperature of 50 [deg]F. An additional high-temperature condition of 
95 [deg]F is also included but noted as optional in appendix B.1.1 to 
AWHS v8.0. DOE is proposing adopt the low ambient air conditions (50 
[deg]F and 58 percent relative humidity) and the high ambient air 
conditions (95 [deg]F and 40 percent relative humidity) for optional 
representations of integral heat pump water heaters. Additionally, AWHS 
v8.0 modifies the inlet water temperatures at these ambient conditions 
to reflect the corresponding mains water temperature expected at each 
outdoor air temperature. At the 50 [deg]F ambient condition, the 
specified inlet water temperature is also 50 [deg]F, and at the 95 
[deg]F ambient condition, the specified inlet water temperature is 67 
[deg]F. Although NEEA's AWHS v8.0 specifies these air and water 
conditions only for integrated heat pump water heaters, DOE has 
tentatively determined that these conditions could also be used for 
heat pump-only water heaters, which typically do not have any outdoor 
components.
    For split-system heat pump water heaters, Appendix B.4 to AWHS v8.0 
includes a note that the test method and calculation procedure is ``in 
progress,'' and test conditions are labeled as ``draft testing 
conditions.'' Appendix B.4 to AWHS v8.0 states, ``broadly, the method 
will consist of calculating an efficiency for each test in Table 8 
following the Uniform Energy Factor calculation method but substituting 
in appropriate temperature conditions.'' For split-system heat pump 
water heaters, AWHS v8.0 determines SCOP at ambient air conditions 
ranging from 5 [deg]F dry bulb temperature and 30 percent relative 
humidity to 95 [deg]F dry bulb temperature and 25 percent relative 
humidity. Similar to the requirements in AWHS v8.0 for integrated heat 
pump water heaters, the supply water temperature requirement varies 
with ambient dry bulb temperature. The four standard test conditions 
for SCOP in AWHS v8.0 are shown in Table 8 of AWHS v8.0 and in Table 
III.1 in this SNOPR.

                                Table III.1--AWHS v8.0 Standard Test Conditions for Split-System Heat Pump Water Heaters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Outdoor conditions                     Water                    Indoor conditions
                                           -------------------------------------------------------------------------------------------------------------
                Test point                   Outdoor dry-    Outdoor wet-
                                                 bulb            bulb          Relative      Supply water      Dry-bulb           Relative humidity
                                              temperature     temperature    humidity (%)     temperature     temperature
--------------------------------------------------------------------------------------------------------------------------------------------------------
A.........................................        5 [deg]F        2 [deg]F              30       42 [deg]F     67.5 [deg]F  Not specified.
B.........................................       34 [deg]F       31 [deg]F              72       47 [deg]F

[[Page 42277]]

 
C.........................................       68 [deg]F       57 [deg]F              50       58 [deg]F
D.........................................       95 [deg]F       69 [deg]F              25       67 [deg]F
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Test point C in AWHS v8.0 most closely resembles the current test 
condition in appendix E. In this SNOPR, DOE is proposing to adopt the 
three additional outdoor air conditions (A, B, and D in AWHS v8.0) for 
optional representations of split-system heat pump water heaters. Where 
indoor relative humidity is not currently specified in AWHS v8.0 for 
split-system heat pump water heaters, DOE is proposing to use the 50-
percent relative humidity requirement from the current appendix E test 
procedure in order to maintain the consistency and comparability of 
results. Tolerances on these conditions would be the same as those 
required for the standard UEF test conditions.
    DOE proposes to adopt the optional test conditions as stand-alone 
metrics in sections 2.8 and 5.6 of appendix E. DOE proposes to adopt a 
new metric, EX (where ``X'' represents the air temperature 
under which the test was conducted if not 67.5 [deg]F), at sections 
1.16 and 6.5 of appendix E for optional representations only. The 
metric EX would represent the result of a test done in 
accordance with the UEF test procedure but at a different set of 
ambient test conditions. With the exception of the different 
temperature (both air and water) and humidity conditions, all other 
aspects of the test procedure would remain identical to those used to 
determine the regulated metric, UEF. The draw pattern used to determine 
EX would be the same draw pattern used to determine UEF. The 
proposed optional test conditions for heat pump water heaters are shown 
in Table III.2.

                                       Table III.2--Proposed Optional Test Conditions for Heat Pump Water Heaters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Outdoor air conditions           Indoor air conditions
                                                                         ----------------------------------------------------------------  Supply water
                     Heat pump type                           Metric         Dry-bulb        Relative        Dry-bulb        Relative       temperature
                                                                            temperature    humidity (%)     temperature    humidity (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Split-System............................................              E5      5.0 [deg]F              30     67.5 [deg]F              50     42.0 [deg]F
                                                                     E34     34.0 [deg]F              72                                     47.0 [deg]F
                                                                     E95     95.0 [deg]F              25                                     67.0 [deg]F
Integrated or Heat Pump-Only............................             E50             N/A             N/A     50.0 [deg]F              58     50.0 [deg]F
                                                                     E95             N/A             N/A     95.0 [deg]F              40     67.0 [deg]F
--------------------------------------------------------------------------------------------------------------------------------------------------------

    DOE seeks information and comments on its proposal to allow 
optional representations of EX in the appendix E test 
procedure to indicate efficiency at different inlet air and water 
conditions. DOE also welcomes feedback on its proposal to use the same 
temperature measurement tolerances for optional Ex 
conditions and the required UEF condition. DOE is interested in data 
which can be used to determine the range of indoor ambient air 
conditions typical in semi-conditioned spaces in different geographical 
regions in the United States, and how these conditions typically 
correlate to outdoor air conditions. DOE is also interested in data 
which may be used to correlate consumer hot water usage patterns with 
different seasonal conditions.
    In order to avoid any potential confusion between heat pump-only 
water heaters and split-system water heaters, DOE is also proposing to 
define ``split-system heat pump water heater'' in section 1.14 of 
appendix E. Specifically, DOE proposes to adopt the definition in AWHS 
v8.0 with minor modifications:
    Split-system heat pump water heater means a heat pump-type water 
heater with an indoor storage tank and outdoor heat pump component.
    DOE welcomes comment on its proposed definition of ``split-system 
heat pump water heater.''
    DOE has tentatively determined that this proposal would not lead to 
additional testing costs or burden for manufacturers or test labs 
because these optional metrics would remain voluntary for 
representations.

C. Storage Tank Over-Heating

    As discussed in the January 2022 NOPR, DOE proposed amendments 
pertaining to 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. 87 FR 1554, 1580 (Jan. 11, 2022). These water 
heaters are meant to be used with a mixing valve (which may or may not 
be provided with, or be 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) 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 conventional 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.

[[Page 42278]]

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. Id.
    For this type of water heater, DOE proposed in the January 2022 
NOPR 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.\18\ 87 FR 1554, 1580 (Jan. 11, 2022).
---------------------------------------------------------------------------

    \18\ The ENERGY STAR program published a Test Method to Validate 
Demand Response for connected residential water heaters on April 5, 
2021 (the ``ENERGY STAR Connected Test Method''). Section 4.1 of the 
ENERGY STAR Connected Test Method addresses the test set-up in which 
a separate mixing valve is required. 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 (Last accessed May 
19, 2022).
---------------------------------------------------------------------------

    In response to the January 2022 NOPR, several commenters requested 
that DOE consider further amendments to the appendix E test procedure 
to provide more representative efficiency results for such storage-type 
water heaters that ``over-heat'' the stored water beyond the delivery 
temperature. These comments are summarized and responded to in the 
paragraphs that follow. In consideration of these comments, DOE is 
proposing additional testing requirements to further address water 
heaters that have an operational mode (or modes) that over-heat the 
stored water.
    NYSERDA commented that DOE should ensure that all test procedure 
requirements surrounding FHR enable comparison between products and 
accurately reflect the in-field performance of water heaters, including 
those which may augment capacity through the use of a mixing valve or 
other approaches. (NYSERDA, No. 32 at p. 4)
    NEEA commented that it supports DOE's proposal to specify 
instructions for the installation of a mixing valve, stating that the 
proposal would improve repeatability and comparability of test results 
by providing clarity on the pipe, valve, and measurement locations. 
(NEEA, No. 30 at p. 2) The commenter further asserted that ensuring 
that inlet temperature is measured before supplying cold water to the 
mixing valve and that outlet temperature is measured after heating and 
mixing would produce the most representative and repeatable test 
results. (Id.) NEEA also recommended that DOE consider ways to account 
for the increased effective capacity enabled by a mixing valve (either 
separate or integrated). (Id.) According to NEEA, products that store 
water at a higher temperature in a mode other than default would have 
an increased effective capacity and lower UEF in this high temperature 
mode. (Id.) NEEA encouraged DOE to consider ways to account for the 
increased effective capacity for products with integrated mixing valves 
and those designed to be used with a mixing valve. (Id.)
    The Joint Advocates expressed support for DOE's proposal to include 
instructions for the installation of a mixing valve and encouraged DOE 
to amend the test procedure to capture the associated increase in 
effective hot water storage volume for water heaters designed to be 
used with a mixing valve. (Joint Advocates, No. 34 at pp. 1-2) The 
Joint Advocates stated that raising the temperature of the stored water 
above the outlet water temperature requirements essentially increases 
the amount of hot water delivered without increasing the size of the 
water heater, and that this is not reflected in the test procedure or 
standards because water heater ratings are calculated based on the 
rated storage volume, not the actual effective volume. (Id.) Therefore, 
the Joint Advocates recommended that DOE amend the test procedure to 
account for the additional effective storage volume enabled by a higher 
operating temperature and mixing valve. Specifically, the Joint 
Commenters encouraged DOE to consider specifying how to calculate the 
effective storage volume for water heaters designed to be installed 
with a mixing valved based on the highest possible temperature setpoint 
and requiring such water heaters to be tested at both 125 5 
[deg]F and at their highest setpoint. (Id.) Furthermore, the Joint 
Advocates commented that water heaters designed to be installed with a 
mixing valve should be subject to the DOE standards based on both their 
rated storage volume (and FHR at the 125  5 [deg]F 
setpoint) and their effective storage volume (and FHR at their highest 
setpoint). (Id.)
    The CA IOUs stated that storage volume and first hour rating are 
often correlated; however, with the increased use of thermostatic 
mixing valves, this correlation has decreased, and FHR has become a 
better representation of hot water delivery than storage volume. (CA 
IOUs, No. 36 at p. 3) The CA IOUs asserted that the FHR metric best 
defines consumer amenity, and that the current standards--which are 
differentiated by storage volume--allow for less-efficient performance 
for larger volume tanks within a given test procedure bin despite 
delivering similar service to the consumer. (Id.) With regard to mixing 
valves specifically, the CA IOUs supported DOE's proposal to require 
the fitting of thermostatic mixing valves between the inlet and outlet 
temperature measurement points when they are not an integral component 
of the water heater and in the absence of manufacturer instructions. 
(Id. at p. 5) The CA IOUs stated that this requirement would align with 
product designs, as manufacturers typically direct the integration of a 
valve or its installation, making it the correct choice to ensure 
comparability of results and to accurately represent real-world energy 
use. (Id.)
    In order to further examine the potential impact of storage tank 
over-heating, DOE performed testing on one 50-gallon electric 
resistance storage water heater that includes built-in mixing valve and 
multiple user-selectable modes to boost the delivery capacity by over-
heating the storage tank. DOE collected data at three different storage 
tank temperatures, each of which provided an outlet water temperature 
at 125 5 [deg]F through the use of the built-in mixing 
valve. The maximum measured mean tank temperature after cut-out 
following the first draw of the 24-hour simulated use test 
(Tmax,1) and the average outlet water temperature during the 
second draw (Tdel,2) were used as indicators of over-
heating. Data from this testing is shown in Table III.3 of this 
document. The first row of data (with maximum mean tank temperature 
value of 124.3) represents the unit as tested according to the current 
test procedure.

[[Page 42279]]



                                Table III.3--Storage Tank Over-Heating Test Data
----------------------------------------------------------------------------------------------------------------
                                                             Tdel,2 **
                   Tmax,1 * ([deg]F)                          ([deg]F)      Corresponding FHR  Corresponding UEF
----------------------------------------------------------------------------------------------------------------
124.3..................................................              121.3             77 gal               0.94
144.5..................................................              124.3             81 gal               0.90
159.6..................................................              124.3             95 gal               0.88
----------------------------------------------------------------------------------------------------------------
* Tmax,1 represents the maximum measured mean tank temperature after cut-out following the first draw of the 24-
  hour simulated-use test.
** Tdel,2 represents the average outlet water temperature during the second draw of the 24-hour simulated-use
  test.

    The test results support NEEA's assertion that storage tank over-
heating could lead to reductions in UEF. The test configuration 
corresponding to the current DOE test procedure produced a UEF value of 
0.94, which surpasses the threshold for compliance with the current 
minimum energy conservation applicable to this unit (minimum UEF of 
0.93). The over-heated configurations with mean tank temperatures of 
144.5 and 159.6 produced UEF values of 0.90 and 0.88, respectively, 
both of which are below the applicable minimum energy conservation 
standard for this unit.
    In addition, the test results indicate that storage tank over-
heating leads to an increase in the measured FHR value. The test 
configuration corresponding to the current DOE test procedure produced 
an FHR value of 77 gallons. The over-heated configurations with mean 
tank temperatures of 144.5 and 159.6 produced FHR values of 81 and 95 
gallons, respectively. DOE notes that an FHR of 95 gallons is 
comparable to that of a 100-gallon electric storage water heater.\19\ 
By comparison, the current minimum energy conservation standard that 
applies to 100-gallon consumer water heaters in the high draw pattern 
is a UEF of 2.13 (which currently can only be achieved through heat 
pump technology).
---------------------------------------------------------------------------

    \19\ For example, DOE's Compliance Certification Database 
includes a 107-gallon electric storage water heater with an FHR 
rating of 94 gallons.
---------------------------------------------------------------------------

    From its review of publicly available product literature, products 
that utilize storage tank over-heating generally offer user-selectable 
operating modes that result in tank temperatures ranging from 100 
[deg]F to 170 [deg]F. Based on DOE's test data, should consumers choose 
to operate these products to a high-capacity mode (which maintains the 
storage tank at, for example, 140 [deg]F while delivering water at 125 
[deg]F), the water heater would likely perform significantly worse than 
a rating determined based on testing without storage tank over-heating 
(i.e., the rated efficiency at the rated delivery capacity would not be 
representative of an average use cycle or period of use when operated 
in a high-capacity mode). Hence, DOE has tentatively determined that 
revisions to the method for determination of UEF and FHR are necessary 
to yield results representative of an average use cycle for these 
products. These proposed amendments are discussed in detail in the 
following sections.
1. Testing in Over-Heated Mode
    Most conventional storage-type water heaters do not include a 
mixing valve and offer a range of temperature setpoints that would, in 
typical installations, deliver outlet water at the temperature 
corresponding to the setpoint temperature (e.g., a 140 [deg]F setting 
on the water heater will deliver a 140 [deg]F outlet temperature). 
Whereas, as discussed previously, water heaters that include a mixing 
valve and provide ``over-heating'' capability offer a range of internal 
temperature setpoints, although the outlet water remains at nominally 
at 125 [deg]F regardless of internal setpoint. For the remainder of 
this discussion, DOE refers to a user-initiated mode that results in an 
elevated internal water temperature without increasing the delivered 
water temperature as ``over-heated mode.''
    Currently, section 5.1 of appendix E states, ``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 its product 
literature for giving selection guidance to the consumer.'' An 
``overheated mode'' in storage-type water heaters is distinct from a 
high-temperature setpoint because the outlet water temperature is 
unaffected by the internal temperature setpoint. DOE surmises that 
consumers who purchase a water heater that provides over-heating 
capability would do so with the intent to use such capability; as such, 
these consumers would be expected to use the over-heated mode some 
portion of the time, ranging from occasional use (e.g., switching 
between the normal mode and the over-heated mode depending on the hot 
water capacity needed at any particular time) to regular use. 
Accordingly, for such products, DOE expects that a representative 
average use cycle would include some portion of time in over-heated 
mode. For this reason, DOE has tentatively concluded that testing only 
in the default mode would not produce results that are representative 
of an average use cycle or period of use for products with this 
capability if the default mode does not provide over-heat capability.
    Considering these factors, DOE has tentatively determined that 
testing storage-type water heaters that offer user-selectable over-
heated modes in the over-heated mode would provide a more 
representative result than testing in the default mode. Therefore, DOE 
proposes to amend section 5.1 of appendix E to require that for water 
heaters that offer a user-selected operational mode(s) in which the 
storage tank is maintained at a temperature higher than the delivery 
temperature, the operational mode shall be that which results in the 
highest mean tank temperature while maintaining an outlet temperature 
of 125 5 [deg]F.
    DOE recognizes that the aforementioned proposal would likely cause 
UEF ratings for these products to decrease if they are currently 
certified using a default operational mode that does not initiate over-
heating. In order to limit potential re-testing and re-certification 
burden for manufacturers, DOE is proposing that the requirement to test 
these products in the over-heated mode go into effect only once DOE 
completes its ongoing review of potential amended energy conservation 
standards for consumer water heaters and residential-duty commercial 
water heaters.\20\
---------------------------------------------------------------------------

    \20\ DOE is concurrently evaluating potential amended energy 
conservation standards for consumer water heaters (Docket No. EERE-
2017-BT-STD-0019) and residential-duty commercial water heaters 
(Docket No. EERE-2021-BT-STD-0027).
---------------------------------------------------------------------------

    Electric storage water heaters with demand-response capabilities 
may undergo utility-initiated over-heating during certain periods in 
order to store additional energy in the water heater for

[[Page 42280]]

use during peak demand periods. This over-heating, when initiated by 
the electric utility company, serves an important purpose for energy 
storage and grid flexibility. Products that offer the ability to 
respond to utility-initiated over-heating requests are distinct in 
function from products that offer user-initiated over-heating, because 
demand-response water heaters do not over-heat to increase the overall 
daily capacity of the water heater. Instead, the capacity is only 
temporarily boosted to counteract the deactivation of the heating 
elements for extended periods of time when demand curtailment is 
occurring. As such, demand-response water heaters with the capability 
to undergo utility-initiated over-heating would not be expected 
increase the capacity of the water heater over a typical average use 
cycle in the same way that a water heater with user-initiated over-
heating would, so DOE has tentatively concluded that testing demand-
response water heaters in the default/normal mode would be the most 
representative for demand-response water heaters.
    In order to clarify which products with over-heating capability 
should be tested in the operational mode that results in the highest 
mean tank temperature while maintaining an outlet temperature of 125 
5 [deg]F and which products with over-heating capability 
should be tested in default/normal mode, DOE is proposing to define 
``demand-response water heater'' in section 1.3 of appendix E. Products 
meeting that definition would be tested in normal/default mode, while 
all other products capable of over-heating the stored water in the tank 
would be tested in the in the operational mode that results in the 
highest mean tank temperature while maintaining an outlet temperature 
of 125 5 [deg]F. The proposed definition for ``demand-
response water heater'' is based on the ENERGY STAR definitions for 
``connected water heater product,'' ``demand response management 
system,'' and ``demand response'' in specification version 5.0, with 
certain modifications made by DOE.\21\ More specifically, DOE proposes 
to define ``demand-response water heater'' as follows:
---------------------------------------------------------------------------

    \21\ The ENERGY STAR Version 5.0 Residential Water Heater Final 
Draft Specification was published on June 1, 2022 and is available 
online at: www.energystar.gov/products/spec/residential_water_heaters_specification_version_5_0_pd (Last 
accessed on June 4, 2022).

    Demand-response water heater means a storage-type water heater 
that--
    (1) Has integrated communications hardware and additional 
hardware and software required to enable connected functionality 
with a utility or third party, which dispatches signals with demand 
response instructions and/or price signals to the product and 
receives messages from the demand-response water heater;
    (2) Meets the communication and equipment standards for Consumer 
Technology Association Standard (CTA) 2045-B (ANSI/CTA-2045-B); \22\
---------------------------------------------------------------------------

    \22\ ANSI/CTA-2045-B, ``Modular Communications Interface for 
Energy Management,'' published February 2021.
---------------------------------------------------------------------------

    (3) Automatically heats the stored water above the delivery 
temperature setpoint only in response to instructions received from 
a utility or third party.

    DOE welcomes comment on its proposed definition of ``demand-
response water heater,'' including the specification for ANSI/CTA-2045-
B to demonstrate connected functionality (as it is the latest version 
of the CTA-2045 standard).
    DOE seeks comment on the proposal to specify that water heaters, 
except demand-response water heaters, that offer an operational mode 
(or modes) causing water to be stored at a temperature higher than the 
delivery temperature must be tested in the ``over-heated mode'' that 
results in the highest internal tank temperature while still while 
maintaining an outlet temperature of 125 5 [deg]F. DOE also 
welcomes feedback on its proposal to require testing in this manner 
only after compliance with amended energy conservation standards for 
consumer water heaters and residential-duty commercial water heaters is 
required. DOE further seeks information and consumer use data to 
identify how often the over-heated mode is used in field installations.
2. Effective Storage Volume
    As discussed in section III.C of this document, the Joint Advocates 
and the CA IOUs both recommended that the increase in water heating 
capacity attained through over-heating the storage tank be considered 
for energy conservation standards. The Joint Advocates suggested that 
compliance with standards should be based on an ``effective storage 
volume,'' whereas the CA IOUs advocated for FHR to be used for 
standards instead of a representation of storage volume.
    The current energy conservation standards at 10 CFR 430.32(d) 
define the minimum required UEF as a function of rated storage volume. 
These standards have been amended over time but are based on the 
original standards prescribed by EPCA at 42 U.S.C. 6295(e)(1), which 
also correlated the efficiency metric to storage volume. In doing so, 
these standards account for differences in standby losses (i.e., heat 
transfer from the hot, stored water to the ambient surroundings) for 
storage tanks of varying sizes. For storage-type water heaters, the 
amount of hot water immediately available for consumer use has 
typically been governed by the storage tank size, with increased tank 
size resulting in a corresponding increase in standby losses. Standby 
losses are primarily dependent upon three factors: (1) surface area of 
the tank; (2) temperature of the stored water, and (3) tank insulation. 
As storage tank volume increases, so do the expected standby losses 
(all else being equal). Similarly, an increased water temperature would 
also increase standby losses. The standards originally prescribed by 
EPCA and subsequently amended by DOE did not contemplate storage tank 
over-heating and its potential impact on standby losses and the amount 
of hot water that is immediately available for consumer use. Therefore, 
DOE has initially concluded that a capacity metric that combines 
information about the tank volume and storage temperature may be more 
appropriate.
    Similar to standby loss, the thermal energy stored in a water 
heater is a function of both the volume and the temperature of the 
water being stored in the tank. The ability to over-heat the tank 
increases the effective thermal energy storage of the tank to that 
equivalent to a larger tank that has been heated to a more 
conventional, lower temperature (i.e., approximately 125 5 
[deg]F). DOE has tentatively determined that a measure of ``effective 
storage volume'' (as suggested by the Joint Advocates) that reflects 
the thermal energy stored in the water heater would allow for a better 
comparison between a smaller water heater with over-heating and a 
larger water heater storing water at a lower temperature.
    Lutz stated that the test procedure should be able to distinguish 
and measure the ability of a water heater to deliver hot water with 
enough energy and to deliver a high enough temperature. Lutz provided 
the example of a bath, where the temperature at every point during the 
draw is not important; contrasted with a shower, where the temperature 
is crucial. (Lutz, No. 35 at p. 1)
    DOE notes that for activities such as filling a bathtub, consumers 
would benefit more from knowing the effective storage volume (i.e., the 
volume of immediately available hot water) of a water heater, whereas 
for activities such as taking a shower, consumers could benefit more 
from knowing the FHR (i.e., ability to deliver hot water for an 
extended period of time). In particular,

[[Page 42281]]

FHR represents one full hour of delivery and does not necessarily 
describe immediate hot water availability, as FHR is also impacted by 
the rate of recovery. Hence, in addition to FHR, DOE has tentatively 
determined that effective storage volume would be a meaningful 
performance metric for consumers. In this SNOPR, DOE proposes a method 
to determine effective storage volume, Veff (expressed in 
gallons or liters), at section 6.3.1.1 of appendix E. For water heaters 
storing water no higher than the delivery temperature, DOE proposes 
that the effective storage volume be equivalent to the measured storage 
volume. DOE proposes that to determine whether the stored water 
temperature is higher than the delivery temperature, the maximum mean 
tank temperature measured after cut-out following the first draw of the 
24-hour simulated-use test (Tmax,1) is to be compared to the 
average outlet water temperature during the second draw of the 24-hour 
simulated-use test (Tdel,2). If Tmax,1 is less 
than or equal to Tdel,2, then the unit would be determined 
to not be capable of over-heating the stored water, and the effective 
storage volume would be set equal to the measured storage volume. DOE 
has tentatively chosen Tmax,1 to represent the temperature 
of the stored water. Based on DOE's review of its own test data, 
Tmax,1 is typically the highest mean tank temperature 
achieved by the water heater, and Tmax values throughout the 
test (i.e., all maximum mean tank temperatures following element cut-
out) typically do not vary significantly. DOE has tentatively chosen 
Tdel,2 to represent the delivered water temperature because 
it corresponds to the first draw after Tmax,1 is observed.
    By contrast, for water heaters capable of over-heating water (as 
determined by Tmax,1 being greater than Tdel,2), 
DOE proposes to calculate the effective storage volume based on a 
volume scaling factor and data already collected during the appendix E 
test. The volume scaling factor would be determined as follows, which 
is based on the relative heat transfer rates calculated from the 
temperature data collected during the test:
[GRAPHIC] [TIFF OMITTED] TP14JY22.000

Where:

kV is the dimensionless volume scaling factor;

[rho](T) is the density of water evaluated at temperature T;

CP(T) is the heat capacity of water evaluated at 
temperature T, and

67.5 [deg]F is the average ambient temperature.

    DOE proposes to determine the effective storage volume by 
multiplying the measured storage volume by kV.
    DOE notes that this approach to calculating effective storage 
volume would allow all calculations to be based on data collected 
during a single 24-hour simulated use test, but it would yield 
meaningful results only if water heaters capable of over-heating are 
required to be tested in an over-heated mode, which is discussed in 
section III.C.1 of this document.
    This SNOPR does not propose to require representations of effective 
storage volume, but DOE may consider such requirements as part of a 
future energy conservation standards rulemaking, should this proposal 
be finalized.
    With respect to the comment from the CA IOUs suggesting that the 
energy conservation standards be based on FHR rather than storage 
volume, DOE notes that changes to the energy conservation standards are 
outside the scope of this test procedure rulemaking. However, this 
recommendation, along with the Joint Advocates' recommendation that 
standards be based on an effective volume, will be considered further 
in DOE's concurrent energy conservation standards rulemaking.
    DOE seeks comment on its tentative determination that effective 
storage volume would be a meaningful performance metric for consumers 
and is a more appropriate measure of thermal energy storage than FHR.
    DOE seeks comment on the proposed equations and approach to 
calculating effective storage volume for water heaters.

D. Separate Storage Tank Requirements

    Some water heaters on the market require a volume of water, 
typically contained in either a storage tank (or tanks) or in a piping 
distribution system of sufficient volume, to operate. These products 
operate by circulating water stored either in the piping system or from 
a separate tank (or multiple separate tanks) to the water heater to be 
heated then back to the piping system or tank until hot water is 
needed. In the January 2022 NOPR, DOE identified two types of products 
that require a volume of water to operate--heat pump-only water heaters 
that require installation with a separate storage tank and circulating 
gas-fired instantaneous water heaters that require installation with a 
separate storage tank or a piping system of sufficient volume. 87 FR 
1554, 1583-1585 (Jan. 11, 2022). Circulating gas-fired instantaneous 
water heaters are distinct from other types of gas-fired instantaneous 
water heaters in that they are not designed to operate independent of a 
storage tank or hot water system, as other gas-fired instantaneous 
water heaters are. This applies generally to circulating water heaters; 
however, DOE has tentatively determined that there are no electric 
resistance or oil-fired circulating water heaters on the market today.
    The current test procedure does not have procedures in place to 
appropriately test circulating water heaters. As such, in the January 
2022 NOPR, DOE proposed to define ``circulating water heater'' 
(including both heat pump-only and gas-fired instantaneous circulating 
water heaters) and to require that such products be tested using an 80 
gallon ( 1 gallon) unfired hot water storage tank 
(``UFHWST'') that meets the energy conservation standards for an 
unfired hot water storage tank at 10 CFR 431.110(a). 87 FR 1554, 1583-
1585 (Jan. 11, 2022).
    In response to the January 2022 NOPR, DOE received a number of 
comments regarding the separate storage tank requirements, primarily 
related to the  1 gallon tolerance, the representativeness 
of an 80-gallon unfired hot water storage tank, and the lack of a 
specification for the upper bound on thermal insulation for the unfired 
hot water storage tank. These comments are summarized and addressed in 
the paragraphs that follow.
    NYSERDA commented that an 80-gallon UFHWST may not be the correct 
tank to use to increase repeatability and represent real world 
conditions. (NYSERDA, No. 32 at p. 2)
    Rheem commented that because a circulating water heater can be 
paired with multiple sizes of tanks (e.g., 40-, 60-, and 80-gallon 
tanks), DOE should consider multiple tank sizes for testing circulating 
water heaters instead of just one 80-gallon storage tank. Rheem also 
suggested that DOE increase the

[[Page 42282]]

tolerance on the volume of the storage tank to match the tolerance 
prescribed by product safety standards,\23\ noting that a 1 
gallon tolerance on an 80-gallon storage volume is too tight. Rheem 
also requested clarification on whether the separately sold storage 
tank may have backup heating (e.g., if the circulating water heater is 
designed to be used with a tank that has backup heating) and whether 
the two products could be rated together as a system. (Rheem, No. 40 at 
pp. 3-4)
---------------------------------------------------------------------------

    \23\ DOE understands this to be a reference to the 10 percent by 
volume tolerances prescribed by UL Standard 174 (``Household 
Electric Storage Tank Water Heaters'') and UL Standard 1453 
(``Standard for Electric Booster and Commercial Storage Tank Water 
Heaters''). These standards can be found online at 
www.shopulstandards.com (Last accessed on June 21, 2022).
---------------------------------------------------------------------------

    AHRI recommended that DOE not adopt a 1 gallon 
tolerance requirement for the storage tank used in the test for a heat 
pump-only water heater, stating that DOE should instead apply 10 
percent volume tolerance, consistent with UL standard 174 or UL 
standard 1453. AHRI also suggested that manufacturers be allowed to 
specify the storage tank used to determine ratings for circulating and 
heat pump-only water heaters. (AHRI, No. 40 at pp. 3-5)
    A.O. Smith stated that it would not be unduly burdensome to use an 
80-gallon tank for heat pump-only water heater testing. However, A.O. 
Smith stated that tank insulation, inlet and outlet connection 
locations, internal tank baffling, and inlet tube designs could impact 
the UEF result, and accordingly, these variables should be addressed in 
the DOE test procedure. A.O. Smith recommended that, to minimize as 
many variables as possible, manufacturers be required to provide the 
model number of the specific tank as part of its certification data, 
and that the test tank should be defined as a part of the test 
apparatus. (A.O. Smith, No. 37 at p. 3) DOE understands this to mean 
that A.O. Smith recommends that the UFHWST model number used for 
testing UEF be certified to DOE by the manufacturer, and that appendix 
E should indicate that the specific UFHWST model certified to DOE must 
be used in the test set-up.
    The CA IOUs stated that the proposed 80-gallon tank size may not 
reflect real-world applications. Additionally, the CA IOUs argued that 
because the proposed requirement would impose a minimum R-value for the 
tank, but no maximum, it could lead to variations in test outcomes. The 
CA IOUs suggested that heat pump-only water heater manufacturers should 
be allowed to test their products with a manufacturer-specified storage 
tank and certify the information about the tank used for testing. The 
CA IOUs also suggested that for heat-pump-only water heaters, DOE 
should specify a traditional consumer electric storage water heater 
tank, as it may be more representative of actual use. (CA IOUs, No. 36 
at p. 5; CA IOUs, No. 27 at p. 31)
    BWC commented that not all storage tanks are designed identically, 
and differences in tank design may lead to differences in ratings for 
circulating and heat pump-only water heaters. BWC also urged DOE to not 
adopt a 1-gallon tolerance on the volume of an 80-gallon storage tank, 
but instead to use a 10-percent tolerance. BWC requested that DOE 
clarify whether the 80-gallon requirement would pertain to nominal 
capacity. (BWC, No. 33 at p. 9)
    After considering the issues raised by commenters, DOE is proposing 
several updates to its earlier proposals (in section 4.10 of appendix 
E) for testing circulating water heaters as initially presented in the 
January 2022 NOPR.
    First, after re-evaluating the market for heat-pump-only water 
heaters, DOE tentatively agrees with the CA IOUs that testing such 
products with a conventional electric storage water (i.e., an electric 
water heater that uses only electric resistance heating elements) would 
be more representative than testing with an UFHWST. Therefore, DOE is 
proposing that heat-pump-only water heaters be tested in the medium 
draw pattern using a 40-gallon traditional electric storage tank (i.e., 
that provides heat only with electric resistance heating elements) that 
has a UEF rating at the minimum required at 10 CFR 430.32(d). DOE chose 
a 40-gallon tank in the medium draw pattern because that size and draw 
pattern combination has the highest number of models currently 
available on the market.\24\ DOE is also proposing that, for heat pump-
only water heaters, the test be carried out using a tank that does not 
``over-heat'' the stored water (see discussion of over-heating in 
section III.C of this document; Tmax,1 (maximum measured 
mean tank temperature after the first recovery period of the 24-hour 
simulated-use test) must be less than or equal to Tdel,2 
(average outlet water temperature during the 2nd draw of the 24-hour 
simulated-use test)). This would ensure that the electric storage tanks 
are not overheating during the test, thereby ensuring consistency 
across tests.
---------------------------------------------------------------------------

    \24\ See Figure 3A.2.8 of the Preliminary Analysis Technical 
Support Document for consumer water heaters (Docket No. EERE-2017-
BT-STD-0019-0018).
---------------------------------------------------------------------------

    In contrast, DOE is maintaining its earlier proposal that a UFHWST 
be used for testing of circulating gas-fired water heaters, as those 
products are more likely to be installed with a UFHWST in the field. 
Therefore, DOE tentatively concludes that testing with an UFHWST would 
be representative for such units.
    In response to AHRI's suggestion that DOE allow manufacturers to 
specify the storage tank used for testing, DOE notes that this approach 
could lead to additional test burden for third-party testing labs, who 
may need to acquire more than one storage tank if they are performing 
tests for multiple manufacturers, each of whom may specify a different 
storage tank for testing. In order to avoid creating the potential for 
additional test burden, DOE has tentatively determined not to allow 
manufacturers to specify the electric storage water heater or unfired 
hot water storage tank used respectively for testing the heat pump-only 
or gas-fired instantaneous circulating water heaters. Additionally, DOE 
will consider relevant amendments to certification and reporting 
requirements in a separate rulemaking.
    After considering the comments regarding the tolerance on the 
storage tank initially proposed in the January 2022 NOPR, DOE has 
tentatively determined that a wider tolerance would reduce potential 
testing burden while still providing representative and reproducible 
results. In other words, DOE tentatively concludes that a 10-percent 
tolerance would increase flexibility for manufacturers by increasing 
the number of tanks that could be used for testing, while not 
materially impacting the UEF test results. Therefore, consistent with 
the recommendations provided by commenters, DOE is proposing to adopt a 
10 percent tolerance (10 percent, allowing products with 
rated storage volumes between 36 gallons and 44 gallons) for the 
electric storage water heater used for testing heat-pump-only water 
heaters.
    In addition, after further review of the market for circulating 
gas-fired instantaneous water heaters and unfired hot water storage 
tanks, DOE is proposing to allow testing with a tank at any storage 
volume between 80- and 120-gallons. Based on further analysis, DOE has 
tentatively determined that variations in the tank size should not 
significantly impact the result of the test. During a water draw, the 
internal tank temperature decreases as hot water exits the tank and is 
replenished by colder water entering the tank.

[[Page 42283]]

Generally, different tank sizes will result in different rates of 
internal temperature decrease during a water draw (e.g., during a 
specified water draw, a smaller tank will generally experience a faster 
decrease in temperature compared to a larger tank). During a test, any 
potential differences in the tank water temperature due to the use of 
different size tanks would be accompanied by a corresponding 
proportional difference in burner on-time, such that the impact on 
measured efficiency (i.e., the ratio of energy output to energy input) 
would be negligible. DOE also recognizes that a larger tank would 
likely have more standby losses than a smaller tank; however, DOE has 
tentatively determined that the impact this would have on measure 
efficiency would also not be significant.
    Providing a range of allowable tank volumes would reduce potential 
burden by providing manufacturers with more tank options, thereby 
allowing them to pair their circulating gas-fired instantaneous water 
heaters with an existing UFHWST model. This approach is also likely to 
be more representative of how the units would be installed in the field 
as opposed to testing with a custom-made tank for testing or a 
competitor's tank that meets a specific volume requirement.
    DOE notes that, as suggested by the CA IOUs and A.O. Smith, the 
lack of an upper bound on the thermal insulation value for the UFHWST 
could lead to differences in measured efficiency that reflect 
differences in tank performance, rather than reflecting differences in 
water heater performance. Therefore, DOE has tentatively determined 
that more specific constraints on tank performance are warranted to 
ensure more comparable test results across the subject water heater 
models. Thus, DOE is proposing to require that UFHWSTs used for testing 
circulating gas-fired instantaneous water heaters exactly meet the 
baseline energy conservation standard for UFHWSTs.\25\ As stated 
previously, A.O. Smith raised the concern that differences in the 
UFHWST's design (insulation, inlet and outlet connection locations, 
internal tank baffling, and inlet tube designs) could lead to variation 
in UEF results; however, A.O. Smith and other commenters did not 
provide suggestions on specific UFHWST designs which should be 
standardized in order to improve representativeness and repeatability 
of the test method. A.O. Smith did not provide any data to demonstrate 
these to be significant concerns. While the variations in insulation 
would most significantly impact the standby losses of the tank (and 
therefore the UEF rating of the circulating water heater), these 
variations would already be minimized by specifying the R-value of the 
UFHWST to be the baseline requirement in the energy conservation 
standards for UFHWSTs. Regarding the other design options, over-
specifying the design of the UFHWST--given the impacts on the UEF 
rating are minimal--could result in a very narrow range of UFHWST 
models which can be used for testing circulating water heaters, thereby 
potentially introducing significant barriers to testing these products 
at third-party laboratories. Additionally, DOE does not currently have 
sufficient information on specifications for the inlet and outlet 
connection locations, internal tank baffling, and inlet tube designs 
for the UFHWST; therefore, DOE is not including these specifications in 
its proposed requirements.
---------------------------------------------------------------------------

    \25\ Currently, baseline energy conservation standards for 
UFHWSTs require a thermal insulation of R-12.5. 10 CFR 431.110(a).
---------------------------------------------------------------------------

    As noted previously, DOE is similarly proposing that the electric 
storage water heater used for testing heat-pump-only water heaters have 
a rated UEF corresponding to the minimum standard found at 10 CFR 
430.32(d), thereby helping to ensure more comparable results.
    In summary, in this SNOPR, DOE proposes to further amend the 
separate storage tank requirements proposed in the January 2022 NOPR 
for heat pump-only and gas-fired circulating water heaters. DOE 
proposes that heat pump-only water heaters be tested with a 40-gallon 
( 4 gallons) electric storage water heater that has a UEF 
value corresponding to the minimum standard for such products; and that 
gas-fired circulating water heaters be tested with an 80- to 120-gallon 
unfired hot water storage tank that is rated equal to the energy 
conservation standard for such equipment.
    DOE requests comment on its proposed separate tank requirements for 
heat pump-only and gas-fired circulating water heaters. DOE also seeks 
comment on whether any additional tank characteristics should be 
specified.
    For gas-fired circulating water heaters, these proposed changes 
could require a one-time purchase of an 80- to 120-gallon unfired hot 
water storage tank. DOE research indicates that such tanks are readily 
commercially available for approximately $2,000. For heat pump-only 
water heaters, the proposed changes could result in a one-time purchase 
of a 40-gallon ( 4 gallons) electric storage water heater. 
DOE research indicates that such water heaters are readily available 
for approximately $500. These estimates reflect costs for third-party 
laboratory testing (i.e., assuming these tanks would have to be 
purchased at retail price).
    DOE seeks comment on the estimated potential increase in costs for 
testing heat pump-only and gas-fired circulating water heaters 
according to this proposal.
    Finally, although this SNOPR does not propose changes to the 
certification requirements, DOE may consider a requirement to certify 
the UFHWST and electric storage water heater models and/or 
characteristics in a future rulemaking.

E. Method for Determining Internal Tank Temperature for Certain Water 
Heaters

    As discussed in the January 2022 NOPR, 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 using any of these means 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. 87 FR 1554, 1586 (Jan. 11, 2022). 
Commenters on the April 2020 RFI suggested an approach whereby the tank 
would be drained down to measure the temperature of the water inside. 
Id. In the January 2022 NOPR, DOE explained how draining down the tank 
would not be possible in the middle of the 24-hour simulated use test, 
when mean tank temperature data is required. Id. Therefore, DOE 
proposed that the internal tank temperature for these products would be 
approximated as the average between the inlet and outlet temperatures 
(i.e., a ``linear temperature gradient'' assumption). Id.
    Rheem agreed with DOE's proposed methodology to estimate the mean 
tank temperature for products for which the internal tank temperature 
cannot be directly measured. (Rheem, No. 31 at p. 4)

[[Page 42284]]

    However, several commenters indicated that the linear temperature 
gradient assumption inherent to the proposed methodology in the January 
2022 NOPR is incorrect. AHRI commented that the proposed procedure 
incorrectly assumes a linear temperature gradient in the tank, which 
can lead to inaccurate calculation of temperature and stored energy in 
the tank.\26\ (AHRI, No. 40 at p. 5)
---------------------------------------------------------------------------

    \26\ Additionally, AHRI stated that the procedure should require 
measurements to be taken 15 seconds after the initial draw to be 
consistent with other proposals.
---------------------------------------------------------------------------

    A.O. Smith commented that it has conducted testing using the 
proposed test method and has found that the assumption of a linear 
temperature gradient is inaccurate when compared to actual temperature 
readings conducted with thermocouples. Accordingly, A.O. Smith 
concluded that it would be premature to incorporate the proposed test 
method into the DOE test procedure at this time. (A.O. Smith, No. 37 at 
pp. 5-6) BWC indicated that, based on its own testing, the proposed 
methodology could record artificially lower tank temperatures, with 
errors as high as 10 to 25 percent. (BWC, No. 33 at p. 10)
    In the final rule that established the current test procedure for 
commercial water heaters, DOE noted that using the average of the 
supply and outlet water temperature as an estimate for the stored water 
temperature is only valid if the water temperature inside the heat 
exchanger has a linear increase in temperature as it moves from the 
inlet to the outlet. 81 FR 79261, 79295 (Nov. 10, 2016). In order to 
estimate the internal tank temperature for commercial instantaneous 
water heaters and hot water supply boilers, DOE adopted a method that 
uses the outlet water temperature as an approximation, because it was 
consistent with the industry-adopted test method for flow-activated 
instantaneous water heaters, found at Annex E.3 of ANSI Standard 
Z21.10.3-2015. Id.
    However, as discussed in section III.C of this SNOPR, DOE is aware 
of consumer water heaters that can store water at temperatures that are 
significantly higher than the outlet temperature, so the method used 
for commercial instantaneous water heaters and hot water supply boilers 
would not be applicable to all types of products covered under this 
rulemaking. Furthermore, outlet water temperature would only be 
representative of the internal tank temperature for consumer water 
heaters and residential-duty commercial water heaters with very limited 
storage volume, where the small volume prevents internal temperature 
stratification.\27\
---------------------------------------------------------------------------

    \27\ Currently, mean tank temperature measurements are not 
required for consumer water heaters or residential-duty commercial 
water heaters less than 2 gallons in rated storage volume.
---------------------------------------------------------------------------

    Based on further consideration of comments received in response to 
the January 2022 NOPR and at previous stages of this rulemaking, DOE is 
proposing in this SNOPR that, for water heaters with rated storage 
volumes greater than or equal to 2 gallons that are unable to have 
their internal tank temperatures measured using thermocouples, the 
internal tank temperature shall be estimated by removing water from the 
water heater, as described in detail in the following paragraphs. This 
method, proposed in a new section 5.4.2.2 of appendix E, is partially 
based on the approaches suggested by Rheem and BWC prior to the January 
2022 NOPR (see Document No. EERE-2019-BT-TP-0032-0012 at p. 5 and 
Document No. EERE-2019-BT-TP-0032-0014 at p. 9), with certain 
modifications.
    As discussed in the January 2022 NOPR, 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). 87 FR 1554, 1586 (Jan. 11, 2022). DOE performed 
an analysis on data collected from its own testing and has initially 
concluded that, for typical storage-type water heaters, T0, 
, Tsu,0, and Tmax,1 are similar in that they 
represent temperatures near the cut-out control temperature. Removing 
the heated water from the tank and measuring the temperature, as 
described in detail below, immediately after cut-out may reasonably 
estimate these temperatures. The mean tank temperature at the end of 
the standby period, Tsu,f, can also be measured by removing 
water and measuring its temperature at the end of a sufficiently long 
standby period at the end of the test, and this value could also 
approximate T24.
    In this SNOPR, DOE is proposing the following methodology for water 
heaters with rated storage volumes greater than or equal to 2 gallons 
that are unable to have their internal tank temperatures measured using 
thermocouples:
    (1) After the FHR test (for non-flow-activated products) or Max GPM 
test (for flow-activated products), allow the water heater to fully 
recover.
    (2) When cut-out occurs, deactivate the burner, compressor, and/or 
electrical heating elements.
    (3) Remove the hot water from the tank by performing a continuous 
draw, while measuring the outlet water temperature at 3-second 
intervals, until the outlet water temperature is within 2 [deg]F of the 
inlet water temperature for five consecutive readings. Perform the draw 
at a flow rate of 3.0 gallons per minute (0.25 gallons per 
minute). Compute the mean tank temperature, Tst, as follows 
and assign this value as T0, Tsu,0, and 
Tmax,1:
[GRAPHIC] [TIFF OMITTED] TP14JY22.001

Where:

Tst = the estimated average internal storage tank 
temperature.

Tp = the average of the inlet and the outlet water 
temperatures at the end of the period defined by [tau]p.

vout,p = the average flow rate during the period.

Vst = the rated storage volume of the water heater.

[tau]p = the duration of the period, determined by the 
length of time taken for the outlet water temperature to be within 2 
[deg]F of the inlet water temperature for 15 consecutive seconds. 
The duration of the period shall include the 15-second stabilization 
period.

Tin,p = the average of the inlet water temperatures 
during the period.

Tout,p = the average of the outlet water temperatures 
during the period.


    (4) Re-activate the burner, compressor, and/or electrical elements 
and perform the 24-hour simulated use

[[Page 42285]]

test as instructed in section 5.4 of appendix E.
    (5) The standby period will start at five minutes after the end of 
the first recovery period after the last draw of the simulated-use 
test. The standby period shall last eight hours, so testing will extend 
beyond the 24-hour duration of the simulated-use test. At the end of 
the final standby measurement, remove water from the tank once again as 
in step #3, including computing the value of mean tank temperature. 
This calculated mean tank temperature is then assigned as 
Tsu,f and T24.
    (6) Determine Tt,stby,1 as the average of 
Tsu,0 and Tsu,f.
    DOE seeks comment on its revised proposed test method to determine 
the internal tank temperature for water heaters that cannot be directly 
measured and are greater than or equal to 2 gallons in rated storage 
volume.
    DOE estimates that, at maximum, the proposed method for estimating 
the internal tank temperature would increase the test duration by 8 
hours (corresponding to the final standby period appended to the 
current 24-hour simulated use test). DOE estimates that the testing a 
water heater to the 24-hour simulated use test currently costs $3,000 
for a fossil-fuel-fired or electric water heater and $4,500 for a heat 
pump water heater. By extending the duration of the test by up to 8 
hours (or 33 percent), this amendment, if finalized, could increase 
testing costs by $1,000 to $1,500 per basic model for water heaters 
with rated storage volume greater than or equal to 2 gallons which 
cannot have their internal storage tank directly measured. However, 
these products are designed in such a way that instruments for 
measuring the internal water temperature cannot be installed, and, 
thus, these products cannot be tested to the current version of 
appendix E.

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866 and 13563

    Executive Order (``E.O.'')12866, ``Regulatory Planning and 
Review,'' 58 FR 51735 (Oct. 4, 1993), as supplemented and reaffirmed by 
E.O. 13563, ``Improving Regulation and Regulatory Review,'' 76 FR 3821 
(Jan. 21, 2011), requires agencies, to the extent permitted by law, to: 
(1) propose or adopt a regulation only upon a reasoned determination 
that its benefits justify its costs (recognizing that some benefits and 
costs are difficult to quantify); (2) tailor regulations to impose the 
least burden on society, consistent with obtaining regulatory 
objectives, taking into account, among other things, and to the extent 
practicable, the costs of cumulative regulations; (3) select, in 
choosing among alternative regulatory approaches, those approaches that 
maximize net benefits (including potential economic, environmental, 
public health and safety, and other advantages; distributive impacts; 
and equity); (4) to the extent feasible, specify performance 
objectives, rather than specifying the behavior or manner of compliance 
that regulated entities must adopt; and (5) identify and assess 
available alternatives to direct regulation, including providing 
economic incentives to encourage the desired behavior, such as user 
fees or marketable permits, or providing information upon which choices 
can be made by the public. DOE emphasizes as well that E.O. 13563 
requires agencies to use the best available techniques to quantify 
anticipated present and future benefits and costs as accurately as 
possible. In its guidance, the Office of Information and Regulatory 
Affairs (``OIRA'') in the Office of Management and Budget (``OMB'') has 
emphasized that such techniques may include identifying changing future 
compliance costs that might result from technological innovation or 
anticipated behavioral changes. For the reasons stated in the preamble, 
this proposed regulatory action is consistent with these principles.
    Section 6(a) of E.O. 12866 also requires agencies to submit 
``significant regulatory actions'' to OIRA for review. OIRA has 
determined that this proposed regulatory action does not constitute a 
``significant regulatory action'' under section 3(f) of E.O. 12866. 
Accordingly, this action was not submitted to OIRA for review under 
E.O. 12866.

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 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 test procedure SNOPR under the provisions of the 
Regulatory Flexibility Act and the policies and procedures previously 
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 rulemaking in satisfaction of the 7-year-lookback 
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.
    On January 11, 2022, DOE published a test procedure NOPR (``January 
2022 NOPR'') in the Federal Register proposing to amend the test 
procedure for consumer water heaters and residential-duty commercial 
gas water heaters. See 87 FR 1554, 1590-1592. In this SNOPR, DOE 
proposes modifications to the January 2022 NOPR.
2. Objectives of, and Legal Basis for, Rule
    EPCA 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. (42 U.S.C. 6292(a)(4) and 42 
U.S.C. 6311(1)(K))
3. Description and Estimate of Small Entities Regulated
    For manufacturers of consumer water heaters and residential-duty 
commercial water heaters, the Small Business Administration (SBA) has 
set a size threshold, which defines those entities classified as 
``small businesses'' for the

[[Page 42286]]

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,\28\ the certified product directory of the AHRI,\29\ 
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 27 manufacturers of 
consumer water heaters and residential-duty commercial water heaters. 
Of these 27 manufacturers, DOE identified one domestic small business 
that manufactures products covered by the proposed test procedure 
amendments in this SNOPR.
---------------------------------------------------------------------------

    \28\ U.S. Department of Energy Compliance Certification 
Management System, available at: www.regulations.doe.gov/ccms. (Last 
accessed March 1, 2022).
    \29\ AHRI Directory of Certified Product Performance, available 
at: www.ahridirectory.org/Search/SearchHome. (Last accessed March 1, 
2022).
---------------------------------------------------------------------------

4. Description and Estimate of Compliance Requirements
    As noted previously, DOE conducted an initial regulatory 
flexibility analysis (``IRFA'') as part of the January 2022 NOPR, in 
which it determined that there is one domestic, small business that 
manufactures residential water heaters impacted by the January 2022 
NOPR. Id. at 87 FR 1591. Under the proposed amendments in the January 
2022 NOPR, DOE anticipated the small business would incur third-party 
re-testing costs of $4,500 for one basic model as result of DOE's 
proposal to require 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. DOE estimated the compliance burden to 
represent less than 0.01 percent of the company's revenue. Id.
    This SNOPR serves to: (1) provide additional specificity for the 
existing test procedure for water heaters with a rated storage volume 
of less than 2 gallons; (2) propose optional rating conditions and 
associated metrics for voluntary representations of heat pump water 
heaters; (3) revise the separate storage tank requirements for 
circulating water heaters proposed in the January 2022 NOPR; (4) 
provide instructions for testing water heaters which store water at a 
temperature higher than the delivery setpoint and for determining the 
effective storage volume of such products, and (5) revise the testing 
requirements for water heaters which are greater than or equal to 2 
gallons in rated storage volume but cannot have the temperature of 
their internal storage tanks directly measured. Each of these proposed 
amendments will be discussed in turn to assess their potential impacts 
in light of the Regulatory Flexibility Act.
    First, DOE proposes to add flow rate tolerances for the 24-hour 
simulated-use test for water heaters with a rated storage volume of 
less than 2 gallons. DOE expects that laboratories may utilize high-
precision water flow rate instrumentation (e.g., Coriolis flow meters) 
to meet the proposed flow rate tolerances. DOE is aware of multiple 
third-party laboratories which already incorporate Coriolis flow meters 
for DOE compliance testing. Further, DOE expects that general industry 
best practice is already applying the flow rate tolerances being 
proposed for section 5.4.3 of appendix E for water heaters with rated 
storage volume less than 2 gallons; therefore, this proposal is 
expected to be consistent with current methodology and practice.
    Additionally, DOE has tentatively determined that the proposed 
amendment would not alter the measured efficiency of consumer water 
heaters and residential-duty commercial water heaters, nor require 
retesting or recertification solely as a result of DOE's adoption of 
the proposed amendments to the test procedure. For these reasons, DOE 
has initially determined that the proposed tolerances would generally 
not impose additional testing burden.
    Second, DOE is proposing to adopt optional test conditions and 
metrics for voluntary representations of heat pump water heater energy 
efficiency at test conditions other than the standard rating 
conditions. If adopted in a final rule, these metrics will not be 
required for reporting or compliance with standards for consumer water 
heaters and residential-duty commercial water heaters. Therefore, DOE 
has initially determined that testing for these optional metrics would 
not be unduly burdensome to conduct.
    Third, DOE previously proposed separate storage tank requirements 
for testing circulating water heaters in the January 2022 NOPR. 87 FR 
1554, 1589 (Jan. 11, 2022). In the January 2022 NOPR, DOE proposed that 
circulating water heaters (including heat pump-only water heaters) be 
tested paired with 80-gallon unfired hot water storage tanks which 
meets the energy conservation standard requirements at 10 CFR 
431.110(a). Id. In this SNOPR, DOE is instead proposing to require 
circulating gas-fired instantaneous water heaters and heat pump-only 
water heaters to be paired with different types of tanks to be more 
representative of field installations.
    For circulating gas-fired instantaneous water heaters, DOE proposes 
that these products be paired with UFHWSTs that exactly meet baseline 
energy conservation standards (as required at 10 CFR 431.110(a)) and 
rated at a capacity between 80 gallons and 120 gallons. Compared to the 
January 2022 NOPR, DOE applied additional specificity to the tank 
performance constraints to improve reproducibility of the test method 
and increased the range of acceptable capacities after reviewing market 
data on which capacities are commercially available at the baseline 
energy conservation standard level.
    DOE estimates that the cost of running the amended test procedure 
for circulating gas-fired instantaneous water heaters 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). However, DOE is not aware of any domestic 
small manufacturers of circulating gas-fired instantaneous water 
heaters at this time.
    For heat pump-only water heaters, DOE is updating its proposal to 
propose that these products be paired with electric storage water 
heaters that have a rated storage volume of 40 gallons  4 
gallons, have an FHR that results in classification at the medium draw 
pattern, and be rated at exactly the minimum required UEF. Compared to 
the January 2022 NOPR, DOE is proposing a different type and size of 
product to be paired with a heat pump-only water heater to better 
reflect how heat pump-only water heaters may be installed in the field.
    DOE estimates that the cost of running the amended test procedure 
for heat pump-only water heaters should be the same as testing a 
comparable water

[[Page 42287]]

heater with storage volume. For this estimate, DOE utilized a third-
party test estimate of $4,500. DOE believes this to represent the high-
end range of the testing cost burden compared to in-house testing.
    DOE is aware of one domestic small manufacturer which has a single 
model that would be affected by this amendment. DOE expects the cost to 
test that model per the test method proposed in this SNOPR to be 
$4,500. This represents less than 0.01 percent of company revenue, and, 
therefore, DOE has tentatively determined that it would not be unduly 
burdensome to conduct.
    Fourth, DOE is proposing to require that water heaters, except for 
demand-response water heaters, which can store water at a temperature 
higher than the delivery setpoint as a result of a user-selected 
operating mode be tested using the setting that provides the highest 
internal mean tank temperature while delivering water at a temperature 
of 125 [deg]F 5 [deg]F, and that an ``effective storage 
volume''--which quantifies the increase in energy storage due to this 
mode of operation--be calculated for all storage water heaters based on 
data that is already being collected per the current appendix E test 
procedure. This proposal, if adopted, would improve representativeness 
and reproducibility for water heaters with such a capability.
    The proposed amendment to test in an ``over-heated'' mode could 
potentially lead to re-testing and re-certification costs for 
manufacturers of such water heaters, as it would impact the UEF rating 
of such products. Should a manufacturer be required to re-testing, DOE 
estimates re-testing costs to be up to $4,500 per basic model using 
third-party testing. DOE believes this to represent the high-end range 
of the testing cost burden compared to in-house testing.
    DOE is not proposing to require compliance with this provision 
until compliance with amended energy conservation standards is also 
required (after the date of a final rule amending the test procedure 
for consumer water heaters and residential-duty commercial water 
heaters). Therefore, DOE has tentatively determined that this proposed 
amendment, if adopted, would not impose additional costs for 
manufacturers until such time as potential amended standards would be 
required. DOE will consider these impacts in a separate rulemaking as 
part of its ongoing review of potential amended energy conservation 
standards.
    Lastly, there is currently no method to determine ratings for water 
heaters which have rated storage volumes of 2 gallons or more but 
cannot have the internal storage tank temperature directly measured by 
means of the instrumentation required in the appendix E test procedure. 
The use of standard instrumentation is limited by the geometries of 
these products. Examples of such cases include products which have 
built-in mixing valves at the water outlet, products which do not use a 
sacrificial anode rod (and therefore do not have the associated opening 
for the anode rod), or products with complex heat exchanger geometries. 
DOE previously proposed to rely on inlet and outlet water temperatures 
to approximate the internal storage tank temperatures for these water 
heaters. 87 FR 1554, 1586 (Jan. 11, 2022). However, in this SNOPR, DOE 
is revising its proposed methodology for determining the internal tank 
temperatures of such products to improve the accuracy as compared to 
the method originally proposed in the January 2022 NOPR.
    The method proposed in this SNOPR relies on drawing out water from 
the tank at the beginning and end of the 24-hour simulated use test and 
monitoring the temperature of the water as it is drawn out to estimate 
the internal tank temperature of the stored water prior to being drawn 
out of the water heater. This method may result in overall testing 
costs of $4,000 to $6,000 per basic model of water heater which cannot 
be directly measured. This is comparable to the average cost of $3,000 
to $4,500 per basic model of water heater which can be directly 
measured. DOE is currently not aware of any small businesses which 
produce water heaters which will have to be tested in this manner, and, 
thus, DOE has tentatively concluded that this amendment, if finalized, 
would not impact small manufacturers.
    DOE requests comment on its understanding of the cost impacts of 
the proposed amendments in this notice on small, domestic 
manufacturers.
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 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 SNOPR, 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 
SNOPR, 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.

C. Review Under the Paperwork Reduction Act of 1995

    Manufacturers of consumer and residential-duty 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 residential-duty 
commercial water heaters. (See generally 10 CFR part 429.) The 
collection-of-information requirement for 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,

[[Page 42288]]

including the time for reviewing instructions, searching existing data 
sources, gathering and maintaining the data needed, and completing and 
reviewing the collection of information.
    DOE is not proposing to amend the certification or reporting 
requirements for consumer and residential-duty commercial water heaters 
in this SNOPR. Instead, DOE may consider proposals to amend the 
certification requirements and reporting for these products under a 
separate rulemaking regarding appliance and equipment certification. 
DOE will address changes to OMB Control Number 1910-1400 at that time, 
as necessary.
    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 SNOPR, DOE proposes test procedure amendments that it 
expects will be used to develop and implement future energy 
conservation standards for consumer and residential-duty commercial 
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 (August 4, 
1999), imposes certain requirements on agencies formulating and 
implementing policies or regulations that preempt State law or that 
have federalism implications. The Executive order 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 Executive order 
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 Executive Order 13132.

F. Review Under Executive Order 12988

    Regarding the review of existing regulations and the promulgation 
of new regulations, section 3(a) of Executive Order 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 Executive Order 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 Executive Order 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 Executive Order 
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 
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 Executive Order 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.

[[Page 42289]]

J. Review Under the 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

    Executive Order 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 
Executive Order 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 residential-duty 
commercial water heaters is not a significant regulatory action under 
Executive Order 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.
    As discussed in the January 11, 2022 NOPR, the proposed 
modifications to the test procedure for consumer and residential-duty 
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 
they fully comply with the requirements of section 32(b) of the FEAA 
(i.e., whether they were 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.

V. Public Participation

    DOE will accept comments, data, and information regarding this 
supplemental proposed rule no later than the date provided in the DATES 
section at the beginning of this SNOPR. Interested parties may submit 
comments, data, and other information 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 itself 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. Otherwise, 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 in a cover letter. Include your first 
and last names, email address, telephone number, and optional mailing 
address. With this instruction followed, 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 telefacsimiles (faxes) will 
be accepted.

[[Page 42290]]

    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 
supplemental notice of proposed rulemaking and request for comment.

List of Subjects in 10 CFR Part 430

    Administrative practice and procedure, Confidential business 
information, Energy conservation, Household appliances, Imports, 
Intergovernmental relations, Reporting and recordkeeping requirements, 
Small businesses.

Signing Authority

    This document of the Department of Energy was signed on July 1, 
2022, 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 July 6, 2022.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.

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

PART 430--ENERGY CONSERVATION PROGRAM FOR CONSUMER PRODUCTS

0
1. 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
2. Appendix E to subpart B of part 430 is amended by:
0
a. Revising the note at the beginning of the appendix;
0
b. Revising section 1;
0
c. Adding new sections 2.8, 4.10;
0
d. Revising sections 5.1, 5.4.2;
0
e. Adding sections 5.6, 6.3.1.1;
0
f. Revising section 6.3.9; and
0
g. Adding new section 6.5;
    The revisions and additions 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 date of publication of the 
final rule in the Federal Register], representations with respect to 
the energy use or efficiency of consumer water heaters and 
residential-duty 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 residential-
duty commercial water heaters covered by this test method, including 
compliance certifications, must be based on testing conducted in 
accordance with this appendix.
    In addition, water heaters subject to section 5.1.2 of this 
appendix may optionally apply the requirements in section 5.1.1 of 
this appendix in lieu of the requirements in section 5.1.2 of this 
appendix until the compliance date of a final rule reviewing 
potential amended energy conservation standards for these products 
published after [date of publication of the final rule in the 
Federal Register].


    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. Demand-response water heater means a storage-type water 
heater that--
    (1) Has integrated communications hardware and additional 
hardware and software required to enable connected functionality 
with a utility or third party, which dispatches signals with demand 
response instructions and/or price signals to the product and 
receives messages from the demand-response water heater;
    (2) Meets the communication and equipment standards for Consumer 
Technology Association Standard 2045-B (CTA-2045-B);
    (3) Automatically heats the stored water above the delivery 
temperature setpoint only in response to instructions received from 
a utility or third party.
    1.4. 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.
    1.5. 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.
    1.6. 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).
    1.7. Flow-Activated describes an operational scheme in which a 
water heater initiates and terminates heating based on sensing flow.
    1.8. 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.
    1.9. 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.

[[Page 42291]]

    1.10. 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.
    1.11. 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.
    1.12. Recovery Efficiency means the ratio of energy delivered to 
the water to the energy content of the fuel consumed by the water 
heater.
    1.13. 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.
    1.14. Split-system heat pump water heater means a heat pump-type 
water heater with an indoor storage tank and outdoor heat pump 
component.
    1.15. Standby means the time, in hours, during which water is 
not being withdrawn from the water heater.
    1.16. 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
EX--energy efficiency of a heat pump-type water heater when the 24-
hour simulated use test is optionally conducted at any of the 
additional air temperature conditions as specified in section 2.8 of 
this appendix, where the subscript ``X'' corresponds to the dry-bulb 
temperature at which the test is conducted.
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
kV--storage tank volume scaling ratio for water heaters with a rated 
storage volume greater than or equal to 2 gallons
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
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 of this appendix
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,stby1--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
Tst--for water heaters which cannot have internal tank temperature 
directly measured, estimated average internal storage tank 
temperature
Tp--for water heaters which cannot have internal tank temperature 
directly measured, average of the inlet and the outlet water 
temperatures at the end of the period defined by [tau]p
Tin,p--for water heaters which cannot have internal tank temperature 
directly measured, average of the inlet water temperatures
Tout,p--for water heaters which cannot have internal tank 
temperature directly measured, average of the outlet water 
temperatures
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

[[Page 42292]]

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
Veff--effective storage volume of water heaters with a rated storage 
volume greater than or equal to 2 gallons
vout,p--for water heaters which cannot have internal tank 
temperature directly measured, average flow rate
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]p--for water heaters which cannot have internal tank 
temperature directly measured, duration of the temperature 
measurement period, determined by the length of time taken for the 
outlet water temperature to be within 2 [deg]F of the inlet water 
temperature for 15 consecutive seconds (including the 15-second 
stabilization period)
[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

    1.17. 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.
    1.18. Uniform Energy Factor means the measure of water heater 
overall efficiency.
    1.19. 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. * * *
    2.8 Optional Test Conditions (Heat Pump-Type Water Heaters).
    The following test conditions may be used for optional 
representations of EX for heat pump-type water heaters. 
When conducting a 24-hour simulated use test to determine 
EX, the test conditions in section 2.1 and sections 2.4 
through 2.7 apply. The ambient air temperature and humidity 
conditions in section 2.2 and the supply water temperature in 
section 2.3 are replaced with the air temperature, humidity, and 
supply water temperature conditions as shown in the following table. 
Testing may optionally be performed at any or all of the conditions 
in the table.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Outdoor air conditions           Indoor air conditions
                                                                         ----------------------------------------------------------------  Supply water
                     Heat pump type                           Metric         Dry-bulb        Relative        Dry-bulb        Relative       temperature
                                                                            temperature    humidity (%)     temperature    humidity (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Split-System............................................              E5      5.0 [deg]F              30     67.5 [deg]F              50     42.0 [deg]F
                                                                     E34     34.0 [deg]F              72                                     47.0 [deg]F
                                                                     E95     95.0 [deg]F              25                                     67.0 [deg]F
Integrated or Heat Pump-Only............................             E50             N/A             N/A     50.0 [deg]F              58     50.0 [deg]F
                                                                     E95             N/A             N/A     95.0 [deg]F              40     67.0 [deg]F
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
    4. * * *
    4.10 Storage Tank Requirement for Circulating Water Heaters.
    When testing a gas-fired, oil-fired, or electric resistance 
circulating water heater (i.e., any circulating water heater that 
does not use a heat pump), the tank to be used for testing shall be 
an unfired hot water storage tank having a certified volume between 
80 and 120 gallons (364-546 liters) that meets but does not exceed 
the minimum energy conservation standards required according to 10 
CFR 431.110. When testing a heat pump circulating water heater, the 
tank to be used for testing shall be an electric storage water 
heater that uses only electric resistance elements for heating, has 
a measured volume of 40 gallons ( 4 gallons), has a 
First-Hour Rating greater than or equal to 51 gallons and less than 
75 gallons resulting in classification under the medium draw 
pattern, and has a rated UEF equal to the minimum UEF standard 
specified at Sec.  430.32(d), rounded to the nearest 0.01. In 
addition, the water heater used for testing shall not be capable of 
``over-heating'' the stored water, as determined by 
Tmax,1 (maximum measured mean tank temperature after the 
first recovery period of the 24-hour simulated-use test) being less 
than or equal to Tdel,2 (average outlet water temperature 
during the 2nd draw of the 24-hour simulated-use test).
    5. * * *
    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). Water heaters subject 
to section 5.1.2 of this appendix may optionally apply the 
requirements in section 5.1.1 in lieu of the requirements in section 
5.1.2 of this appendix until the compliance date of a final rule 
reviewing potential amended energy conservation standards for these 
products published after [date of publication of the test procedure 
final rule in the Federal Register]
    5.1.1 Water Heaters Without Storage Tank Over-heating 
Capability. If a non-flow-activated water heater does not have any 
user-selectable operational modes where the mean temperature of the 
storage tank can be maintained at a temperature higher than the 
delivery setpoint temperature (e.g., by use of a mixing valve), the 
instructions in this section apply. The 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.
    5.1.2 Water Heaters With Storage Tank Over-heating Capability. 
If a non-flow-activated water heater that is not a demand-response 
water heater (as defined in section 1.3 of this appendix) has a 
user-selectable operational mode where the mean temperature of the 
storage tank can be maintained at a temperature higher than the 
delivery setpoint temperature (e.g., by use of a mixing valve), set 
the unit to maintain the highest mean tank temperature possible 
while delivering water at 125 [deg]F 5 [deg]F. Maintain 
this setting throughout the entirety of the test.
* * * * *
    5.4 * * *
    5.4.2 Test Sequence for Water Heater With Rated Storage Volume 
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

[[Page 42293]]

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.
    For water heaters that can have their internal storage tank 
temperature measured directly, perform testing in accordance with 
the instructions in section 5.4.2.1 of this appendix. For water 
heaters that cannot have their internal tank temperatures measured, 
perform testing in accordance with the instructions in section 
5.4.2.2. of this appendix.
    5.4.2.1 Water Heaters which Can Have Internal Storage Tank 
Temperature Measured Directly.
    After the 1-hour period specified in section 5.4.2 of this 
appendix, the 24-hour simulated-use test will begin. One minute 
prior to the start of the 24-hour test simulated-use test, record 
the mean tank temperature (T0).
    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 1.0 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 3.0 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). 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. 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. 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). At 1-minute 
intervals, record ambient temperature, the electric and/or fuel 
instrument readings and 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. 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. 
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.
    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

[[Page 42294]]

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.
    5.4.2.2 Water Heaters which Cannot Have Internal Storage Tank 
Temperature Measured Directly.
    After the water heater has undergone a 1-hour idle period (as 
described in section 5.4.2 of this appendix), deactivate the burner, 
compressor, or heating element(s).
    Remove the water from the storage tank by performing a 
continuous draw at a flow rate of 3.0 GPM (11.4 L/min)  
0.25 GPM (0.9 L/min) until the outlet water temperature is within 
2 [deg]F (1.1 [deg]C) of the inlet water 
temperature for 15 consecutive seconds. While removing the hot 
water, measure the inlet and outlet temperature beginning 15 seconds 
after initiating the draw and at 3-second intervals thereafter until 
the outlet condition has stabilized. Determine the mean tank 
temperature using section 6.3.9 of this appendix and assign this 
value of Tst for T0, Tmax,1, and 
Tsu,0.
    After completing the draw, reactivate the burner, compressor, or 
heating elements(s) and allow the unit to fully recover such that 
the main burner, heating elements, or heat pump compressor is no 
longer raising the temperature of the stored water. Let the water 
heater sit idle again for 1 hour prior to beginning the 24-hour 
test, during which time no water shall be drawn from the unit, and 
there shall be no energy input to the main heating elements. After 
the 1-hour period, the 24-hour simulated-use test will begin.
    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 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 1.0 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 3.0 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 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 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 standby period begins at five minutes after the first time a 
recovery ends following last draw of the simulated-use test and 
shall continue for 8 hours. At the end of the 8-hour standby period, 
record the total amount of time elapsed since the start of the 24-
hour simulated-use test (i.e., since [tau] = 0).
    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 ambient temperature and the 
electric and/or fuel instrument readings at 1-minute intervals until 
the end of the 8-hour period. At the 8-hour mark, deactivate the 
water heater and before drawing water from the tank. Remove water 
from the storage tank by performing a continuous draw at a flow rate 
of 3.0 GPM (11.4 L/min)  0.25 GPM (0.9 L/min) until the 
outlet water temperature is within 2 [deg]F (1.1 [deg]C) of the inlet water temperature for 15 consecutive 
seconds. While removing the hot water, measure the inlet and outlet 
temperature beginning 15 seconds after initiating the draw and at 3-
second intervals thereafter until the outlet condition has 
stabilized. Determine the mean tank temperature using section 6.3.9 
of this appendix and assign this value of Tst for 
Tsu,f and T24.
    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). The average mean tank temperature from the 
start of the standby period to the end of the standby period 
(Tt,stby,1) shall be the average of Tsu,0 and 
Tsu,f.
    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 3.0 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

[[Page 42295]]

(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) unless the 
unit being tested has a rated Max GPM of less than 1 gallon per 
minute, in which case the tolerance shall be  25% of the 
rated Max GPM. 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.
* * * * *
    5.6 Optional Tests (Heat Pump-Type Water Heaters).
    Optional testing may be conducted on heat pump-type water 
heaters to determine EX. If optional testing is 
performed, conduct the additional 24-hour simulated use test(s) at 
one or multiple of the test conditions specified in section 2.8 of 
this appendix. Prior to conducting a 24-hour simulated use test at 
an optional condition, confirm the air and water conditions 
specified in section 2.8 are met and re-set the outlet discharge 
temperature in accordance with section 5.2.2 of this appendix. 
Perform the optional 24-hour simulated use test(s) in accordance 
with section 5.4 of this appendix using the same draw pattern used 
for the determination of UEF.
* * * * *
    6.3 * * *
    6.3.1.1 Effective Storage Volume. The effective storage tank 
capacity, Veff, is computed as follows:

Veff = kvVst

where:

Vst = as defined in section 6.3.1 and

kV = a dimensionless volume scaling factor determined as 
follows:
[GRAPHIC] [TIFF OMITTED] TP14JY22.002

where:

Tmax,1 = the maximum measured mean tank temperature after 
cut-out following the first draw of the 24-hour simulated-use test, 
[deg]F([deg]C).

Tdel,2= the average outlet water temperature during the 
second draw of the 24-hour simulated-use test, [deg]F([deg]C).

[rho](Tmax,1) = the density of the stored hot water 
evaluated at the maximum measured mean tank temperature after cut-
out following the first draw of the 24-hour simulated-use test 
(Tmax,1), lb/gal (kg/L).

Cp(Tmax,1) = the specific heat of the stored 
hot water, evaluated at Tmax,1, Btu/(lb[middot][deg]F) 
(kJ/(kg[middot][deg]C)).

[rho](125 [deg]F) = the density of the stored hot water at 125 
[deg]F, lb/gal (kg/L).

Cp(125 [deg]F) = the specific heat of the stored hot 
water at 125 [deg]F, Btu/(lb[middot][deg]F) (kJ/(kg[middot][deg]C)).

125 [deg]F (51.7 [deg]C) = the nominal maximum mean tank temperature 
for a storage tank that does not utilize a mixing valve to achieve a 
125 [deg]F delivery temperature.

67.5 [deg]F (19.7 [deg]C) = the nominal average ambient air 
temperature.
* * * * *
    6.3.9 Estimated Mean Tank Temperature for Water Heaters with 
Rated Storage Volumes Greater Than or Equal to 2 Gallons. If testing 
is conducted in accordance with section 5.4.2.2 of this appendix, 
calculate the mean tank temperature immediately prior to the 
internal tank temperature determination draw using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP14JY22.003


Where:

Tst = the estimated average internal storage tank 
temperature, [deg]F ([deg]C)

Tp = the average of the inlet and the outlet water 
temperatures at the end of the period defined by [tau]p, 
[deg]F ([deg]C).

vout,p = the average flow rate during the period, gal/min 
(L/min).

Vst = the rated storage volume of the water heater, gal 
(L).

[tau]p = the number of minutes in the duration of the 
period, determined by the length of time taken for the outlet water 
temperature to be within 2 [deg]F of the inlet water temperature for 
15 consecutive seconds and including the 15-second stabilization 
period.

Tin,p = the average of the inlet water temperatures 
during the period, [deg]F ([deg]C).

Tout,p = the average of the outlet water temperatures 
during the period, [deg]F ([deg]C).

* * * * *
    6.5 Energy Efficiency at Optional Test Conditions. If testing is 
conducted at optional test conditions in accordance with section 5.6 
of this appendix, calculate the energy efficiency at the test 
condition, EX, using the formulas section 6.3 or 6.4 of 
this appendix (as applicable), except substituting the applicable 
ambient temperature and supply water temperature used for testing 
(as specified in section 2.8 of this appendix) for the nominal 
ambient temperature and supply water temperature conditions used in 
the equations for determining UEF (i.e., 67.5 [deg]F and 58 [deg]F).

[FR Doc. 2022-14687 Filed 7-13-22; 8:45 am]
BILLING CODE 6450-01-P