[Federal Register Volume 89, Number 72 (Friday, April 12, 2024)]
[Rules and Regulations]
[Pages 25780-25804]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-07620]


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DEPARTMENT OF ENERGY

10 CFR Part 430

[EERE-2020-BT-TP-0041]
RIN 1904-AE15


Energy Conservation Program: Test Procedure for Consumer Furnace 
Fans

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

ACTION: Final rule.

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SUMMARY: The U.S. Department of Energy (``DOE'') is amending the test 
procedure for consumer furnace fans to: clarify the scope of 
applicability of the furnace fan test procedure; incorporate by 
reference the most recent versions of industry test methods; establish 
a test method for furnace fans incapable of operating at the required 
external static pressure; clarify testing of certain products, 
including furnace fans with

[[Page 25781]]

modulating controls, certain two-stage furnaces that operate at reduced 
input only for a preset period of time, and dual-fuel furnaces; and 
make updates to improve test procedure repeatability and 
reproducibility.

DATES: The effective date of this rule is June 26, 2024. The amendments 
will be mandatory for product testing starting October 9, 2024.
    The incorporation by reference of certain material listed in this 
rule is approved by the Director of the Federal Register on June 26, 
2024.

ADDRESSES: The docket, which includes Federal Register notices, public 
meeting 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 those containing information that is exempt from 
public disclosure.
    A link to the docket web page can be found at www.regulations.gov/docket/EERE-2020-BT-TP-0041. The docket web page contains instructions 
on how to access all documents, including public comments, in the 
docket.
    For further information on how to review the docket, contact the 
Appliance and Equipment Standards Program staff at (202) 287-1445 or by 
email: [email protected].

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: 
(240) 597-6737. Email: [email protected].
    Ms. Kristin Koernig, U.S. Department of Energy, Office of the 
General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC, 
20585-0121. Telephone: (202) 586-3593. Email: 
[email protected].

SUPPLEMENTARY INFORMATION: DOE maintains a previously approved 
incorporation by reference (ASHRAE 41.1-1986 (Reapproved (``RA'') 
2006)) and incorporates by reference the following industry standards 
into 10 CFR part 430:

ANSI/ASHRAE Standard 37-2009 (Reaffirmed 2019), Methods of Testing 
for Rating Electrically Driven Unitary Air-Conditioning and Heat 
Pump Equipment,'' ASHRAE approved June 21, 2019 (``ASHRAE 37-2009 
(RA 2019)'').
ANSI/ASHRAE Standard 37-2009 Errata Sheet, Errata Sheet for ANSI/
ASHRAE Standard 37-2009--Methods of Testing for Rating Electrically 
Driven Unitary Air-Conditioning and Heat Pump Equipment, ASHRAE 
approved March 27, 2019 (``ASHRAE 37-2009 Errata Sheet'').
ANSI/ASHRAE Standard 103-2017, Method of Testing for Annual Fuel 
Utilization Efficiency of Residential Central Furnaces and Boilers, 
ANSI-approved July 3, 2017 (``ASHRAE 103-2017'').
2021 ASHRAE Handbook--Fundamentals Inch-Pound Edition, Chapter 1, 
``Psychrometrics''; copyright 2021 (``2021 ASHRAE Handbook'').

    Copies of ASHRAE Standard 37-2009 (RA 2019), ASHRAE 37-2009 Errata 
Sheet, ASHRAE Standard 103-2017, and the 2021 ASHRAE Handbook can be 
obtained from the American Society of Heating, Refrigerating and Air-
Conditioning Engineers (``ASHRAE''), 180 Technology Parkway NW, 
Peachtree Corners, GA 30092,(800) 527-4723 or (404) 636-8400, or online 
at www.ashrae.org.
    For a further discussion of these standards, please see section 
IV.N of this document.

Table of Contents

I. Authority and Background
    A. Authority
    B. Background
II. Synopsis of the Final Rule
III. Discussion
    A. Scope and Definitions
    1. Air-Conditioning Products and Testing During Cooling 
Operation
    2. Dual-Fuel Heating Products
    B. Referenced Industry Standards
    1. Updates to Industry Standards
    2. Additional References
    C. Furnace Fans That Operate at Low External Static Pressures
    D. Test Procedure Repeatability and Reproducibility
    1. Fuel Input Rate Tolerance
    2. Ambient Conditions
    3. Airflow Determination
    4. Location of External Static Pressure Measurements
    5. Language Updates
    E. Nomenclature and Equations
    F. Thermocouple Accuracy
    G. Alternatives to the FER Metric
    H. Test Procedure Costs
    I. Effective and Compliance Dates
IV. Procedural Issues and Regulatory Review
    A. Review Under Executive Orders 12866, 13563, and 14094
    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
    M. Congressional Notification
    N. Description of Materials Incorporated by Reference
V. Approval of the Office of the Secretary

I. Authority and Background

    The Energy Policy and Conservation Act, as amended (``EPCA''),\1\ 
authorizes DOE to establish and amend energy conservation standards and 
test procedures for consumer furnace fans. (42 U.S.C. 6295(f)(4)(D)) 
DOE's energy conservation standards and test procedure for consumer 
furnace fans are currently prescribed at title 10 of the Code of 
Federal Regulations (``CFR''), part 430, Sec.  430.32(y), and 10 CFR 
part 430, subpart B, appendix AA (``appendix AA''), respectively. The 
following sections discuss DOE's authority to establish a test 
procedure for consumer furnace fans and relevant background information 
regarding DOE's consideration of a test procedure for this product.
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    \1\ All references to EPCA in this document refer to the statute 
as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 
27, 2020), which reflect the last statutory amendments that impact 
Parts A and A-1 of EPCA.
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A. Authority

    EPCA authorizes DOE to regulate the energy efficiency of a number 
of consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317) Title III, Part B of EPCA \2\ established the Energy Conservation 
Program for Consumer Products Other Than Automobiles, which sets forth 
a variety of provisions designed to improve energy efficiency. These 
products include consumer furnace fans, the subject of this document. 
(42 U.S.C. 6295(f)(4)(D))
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    \2\ For editorial reasons, upon codification in the U.S. Code, 
Part B was redesignated Part A.
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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), 
test procedures (42 U.S.C. 6293), labeling provisions (42 U.S.C. 6294), 
energy conservation standards (42 U.S.C. 6295), and the authority to 
require information and reports from manufacturers (42 U.S.C. 6296).
    The testing requirements consist of test procedures that 
manufacturers of covered products must use as the basis

[[Page 25782]]

for (1) certifying to DOE that their products comply with the 
applicable energy conservation standards adopted under EPCA (42 U.S.C. 
6295(s)), and (2) making other representations about the efficiency of 
those products (42 U.S.C. 6293(c)). Similarly, DOE must use these test 
procedures to determine whether the products comply with any relevant 
standards promulgated under EPCA. (42 U.S.C. 6295(s))
    Federal energy efficiency requirements for covered products 
established under EPCA generally supersede State laws and regulations 
concerning energy conservation testing, labeling, and standards. (42 
U.S.C. 6297) DOE may, however, grant waivers of Federal preemption for 
particular State laws or regulations, in accordance with the procedures 
and other provisions of EPCA. (42 U.S.C. 6297(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. EPCA requires that any test procedures prescribed or 
amended under this section 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 (as determined by the Secretary) or period of use and 
shall not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3))
    EPCA also requires that, at least once every 7 years, DOE evaluate 
test procedures for each type of covered product, including consumer 
furnace fans, 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 period of use. (42 U.S.C. 6293(b)(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. The comment period on a proposed rule 
to amend a test procedure shall be at least 60 days and may not exceed 
270 days. In prescribing or amending a test procedure, the Secretary 
shall take into account such information as the Secretary determines 
relevant to such a 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 its 
determination not to amend the test procedures.
    In addition, EPCA requires that DOE amend its test procedures for 
all covered products to integrate measures of standby mode and off mode 
energy consumption into the overall energy efficiency, energy 
consumption, or other energy descriptor, unless the current test 
procedure already incorporates the standby mode and off mode energy 
consumption, or if such integration is technically infeasible. (42 
U.S.C. 6295(gg)(2)(A)) If an integrated test procedure is technically 
infeasible, DOE must prescribe separate standby mode and off mode 
energy use test procedures for the covered product, if a separate test 
is technically feasible. (42 U.S.C. 6295(gg)(2)(A)(iii)) Any such 
amendment must consider the most current versions of the International 
Electrotechnical Commission (``IEC'') Standard 62301 \3\ and IEC 
Standard 62087 \4\ as applicable. (42 U.S.C. 6295(gg)(2)(A))
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    \3\ IEC 62301, Household electrical appliances--Measurement of 
standby power (Edition 2.0, 2011-01).
    \4\ IEC 62087, Audio, video and related equipment--Methods of 
measurement for power consumption (Edition 1.0, Parts 1-6: 2015, 
Part 7: 2018).
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    DOE is publishing this final rule pursuant to the 7-year review 
requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A))

B. Background

    As discussed, DOE's existing test procedure for consumer furnace 
fans appears at appendix AA. Appendix AA provides procedures and 
calculations to determine the fan energy rating (``FER''), expressed as 
watts per 1,000 cubic feet per minute of airflow (``W/1000 cfm'').
    DOE established the test procedure for consumer furnace fans at 
appendix AA in a final rule published on January 3, 2014 (``January 
2014 Final Rule''). 79 FR 499. The test procedure is applicable to 
furnace fans used by weatherized and non-weatherized gas furnaces, oil 
furnaces, electric furnaces, and modular blowers.\5\ See section 1, 
appendix AA. For each of these categories, the test procedure covers 
both mobile home and non-mobile home models. The test procedure is not 
applicable to non-ducted products, such as whole-house ventilation 
systems without ductwork, central air-conditioning (``CAC'') condensing 
unit fans, room fans, and furnace draft inducer fans because a 
``furnace fan'' is defined as ``an electrically-powered device used in 
a consumer product for the purpose of circulating air through 
ductwork.'' 10 CFR 430.2.
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    \5\ DOE defines the term ``modular blower'' in section 2.9 of 
appendix AA as a product which only uses single-phase electric 
current, and which is: (a) designed to be the principal air 
circulation source for the living space of a residence; (b) not 
contained within the same cabinet as a furnace or central air 
conditioner; and (c) designed to be paired with heating, 
ventilating, and air-conditioning (``HVAC'') products that have a 
heat input rate of less than 225,000 Btu per hour and cooling 
capacity less than 65,000 Btu per hour.
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    As established in the January 2014 Final Rule, appendix AA 
incorporates by reference the definitions, test setup and equipment, 
and procedures for measuring steady-state combustion efficiency from 
the 2007 version of American National Standards Institute (``ANSI'')/
American Society of Heating, Refrigeration, and Air-Conditioning 
Engineers (``ASHRAE'') Standard 103, ``Method of Testing for Annual 
Fuel Utilization Efficiency of Residential Central Furnaces and 
Boilers'' (``ASHRAE 103-2007''). In addition to these provisions, 
appendix AA includes provisions for apparatuses and procedures for 
measuring temperature rise, external static pressure (``ESP''), and 
furnace fan electrical input power. Appendix AA also incorporates by 
reference provisions for measuring temperature and ESP from ANSI/ASHRAE 
37-2009, ``Methods of Testing for Rating Electrically Driven Unitary 
Air-Conditioning and Heat Pump Equipment'' (``ASHRAE 37-2009''), 
including its reference in section 5.1 to ASHRAE 41.1-1986 (RA 2006), 
``Standard Method for Temperature Measurement.'' Lastly, appendix AA 
includes a reference to the psychrometric chapter (i.e., chapter 1) in 
the 2001 ASHRAE Handbook--Fundamentals (``2001 ASHRAE Handbook'') for 
use in calculating the specific volume of dry air at specified 
operating conditions.
    In the January 2014 Final Rule, DOE determined that there is no 
need to address standby and off mode energy use in the test procedure 
for consumer furnace fans, as the standby mode and off mode energy use 
associated with furnace fans is measured by test procedures for the 
products in which furnace fans are used (i.e., consumer furnaces and 
consumer CACs and heat pumps). 79 FR 499, 504-505.
    On July 7, 2021, DOE published in the Federal Register a request 
for information (``July 2021 RFI'') seeking

[[Page 25783]]

comments on the existing DOE test procedure for consumer furnace fans 
to determine whether amendments are warranted for the test procedure 
for consumer furnace fans. 86 FR 35660. More specifically, DOE 
requested comments, information, and data about a number of issues, 
mainly concerning: test settings (including selection of airflow 
control settings and ESP requirements for airflow settings other than 
the maximum setting); incorporation by reference of the most recent 
industry test method; clarifications for testing of certain products, 
including furnace fans with modulating controls, furnace fans and 
modular blowers tested with electric heat kits, certain two-stage 
furnaces that operate at reduced input only for a preset period of 
time, dual-fuel furnaces, and certain oil-fired furnaces; and issues 
related to test procedure repeatability and reproducibility. Id.
    On May 13, 2022, DOE published in the Federal Register a notice of 
proposed rulemaking (``NOPR'') proposing to update appendix AA (``May 
2022 NOPR''). 87 FR 29576. Specifically, DOE proposed to: (1) specify 
testing instructions for furnace fans incapable of operating at the 
required ESP; (2) incorporate by reference the most recent versions of 
industry standards, ASHRAE 103-2017 and ASHRAE 37-2009 (RA 2019), in 10 
CFR 430.3; (3) define dual-fuel furnace fans and exclude them from the 
scope of appendix AA; (4) change the term ``default airflow-control 
settings'' to ``specified airflow-control settings''; (5) add 
provisions to directly measure airflow; (6) revise the ambient 
temperature conditions allowed during testing to between 65 degrees 
Fahrenheit (``[deg]F'') and 85 [deg]F for all units (both condensing 
and non-condensing); and (7) assign an allowable range of relative 
humidity during testing to be between 20 percent and 80 percent. 87 FR 
29576, 29579. DOE held a webinar related to the May 2022 NOPR on May 
19, 2022 (hereafter, the ``NOPR webinar'').
    DOE received comments in response to the May 2022 NOPR from the 
interested parties listed in Table II.1.

                         Table II.1--List of Commenters in Response to the May 2022 NOPR
----------------------------------------------------------------------------------------------------------------
                                            Reference in this final   Comment No. in
              Commenter(s)                           rule               the docket          Commenter type
----------------------------------------------------------------------------------------------------------------
Air-Conditioning, Heating, and            AHRI......................              15  Trade Organization.
 Refrigeration Institute.
Appliance Standards Awareness Project,    Joint Commenters..........              14  Efficiency Advocacy
 American Council for an Energy-                                                       Organizations.
 Efficient Economy, Northwest Energy
 Efficiency Alliance, and the National
 Consumer Law Center.
Pacific Gas and Electric Company, San     CA IOUs...................         13; * 9  Utilities.
 Diego Gas and Electric, Southern
 California Edison; collectively, the
 California Investor-Owned Utilities.
Carrier Global Corporation..............  Carrier...................              12  Manufacturer.
Johnson Controls Inc....................  JCI.......................              10  Manufacturer.
Lennox International Inc................  Lennox....................              11  Manufacturer.
Morrison Products, Inc..................  Morrison..................             * 9  Manufacturer.
Rheem Manufacturing.....................  Rheem.....................             * 9  Manufacturer.
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* Comment No. 9 corresponds to the transcript for NOPR webinar.

    A parenthetical reference at the end of a comment quotation or 
paraphrase provides the location of the item in the public record.\6\ 
To the extent that interested parties have provided written comments 
that are substantively consistent with any oral comments provided 
during the NOPR webinar, DOE cites the written comments throughout this 
final rule. Any oral comments provided during the webinar that are not 
substantively addressed by written comments are summarized and cited 
separately throughout this final rule.
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    \6\ The parenthetical reference provides a reference for 
information located in the docket of DOE's rulemaking to develop 
test procedures for consumer furnace fans. (Docket No. EERE-2020-BT-
TP-0041, 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 the Final Rule

    In this final rule, DOE amends appendix AA to subpart B of 10 CFR 
part 430, ``Uniform test method for measuring the energy consumption of 
furnace fans,'' as follows:
     Specify testing instructions for furnace fans incapable of 
operating at the required ESP;
     Incorporate by reference the most recent versions of 
industry standards, ASHRAE 103-2017 and ASHRAE 37-2009 (RA 2019), in 10 
CFR 430.3;
     Incorporate by reference chapter 1 of the 2021 ASHRAE 
Handbook;
     Define dual-fuel furnace fans and exclude them from the 
scope of appendix AA;
     Change the term ``default airflow-control settings'' to 
``specified airflow-control settings;''
     Make clarifications to nomenclature, correct the value of 
the conversion factor from Watts to BTU/h, and correct the units of 
specific volume of dry air;
     Revise the ambient temperature conditions allowed during 
testing to between 65 [deg]F and 85 [deg]F for all units (both 
condensing and non-condensing);
     Assign an allowable range of relative humidity during 
testing to be between 20 percent and 80 percent; and
     Require that the power measurements be determined as an 
average over the last 30 seconds of each steady state period at 
intervals of no less than 1 per second, rather than taken as a single 
point measurement.
    The adopted amendments are summarized in Table II.1 compared to the 
test procedure provision prior to the amendment, as well as the reason 
for the adopted change.

[[Page 25784]]



 Table II.1--Summary of Changes in the Amended Consumer Furnace Fan Test
                                Procedure
------------------------------------------------------------------------
   DOE test procedure prior to       Amended test
            amendment                  procedure          Attribution
------------------------------------------------------------------------
Does not specify instructions     Specifies testing   Address waiver
 for testing furnace fans that     instructions for    from the prior
 are incapable of operating at     furnace fans        test procedure.
 the specified ESP.                incapable of
                                   operating at the
                                   specified ESP.
Incorporates by reference ASHRAE  Incorporates by     Incorporate by
 103-2007 and ASHRAE 37-2009.      reference ASHRAE    reference the
                                   103-2017 and        most recent
                                   ASHRAE 37-2009      industry test
                                   (RA 2019).          procedures.
References 2001 ASHRAE Handbook   Incorporates by     Incorporate by
 psychrometric chapter.            reference the       references all
                                   2021 ASHRAE         industry test
                                   Handbook            procedures that
                                   psychrometric       are referenced in
                                   chapter (i.e.,      appendix AA.
                                   chapter 1).
Does not address dual-fuel        Defines dual-fuel   Clarify scope of
 furnace fans.                     furnace fans in     coverage of the
                                   appendix AA and     test procedure.
                                   explicitly
                                   excludes them
                                   from the scope of
                                   the test method.
Defines ``default airflow-        Defines             Clarify selection
 control settings''.               ``specified         of airflow
                                   airflow-control     control settings
                                   settings'' to       during testing
                                   differentiate the
                                   settings used in
                                   testing from the
                                   as-shipped
                                   settings.
Utilizes potentially unclear      Utilizes clearer    Clarify
 nomenclature, attributes the      nomenclatures,      nomenclature and
 wrong value to the conversion     attributes the      correct typos.
 factor from Watts to BTU/h, and   correct value to
 assigns the incorrect units to    the conversion
 the specific heat of dry air.     factor from Watts
                                   to BTU/h, and
                                   assigns the
                                   correct units to
                                   the specific heat
                                   of dry air.
Ambient temperature must remain   Ambient             Improve
 between 65 [deg]F and 100         temperature must    repeatability and
 [deg]F for non-condensing         remain between 65   reproducibility
 furnaces and between 65 [deg]F    [deg]F and 85       of test results.
 and 85 [deg]F for condensing      [deg]F for all
 furnaces.                         furnaces.
Does not specify an allowable     Requires ambient    Improve
 range of relative humidity.       relative humidity   repeatability and
                                   to be maintained    reproducibility
                                   between 20% and     of test results.
                                   80% for all
                                   furnaces.
Electrical input power is         Electrical input    Improve
 measured as single point after    power will be       repeatability and
 steady-state conditions are met.  determined as the   reproducibility
                                   average value of    of test results.
                                   readings taken
                                   over the last 30
                                   seconds of each
                                   steady state
                                   period at
                                   intervals of no
                                   less than 1 per
                                   second.
------------------------------------------------------------------------

    DOE has determined that the amendments described in section III of 
this document and adopted in this document will not alter the measured 
efficiency of consumer furnace fans or require retesting or 
recertification solely as a result of DOE's adoption of the amendments 
to the test procedure. Additionally, DOE has determined that the 
amendments will not increase the cost of testing. Discussion of DOE's 
actions are addressed in detail in section III of this document
    The effective date for the amended test procedure adopted in this 
final rule is 75 days after publication of this document in the Federal 
Register. Representations of energy use or energy efficiency must be 
based on testing in accordance with the amended test procedure 
beginning 180 days after the publication of this final rule.

III. Discussion

A. Scope and Definitions

1. Air-Conditioning Products and Testing During Cooling Operation
    As discussed, a ``furnace fan'' is an electrically-powered device 
used in a consumer product for the purpose of circulating air through 
ductwork. 10 CFR 430.2. And, as stated, DOE's test procedure is 
applicable to furnace fans used in weatherized and non-weatherized gas 
furnaces, oil furnaces, electric furnaces, and modular blowers. See 
section 1, appendix AA. The test procedure is not applicable to non-
ducted products, such as whole-house ventilation systems without 
ductwork, CAC or central air-conditioning heat pump (``HP'') condensing 
unit fans, small-duct high-velocity (``SDHV'') air conditioner unit 
fans, room fans, and furnace draft inducer fans.
    DOE received a comment in response to the July 2021 RFI that 
suggested modifying the consumer furnace fans test procedure to account 
for lower fan power during low-stage cooling operation. In the May 2022 
NOPR, DOE requested information and data regarding the electrical 
energy consumption of multi-stage furnace fans during low-stage cooling 
operation, specifically in relation to single-stage furnace fans in 
cooling mode. 87 FR 29576, 29580.
    In response, JCI commented that a two-stage cooling blower offers 
significant energy savings resultant, in part, from the circulating air 
blower operating at a lower speed during low-stage cooling. JCI stated 
that the electronically commutated motors (``ECMs'') used in units with 
two-stage blowers are more efficient at lower speeds. JCI also 
commented that the increased motor efficiency at low stage is not 
reflected in the current furnace fan test procedure. JCI commented 
that, unlike furnaces designed for strictly single-stage cooling, 
furnaces designed for two-stage cooling applications typically include 
thermostat connections for control and have the ability to switch 
automatically to a lower blower speed when low-stage cooling is in 
operation. JCI commented that the consumer furnace fan test procedure 
should be modified to properly capture the actual field behavior of 
two-stage cooling units. (JCI, No. 10 at p. 1)
    Lennox stated that fan energy consumption is significantly reduced 
when operating multi-stage furnace fans during low-stage cooling 
operation relative to single-stage furnace fans operating in cooling 
mode. Lennox suggested that fan energy for low-stage operations is 
reduced by over 25 percent for two-stage products. Lennox commented 
that field data indicate multi-stage products spend the majority of 
operating hours in low-stage operation and that DOE should fully 
consider low-stage and multi-stage operation because they are 
representative of actual field operation. Lennox expressed support for 
transitioning the currently applicable consumer furnace fan test 
procedure to

[[Page 25785]]

include low-stage operation. (Lennox, No. 11 at p. 3)
    Carrier commented that it does not have data regarding low-stage 
cooling operation in relation to single-stage furnace fans in cooling 
mode. However, Carrier stated that engineering principles suggest that 
accounting for the low-stage fan electrical energy consumption would 
make the FER rating more representative than the current method of 
using the high-stage fan electrical energy consumption as if it were a 
single-stage blower unit. Carrier suggested that DOE consider creating 
a cooling capacity ratio multiplier to account for the reduced fan 
electrical energy in low stage. (Carrier, No. 12 at pp. 1-2)
    AHRI commented that there may be significant energy savings 
associated with running multi-stage furnace fans during low-stage 
cooling operation. AHRI stated that it is in favor of using low-stage 
cooling operation for package units that employ two-stage or multi-
stage cooling modes. (AHRI, No. 15 at p. 2)
    In response to these comments, DOE continues to evaluate the 
potential benefits of accounting for lower fan power during low-stage 
cooling operation, as well any additional testing burden that such test 
provisions would entail. DOE has considered the feedback provided by 
commenters and has concluded that at this time, DOE does not have 
sufficient data and information to specify amended procedures for 
testing furnace fans at low-stage cooling operation. In particular, 
commenters did not provide sufficient data at this time to determine 
representative additional test points and reapportion the operating 
hours outlined in table IV.2 of appendix AA to reflect low-stage 
cooling. Further, adding test points to DOE's test procedure for 
consumer furnace fans would likely require manufacturers to recertify 
units and could add burden to the test procedure. DOE is therefore not 
modifying the consumer furnace fans test procedure to account for lower 
fan power during low-stage cooling operation in this final rule, but 
DOE may consider such provisions in a future test procedure rulemaking 
for furnace fans.
    In the May 2022 NOPR, DOE stated that it was not proposing to 
include fans used in other types of heating, ventilating, and air-
conditioning (``HVAC'') products--such as CACs, HPs, and SDHV modular 
blowers--within the scope of appendix AA. DOE tentatively concluded 
that the electrical energy consumption of furnace fans used in the 
aforementioned types of HVAC products will be accounted for by the 
seasonal energy efficiency ratio 2 (``SEER2'') and heating seasonal 
performance factor 2 (``HSPF2'') metrics measured by the test procedure 
for CACs and HPs at appendix M1 to subpart B of part 430 (``appendix 
M1''). 87 FR 29576, 29580.
    In response to the May 2022 NOPR, the CA IOUs stated that the 
calculations for the SEER2 and HSPF2 metrics do not account for the 
fractional bin hours between 55 [deg]F and 64 [deg]F. The CA IOUs 
commented that fan energy during any air circulation through the 
ductwork at those temperatures is unaddressed in SEER2 and HSPF2; 
therefore, the CA IOUs recommended that DOE further investigate the 
fans installed in these residential HVAC products to determine if such 
fans would meet the current furnace fan energy conservation standards 
and consider including them in this rulemaking. (CA IOUs, No. 13 at p. 
4)
    The Joint Commenters stated that they agreed with DOE regarding 
potential backsliding concerns about furnace fan energy use if single-
package air conditioner units with gas heat were excluded from the 
scope of the furnace fan test procedure and stated that they support 
continued inclusion of these products within the scope of the furnace 
fan test procedure. (Joint Commenters, No. 14 at p. 1)
    With regards to the comments from the CA IOUs and the Joint 
Commenters. DOE notes that the test method of determining SEER2, Energy 
Efficiency Ratio 2 (``EER2''), HSPF2, and PW,OFF for CACs 
and HPs is provided at appendix M1. Table 19 of appendix M1 specifies 
the distribution of fractional hours within cooling season temperature 
bins for the calculation of SEER2. These bins range from 65 [deg]F to 
104 [deg]F, and, accordingly, do not cover the 55 [deg]F to 64 [deg]F 
range, as mentioned by the CA IOUs. Table 20 specifies the distribution 
of fractional hours within heating season temperature bins for the 
calculation of HSPF2, which range from -23 [deg]F to 62 [deg]F. 
Collectively, these two tables cover the entire temperature range from 
-23 [deg]F to 104 [deg]F except for the relatively narrow range between 
62 [deg]F and 65 [deg]F.
    As discussed in section I.A of this document, DOE is required by 
EPCA to develop test procedures that are 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 (as determined by the Secretary) or period of use and 
shall not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) 
Accordingly, the SEER2 and HSPF2 metrics must reflect representative 
average annual use of products subject to those metrics, including 
CACs, HPs, and SDHV modular blowers, but do not necessarily need to 
account for performance at every possible temperature condition. DOE 
has previously determined that SEER2 and HSPF2 capture a representative 
measure of CAC and HP performance, including fan energy consumption, 
during heating and cooling operations. (See, for example, discussion of 
appendix M1 amendments at 82 FR 1426, 1446-1460 (Jan. 5, 2017)) 
Therefore, DOE has determined that the consumer furnace fan test 
procedure does not need to be amended to specifically address fan 
energy use in CACs and HPs.
2. Dual-Fuel Heating Products
    Some consumer heating products include an electric heat pump as 
well as a gas burner and are often referred to as ``dual-fuel'' or 
``hybrid heating'' units. These products are designed to provide space 
heating with the heat pump and/or gas burner, depending on the 
operating conditions (e.g., outdoor air temperature and heating 
demand). The annual operating characteristics of a dual-fuel product 
may differ significantly from a typical furnace because the inclusion 
of a heat pump may change the operating time necessary to meet the 
heating load demand when compared with a gas burner alone, resulting in 
changes to the operating hours of the furnace fan. Additionally, as 
stated in the May 2022 NOPR, the current DOE consumer furnace fan test 
procedure does not specify provisions to set up or operate furnace fans 
for dual-fuel heating units, and the estimated annual national 
operating values in appendix AA may not be representative of average 
use cycle for furnace fans installed in dual-fuel applications. 87 FR 
29576, 29580.
    However, as was also discussed in the May 2022 NOPR, dual-fuel 
units are subject to the separate applicable standards for both HPs 
(i.e., in terms of SEER2 and HSPF2) and furnaces (i.e., in terms of 
annual fuel utilization efficiency (``AFUE'')). Therefore, DOE 
tentatively concluded that the fan energy use of these products is 
already accounted for by the metrics measured by the applicable test 
procedure. The SEER2 and HSPF2 metrics measure the fan energy in its 
cooling and heating modes, respectively, covering the two major 
functions of furnace fans. Furthermore, furnace fans in dual-fuel 
models have not been subject to appendix AA and, therefore, were not

[[Page 25786]]

part of the previous standards analysis. Id. at 87 FR 29581.
    In the May 2022 NOPR, DOE proposed to define dual-fuel units as a 
consumer product that includes both a heat pump and a burner in a 
single cabinet. Further, DOE proposed to explicitly exclude furnace 
fans used in them from the scope of appendix AA. Id.
    In response to the May 2022 NOPR, the CA IOUs commented that dual-
fuel products--such as package units with electric heat pumps and a gas 
burner that are intended to provide the same utility as a typical 
weatherized, non-condensing furnace fan and a weatherized gas furnace--
will likely grow in popularity for consumers. The CA IOUs agreed with 
DOE's assertion that the annual operating characteristics of a dual-
fuel product may differ significantly from a typical furnace but noted 
this is not sufficient justification for exclusion from this 
rulemaking. Moreover, the CA IOUs stated that manufacturers currently 
need to test these furnace fans in otherwise identical package units 
with a cooling-only coil and a furnace; therefore, including such 
furnace fans in the scope would not increase manufacturer burden. The 
CA IOUs suggested that because heat pump capacity is expected to 
correlate to cooling capacity, units with lower heating capacity than 
cooling capacity installed in high-heat-demand climate zones would 
result in more gas-specific heating operation for a dual-fuel system 
during heating degree days. The CA IOUs stated that, as a result, the 
estimated national average operating hour values for calculating FER 
are also relevant for dual-fuel systems. The CA IOUs therefore 
recommended that DOE not exclude the furnace fans in dual-fuel heating 
products from the scope of the test procedure. (CA IOUs, No. 13 at p. 
4)
    The Joint Commenters stated that the gas furnaces that are part of 
dual-fuel units are essentially identical to those that are part of 
currently covered single-package air conditioning units with a gas 
furnace. The Joint Commenters added that they were unclear as to how 
DOE made the determination that dual-fuel fans are presently excluded 
from the currently applicable test procedure. The Joint Commenters 
encouraged DOE to clarify its determination that dual-fuel fans are 
excluded from the scope of the currently applicable consumer furnace 
fan test procedure and to consider adding provisions for testing these 
furnace fans. (Joint Commenters, No. 14 at pp. 1-2)
    Conversely, Carrier, Lennox, and AHRI commented in support of the 
proposed definition for dual-fuel units and the proposal to exclude the 
furnace fans in them from the scope of appendix AA. (Carrier, No. 12 at 
p. 2; Lennox, No. 11 at p. 3; AHRI, No. 15 at p. 2)
    In response to these comments, DOE notes that although furnace fans 
used in dual-fuel units were not explicitly excluded in the currently 
applicable consumer furnace fan test procedure, the test procedure does 
not specify provisions for the testing of these products. Additionally, 
in response to the CA IOUs' suggestion that heating contribution from 
the heat pump may be small in comparison to the furnace component, DOE 
notes that these assumptions would not be applicable to all product 
designs, nor is it necessarily representative of typical installations 
and usage patterns throughout the U.S. Therefore, DOE continues to 
conclude that the operating hours used in appendix AA would not be 
representative of the fans in dual-fuel units. It follows that these 
products necessarily were not intended to be subject to the currently 
applicable consumer furnace fan test procedure. DOE further notes that 
there is a distinction between packaged dual-fuel units, which include 
both a furnace for heating operation and a heat pump for heating and 
cooling operation, and package air conditioner units, which include 
only a furnace for heating operation (along with an air conditioner 
that provides cooling only). The single-package air conditioner system 
can be tested according to the currently applicable test procedure for 
furnace fans, the operating hours are representative for these 
products, and furnace fans used in package air conditioners are 
currently subject to the standards established for this product type. 
Further, as noted previously in this section, the energy consumption of 
the fans in dual-fuel heating products is already captured in the SEER2 
and HSPF2 metrics specified in appendix M1. Therefore, to clarify the 
distinction between dual-fuel products and products within the scope of 
this consumer furnace fan test procedure, DOE is finalizing its 
proposed definition for dual-fuel units within appendix AA in this 
final rule. Accordingly, DOE is finalizing its proposal to specify more 
explicitly that furnace fans in dual-fuel products are excluded from 
the scope of appendix AA.

B. Referenced Industry Standards

1. Updates to Industry Standards
    The currently applicable DOE test procedure for consumer furnace 
fans incorporates by reference ASHRAE 103-2007, ASHRAE 37-2009, and 
ASHRAE 41.1-1986 (RA 2006). Since publication of the January 2014 Final 
Rule, ASHRAE published an update to ASHRAE 103, i.e., ASHRAE 103-2017, 
and two addenda to ASHRAE 37-2009 (ASHRAE 37-2009 (RA 2019)). In the 
May 2022 NOPR, DOE proposed to incorporate by reference ASHRAE 103-2017 
and ASHRAE 37-2009 (RA 2019) in its test procedure for consumer furnace 
fans to stay consistent with the latest industry testing practices. 87 
FR 29576, 29581. Further, DOE proposed to update all references of 
ASHRAE 37-2009 to ASHRAE 37-2009 (RA 2019). Id. Finally, DOE proposed 
to maintain reference to ASHRAE 41.1-1986 (RA 2006). Id.
    In response to the May 2022 NOPR, Carrier commented that it agrees 
with the incorporation by reference of ASHRAE 103, ASHRAE 37, and 
ASHRAE 41.1. Carrier stated these references are important for the 
direct measurement method. (Carrier, No. 12 at p. 2) Additionally, 
Carrier and AHRI recommended that the DOE adopt the most recent 
versions of all ASHRAE standards relevant to this rule (i.e., ASHRAE 
103-2022 and ASHRAE 41.1-2020). (Carrier, No. 12 at p. 2; AHRI, No. 15 
at p. 2) Rheem and AHRI commented that DOE should consider the new 
version of ASHRAE 37 that will be coming out soon. (Rheem, NOPR Webinar 
Transcript, No. 9 at pp. 19-20; AHRI, No.15 at p. 4)
    For the reasons discussed in the preceding section and in the May 
2022 NOPR, DOE is finalizing its proposal to incorporate by reference 
in appendix AA the most recent version of ASHRAE 37 (ASHRAE 37-2009 (RA 
2019)). With regards to the comments from Rheem and AHRI, DOE notes 
that a new version of ASHRAE 37 has not been published yet so DOE is 
incorporating by reference the most recent version of ASHRAE 37. 
Relatedly, DOE notes that ASHRAE 37-2009 (RA 2019) references ASHRAE 
41.1-1986 (RA 2006) as opposed to the more recent ASHRAE 41.1-2020. 
Consequently, to maintain consistency with ASHRAE 37-2009 (RA 2019), 
DOE is finalizing its proposal to maintain the incorporation by 
reference of ASHRAE 41.1-1986 (RA 2006) in appendix AA. In response to 
the comments from Carrier and AHRI, DOE notes that ASHRAE 103-2022 
updated the references to relevant standard test methods and standard 
specifications from ASHRAE 103-2017. Notably, the amended ASHRAE 103 
standard adds references to ASTM D396-2019, ``Standard Specification 
for Fuel Oils'' and ANSI/ASHRAE Standard 41.6-2014, ``Standard Methods 
for Humidity

[[Page 25787]]

Measurement,'' while removing the reference to Heat Transmission by 
W.H. McAdams. As discussed, in the May 2022 NOPR, DOE proposed to 
incorporate by reference ASHRAE 103-2017. 87 FR 29576, 29581. Although 
DOE continues to evaluate the differences between ASHRAE 103-2017 and 
ASHRAE 103-2022 (and the standards referenced therein), DOE has not yet 
determined whether the changes between the versions of the standards 
would impact appendix AA and, in turn, FER ratings. Therefore, DOE 
maintains its proposal in the May 2022 NOPR and incorporates by 
reference ASHRAE 103-2017 into appendix AA in this final rule. DOE will 
continue to evaluate ASHRAE 103-2022 for future incorporation by 
reference.
2. Additional References
    Appendix AA as established in the January 2014 Final Rule included 
a reference to the psychrometric chapter (i.e., chapter 1) in the 2001 
ASHRAE Handbook for use in calculating the specific volume of dry air 
at specified operating conditions. Although the 2001 ASHRAE Handbook 
was not incorporated by reference in appendix AA at the time in the 
January 2014 Final Rule, DOE notes that its inclusion in the test 
procedure should necessitate its incorporation by reference. As the 
2001 version of the ASHRAE Handbook is no longer widely available, DOE 
is updating appendix AA to reference to the 2021 version of the ASHRAE 
Handbook. Because appendix AA already references the 2001 version of 
the ASHRAE Handbook, which uses the same method to determine the 
specific volume of dry air as the 2021 version of the ASHRAE Handbook, 
incorporating by reference chapter 1 of the 2021 ASHRAE Handbook will 
not change the results of FER. DOE is therefore incorporating by 
reference chapter 1, ``Psychrometrics'' of the 2021 ASHRAE Handbook 
into appendix AA in this final rule.

C. Furnace Fans That Operate at Low External Static Pressures

    On February 20, 2019, DOE received a petition for waiver and an 
application for interim waiver from ECR International, Inc. (``ECR'') 
for certain basic models of furnace fans that ECR described as belt-
driven, single-speed furnace fans designed for heating-only 
applications in oil-fired warm air furnaces.\7\ ECR asserted that the 
furnace fan basic models specified in the petition have design 
characteristics that prevent testing of the basic model according to 
the test procedure prescribed in the currently applicable appendix AA. 
Specifically, ECR claimed that the specified products are not designed 
to operate within the range of ESP required in the currently applicable 
appendix AA and that testing such furnace fans at the required ESP 
reduces airflow and increases temperature rise to the point where the 
units shut off during testing due to high temperature limits, making it 
impossible to achieve the steady-state operation required for 
testing.\8\
---------------------------------------------------------------------------

    \7\ See www.regulations.gov/document?D=EERE-2019-BT-WAV-0004-0001 at p. 1.
    \8\ See id. at pp. 2-3.
---------------------------------------------------------------------------

    On March 9, 2021, DOE published a Decision and Order (``2021 
Decision and Order'') granting ECR a test procedure waiver specifying 
an alternate test procedure that must be used to test and rate the 
specified basic models.\9\ 86 FR 13530, 13534-13535.
---------------------------------------------------------------------------

    \9\ See www.regulations.gov/document/EERE-2019-BT-WAV-0004-0015.
---------------------------------------------------------------------------

    Specifically, the 2021 Decision and Order specified adjustments to 
the ESP test conditions specified in section 8.6.1.2 of the currently 
applicable appendix AA. Basic models subject to the 2021 Decision and 
Order must be tested at the specified ESP. Id. The alternate test 
procedure in the 2021 Decision and Order further specifies that if the 
unit under test shuts down prior to completion of the test, the ESP 
range is incrementally reduced by 0.05 inches of water column 
(``w.c.''), and the test is to be re-run. Id. This process is repeated 
until a range is reached at which the test can be conducted to its 
conclusion, with a minimum allowable ESP range of 0.30-0.35'' w.c., 
which corresponds to the lowest ESP at which shut-off occurred in the 
ECR data. Id.
    The test procedure waiver provision at 10 CFR 430.27(l) provides 
that, as soon as practicable after the granting of any waiver, DOE will 
publish in the Federal Register a NOPR to amend its regulations so as 
to eliminate any need for the continuation of such waiver. As soon 
thereafter as practicable, DOE will publish in the Federal Register a 
final rule. 10 CFR 430.27(l). Therefore, to amend the test procedure so 
as to eliminate any need for the continuation of this waiver, in the 
May 2022 NOPR, DOE proposed to add provisions requiring that furnace 
fans be initially tested at the applicable ESP range specified in table 
1 of appendix AA. If the unit under test is unable to complete the 
testing (i.e., the unit shuts down), the ESP range would be 
incrementally reduced by 0.05'' w.c. (e.g., for units designed to be 
paired with an evaporator coil but without one installed, first from 
0.65''-0.70'' to 0.60''-0.65'' w.c.). This process would be repeated 
until an ESP range at which the test can be conducted to its conclusion 
is reached. 87 FR 29576, 29582-29583.
    In response to the May 2022 NOPR, Lennox, Carrier, and AHRI 
commented that they support the proposed test procedure instructions 
for products that cannot be tested at the ESPs in the currently 
applicable test procedure. (Lennox, No. 11 at p. 3; Carrier, No. 12 at 
p. 2; AHRI, No. 15 at p. 2) Lennox stated that it supports these test 
procedure changes, which would eliminate the current test procedure 
waiver and not create separate product classes for low-ESP products. 
(Lennox, No. 11 at p. 3) JCI commented that the FER test procedure 
should not specify a static pressure setting that is above the maximum 
static pressure specified by the furnace manufacturer. (JCI, No. 10 at 
pp. 4-5)
    The Joint Commenters commented that this proposal could allow the 
products subject to the 2021 Decision and Order (i.e., ``heating only'' 
products that cannot be tested at the ESPs in the currently applicable 
test procedure) to meet the standard more easily. The Joint Commenters 
stated that despite DOE's discussion in the May 2022 NOPR that these 
``heating only'' furnace fans are not manufactured for the same 
applications as other covered furnace fans (e.g., in a system with 
cooling), the manufacturer literature for these ``heating-only'' models 
repeatedly discusses usage in cooling applications. The Joint 
Commenters encouraged DOE to further consider appropriate testing 
provisions for ``heating-only'' furnace fans that cannot reach the ESPs 
defined in appendix AA. (Joint Commenters, No. 14 at p. 2)
    The CA IOUs commented that DOE should not require furnace fans that 
cannot meet the required ESP to be tested using an alternative test 
procedure because it would result in an unrepresentative metric. 
Instead, the CA IOUs recommended that DOE either add a correction 
factor or create a new product class for these products. (CA IOUs, No. 
13 at p. 1) The CA IOUs stated that the method of reducing ESP until a 
test could be complete would result in testing at a much lower airflow 
and higher temperature rise than the maximum shown on the furnace 
nameplate. The CA IOUs stated that operating at this condition 
contradicts the manufacturer's installation and operating instructions 
and is not representative of field use. The CA IOUs expressed concern 
that this approach sets a precedent for manufacturers of

[[Page 25788]]

other products to deviate from Federal test procedures without changing 
their product rating. (Id. at pp. 1-2) The CA IOUs stated that the 
product for which the waiver was granted has a motor capable of 
operating at the required ESP. Further, the CA IOUs stated that the 
motor is supplied with a fixed belt drive that does not allow the fan 
to run at the speed necessary to achieve the higher ESP. Finally, the 
CA IOUs stated that the manufacturer's literature provides instructions 
for changing the pulleys in the field to work at the required speed. 
(Id. at p. 2)
    In response to these comments, DOE notes that, as is discussed in 
the grant of an interim waiver to ECR, test data submitted by ECR 
showed that the specified furnace fan basic models stop operating at an 
ESP between 0.30'' and 0.60'' w.c., depending on the particular basic 
model, with units shutting down at an average ESP of 0.47'' w.c. 85 FR 
50808, 50811. These ESPs are below the values listed in table 1 of 
appendix AA, indicating that these units could not complete a test 
according to the current consumer furnace fan test procedure without 
the proposed changes to ESP requirements. DOE further notes that a unit 
using a different motor or replacing the pulley, belt, or other 
components would constitute a different basic model.
    The CA IOUs reiterated their comments previously submitted in 
response to the July 2021 RFI in which they demonstrated that for a 
given speed, forward curve fan efficacy is higher at low airflow and 
high ESP than at a low ESP with high airflow. The CA IOUs commented 
that the requirement in the proposed test procedure would test the 
fixed-speed fan at a much lower airflow and higher ESP than the fan 
would operate at under normal conditions, resulting in a measured 
efficacy that is significantly better than would result if the fan were 
tested at a representative airflow. (Id. at p. 2) The CA IOUs stated 
that the problem is exacerbated by the lack of correction to account 
for the difference between the tested ESP and the ESP listed in table 1 
of appendix AA in the reported FER. The CA IOUs noted that while they 
are unaware of a validated equation specifically for FER, DOE employs a 
similar correction for water-source heat pumps by incorporating ANSI/
AHRI/ASHRAE ISO Standard 1346-1:1998 (RA 2012). The CA IOUs noted that 
water-source heat pumps require this correction to determine the power 
consumption and capacity at the rating condition of 0.0'' wc because 
the actual tests use a positive ESP. The CA IOUs commented that they 
believe this DOE-approved equation applies equally well to furnace 
fans. (Id. at pp. 2-3)
    The CA IOUs also recommended that DOE require testing at an airflow 
no less than that required to meet the maximum temperature rise on the 
furnace nameplate. Alternatively, the CA IOUs suggested that DOE create 
a new product class for heating-only units and require a specific ESP 
in table 1 of appendix AA that is lower. The CA IOUs stated that this 
would reduce test burden because the products would complete testing on 
the first attempt rather than incrementally reducing ESP in further 
attempts. The CA IOUs noted that there is a similar breakdown of 
products based on application and static pressure for ducted blower 
coil systems for central air conditioners and heat pumps. Further, the 
CA IOUs stated that appendix M1 has different ESP test conditions for 
conventional, low static, and mid static blower coil systems based on 
the external static pressure produced during operation. (Id. at p.3)
    In response to the comment from the CA IOUs, DOE notes that no data 
indicate that the correction equation used for water-source heat pumps 
is appropriate for use in the furnace fans test procedure. Because 
these two products are tested according to different procedures, DOE 
cannot conclude that this equation would be appropriate to use to 
predict the change in FER. Further, as previously stated in the 2021 
Decision and Order, validating an equation for extrapolating to FER at 
an ESP that is higher than that at which the unit can operate may be 
difficult or even not possible (as the unit cannot operate at that 
point). See 86 FR 13530, 13533.
    In addition, products that operate at low ESPs are typically used 
in heating-only applications, and the products subject to the waiver 
are not to make any representations in any public-facing materials that 
these basic models are designed to be installed in systems that provide 
both heating and cooling. Id. Therefore, DOE concludes that these 
heating-only products do not compete with products intended for both 
heating and cooling, and DOE is not implementing an adjustment factor 
to the test procedure for furnace fans that are unable to complete 
testing at the ESPs specified in table 1 of the revised appendix AA. 
Additionally, DOE concludes that the proposed modified test provisions 
reflect the actual use of these products that cannot operate at higher 
ESPs and result in a metric that is representative.
    Therefore, for the reasons discussed here and in the May 2022 NOPR, 
in this final rule, DOE is finalizing its proposal to adopt the 
modified test provisions for units that cannot meet the ESPs outlined 
in table 1 of appendix AA.

D. Test Procedure Repeatability and Reproducibility

    Comment responses to the July 2021 RFI indicated that stakeholders 
encountered difficulty obtaining repeatable and reproducible FER 
results using the current appendix AA. Based on feedback collected 
during manufacturer interviews prior to the May 2022 NOPR, DOE 
understands that there are several key areas of possible revision to 
the currently applicable consumer furnace fan test procedure that could 
improve repeatability and reproducibility. 87 FR 29576, 29583.
    In response to the May 2022 NOPR, Lennox commented that it 
evaluated over 60 furnace fans tested through the AHRI audit program 
and found the correlation between manufacturer test values and audit 
test values to be within an acceptable variation, such that test 
procedure repeatability is not a concern. (Lennox, No. 11 at p. 1)
    JCI referenced AHRI work project 8020 which, JCI stated, studied 
the FER metric, attempted to develop a predictive metric, and reviewed 
possible alternatives to the current standard. JCI quoted the results 
of the AHRI project as follows: ``Appendix AA results in a wide metric 
tolerance. AHRI's members report, and the research shows, that the 
results are affected by the natural gas input rate and relative 
humidity, which is problematic as testing is not conducted in a 
controlled environment. Further, the current test method lends itself 
to test inaccuracies resulting in the inability to achieve 
repeatability.'' JCI also listed AHRI's recommendations for member 
companies as follows: (1) evaluate their lab measurement systems, 
procedures, and the uncertainty of each input variable; (2) test in a 
controlled environment to reduce variability; and (3) complete a 
statistical number of tests to improve rating confidence. JCI commented 
that the first and third recommendations are feasible and less 
expensive to the test labs, but JCI suggested that reduced variability 
could be achieved through actions other than testing in a controlled 
environment. (JCI, No. 10 at p. 2)
    DOE notes that feedback from comment responses to the July 2021 RFI 
and manufacturer interviews have indicated challenges with test 
procedure repeatability and reproducibility in contrast to the comment 
from Lennox. Additionally, DOE has received feedback that units are 
often rated conservatively due to these repeatability

[[Page 25789]]

challenges. Further, in the May 2022 NOPR, DOE proposed and requested 
feedback on specific solutions to minimize variability and uncertainty 
in results. 87 FR 29576, 29583-29586. The following sections address 
specific topics on which DOE has received feedback in this regard.
1. Fuel Input Rate Tolerance
    DOE received feedback in response to the July 2021 RFI that the 
natural gas input rate could impact FER, so DOE considered whether 
tightening the tolerance on firing rate (from 2 percent) 
would improve the repeatability of the test procedure without imposing 
substantial burden. In a NOPR published on March 11, 2015, DOE 
determined that it could not change the tolerance on firing rate 
without increasing manufacturer burden because of variations in gas 
valve performance. 80 FR 12875, 12886-12887. Because DOE is not aware 
of any data suggesting it would now be possible to tighten this 
tolerance without imposing substantial test burden, DOE did not propose 
to change the tolerance on fuel input rating in the May 2022 NOPR. 87 
FR 29576, 29583-29584.
    In response to the May 2022 NOPR, AHRI, Carrier, and Lennox 
commented that they support the decision not to tighten the tolerance 
on fuel input ratings beyond what is required in ASHRAE 103-2017. 
(AHRI, No. 15 at p. 2; Carrier, No. 12 at p. 2; Lennox, No. 11 at p. 3) 
Lennox stated also that tightening the tolerance beyond  2 
percent would increase manufacturer burden. (Lennox, No. 11 at p. 3)
    For the reasons discussed in the May 2022 NOPR, and as supported by 
these comments, DOE is not making any changes to the fuel input rating 
in this final rule.
2. Ambient Conditions
    In the May 2022 NOPR, DOE tentatively concluded that FER results 
are affected by ambient air temperature and humidity. To help improve 
the repeatability and reproducibility of test results, DOE proposed to 
tighten the range of allowable ambient conditions during testing. 
Specifically, DOE proposed to specify that ambient air temperature must 
be maintained between 65 [deg]F and 85 [deg]F and relative humidity 
must be maintained between 20 percent and 80 percent. 87 FR 29576, 
29584. DOE tentatively concluded that these limits would not impose 
additional burden on manufacturers while maintaining the 
representativeness of the test procedure. Id.
    DOE requested comment on these proposed constraints, and on its 
tentative determination that this proposal would decrease variability 
between tests. Id. at 87 FR 29584-29585.
    In response to the May 2022 NOPR, Lennox, Carrier, and the Joint 
Commenters commented that they support the proposed modifications to 
the allowable ambient temperature range in appendix AA to be between 65 
[deg]F and 85 [deg]F for non-condensing and condensing furnaces. 
(Lennox, No. 11 at p. 4; Carrier, No. 12 at p. 3; Joint Commenters, No. 
14 at p. 2) AHRI similarly commented that it supports the change in the 
ambient air temperature requirement in appendix AA and suggested that 
the change would not introduce additional burden. (AHRI, No. 15 at p. 
2) Lennox and Carrier both commented that their laboratories have the 
capability to condition the ambient air within the newly specified 
range; therefore, the requirement will not add significant burden. 
(Lennox, No. 11 at p. 4; Carrier, No. 12 at p. 3) Lennox stated that 
this change will reduce FER variability for non-condensing furnaces as 
well as standardize existing requirements for condensing furnaces. 
(Lennox, No. 11 at p. 4)
    Lennox, Carrier, JCI, and AHRI further commented that they support 
the proposal to require maintaining the room relative humidity between 
20 percent and 80 percent because it will decrease test variability 
without adding significant burden. (Lennox, No. 11 at p. 4; Carrier, 
No. 12 at p. 3; JCI, No. 10 at p. 2; AHRI, No. 15 at p. 3) However, 
they each commented that a tighter range, for example 30 percent to 50 
percent, for relative humidity would require FER testing to be 
conducted in a special conditioned test room rather than in the main 
laboratory test area, which would add significant manufacturer testing 
burden. (Id.) Additionally, AHRI stated that the narrower band of 30 to 
50 percent would require using tighter humidity controls in the test 
room than the current requirement. (AHRI, No. 15 at p. 3) JCI similarly 
stated that a tighter humidity range of 30 to 50 percent is beyond the 
capability of existing lab facilities where FER testing is currently 
performed. JCI stated that it does not support a relative humidity 
range tighter than 20 to 80 percent. Furthermore, JCI commented that 
the test repeatability of FER is less significantly sensitive to the 
tolerance in relative humidity (``RH'') compared to other test 
parameters. (JCI, No. 10 at p. 2)
    For the reasons discussed in the May 2022 NOPR, and in 
consideration of these stakeholder comment responses, DOE is finalizing 
its proposal to specify in section 7.1 of appendix AA that the room 
temperature shall not fall below 65 [deg]F (18.3 [deg]C) or exceed 85 
[deg]F (29.4 [deg]C) and the relative humidity shall not fall below 20 
percent or exceed 80 percent in this final rule.
3. Airflow Determination
    Section 10.1 of the current appendix AA compares the input heat 
energy to the heat picked up by the air when the furnace is in heating 
mode based on the temperature rise of air passing through the furnace 
and the specific conditions of the inlet air to calculate airflow in 
the specified heating setting (``Qheat''). If this heating 
mode airflow setting is the maximum airflow-control setting, then 
Qheat is equal to the expected airflow at the maximum 
airflow-control setting (``Qmax''). If this heating mode 
airflow setting is not the maximum airflow-control setting, a second 
calculation is performed to calculate Qmax based on 
Qheat. Section 10.1, appendix AA. In the May 2022 NOPR, DOE 
evaluated whether the current method of calculating airflow indirectly 
based on measurements of other parameters leads to repeatability 
challenges within the test procedure. 87 FR 29576, 29585.
    Each parameter involved in the calculation of Qmax and 
FER has its own inherent variability. Measuring airflow directly 
reduces the number of parameters required to be measured and therefore 
could reduce the overall variation inherent in the final FER value.
    In the May 2022 NOPR, DOE acknowledged that requiring the use of an 
airflow-measuring device for furnace fans could introduce a one-time 
cost for manufacturers that either do not utilize such devices for 
their current testing programs (presumably of other products) or do not 
have enough of such devices available to test furnace fans in addition 
to other HVAC products that use airflow-measuring devices. The 
estimated cost of an airflow-measuring device is up to $50,000. Id.
    In the May 2022 NOPR, DOE tentatively concluded that the benefits 
of measuring airflow would directly outweigh the associated burdens and 
that the requirement to directly measure airflow would not be unduly 
burdensome. Id. DOE therefore proposed to require that airflow be 
measured directly during each test. Id. Specifically, DOE proposed that 
this measurement be done using the procedures and methods for measuring 
airflow specified in ASHRAE 37-2009 (RA 2019), similar to how it is 
done for central air conditioners and heat pumps.

[[Page 25790]]

Id. As part of this proposal, DOE proposed to incorporate by reference 
Figure 12 of ANSI/Air Movement and Control Association International, 
Inc. (``AMCA'') 210-07, ANSI/ASHRAE 51-07 (``AMCA 210-2007''), titled 
``Laboratory Methods of Testing Fans for Certified Aerodynamic 
Performance Rating;'' and Figure 14 of ANSI/ASHRAE Standard 41.2-1987 
(RA 92), (``ASHRAE 41.2-1987 (RA 1992)''), titled ``Standard Methods 
for Laboratory Airflow Measurement.'' Id. DOE requested comment on this 
proposal. Id.
    In the May 2022 NOPR, DOE also requested comment on whether it is 
necessary to reference AMCA 210-2007 and ASHRAE 41.2-1987 (RA 1992) in 
the test procedure instructions for constructing an airflow measuring 
apparatus. Id. DOE also requested comment on alternative methods of 
directly measuring airflow, such as methods outlined in AMCA 210 (e.g., 
the pitot traverse method),\10\ as well as duct-mounted airflow 
measurement devices and anemometers, and whether these methods could 
prove more accurate and repeatable. Id. Specifically, DOE requested 
comment on alternative methods of direct airflow measurement, including 
on the level of measurement accuracy associated with each approach and 
any associated test burden. Id. at 87 FR 29585-29586.
---------------------------------------------------------------------------

    \10\ See www.amca.org/assets/resources/public/pdf/Education%20Modules/AMCA%20210-16.pdf (last accessed January 11, 
2023.)
---------------------------------------------------------------------------

    In response to the May 2022 NOPR, the Joint Commenters expressed 
support for the proposed requirement for direct measurement of airflow, 
suggesting that it should improve repeatability and reproducibility. 
(Joint Commenters, No. 14 at p. 2) Carrier commented that it would 
support the test procedure change to direct airflow measurement 
provided that gas heat operation is not required during the direct 
airflow measurement test. (Carrier, No. 12 at pp. 3-4) Carrier added 
that it performed comparison tests without gas heating operation on 
four models, which represented a cross-section of non-weatherized gas 
furnaces, to compare the methods of the currently applicable test 
procedure to the proposed direct airflow measurement method. Carrier 
reported that the results of the test showed slight favoring of the 
current method over the direct measurement method; however, Carrier 
stated that the FER results differed by less than 1 percent and maximum 
airflow averaged 2 percent lower when using the direct measurement 
method. (Id. at p. 4) AHRI stated that it has a limited data set and is 
unable to provide a meaningful comparison between FER generated by the 
direct and indirect airflow measurement methods. (AHRI, No. 15 at p. 3)
    Lennox stated that the variation in airflow between DOE sample 
units and AHRI audit units calculated under the currently applicable 
test procedure would be similar to the typical variation when using 
direct airflow measurement systems, as motor performance variation is 
the primary driver for the airflow variation. (Lennox, No. 11 at p. 5) 
Lennox commented that it did not support the proposal to change the 
test procedure from the current method to a direct airflow measurement 
method as it would cause a significant increase in manufacturer burden. 
(Id. at p. 4) However, Lennox commented that, if DOE were to adopt the 
proposal to measure airflow directly, DOE should carefully ensure that 
results are cross-walked should ratings change as a result of direct 
airflow measurement. (Id. at p. 5)
    JCI commented that it does not support changing to direct 
measurement of airflow because JCI is unsure if the proposed change to 
directly measure airflow would resolve the repeatability issues 
associated with the furnace fan test procedure. (JCI, No. 10 at pp. 2-
3, 4) JCI agreed that measuring airflow directly should reduce the 
uncertainty in calculating maximum airflow compared to the current 
method, but the proposed change does not guarantee that it would 
constrain the uncertainty in the FER. JCI commented that the proposal 
does not address furnace fan electrical consumption, which also has an 
associated uncertainty. (JCI, No. 10 at pp. 2-3)
    Carrier commented that the direct measurement method would improve 
the accuracy of the test procedure while reducing the difficulty to run 
it. Carrier suggested that, if DOE were to adopt the direct airflow 
measurement method, DOE should consider applying the new test procedure 
only to new models and allowing models tested under the existing test 
procedure to remain compliant until that model is discontinued. 
(Carrier, No. 12 at p. 4) Carrier stated that the proposed method of 
direct airflow measurement would be a slight improvement in the burden 
imposed on manufacturers from the furnace fans test procedure. (Id. at 
p. 7)
    AHRI noted that transitioning to the direct method would create a 
significant burden for manufacturer test labs and third-party testing 
facilities as the direct method would require a different set of 
measurements and therefore additional equipment along with a 
reconfiguration of the test setup that would require additional floor 
space. AHRI added that the direct method would further increase testing 
burden through doubling the number of samples run on code testers. 
(AHRI, No. 15 at p. 3) AHRI commented that third-party and manufacturer 
testing facilities would be required to construct code testers and 
reconfigure heating labs to fit the sizeable instrumentation in order 
to have the necessary set-up and capacity to conduct direct airflow 
measurements. AHRI stated that if this is not an option due to space 
constraints, third-party test facilities would need to move the set-up 
equipment to small unitary test facilities that already have the built-
in flow meters. AHRI concluded that both of these options would 
significantly increase test time and expenses, including operating 
costs, and there would be a significant increase in burden for labs not 
already set up to conduct this type of testing. (Id. at p. 7) AHRI 
commented that manufacturers are equipped to conduct the current 
furnace fan test procedure and stated that the additional burden posed 
by transitioning to the direct method will outweigh the value of any 
potential increased accuracy offered. (Id. at p. 3)
    Additionally, AHRI commented that should DOE proceed with the 
direct measurement method, the equipment should remain unfired 
throughout the testing process. AHRI added that the use of flow 
measurement devices with high temperature applications will create 
significant issues and may decrease the life of said measurement 
devices. AHRI stated that there is limited data available to make 
accurate comparisons between methods. AHRI requested that data 
supporting the reasoning for a transition to the direct measurement 
method be made available prior to requiring the change. AHRI requested 
that DOE conduct an adequate evaluation of the impact that the direct 
measurement method will have on FER values and that a crosswalk be 
created if necessary. Finally, AHRI suggested that DOE consider 
alternative approaches to reduce testing burden while achieving the 
same objectives. (Id. at p. 4)
    Lennox commented that it does not support the proposed change of 
the furnace fan test procedure from the current method to the direct 
airflow measurement method due to the increased burden it would impose. 
(Lennox, No. 11 at p. 1) Lennox commented that the current furnace fan 
test setup allows the AFUE and FER test to be conducted in a single 
setup, but a direct airflow measurement approach would require a second 
setup which would significantly increase burden. (Id. at p. 5) Lennox 
stated that measuring

[[Page 25791]]

airflow directly would cause significant upfront manufacturer costs to 
purchase code testers and would additionally create ongoing operating 
costs. Lennox added that additional investments in adequate lab and 
personnel capacity for direct airflow measurement would be required. 
Lennox stated that it has multiple product development facilities where 
furnace fan testing is conducted, so investments would need to be made 
in each facility. Lennox estimated the ongoing increase in burden to 
conduct FER direct airflow testing to be up to a 100-percent increase 
over the currently applicable test method. Lennox stated that DOE 
should consider the total cumulative regulatory burden associated with 
any changes to the FER test procedure to require direct airflow 
measurement. (Lennox, No. 11 at p. 7) Lennox added that, because the 
FER metric is a part of the AHRI audit program, the additional setup 
would increase burden when conducting audits. Lennox commented that, 
while manufacturers do directly measure airflow in the process of 
developing airflow application tables, it is often done on one sample 
and is not inclusive of all the iterations required in furnace 
development, so burden would be added. (Id. at p. 5)
    JCI commented that the instrumentation for airflow measurement is 
often found in a different location than the gas lab, where heating 
equipment is tested, and code tester labs are frequently unequipped to 
supply fuel gas to a furnace or to dispose of flue gas. Furthermore, 
JCI stated that the airflow code testers used by JCI and other 
manufacturers are not intended to have heated air passing through them. 
JCI noted that the proposed procedure presents issues because it 
directs that the furnace burners be fired at the same time as the unit 
is set up on the code tester for direct measurement of airflow. (JCI, 
No. 10 at p. 3) JCI commented also that the only reason that burners 
are fired in the current furnace fan test procedure is because they 
must be fired in order to obtain the temperature rise value used in the 
calculation of Qmax. JCI stated that if the airflow is to be 
measured directly, there is no need to fire the burners during testing. 
JCI also commented that changing to a direct airflow measurement would 
add significant burden because it would require a separate setup from 
the furnace test procedure, whereas the current furnace fan test 
procedure setup is the same as the setup used for the furnace AFUE test 
procedure. (Id. at p. 4)
    JCI stated that independent testing should be conducted to verify 
that the two test methods yield the same FER ratings. JCI noted that 
DOE regulations require that if there is a change of test method, then 
a unit that complies when tested by the old method must still be 
compliant when tested by the new method. JCI stated that it would take 
many months to verify that the hundreds of products they produce which 
comply with the standards when tested to the currently applicable test 
procedure still comply when tested according to the proposed method. 
JCI commented that if test data reveal that the FER results are 
different when tested according to the proposed method, DOE should be 
prepared to adjust the maximum allowable FER rating to accommodate the 
difference. (Id. at p. 3) Finally, JCI commented that the proposed 
method would impose substantial additional test burden and/or equipment 
costs and that there has been no demonstrated benefit to making the 
change to direct airflow measurement. (Id. at p. 5)
    Morrison commented that there are a variety of factors in the 
airflow measurement procedure as outlined by ASHRAE 37 that could lead 
to uncertainty associated with this procedure. Morrison noted that DOE 
should investigate the error specific to this procedure as it relates 
to furnace fan testing. (Morrison, NOPR Webinar Transcript, No. 9 at 
pp. 20-23)
    In response to the May 2022 NOPR, Lennox commented that AMCA 210-
2007 and ASHRAE 41.2-1987 (RA 1992) are associated with the direct 
airflow measurement method, which Lennox does not support; therefore, 
Lennox stated, the current furnace fan test procedure airflow 
calculation is adequate. (Lennox, No. 11 at p. 5) Carrier recommended 
that DOE reference ASHRAE 41.2-2018 as it is a newer and more current 
standard. Carrier further commented that it does not recommend other 
methods beyond ASHRAE 37-2009. (Carrier, No. 12 at p. 4) AHRI 
recommended that DOE reference ASHRAE 41.2-2018, as opposed to ASHRAE 
41.2-1987 (RA 1992), because it is more current. AHRI suggested that 
establishing standardization across original equipment manufacturers 
(``OEMs'') would be the best practice. AHRI stated that an updated 
version of ASHRAE 37 is coming out soon and that ASHAE 37-2009 is the 
industry standard for equipment and is preferred over AMCA 210-2007, 
which is a fan-only standard. (AHRI, No. 15 at p. 4)
    JCI stated that there are other less expensive measures that, if 
progressively implemented, would result in repeatability improvements 
in the furnace fan test procedure and, specifically, reduction in 
maximum airflow variability. These measures include higher accuracy 
requirements for instrumentation; providing additional clarity 
regarding the thermocouple grid, statistical, and sampling techniques; 
and limiting uncertainty in fuel input rate. JCI stated that these 
measures would not impose additional burden and disruption to lab 
facilities, would only require programmatic updates, would not incur 
the expenses associated with purchasing a code tester, would not put 
smaller OEMs at a competitive disadvantage, and would expedite 
improving test procedure repeatability. (JCI, No. 10 at p. 3) Lennox 
stated that while other airflow measurement methods exist, they are 
generally less accurate than the methods specified in ASHRAE 37-2009 
(RA 2019) and would consequently negate the purpose of transitioning to 
a direct-airflow measurement method. (Lennox, No. 10 at p. 6)
    AHRI noted that there are alternative instruments for direct 
airflow measurement, but they are less accurate than the methods 
specified in ASHRAE 37-2009 and would consequently negate the purpose 
of transitioning to a direct airflow measurement method. (AHRI, No. 15 
at p. 4)
    The CA IOUs commented that ASHRAE 37 is sufficient, and that 
referencing AMCA 210 is not necessary. The CA IOUs further commented 
that they expect that a commercial industrial fans NOPR would lead to 
an update AMCA 210-2016, and that this test procedure should reference 
the 2016 version of AMCA 210 if any version is referenced. (CA IOUs, 
NOPR Webinar Transcript, No. 9 at pp. 25-26)
    In response to these comments regarding the proposals to measure 
airflow directly in the furnace fan test procedure and to reference 
AMCA 210-2007 and ASHRAE 41.2-1987 (RA 1992) in the furnace fan test 
procedure, DOE maintains that measuring airflow directly using a code 
tester could reduce the error associated with airflow measurement in 
comparison to calculating the airflow and, in turn, reduce concerns 
about the repeatability and reproducibility of the furnace fan test 
procedure. However, since the May 2022 NOPR, DOE has conducted 
preliminary testing to compare the values of Qmax and FER 
determined according to the current test procedure for consumer furnace 
fans and a modified test method similar to that proposed in the May 
2022 NOPR that included direct airflow measurements.

[[Page 25792]]

The preliminary results indicated that values determined from tests 
directly measuring airflow could differ from values determined using 
the current test method. This preliminary testing did not indicate 
whether such differences would be more or less representative than the 
results obtained under the current test procedure requirements. 
Further, during the preliminary testing, DOE attempted to test some 
units in the heating mode without the burner firing, as suggested by 
commenters in response to the May 2022 NOPR, but found that some units 
were not able to be operated in this way, indicating that a test 
procedure that requires the test to be conducted unfired may not be 
possible for all furnace fans. Due to these concerns combined with 
concerns raised by commenters about potential changes to ratings and 
the burden associated with implementing this change, DOE has determined 
to not finalize the proposal from the May 2022 NOPR to measure airflow 
directly in this final rule. Relatedly, DOE is not incorporating by 
reference AMCA 210-2007 and ASHRAE 41.2-1987 (RA 1992). Additionally, 
DOE is adopting other provisions in this final rule that are intended 
to improve repeatability of the current test procedure without 
affecting existing ratings or significantly increasing test burden, as 
discussed elsewhere in section III.D of this document. However, DOE is 
still investigating the impact of direct airflow measurement on furnace 
fan ratings, including the impact of running tests with and without the 
burners firing during heating-mode tests, and may further assess 
directly measuring airflow in a future test procedure rulemaking for 
consumer furnace fans.
4. Location of External Static Pressure Measurements
    Appendix AA currently requires that external static pressure be 
measured 18 inches from the outlet. This differs from the requirements 
outlined in section 6.4 of ASHRAE 37-2009, in which the measurement 
location varies depending on the dimensions of the duct outlet. In the 
May 2022 NOPR, DOE reevaluated this provision and how it might impact 
the repeatability of the test procedure. 87 FR 29576, 29586. DOE 
expressed concern that measuring at a fixed location of 18 in from the 
outlet could lead to a less accurate and less repeatable measurement 
than the approach provided in ASHRAE 37-2009 because the airflow 
profile may not be fully developed. Id.
    However, DOE did not have sufficient information to propose a 
change in the May 2022 NOPR, and therefore requested comment on whether 
requiring that the external static pressure be measured at the location 
specified in section 6.4 of ASHRAE 37-2009, as opposed to specifying 
that external static pressure taps always be placed 18 in from the 
outlet (i.e., the instructions currently in appendix AA), could improve 
test repeatability. Id. DOE also requested comment on whether 
manufacturer facilities and other test laboratories would be able to 
accommodate the added duct length during testing. Id. Further, if test 
facilities would not be able to accommodate the added duct length 
during testing, DOE requested comment on whether a different length 
requirement could improve test repeatability while not preventing any 
existing test facilities from completing a valid test for furnace fans. 
Id.
    In response to the May 2022 NOPR, Carrier and AHRI commented that 
they are opposed to the change in location of measurement if the change 
results in a higher FER value. If the change does not result in a 
higher FER value, Carrier and AHRI stated that they would not be 
opposed to the change. (Carrier, No. 12 at p. 5; AHRI, No. 15 at p. 5) 
AHRI recommended that the furnace fan test procedure be aligned with 
furnace test procedures because existing ductwork can be utilized and 
AFUE will meet existing space constraints. (AHRI, No. 15 at p. 5)
    AHRI and JCI stated that they do not support any change to the 
location of pressure taps for furnace fan testing, and that if the 
furnace is to be tested on the code tester, the ASHRAE standard for 
that airflow measurement process includes a description of the duct 
design and the location of pressure taps. (AHRI, No. 15 at p. 5; JCI, 
No. 10 at p. 4) AHRI and JCI noted that for furnaces tested in the gas 
heating lab, the ASHRAE 103 standard includes a description of the 
ducts and pressure tap locations. (Id.) AHRI added that these standards 
have been in use for many years and yield reliable and repeatable 
results. AHRI stated that the FER test procedure does not need to 
specify test duct details; it only needs to reference the appropriate 
existing standard. (AHRI, No. 15 at p. 5) JCI commented that these 
standards (e.g., ASHRAE 103) have been in use for many years and 
provide reliable and repeatable results. JCI stated that the research 
they conducted concluded that repeatability will not be improved by 
changing the location of the pressure taps. Moreover, JCI stated that 
placing the pressure taps at 18 in from the outlet (instead of at a 
location based on the outlet dimensions) will result in measuring 
pressure at inconsistent duct lengths within the turbulent flow 
development region into the supply duct. JCI commented that DOE should 
engage with OEMs in a research effort to test the assumption in this 
proposal before finalizing the change. (JCI, No. 10 at p. 4)
    Lennox commented that for the current method of calculating airflow 
based on temperature rise, DOE should maintain the location of 18 in 
from the outlet to standardize to the same test ducts used for all 
safety and performance tests performed under Z21.47 and ASHRAE 103-
2017. Lennox added that DOE should gather test data that show that a 
longer duct required by ASHRAE 37-2009, which would require an elbow 
with 9 thermocouples added to measure outlet temperature, would justify 
the added manufacturer burden of building additional ducts and 
switching back and forth between these and those required by all other 
tests. (Lennox, No. 11 at p. 6)
    DOE notes that, in response to the discussion presented in the May 
2022 NOPR regarding whether the current method for measuring ESP at a 
fixed location of 18 in from the outlet could lead to a less accurate 
and less repeatable measurement than the approach provided in ASHRAE 
37-2009, commenters have not provided any data that demonstrate the 
impact on accuracy or repeatability of changing the location of 
external static pressure measurements, nor does DOE have any additional 
information beyond the discussion provided in the May 2022 NOPR. And in 
response to the comment from JCI, DOE notes that the currently 
applicable test procedure at appendix AA requires that external static 
pressure be measured 18 inches from the outlet, as opposed to a 
measurement location that varies depending on the dimensions of the 
duct outlet. Additionally, commenters generally did not support the 
change to the location of pressure taps for consumer furnace fan 
testing. For these reasons, DOE is not changing the ESP measurement 
location in this final rule.
5. Language Updates
    In the May 2022 NOPR, DOE responded to several comments in response 
to the July 2021 RFI regarding revisions to the language in appendix AA 
that could reduce confusion about the test procedure and, in turn, 
improve test procedure repeatability. 87 FR 29576, 29586-29589.
a. Definitions
    For furnace fans used in furnaces or modular blowers with single-
stage

[[Page 25793]]

heating, the three airflow-control settings required to be tested are: 
the maximum setting, the default constant-circulation setting, and the 
default setting when operated using the maximum heat input rate.\11\ 
For furnace fans used in furnaces or modular blowers with multi-stage 
heating or modulating heating, the airflow-control settings to be 
tested are: the maximum setting, the default constant-circulation 
setting, and the default setting when operated using the reduced heat 
input rate. See sections 8.6.1, 8.6.2, 8.6.3, appendix AA. For both 
single-stage and two-stage or modulating units, if a default constant-
circulation setting is not specified, the lowest airflow-control 
setting is used to represent constant circulation for testing. See 
section 8.6.2, appendix AA.
---------------------------------------------------------------------------

    \11\ For furnace fans where the maximum airflow control setting 
is a heating setting, the maximum airflow-control setting test and 
the default heating airflow-control setting test would be identical, 
such that only two tests are required: (1) maximum airflow (which is 
the same as the default heating setting) and (2) constant 
circulation.
---------------------------------------------------------------------------

    In addition, if the manufacturer specifies multiple heating 
airflow-control settings, the highest heating airflow-control setting 
specified for the given function (i.e., at the maximum or reduced 
input, as applicable) is used. See section 8.6.3, appendix AA.
    Inquiries sent to DOE since the publication of the January 2014 
Final Rule indicate that there are differing interpretations regarding 
the appropriate airflow-control settings for testing, with some 
manufacturers interpreting the DOE consumer furnace fan test procedure 
as requiring testing only the ``as-shipped'' airflow-control settings. 
However, the definition for ``default airflow-control setting'' 
specifically states that ``[i]n instances where a manufacturer 
specifies multiple airflow-control settings for a given function to 
account for varying installation scenarios, the highest airflow-control 
setting specified for the given function shall be used for the 
procedures specified in this appendix.'' Section 2.6, appendix AA. 
Further, the default airflow-control settings are defined as airflow-
control settings specified for installed use by the manufacturer. That 
section in turn clarifies that the ``manufacturer specifications for 
installed use'' are those specifications provided for typical consumer 
installations in the product literature shipped with the product in 
which the furnace fan is installed.
    Additionally, inquiries sent to DOE indicate that some 
manufacturers may be interpreting the test procedure to require testing 
according to installation instructions printed on the control board. 
However, DOE notes that the same control board may be used across 
multiple products to reduce manufacturing complexity and costs, and, as 
a result, instructions provided on a control board may not be 
applicable to every unit in which a control board is used and could 
contradict the specifications in product literature. For this reason, 
DOE specifies in the definition of ``default airflow-control setting'' 
that the manufacturer specifications for installed use are those 
specifications provided for typical consumer installations in the 
product literature shipped with the product in which the furnace fan is 
installed. Section 2.6, appendix AA.
    Based on feedback received in response to the July 2021 RFI, DOE 
proposed in the May 2022 NOPR to change the defined term at section 2.6 
in appendix AA from ``default airflow-control settings'' to ``specified 
airflow-control settings.'' This revised definition would avoid 
potential misinterpretation of the term ``default,'' which is not 
intended to limit testing to the as-shipped airflow-control settings. 
87 FR 29576, 29587.
    DOE also notes that there is currently conflicting direction from 
sections 8.6.2 and 2.6 of appendix AA, with section 2.6 specifying that 
the testing laboratory use the highest available airflow-control 
setting and section 8.6.2 specifying that the testing laboratory use 
the lowest available airflow-control setting. To address this 
discrepancy, DOE also proposed in the May 2022 NOPR to add the phrase 
``unless otherwise specified within the test procedure'' to the end the 
definition of ``specified airflow-control settings'' to clarify that 
the hierarchy within appendix AA is for the airflow-control settings to 
be selected according to section 2.6, unless section 8.6.2 applies, in 
which case section 8.6.2 should be used to select airflow-control 
settings. Id.
    In response to the May 2022 NOPR, Lennox and Carrier commented that 
they support the proposal to change the term ``default airflow-control 
settings'' to ``specified airflow-control settings.'' (Lennox, No. 11 
at p. 6; Carrier, No. 12 at p. 5) JCI commented that while it agrees 
with the need to clarify what speed tap is to be used for testing a 
furnace in heating mode, the rule should explicitly state that the 
heating speed to be used during heat-mode testing is the speed tap 
specified by the furnace manufacturer in the product literature shipped 
with the furnace. (JCI, No. 10 at p. 4) AHRI requested that DOE provide 
clarification regarding what ``default airflow-control settings'' 
refers to and provide the reasoning for this change. AHRI also 
suggested that DOE specify what is meant by ``unless otherwise 
specified within the test procedure.'' (AHRI, No. 15 at p. 5)
    Lennox added that it also supports the addition of the phrase 
``unless otherwise specified within the test procedure.'' Lennox stated 
that these changes would improve clarity. (Lennox, No. 11 at p. 6) JCI 
commented that the phrase ``unless otherwise specified within the test 
procedure'' is confusing, as the furnace should always be tested at the 
manufacturer-specified heating speed and the test procedure should not 
specify otherwise. (JCI, No. 10 at p. 4)
    In response to the comment from JCI, DOE notes that the definition 
it proposed in the May 2022 NOPR and is adopting in this final rule for 
specified airflow-control settings explicitly states that these 
settings are those in the product literature shipped with the product 
in which the furnace fan is installed. In response to the comment from 
AHRI, DOE notes that this change was proposed in response to inquiries 
received since the publication of the January 2014 Final Rule. Some 
inquiries expressed confusion regarding the distinction between the 
``default airflow-control settings'' and the ``as-shipped airflow-
control settings.'' Others indicated that some manufacturers may be 
interpreting the test procedure to require testing according to 
installation instructions printed on the control board. By proposing to 
change ``default airflow-control settings'' to ``specified airflow-
control settings,'' DOE intended to clarify that this refers to the 
manufacturer-specified settings for each testing mode.
    To provide clarity and resolve the conflicting instruction, in this 
final rule, DOE is finalizing its proposal to change the term ``default 
airflow-control settings'' to ``specified airflow-control settings'' 
and to add the phrase ``unless otherwise specified within the test 
procedure'' to the end the definition of ``specified airflow-control 
settings'' in section 2.9 of appendix AA.
b. Heating Airflow-Control Settings
    In the May 2022 NOPR, DOE stated that it expects that if a fan 
setting is identified for heating mode operation that the fan would be 
capable operating in that mode at the ESP specified in appendix AA 
(which is representative of a typical ESP that would be encountered in 
the field) and at the specified temperature rise range. DOE requested 
comment on whether it is necessary to specify that the maximum heating 
airflow-control setting used during

[[Page 25794]]

testing be one that also allows for operation within the manufacturer-
specified temperature rise range during testing. DOE also requested 
information regarding how often furnace fans operate outside of the 
manufacturer-specified temperature rise range during FER testing under 
the current requirements. 87 FR 29576, 29587.
    In response to the May 2022 NOPR, Lennox, Carrier, AHRI, and JCI 
suggested that the maximum heating airflow-control setting should allow 
for operation within the manufacturer's specified rise range during 
testing. (Lennox, No. 11 at p. 6; Carrier, No. 12 at p. 5; AHRI, No. 15 
at p. 6; JCI, No. 10 at p. 4) Carrier stated that it creates 
unnecessary confusion to require compliance otherwise. (Carrier, No. 12 
at p. 5) JCI commented that realistic FER ratings depend on operating 
the furnace in a realistic manner. JCI added that testing at heating 
speeds resulting in a temperature rise outside of the manufacturer-
specified range is not a realistic operating condition. (JCI, No. 10 at 
p. 4)
    DOE agrees with the commenters that the temperature rise during 
testing should be within the manufacturer-specified range. If the 
temperature rise were outside of the manufacturer-specified range, it 
would not be representative of typical performance. Therefore, in this 
final rule, DOE is adding clarification in section 8.6.3 of appendix AA 
that the maximum heating airflow-control setting used during testing be 
one that also allows for operation within the manufacturer-specified 
temperature rise range during testing.
c. Power Measurements
    Sections 8.6.1.1, 8.6.1.2, 8.6.2, and 8.6.3 of appendix AA require 
the following parameters to be measured after steady-state operation is 
achieved: the furnace fan electrical input power, fuel or electric 
resistance heat kit input energy, external static pressure, steady-
state efficiency, outlet air temperature, and/or temperature rise. DOE 
is aware that some test facilities take a single reading for each of 
these parameters after achieving the steady-state criteria. As noted in 
the May 2022 NOPR, in DOE testing, during which these parameters were 
measured in 1-second intervals throughout the steady-state period, data 
showed that the values fluctuate sometimes significantly between 
readings, even while steady-state conditions are maintained. 87 FR 
29576, 29588. Due to the potential for significant differences from one 
reading to the next, these fluctuations could contribute to 
repeatability issues in FER testing if a value from a single point in 
time is used for each test. In particular, DOE testing has shown that 
the standard deviation of furnace fan power measurements for most units 
over a 30-minute period (at steady state operation) can be up to 16 
percent of the average, although for most units the standard deviation 
is less than 1 percent of the average power consumption. DOE stated in 
the May 2022 NOPR that it was considering whether further 
clarifications are necessary for appendix AA to clarify how 
manufacturers should take power measurements. Specifically, DOE 
explained that that increasing the number of discrete measurements 
taken (i.e., increasing the sample size) and averaging them to 
determine each furnace fan power consumption measurement may yield a 
result that is more representative and repeatable than using single 
point measurements of the furnace fan power. Id. For example, DOE could 
require that power measurements be based on the average value over a 1-
minute interval beginning immediately after steady-state operation has 
been achieved, during which the power is measured at least once per 
second. Alternatively, DOE could require furnace fan power measurements 
to be based on the average of measurements taken over the entire 
steady-state period at certain specified intervals (e.g., every minute 
or every 5 minutes). Id.
    In the May 2022 NOPR, DOE requested data and information on the 
methods and granularity with which test facilities currently measure 
the aforementioned variables, particularly furnace fan power 
(EMax, ECirc, and EHeat). DOE also 
requested comment on the intervals at which test facilities are 
currently capable of recording these measurements with their current 
instrumentation. Finally, DOE requested information on whether there 
are variables aside from the fan power consumption variables for which 
there are significant fluctuations in measurements that DOE should also 
consider requiring be determined as an average of multiple 
measurements. Id. at 87 FR 29588-29589.
    DOE also requested comment on the number of samples that should be 
taken, and the length of time over which data should be collected in 
order for a representative average to be achieved. DOE requested 
comment on the associated costs, if any, to upgrade measurement 
instruments or software to be able to collect furnace fan power 
consumption measurements at frequencies of once per second, once per 
minute, once per 5 minutes, and/or other recommended sampling 
frequencies. Id. at 87 FR 29589.
    In response to the May 2022 NOPR, AHRI commented that the number of 
samples per period of time is dependent on the specific testing 
conditions; however, AHRI suggested that, generally, manufacturers take 
power samples every second for 30 seconds, and in alternative testing 
scenarios once every 2 seconds for 60 seconds to achieve representative 
averages. (AHRI, No. 15 at p. 6)
    Carrier, JCI, and AHRI recommended that short periods of average 
power measurements should be allowed for instrumentation accuracy and 
consistency. (Carrier, No. 12 at p. 5; Joint Commenters, No. 14 at pp. 
2-3; AHRI, No. 15 at p. 6) Carrier stated that airflow pressure 
measurements can fluctuate such that using a sample rate of one reading 
per second for 30 seconds or some other variation to obtain a several-
reading average would be preferred. (Carrier, No. 12 at pp. 5-6) AHRI 
commented that airflow pressure measurements especially have 
fluctuations that are improved using averaging techniques over multiple 
measurements and stated that the currently applicable test method on 
existing equipment does not have the capacity to automatically collect 
the requested data and information. AHRI noted that the test stand does 
not have significant fluctuations in data values. (AHRI, No. 15 at p. 
6) The Joint Commenters commented that DOE should consider requiring 
time-averaged values for other test variable measurements as well. 
(Joint Commenters, No. 14 at p. 3)
    Carrier stated that it has not evaluated the associated costs to 
upgrade lab infrastructure for more frequent readings. (Carrier, No. 12 
at p. 6)
    These stakeholder comments suggest that current laboratory setups 
are capable of reporting power data in 1-second intervals and averaging 
this reported data over the last thirty seconds of the furnace fan test 
without incurring additional cost or burden. Therefore, in this final 
rule, DOE is clarifying in section 8.6 of appendix AA that furnace fan 
electrical input power (EMax, ECirc, and 
EHeat) shall be determined using an average of the 
measurements taken over the final 30 seconds of the test at an interval 
no less frequent than every 1 second.
d. Other Language Clarifications
    The title of section 8.3 of appendix AA is ``Steady-State 
Conditions for Gas and Oil Furnaces,'' the title of section 8.4 is 
``Steady-State Conditions for Electric Furnaces and Modular

[[Page 25795]]

Blowers,'' and the title of section 8.5 of appendix AA is ``Steady-
State Conditions for Cold Flow Tests.'' Sections 8.3 and 8.4 describe 
the steady-state conditions for ``hot flow'' tests during which the 
burner or heating element is on, while section 8.5 describes the 
steady-state conditions for ``cold flow'' tests during which the burner 
or heating element is off.
    In the May 2022 NOPR, DOE proposed to amend the section titles to 
include the terminology ``for Hot Flow Tests'' in the titles to provide 
better consistency between the section titles and to provide clarity 
for the intended use of sections 8.3 and 8.4 of appendix AA. 87 FR 
29576, 29589. DOE did not receive any comments in response to this 
proposal. For the reasons discussed here and in the May 2022 NOPR, DOE 
is finalizing this change as proposed.
    DOE also proposed in the May 2022 NOPR to redesignate the 
description of operating-mode hours from ``cooling hours'' with 
variable ``CH'' to ``maximum airflow hours'' with variable ``MH.'' DOE 
tentatively concluded that these descriptions would be more accurate, 
as the maximum airflow-control setting is not necessarily a cooling 
airflow-control setting, and that this proposed change would provide 
consistency with the description of the operational mode and 
EMax measurement and avoid the implication that the maximum 
airflow-control setting will always be a cooling mode. Id.
    Finally, in the May 2022 NOPR, DOE proposed to add an asterisk 
prior to the statement ``once the specified ESP has been achieved, the 
same outlet duct restrictions shall be used for the remainder of the 
furnace fan test'' in section 8.6.1.2 of appendix AA to link this 
statement to the ESP column of table 1. Id. at 87 FR 29588. This change 
would clarify the appropriate duct restrictions for testing and not 
make any substantive changes. Id.
    DOE did not receive any comments in response to these proposals. 
Therefore, for the reasons discussed in this final rule and in the May 
2022 NOPR, DOE is finalizing these changes as proposed.

E. Nomenclature and Equations

    In response to comments submitted following the July 2021 RFI, DOE 
considered several changes to the nomenclature and equations in 
appendix AA. First, in the May 2022 NOPR, DOE noted the term 
Qi in appendix AA, which refers to the airflow control 
setting in airflow-control setting i, could lead to confusion as the 
subscript ``i'' has two different meanings: the airflow-control setting 
and the heat input setting. Id. at 87 FR 29589.
    DOE also evaluated revising the nomenclature for variables and 
conversion factors, including steady-state efficiency 
(``EffySS''), the specific volume of dry air 
(``vair''), jacket loss (``LJ''), airflow 
(``Qi''), the conversion factor from hours to minutes (60), 
the approximate specific heat of dry air (0.24), and the approximate 
specific heat capacity of saturated water vapor (0.44). Id. at 87 FR 
29589-29590.
    In the May 2022 NOPR, DOE noted that, should DOE adopt its proposal 
to measure airflow directly, the equations to calculate airflow would 
no longer be needed. Id. at 87 FR 29590. (However, as discussed in 
section III.D.3 of this document, DOE is not adopting its proposal to 
measure airflow directly and is instead maintaining the equations for 
calculating airflow.) Further, because the variable QIN,i 
would be relevant regardless of whether DOE ultimately adopts its 
proposal to directly measure airflow, DOE proposed to revise the 
variable QIN,i within the test procedure for furnace fans at 
appendix AA. Id. DOE also stated that should DOE not adopt the proposal 
to measure airflow directly, DOE would propose to include the following 
definitions in section 9 of appendix AA:

 60 = conversion factor from hours to minutes (min/h)
 0.24 = approximate specific heat capacity of dry air (Btu/lb-
[deg]F)
 0.44 = approximate specific heat capacity of saturated water 
vapor, (Btu/lb-[deg]F)
 Effyss,i = Steady-State Efficiency in airflow-
control setting i. For gas and oil furnaces, Effyss,i as 
specified in sections 11.2.7 (Non-Condensing and Non modulating), 
11.3.7.3 (Condensing and Non modulating), 11.4.8.8 (Non-Condensing and 
Modulating), or 11.5 (Condensing and Modulating) of ASHRAE 103-2017, in 
%. For electric furnaces or modular blowers, Effyss,i equals 
100, in %.
 LJ = jacket loss as determined as specified in 
section 8.6 of ASHRAE 103-2017 or a default value of 1% if the jacket 
loss test is not performed, in %.
 Ti,k, In = inlet air temperature at time of the 
electrical power measurement, in [deg]F, in airflow-control setting i 
and heat setting k, where i can be ``Circ'' to represent constant-
circulation (or minimum airflow) mode, ``Heat'' to represent heating 
mode, or ``Max'' to represent maximum airflow (typically designated for 
cooling) mode. If i = Heat, k can be ``H'' to represent the high heat 
setting or ``R'' to represent the reduced heat setting. If i = Max or 
Circ, k is not needed.
 Ti,k, Out = average outlet air temperature as 
measured by the outlet thermocouple grid at time of the electrical 
power measurement, in [deg]F, in airflow-control setting i and heat 
setting k, where i can be ``Circ'' to represent constant-circulation 
(or minimum airflow) mode, ``Heat'' to represent heating mode, or 
``Max'' to represent maximum airflow (typically designated for cooling) 
mode If i = Heat, k can be ``H'' to represent the high heat setting or 
``R'' to represent the reduced heat setting. If i = Max or Circ, k is 
not needed.
 [Delta]Ti,k = Ti,k, Out minus 
Ti,k, In, which is the air throughput temperature rise in 
setting i and heat setting k, in [deg]F
 Qi,k = airflow in airflow-control setting i and 
heat setting k, in cubic feet per minute (CFM)
 QIN,k = measured fuel energy input rate, in Btu/h, 
at specified operating conditions k based on the fuel's high heating 
value (HHV) determined as required in section 8.2.1.3 or 8.2.2.3 of 
ASHRAE 103-2017, where k can be ``H'' for the maximum heat setting or 
``R'' for the reduced heat setting
 vair = specific volume of dry air at specified 
operating conditions per chapter 1 of the 2021 ASHRAE Handbook in 
ft\3\/lb \12\
---------------------------------------------------------------------------

    \12\ The current version of appendix AA defines vair 
as ``the specific volume of dry air at specified operating 
conditions per the equations in the psychrometric chapter in the 
2001 ASHRAE Handbook in ft\3\/lb.'' DOE proposed an identical 
definition in the May 2022 NOPR. 87 FR 29576, 29591. However, the 
specific volume of dry air can be read from tables so, in this final 
rule, DOE is removing the reference to equations in this definition 
for clarity. Additionally, as previously discussed in section 
III.B.2 in this document, DOE is now incorporating by reference 
chapter 1 of the 2021 AHSRAE Handbook, which uses the same method to 
determine the specific volume of dry air as the psychrometric 
chapter of the 2001 ASHRAE Handbook.
---------------------------------------------------------------------------

Id.
    Further, DOE proposed to correct the conversion factor from watts 
to Btu/h to match the units designated for the fuel energy input rate 
(QIN,k), changing it from 3,413 to 3.413. Id. Finally, DOE 
noted that there should be different variables assigned to represent 
relative humidity and the humidity ratio. To provide clarity regarding 
these variables, DOE proposed to redesignate the variable for relative 
humidity from ``W'' to ``q.'' Id. at 87 FR 29590-29591.
    In response, AHRI and Carrier commented that ``W'' is defined as 
humidity ratio; therefore, it would not be necessary to change ``W'' to 
``q.'' (AHRI, No. 15 at p. 6; Carrier, No. 12 at p. 6) Lennox commented 
it agreed with adding definitions to certain variables

[[Page 25796]]

and constants as proposed and to change the conversion factor to (Btu/
h)/W. (Lennox, No. 11 at p. 7)
    With regards to the comments from AHRI and Carrier, while ``W'' is 
defined as the humidity ratio in section 9 of appendix AA, DOE notes 
that ``W'' is also defined as relative humidity in section 8.6.1 of 
appendix AA. To provide clarity and distinguish between the two terms, 
DOE is finalizing its proposal to designate ``q'' as the relative 
humidity in section 8.6.1 of appendix AA. For the reasons discussed in 
this final rule and in the May 2022 NOPR, DOE is finalizing the 
additional proposals regarding nomenclature and equation adjustments in 
appendix 9 of appendix AA, consistent with the proposals in the May 
2022 NOPR.

F. Thermocouple Accuracy

    Section 5.1 of appendix AA, which references section 5.1 of ASHRAE 
37-2009, requires that temperature-measuring instruments must be 
accurate to within 0.75 [deg]F. Section 6 of appendix AA references 
section 7 of ASHRAE 103-2007 for the test apparatus setup. Section 7.6 
of ASHRAE 103-2007 includes instructions to take temperature 
measurements with thermocouple grids constructed of either 5, 9, or 17 
thermocouples, depending on the stack diameter. The measurement 
accuracy of a thermocouple grid depends on the type and number of 
thermocouples used, as well as the magnitude of the air temperature 
being measured.
    In the May 2022 NOPR, DOE evaluated commenter feedback to the July 
2021 RFI and tentatively concluded that, assuming that the stack 
temperatures of gas furnaces would not likely exceed 450 [deg]F, 
current instrumentation is adequate to measure the stack temperature of 
furnaces on the market. Thus, DOE did not propose any changes to the 
accuracy of temperature-measuring instruments in appendix AA. 87 FR 
29576, 29591. DOE did not receive any comments in response to the May 
2022 NOPR. As a result, this final rule makes no changes to the 
specified accuracy of temperature measuring instruments in appendix AA.

G. Alternatives to the FER Metric

    In response to the May 2022 NOPR, AHRI stated that the FER metric 
may not be the most appropriate method for testing furnace fans. AHRI 
stated that furnace fans are not sold directly to consumers and 
consumers are generally unconcerned with FER values when selecting the 
best product for their application. AHRI stated that it would 
appreciate DOE working through concerns about this test procedure with 
manufacturers to achieve a workable solution. (AHRI, No. 15 at p. 4)
    Lennox stated that furnace fan standards do not impact consumer 
buying decisions for the furnaces in which residential furnace fans are 
used. Lennox added that when considering energy efficiency, consumers 
evaluate AFUE because it represents the majority of the energy use of a 
furnace, and furnace fans consume less than 2 percent of the overall 
energy use of a residential furnace. Lennox recommended that DOE 
explore less burdensome approaches regarding ensuring minimum furnace 
fan efficiency. Lennox added that there are limited opportunities for 
manufacturers to improve furnace fan energy efficiency and that it is 
not likely to be economically justified for non-weatherized and 
weatherized gas furnaces. (Lennox, No. 11 at p. 2)
    In response to the comments from AHRI and Lennox, DOE notes that 
AHRI and Lennox did not provide any specific suggestions as to an 
alternate test procedure that would better satisfy EPCA's requirement 
that the test procedure produce test results which measure energy 
efficiency, energy use, or estimated annual operating cost of a furnace 
fan during a representative average use cycle or period of use without 
being unduly burdensome to conduct. (42 U.S.C. 6293(b)(3)) Throughout 
this final rule, DOE has considered and responded to each comment 
received regarding specific aspects of the furnace fan test procedure. 
DOE has determined that the amended test procedure adopted in this 
final rule produces a representative measure of furnace fan energy 
efficiency and is not unduly burdensome to conduct. Regarding improved 
furnace fan efficiencies, DOE evaluates opportunities for increased 
efficiency as part of the separate energy conservation standards 
rulemaking for consumer furnace fans.\13\
---------------------------------------------------------------------------

    \13\ See docket ID EERE-2021-BT-STD-0029 on www.regulations.gov.
---------------------------------------------------------------------------

H. Test Procedure Costs

    EPCA requires that test procedures proposed by DOE not be unduly 
burdensome to conduct. (42 U.S.C. 6293(b)(3)) In this final rule, DOE 
is finalizing its proposals to amend the existing test procedure for 
consumer furnace fans by specifying a test method for furnace fans that 
operate at low ESPs, updating the incorporation by reference of certain 
industry test procedures to the most recent versions, clarifying the 
scope of the definition of ``furnace fans,'' tightening ambient 
conditions, clarifying language for airflow-control settings, 
clarifying nomenclature, and correcting typographical errors. As 
discussed in section III.D.3 of this document, DOE is not finalizing 
its proposal to require direct measurement of airflow in this final 
rule. DOE has determined that the amendments adopted in this final rule 
will not impact test costs, as discussed in the remainder of this 
section.
    In response to a petition for waiver and an application for interim 
waiver for heating-only furnace fans, DOE granted a waiver requiring 
use of an alternate test procedure that specifies alternate ESP test 
conditions for furnace fans that operate at low ESPs. Any such furnace 
fan models currently on the market have already been granted a test 
procedure waiver from DOE, which specifies use of the alternate test 
procedure. As such, incorporating a similar methodology as the waiver 
methodology into the test procedure for furnace fans that operate at 
low ESPs will not result in any additional costs for manufacturers.
    DOE is updating the material it incorporates by reference to 
include more recent versions of ASHRAE 103 and ASHRAE 37. DOE is also 
incorporating by reference chapter 1 of 2021 ASHRAE Handbook. As 
discussed previously, DOE's review of these standards indicates that 
reference to the revised versions of them will not impact FER ratings 
and will not require that manufacturers recertify their units. 
Therefore, manufacturers will not incur any additional costs.
    Defining and explicitly excluding dual-fuel furnace fans from the 
scope of appendix AA will make clear that such products are not subject 
to testing under appendix AA and will not impose any additional burden.
    In this final rule, DOE is also tightening ambient conditions to 
limit the permissible ambient temperature range to between 65 [deg]F 
and 85 [deg]F and the ambient humidity range to between 20 percent and 
80 percent for both condensing and non-condensing furnaces. As 
discussed, appendix AA currently already limits ambient temperatures to 
between 65 [deg]F and 85 [deg]F, as well as humidity to below 80 
percent for condensing furnaces, and DOE understands that testing 
laboratories are generally able to meet these criteria in their testing 
laboratories without the use of a specialized test chamber. 
Additionally, based on feedback received from Lennox, Carrier, JCI, and 
AHRI as outlined in section III.D.2 of this document and in 
confidential manufacturer interviews, DOE has

[[Page 25797]]

concluded that it is unlikely that test laboratories would be unable to 
meet a minimum relative humidity requirement of 20 percent because that 
limit would exclude only the driest conditions. Therefore, DOE expects 
that test laboratories will not incur additional cost in applying these 
same temperature tolerances to testing of non-condensing furnaces as 
well. These changes to the ambient condition requirements are intended 
to increase the accuracy of FER ratings and the consistency of test 
results but are not expected to change the actual performance of any 
units. Additionally, DOE will not require units that are currently 
certified to retest according to the updated test procedure.
    DOE's remaining changes (clarifying nomenclature and fixing 
typographic errors) will similarly not result in any changes to the 
test conduct and therefore will not affect the cost of testing. For 
these reasons, manufacturers will be able to rely on data generated 
under the test procedure in effect prior to the adoption of this 
amendment. However, if a manufacturer chooses to retest as a result of 
these test procedure amendments, DOE estimates a testing cost of $3,500 
per unit and a minimum total cost of $7,000 per basic model.

I. Effective and Compliance Dates

    The effective date for the adopted test procedure amendment will be 
75 days after publication of this final rule in the Federal Register. 
EPCA prescribes that all representations of energy efficiency and 
energy use, including those made on marketing materials and product 
labels, must be made in accordance with an amended test procedure, 
beginning 180 days after publication of the final rule in the Federal 
Register. (42 U.S.C. 6293(c)(2)) EPCA provides an allowance for 
individual manufacturers to petition DOE for an extension of the 180-
day period if the manufacturer may experience undue hardship in meeting 
the deadline. (42 U.S.C. 6293(c)(3)) To receive such an extension, 
petitions must be filed with DOE no later than 60 days before the end 
of the 180-day period and must detail how the manufacturer will 
experience undue hardship. (Id.)
    Upon the compliance date of test procedure provisions in this final 
rule, any waivers that had been previously issued and are in effect 
that pertain to issues addressed by such provisions are terminated. 10 
CFR 430.27(h)(3). Recipients of any such waivers are required to test 
the products subject to the waiver according to the amended test 
procedure as of the compliance date of the amended test procedure. The 
amendments adopted in this document pertain to issues addressed by 
waivers granted to ECR International, Inc. (Case number 2019-001). See 
86 FR 13530.

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866, 13563, and 14094

    Executive Order (``E.O.'') 12866, ``Regulatory Planning and 
Review,'' as supplemented and reaffirmed by E.O. 13563, ``Improving 
Regulation and Regulatory Review,'' 76 FR 3821 (Jan. 21, 2011), and 
amended by E.O. 14094, ``Modernizing Regulatory Review,'' 88 FR 21879 
(April 11, 2023), 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 this 
preamble, this final 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 final 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 a final regulatory flexibility analysis (``FRFA'') for 
any final rule where the agency was first required by law to publish a 
proposed rule 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 final rule under the 
provisions of the Regulatory Flexibility Act and the procedures and 
policies published on February 19, 2003. DOE has concluded that the 
rule would not have a significant impact on a substantial number of 
small entities. The factual basis for this certification is as follows.
    DOE used the Small Business Administration's (``SBA'') small 
business size standards to determine whether any small entities would 
be subject to the requirements of the rule. The size standards are 
listed by North American Industry Classification System (``NAICS'') 
code as well as by industry description and are available at 
www.sba.gov/document/support--table-size-standards. Manufacturing of 
consumer furnace fans is classified under NAICS 333415, ``Air-
Conditioning and Warm Air Heating Equipment and Commercial and 
Industrial Refrigeration Equipment Manufacturing.'' The SBA sets a 
threshold of 1,250 employees or fewer for an entity to be considered as 
a small business for this category.\14\
---------------------------------------------------------------------------

    \14\ U.S. Small Business Administration, ``Table of Size 
Standards'' (effective December 19, 2022). Available at: 
www.sba.gov/document/support-table-size-standards (last accessed 
January 23, 2022).
---------------------------------------------------------------------------

    DOE used available public information to identify potential small 
manufacturers. DOE reviewed the

[[Page 25798]]

Compliance Certification Database \15\ (``CCD''), the Modernized 
Appliance Efficiency Database System \16\ (``MAEDbS''), individual 
company websites, and prior consumer furnace fan energy conservation 
standards rulemakings to create a list of companies that import or 
otherwise manufacture the products covered by this final rule. DOE then 
consulted other publicly available data, such as manufacturer 
specifications and product literature, U.S. import and export data 
(e.g., Panjiva \17\) and basic model numbers, to identify OEMs of the 
products covered by this rulemaking. DOE further relied on public 
sources and subscription-based market research tools (e.g., Dun & 
Bradstreet reports \18\) to determine company location, headcount, and 
annual revenue. DOE screened out companies that do not offer products 
covered by this rulemaking, do not meet the SBA's definition of a 
``small business,'' or are foreign-owned and operated.
---------------------------------------------------------------------------

    \15\ U.S. Department of Energy, Compliance Certification 
Database. Available at: www.regulations.doe.gov/certification-data/#q=Product_Group_s%3A* (last accessed February 4, 2022).
    \16\ California Energy Commission, Modernized Appliance 
Efficiency Database System. Available at: 
cacertappliances.energy.ca.gov/Pages/ApplianceSearch.aspx (last 
accessed February 4, 2022).
    \17\ Panjiva: S&P Global. Available at: panjiva.com/import-export/United-States (last access January 20, 2023).
    \18\ The Dun & Bradstreet Hoovers subscription login is 
accessible online at app.dnbhoovers.com/ (last accessed January 20, 
2023).
---------------------------------------------------------------------------

    DOE identified 25 OEMs offering consumer furnace fans for the U.S. 
market. Of the 25 OEMs identified, DOE estimates that 8 companies 
qualify as small businesses and are not foreign-owned and operated.
    DOE did not receive written comments that specifically addressed 
impacts on small businesses or that were provided in response to the 
initial regulatory flexibility analysis.
    In this final rule, DOE is finalizing its proposals to amend the 
existing test procedure for consumer furnace fans by specifying a test 
method for furnace fans that operate at low ESPs, incorporating by 
reference the most recent industry test procedures, clarifying the 
scope of the definition of ``furnace fans,'' tightening ambient 
conditions, clarifying language for airflow-control settings, and 
clarifying nomenclature and correcting typographical errors. DOE is not 
finalizing its proposal to require direct measurement of airflow in 
this final rule. DOE has determined that the amendments adopted in this 
final rule will not impact test costs.
    In response to a petition for waiver and an application for interim 
waiver for heating-only furnace fans, DOE granted a waiver requiring 
use of an alternate test procedure that specifies alternate ESP test 
conditions for furnace fans that operate at low ESPs. Any such furnace 
fan models currently on the market have already been granted a test 
procedure waiver from DOE, which specifies use of the alternate test 
procedure. As such, incorporating a similar methodology as the waiver 
methodology into the test procedure for furnace fans that operate at 
low ESPs will not result in any additional costs for manufacturers. DOE 
is updating the material it incorporates by reference to include more 
recent versions of ASHRAE 103 and ASHRAE 37. DOE is also incorporating 
by reference chapter 1 of 2021 ASHRAE Handbook. As discussed 
previously, DOE's review of these standards indicates that reference to 
the newer versions of them will not impact FER and will not require 
that manufacturers recertify their units. Therefore, manufacturers will 
not incur any additional costs. Defining and explicitly excluding dual-
fuel furnace fans from the scope of appendix AA will make clear that 
such products are not subject to testing under appendix AA and will not 
impose any additional burden.
    DOE is also tightening ambient conditions to limit the permissible 
ambient temperature range to between 65 [deg]F and 85 [deg]F and the 
ambient humidity range to between 20 percent and 80 percent for both 
condensing and non-condensing furnaces. As discussed, appendix AA 
currently already limits ambient temperatures to between 65 [deg]F and 
85 [deg]F, as well as humidity to below 80 percent for condensing 
furnaces, and DOE understands that testing laboratories are generally 
able to meet these criteria in their testing laboratories without the 
use of a specialized test chamber. Additionally, DOE concluded that it 
is unlikely that test laboratories would be unable to meet a minimum 
requirement of 20 percent, because that limit would exclude only the 
driest conditions. Therefore, DOE expects that test laboratories will 
not incur additional cost in applying these same temperature tolerances 
to testing of non-condensing furnaces as well. These changes to the 
ambient condition requirements are intended to increase the accuracy of 
FER ratings and the consistency of test results but are not expected to 
change the actual performance of any units. DOE will not require units 
that are currently certified to retest according to the updated test 
procedure.
    DOE's remaining changes, which clarify nomenclature and fix 
typographic errors, will not result in any changes to the test conduct 
and therefore will not affect the cost of testing. For these reasons, 
manufacturers will be able to rely on data generated under the test 
procedure in effect prior to the adoption of this amendment.
    DOE has determined that the amendments described in section III of 
the final rule will not alter the measured efficiency of consumer 
furnace fans, or require retesting or recertification solely as a 
result of DOE's adoption of the amendments to the test procedures. 
Additionally, DOE has determined that the amendments will not increase 
the cost of testing. Therefore, DOE concludes that the cost effects 
accruing from the final rule would not have a ``significant economic 
impact on a substantial number of small entities,'' and that the 
preparation of a FRFA is not warranted. DOE has submitted a 
certification and supporting statement of factual basis to the Chief 
Counsel for Advocacy of the Small Business Administration for review 
under 5 U.S.C. 605(b).

C. Review Under the Paperwork Reduction Act of 1995

    Manufacturers of consumer furnace fans 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 furnace fans. (See generally 10 CFR part 429.) The collection-
of-information requirement for the certification and recordkeeping is 
subject to review and approval by OMB under the Paperwork Reduction Act 
(``PRA''). This requirement has been approved by OMB under OMB control 
number 1910-1400. Public reporting burden for the certification is 
estimated to average 35 hours per response, including the time for 
reviewing instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information.
    DOE is not amending the certification or reporting requirements for 
consumer furnace fans in this final rule.

[[Page 25799]]

    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 final rule, DOE establishes test procedure amendments that 
it expects will be used to develop and implement future energy 
conservation standards for consumer furnace fans. 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 examined this final 
rule and determined that it will 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 final 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, 
this final 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 regulatory action resulting 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 final 
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 final rule will 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 regulation will not 
result in any takings that might require compensation under the Fifth 
Amendment to the U.S. Constitution.

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

    Section 515 of the Treasury and General Government Appropriations 
Act, 2001 (44 U.S.C. 3516 note) provides for agencies to review most 
disseminations of information to the public under guidelines 
established by each agency pursuant to general guidelines issued by 
OMB. OMB's guidelines were published at 67 FR 8452 (Feb. 22, 2002), and 
DOE's guidelines were published at 67 FR 62446 (Oct. 7, 2002). Pursuant 
to OMB Memorandum M-19-15, Improving Implementation of the Information 
Quality Act (April 24, 2019), DOE published updated guidelines which 
are available at www.energy.gov/sites/prod/

[[Page 25800]]

files/2019/12/f70/
DOE%20Final%20Updated%20IQA%20Guidelines%20Dec%202019.pdf. DOE has 
reviewed this final 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 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 significant energy action, the 
agency must give a detailed statement of any adverse effects on energy 
supply, distribution, or use if the regulation is implemented, and of 
reasonable alternatives to the action and their expected benefits on 
energy supply, distribution, and use.
    This regulatory action 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.
    The modifications to the test procedure for consumer furnace fans 
adopted in this final rule incorporate testing methods contained in 
certain sections of the following commercial standards: ASHRAE 103-
2017, ASHRAE 37-2009 (RA 2019), and ASHRAE 41.1-1986 (RA 2006), as well 
as chapter 1 of the 2021 ASHRAE Handbook. 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 has consulted with both the Attorney General 
and the Chairman of the FTC about the impact on competition of using 
the methods contained in these standards and has received no comments 
objecting to their use.

M. Congressional Notification

    As required by 5 U.S.C. 801, DOE will report to Congress on the 
promulgation of this final rule before its effective date. The report 
will state that it has been determined that the rule is not a ``major 
rule'' as defined by 5 U.S.C. 804(2).

N. Description of Materials Incorporated by Reference

    ASHRAE Standard 37-2009 (RA 2019) is an industry-accepted test 
procedure that provides a method of test for many categories of air 
conditioning and heating equipment. ANSI/ASHRAE Standard 37-2009 (RA 
2019) is available on ANSI's website at webstore.ansi.org/RecordDetail.aspx?sku=ANSI%2FASHRAE+Standard+37-2009.
    ASHRAE 37-2009 Errata Sheet is a technical corrections sheet for 
ASHRAE 37-2009. The errata sheet for ASHRAE 37-2009 is reasonably 
available on ASHRAE's website at: www.ashrae.org/.
    ASHRAE 103-2017 is an industry-accepted test procedure for 
measuring the performance of consumer furnaces and boilers. Copies of 
ASHRAE 103-2017 may be purchased from ANSI at 1899 L Street, NW, 11th 
Floor, Washington DC 20036, or by going to webstore.ansi.org/standards/ashrae/ansiashrae1032017.
    The 2021 ASHRAE Handbook is an industry-accepted handbook that 
covers basic principles and data used in the heating, ventilation, air-
conditioning, and refrigeration industries. The 2021 ASHRAE Handbook is 
available on ASHRAE's website at www.ashrae.org/technical-resources/ashrae-handbook.
    The following standard was previously approved for incorporation by 
reference in the sections where it appears in this final rule and no 
change is made: ASHRAE 41.1-1986 (RA 2006).

V. Approval of the Office of the Secretary

    The Secretary of Energy has approved publication of this final 
rule.

List of Subjects in 10 CFR Part 430

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

Signing Authority

    This document of the Department of Energy was signed on March 25, 
2024, by Jeff Marootian, 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 April 5, 2024.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.

    For the reasons stated in the preamble, DOE amends 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. Amend Sec.  430.3 by:
0
a. In paragraph (g)(3), removing the text ``appendices AA, CC, and 
CC1'' and adding in its place the text ``appendices CC and CC1'';
0
b. Removing paragraph (g)(18);
0
c. Redesignating paragraphs (g)(19) through (22) as paragraphs (g)(20) 
through (23);
0
d. Redesignating paragraphs (g)(5) through (17) as paragraphs (g)(7) 
through (19), respectively;

[[Page 25801]]

0
e. Adding new paragraphs (g)(5) and (6);
0
f. In newly redesignated paragraph (g)(20), removing the text 
``appendices O and EE'' and adding in its place the text ``appendices 
O, AA, and EE''; and
0
g. Adding paragraph (g)(24).
    The additions read as follows:


Sec.  430.3  Materials incorporated by reference.

* * * * *
    (g) * * *
    (5) ANSI/ASHRAE Standard 37-2009 (RA 2019) (``ASHRAE 37-2009 (RA 
2019)''), Methods of Testing for Rating Electrically Driven Unitary 
Air-Conditioning and Heat Pump Equipment, ASHRAE-approved June 21, 
2019; IBR approved for appendix AA to subpart B.
    (6) ANSI/ASHRAE Standard 37-2009 Errata Sheet (``ASHRAE 37-2009 
Errata Sheet''), Errata Sheet for ANSI/ASHRAE Standard 37-2009--Methods 
of Testing for Rating Electrically Driven Unitary Air-Conditioning and 
Heat Pump Equipment, ASHRAE-approved March 27, 2019; IBR approved for 
appendix AA to subpart B.
* * * * *
    (24) 2021 ASHRAE Handbook--Fundamentals Inch-Pound Edition, Chapter 
1, ``Psychrometrics'' (``2021 ASHRAE Handbook''), copyright 2021; IBR 
approved for appendix AA to subpart B.
* * * * *

0
3. Appendix AA to subpart B of part 430 is revised to read as follows:

Appendix AA to Subpart B of Part 430--Uniform Test Method for Measuring 
the Energy Consumption of Furnace Fans

    Note: Prior to October 9, 2024, any representations with respect 
to energy use or efficiency of furnace fans must be made either in 
accordance with the results of testing pursuant to this appendix or 
with the results of testing pursuant to this appendix as it appeared 
in the 10 CFR parts 200-499 edition revised as of January 1, 2023. 
On or after October 9, 2024, any representations, including 
certifications of compliance, made with respect to the energy use or 
efficiency of furnace fans must be made in accordance with the 
results of testing pursuant to this appendix.

0. Incorporation by Reference

    DOE incorporated by reference in Sec.  430.3, the entire 
standard for ASHRAE 37-2009 (RA 2019), as corrected by the ASHRAE 
37-2009 Errata Sheet; ASHRAE 41.1-1986; as well as Chapter 1 of the 
2021 ASHRAE Handbook and ASHRAE 103-2017. In cases where there is a 
conflict, the language of the test procedure in this appendix takes 
precedence over the incorporated standards.
    1. Scope. This appendix covers the test requirements used to 
measure the energy consumption of fans used in weatherized and non-
weatherized gas furnaces, oil furnaces, electric furnaces, and 
modular blowers. This appendix does not apply to furnace fans used 
in dual-fuel units.
    2. Definitions. Definitions include the definitions as specified 
in section 3 of ASHRAE 103-2017 and the following additional 
definitions, some of which supersede definitions found in ASHRAE 
103-2017:
    2.1. Active mode means the condition in which the product in 
which the furnace fan is integrated is connected to a power source 
and circulating air through ductwork.
    2.2. Airflow-control settings are programmed or wired control 
system configurations that control a fan to achieve discrete, 
differing ranges of airflow--often designated for performing a 
specific function (e.g., cooling, heating, or constant 
circulation)--without manual adjustment other than interaction with 
a user-operable control such as a thermostat that meets the 
manufacturer specifications for installed-use. For the purposes of 
this appendix, manufacturer specifications for installed-use shall 
be found in the product literature shipped with the unit.
    2.3. Dual-fuel unit means a consumer product that includes both 
a heat pump and a burner in a single cabinet.
    2.4. External static pressure (ESP) means the difference between 
static pressures measured in the outlet duct and return air opening 
(or return air duct when used for testing) of the product in which 
the furnace fan is integrated.
    2.5. Furnace fan means an electrically-powered device used in a 
consumer product for the purpose of circulating air through 
ductwork.
    2.6. Modular blower means a product which only uses single-phase 
electric current, and which:
    (a) Is designed to be the principal air circulation source for 
the living space of a residence;
    (b) Is not contained within the same cabinet as a furnace or 
central air conditioner; and
    (c) Is designed to be paired with HVAC products that have a heat 
input rate of less than 225,000 Btu per hour and cooling capacity 
less than 65,000 Btu per hour.
    2.7. Off mode means the condition in which the product in which 
the furnace fan is integrated either is not connected to the power 
source or is connected to the power source but not energized.
    2.8. Seasonal off switch means a switch on the product in which 
the furnace fan is integrated that, when activated, results in a 
measurable change in energy consumption between the standby and off 
modes.
    2.9. Specified airflow-control settings are the airflow-control 
settings specified for installed-use by the manufacturer. For the 
purposes of this appendix, manufacturer specifications for 
installed-use are those specifications provided for typical consumer 
installations in the product literature shipped with the product in 
which the furnace fan is installed. In instances where a 
manufacturer specifies multiple airflow-control settings for a given 
function to account for varying installation scenarios, the highest 
airflow-control setting specified for the given function shall be 
used for the procedures specified in this appendix, unless otherwise 
specified within this test procedure.
    2.10. Standby mode means the condition in which the product in 
which the furnace fan is integrated is connected to the power source 
and energized, but the furnace fan is not circulating air.
    2.11. Thermal stack damper means a type of stack damper that 
opens only during the direct conversion of thermal energy of the 
stack gases.
    3. Classifications. Classifications are as specified in section 
4 of ASHRAE 103-2017.
    4. Requirements. Requirements are as specified in section 5 of 
ASHRAE 103-2017. In addition, Fan Energy Rating (FER) of furnace 
fans shall be determined using test data and estimated national 
average operating hours pursuant to section 10.1 of this appendix.
    5. Instruments. Instruments must be as specified in section 6, 
not including section 6.2, of ASHRAE 103-2017; and as specified in 
sections 5.1 and 5.2 of this appendix.
    5.1. Temperature. Temperature measuring instruments shall meet 
the provisions specified in section 5.1 of ASHRAE 37-2009 (RA 2019) 
(as corrected by the ASHRAE 37-2009 Errata Sheet), including the 
references to ASHRAE 41.1-1986, and shall be accurate to within 0.75 
degrees Fahrenheit (within 0.4 degrees Celsius).
    5.1.1. Outlet Air Temperature Thermocouple Grid. Outlet air 
temperature shall be measured as described in section 8.2.1.5.5 of 
ASHRAE 103-2017 and illustrated in Figure 2 of ASHRAE 103-2017. 
Thermocouples shall be placed downstream of pressure taps used for 
external static pressure measurement.
    5.2. Humidity. Air humidity shall be measured with a relative 
humidity sensor that is accurate to within 5% relative humidity. Air 
humidity shall be measured as close as possible to the inlet of the 
product in which the furnace fan is installed.
    6. Apparatus. The apparatus used in conjunction with the furnace 
during the testing shall be as specified in section 7 of ASHRAE 103-
2017 except for section 7.1, the second paragraph of sections 
7.2.2.2, 7.2.2.5, and 7.7, and as specified in sections 6.1, 6.2, 
6.3, 6.4, 6.5, and 6.6 of this appendix.
    6.1. General. The product in which the furnace fan is integrated 
shall be installed in the test room in accordance with the product 
manufacturer's written instructions that are shipped with the 
product unless required otherwise by a specific provision of this 
appendix. The apparatus described in this section is used in 
conjunction with the product in which the furnace fan is integrated. 
Each piece of the apparatus shall conform to material and 
construction specifications and the reference standard cited. Test 
rooms containing equipment shall have suitable facilities for 
providing the utilities necessary for performance of the test and be 
able to maintain conditions within the limits specified.
    6.2. Downflow furnaces. Install the internal section of vent 
pipe the same size as the flue collar for connecting the flue collar 
to the top

[[Page 25802]]

of the unit, if not supplied by the manufacturer. Do not insulate 
the internal vent pipe during steady-state test described in section 
9.1 of ASHRAE 103-2017. Do not insulate the internal vent pipe 
before the cool-down and heat-up tests described in sections 9.5 and 
9.6, respectively, of ASHRAE 103-2017. If the vent pipe is 
surrounded by a metal jacket, do not insulate the metal jacket. 
Install a 5-ft test stack of the same cross-sectional area or 
perimeter as the vent pipe above the top of the furnace. Tape or 
seal around the junction connecting the vent pipe and the 5-ft test 
stack. Insulate the 5-ft test stack with insulation having a minimum 
R-value of 7 and an outer layer of aluminum foil. (See Figure 3-E of 
ASHRAE 103-2017.)
    6.3. Modular Blowers. A modular blower shall be equipped with 
the electric heat resistance kit that is likely to have the largest 
volume of retail sales with that particular basic model of modular 
blower.
    6.4. Ducts and Plenums. Ducts and plenums shall be built to the 
geometrical specifications in section 7 of ASHRAE 103-2017 and 
section 6.7 of this appendix. An apparatus for measuring external 
static pressure shall be integrated in the plenum and test duct as 
specified in sections 6.4 of ASHRAE 37-2009 (RA 2019) (as corrected 
by the ASHRAE 37-2009 Errata Sheet), excluding specifications 
regarding the minimum length of the ducting and minimum distance 
between the external static pressure taps and product inlet and 
outlet, and section 6.5 of ASHRAE 37-2009 (RA 2019) (as corrected by 
the ASHRAE 37-2009 Errata Sheet). External static pressure measuring 
instruments shall be placed between the furnace openings and any 
restrictions or elbows in the test plenums or ducts. For all test 
configurations, external static pressure taps shall be placed 18 
inches from the outlet.
    6.4.1. For tests conducted using a return air duct. Additional 
external static pressure taps shall be placed 12 inches from the 
product inlet. Pressure shall be directly measured as a differential 
pressure as depicted in Figure 8 of ASHRAE 37-2009 (RA 2019) rather 
than determined by separately measuring inlet and outlet static 
pressure and subtracting the results.
    6.4.2. For tests conducted without a return air duct. External 
static pressure shall be directly measured as the differential 
pressure between the outlet duct static pressure and the ambient 
static pressure as depicted in Figure 7a of ASHRAE 37-2009 (RA 
2019).
    6.5. Air Filters. Air filters shall be removed.
    6.6. Electrical Measurement. Only electrical input power to the 
furnace fan (and electric resistance heat kit for electric furnaces 
and modular blowers) shall be measured for the purposes of this 
appendix. Electrical input power to the furnace fan and electric 
resistance heat kit shall be sub-metered separately. Electrical 
input power to all other electricity-consuming components of the 
product in which the furnace fan is integrated shall not be included 
in the electrical input power measurements used in the FER 
calculation. If the procedures of this appendix are being conducted 
at the same time as another test that requires metering of 
components other than the furnace fan and electric resistance heat 
kit, the electrical input power to the furnace fan and electric 
resistance heat kit shall be sub-metered separately from one another 
and separately from other electrical input power measurements.
    7. Test Conditions. The testing conditions shall be as specified 
in section 8, not including sections 8.5.2 and 8.6.1.1 of ASHRAE 
103-2017; and as specified in sections 7.1 and 7.2 of this appendix.
    7.1 Ambient Temperature and Humidity Conditions. During the time 
required to perform all tests, maintain the room temperature within 
5 [deg]F (2.8 [deg]C) of the air temperature value 
measured at the end of the steady-state performance test 
(TRA). For condensing furnaces and boilers, maintain the 
relative humidity within 5% of the relative humidity 
measured at the end of the steady-state performance test. During all 
tests, the room temperature shall not fall below 65 [deg]F (18.3 
[deg]C) or exceed 85 [deg]F (29.4 [deg]C) and the relative humidity 
shall not fall below 20% or exceed 80%.
    7.2. Measurement of Jacket Surface Temperature (optional). The 
jacket of the furnace or boiler shall be subdivided into 6-inch 
squares when practical, and otherwise into 36-square-inch regions 
comprising 4 in. x 9 in. or 3 in. x 12 in. sections, and the surface 
temperature at the center of each square or section shall be 
determined with a surface thermocouple. The 36-square-inch areas 
shall be recorded in groups where the temperature differential of 
the 36-square-inch area is less than 10 [deg]F for temperature up to 
100 [deg]F above room temperature and less than 20 [deg]F for 
temperature more than 100 [deg]F above room temperature. For forced 
air central furnaces, the circulating air blower compartment is 
considered as part of the duct system and no surface temperature 
measurement of the blower compartment needs to be recorded for the 
purpose of this test. For downflow furnaces, measure all cabinet 
surface temperatures of the heat exchanger and combustion section, 
including the bottom around the outlet duct, and the burner door, 
using the 36 square-inch thermocouple grid. The cabinet surface 
temperatures around the blower section do not need to be measured 
(see Figure 3-E of ASHRAE 103-2017.)
    8. Test Procedure. Testing and measurements shall be as 
specified in section 9 of ASHRAE 103-2017 except for sections 
9.1.2.1, 9.3, 9.5.1.1, 9.5.1.2.1, 9.5.1.2.2, 9.5.2.1, and section 
9.7.1; and as specified in sections 8.1 through 8.6 of this 
appendix.
    8.1. Direct Measurement of Off-Cycle Losses Testing Method. 
[Reserved]
    8.2. Measurement of Electrical Standby and Off Mode Power. 
[Reserved]
    8.3. Steady-State Conditions for Hot Flow Tests for Gas and Oil 
Furnaces. Steady-state conditions are indicated by an external 
static pressure within the range shown in table 1 to this appendix 
and a temperature variation in three successive readings, taken 15 
minutes apart, of not more than any of the following:
    (a) 3 [deg]F in the stack gas temperature for furnaces equipped 
with draft diverters;
    (b) 5 [deg]F in the stack gas temperature for furnaces equipped 
with either draft hoods, direct exhaust, or direct vent systems; and
    (c) 1 [deg]F in the flue gas temperature for condensing 
furnaces.
    8.4. Steady-State Conditions for Hot Flow Tests for Electric 
Furnaces and Modular Blowers. Steady-state conditions are indicated 
by an external static pressure within the range shown in table 1 to 
this appendix and a temperature variation of not more than 5 [deg]F 
in the outlet air temperature in four successive temperature 
readings taken 15 minutes apart.
    8.5. Steady-State Conditions for Cold Flow Tests. For tests 
during which the burner or electric heating elements are turned off 
(i.e., cold flow tests), steady-state conditions are indicated by an 
external static pressure within the range shown in table 1 to this 
appendix and a variation in the difference between outlet 
temperature and ambient temperature of not more than 3 [deg]F in 
three successive temperature readings taken 15 minutes apart.
    8.6. Fan Energy Rating (FER) Test.
    8.6.1. Initial FER test conditions and maximum airflow-control 
setting measurements. Measure the relative humidity (q) and dry bulb 
temperature (Tdb) of the test room.
    8.6.1.1. Furnace fans for which the maximum airflow-control 
setting is not a specified heating airflow-control setting. The main 
burner or electric heating elements shall be turned off. Adjust the 
external static pressure to within the range shown in table 1 to 
this appendix. Maintain these settings until steady-state conditions 
are attained as specified in sections 8.3, 8.4, and 8.5 of this 
appendix. Measure furnace fan electrical input power 
(EMax), external static pressure (ESPMax), and 
outlet air temperature (TMax,Out). The measurement of 
EMax shall be taken over the final 30 seconds of the 
steady-state period, at intervals of no less than 1 per second, and 
averaged over the 30 second period.
    8.6.1.2. Furnace fans for which the maximum airflow-control 
setting is a specified heating airflow-control setting. Adjust the 
main burner or electric heating element controls to the default heat 
setting designated for the maximum airflow-control setting. Burner 
adjustments shall be made as specified by section 8.4.1 of ASHRAE 
103-2017. Adjust the furnace fan controls to the maximum airflow-
control setting. Adjust the external static to within the range 
shown in table 1 to this appendix. Maintain these settings until 
steady-state conditions are attained as specified in sections 8.3, 
8.4, and 8.5 of this appendix and the temperature rise 
([Delta]TMax) is at least 18 [deg]F. Measure furnace fan 
electrical input power (EMax), fuel or electric 
resistance heat kit input energy (QIN,H), external static 
pressure (ESPMax), steady-state efficiency for this 
setting (EffySS,Max) as specified in sections 11.2 and 
11.3 of ASHRAE 103-2017, outlet air temperature 
(TMax,Out), and temperature rise 
([Delta]TMax). The measurement of EMax shall 
be taken over the final 30 seconds of the steady-state period, at 
intervals of no less than 1 per second, and averaged over the 30 
second period.

[[Page 25803]]



    Table 1--Required Minimum External Static Pressure in the Maximum
              Airflow-Control Setting by Installation Type
------------------------------------------------------------------------
                                                           ESP (in. wc.)
                    Installation type                            *
------------------------------------------------------------------------
Units with an internal, factory-installed evaporator           0.50-0.55
 coil...................................................
Units designed to be paired with an evaporator coil, but       0.65-0.70
 without one installed..................................
Mobile home.............................................       0.30-0.35
------------------------------------------------------------------------
* Once the specified ESP has been achieved, the same outlet duct
  restrictions shall be used for the remainder of the furnace fan test.
  If the unit under test is unable to complete the testing (i.e., the
  unit shuts down before completing a test), reduce the target ESP range
  by 0.05'' w.c. and restart the test. Repeat this process until the
  test can be completed.

    8.6.2. Constant circulation airflow-control setting 
measurements. The main burner or electric heating elements shall be 
turned off. The furnace fan controls shall be adjusted to the 
specified constant circulation airflow-control setting. If the 
manufacturer does not specify a constant circulation airflow-control 
setting in the installation and operations manual supplied with the 
unit, the lowest airflow-control setting shall be used. Maintain 
these settings until steady-state conditions are attained as 
specified in sections 8.3, 8.4, and 8.5 of this appendix. Measure 
furnace fan electrical input power (ECirc) and external 
static pressure (ESPCirc). The measurement of 
ECirc shall be taken over the final 30 seconds of the 
steady-state period, at intervals of no less than 1 per second, and 
averaged over the 30 second period.
    8.6.3. Heating airflow-control setting measurements. For single-
stage gas and oil furnaces, the burner shall be fired at the maximum 
heat input rate. For single-stage electric furnaces, the electric 
heating elements shall be energized at the maximum heat input rate. 
For multi-stage and modulating furnaces, the reduced heat input rate 
settings shall be used. Burner adjustments shall be made as 
specified by section 8.4.1 of ASHRAE 103-2017. After the burner is 
activated and adjusted or the electric heating elements are 
energized, the furnace fan controls shall be adjusted to operate the 
fan in the specified heating airflow-control setting that also 
allows for operation within the manufacturer-specified temperature 
rise range. In instances where a manufacturer specifies multiple 
airflow-control settings for a given function to account for varying 
installation scenarios, the highest airflow-control setting 
specified for the given function that also allows for operation 
within the manufacturer-specified temperature rise range shall be 
used. High heat and reduced heat shall be considered different 
functions for multi-stage heating units. Maintain these settings 
until steady-state conditions are attained as specified in sections 
8.3, 8.4, and 8.5 of this appendix and the temperature rise 
([Delta]THeat) is at least 18 [deg]F. Measure furnace fan 
electrical input power (EHeat), fuel or electric 
resistance heat kit input energy (QIN,k)external static 
pressure (ESPHeat), steady-state efficiency for this 
setting (EffySS) as specified in sections 11.2 and 11.3 
of ASHRAE 103-2017, outlet air temperature (THeat, Out) 
and temperature rise ([Delta]THeat). The measurement of 
EHeat shall be taken over the final 30 seconds of the 
steady-state period, at intervals of no less than 1 per second, and 
averaged over the 30 second period.
    9. Nomenclature. Nomenclature shall include the nomenclature 
specified in section 10 of ASHRAE 103-2017 and the following 
additional variables:

60 = conversion factor from hours to minutes, (min/h)
0.24 = approximate specific heat capacity of dry air, (Btu/lb-
[deg]F)
0.44 = approximate specific heat capacity of saturated water vapor, 
(Btu/lb-[deg]F)
EffySS,i = Steady-State Efficiency in airflow-control 
setting i. For gas and oil furnaces EffySS,i is specified 
in sections 11.2.7 (Non-Condensing and Modulating), 11.3.7.3 
(Condensing and Non-modulating), 11.4.8.8 (Non-Condensing and Non-
modulating), or 11.5 (Condensing and Modulating) of ASHRAE 103-2017, 
in %. For electric furnaces or modular blowers, EffySS,i 
equals 100, in %.
LJ = jacket loss as determined as specified in section 
8.6 of ASHRAE 103-2017 or a default value of 1% if the jacket loss 
test is not performed, in %
CCH = annual furnace fan constant-circulation hours
ECirc = furnace fan electrical consumption at the 
specified constant-circulation airflow-control setting (or minimum 
airflow-control setting operating point if a default constant-
circulation airflow-control setting is not specified), in watts
EHeat = furnace fan electrical consumption in the 
specified heat airflow-control setting for single-stage heating 
products or the specified low-heat setting for multi-stage heating 
products, in watts
EMax = furnace fan electrical consumption in the maximum 
airflow-control setting, in watts
ESPi = external static pressure, in inches water column, 
at time of the electrical power measurement in airflow-control 
setting i, where i can be ``Circ'' to represent constant-circulation 
(or minimum airflow) mode, ``Heat'' to represent heating mode, or 
``Max'' to represent cooling (or maximum airflow mode).
FER = fan energy rating, in watts/1000 cfm
HH = annual furnace fan heating operating hours
HCR = heating capacity ratio (nameplate reduced heat input capacity 
divided by nameplate maximum input heat capacity)
kref = physical descriptor characterizing the reference 
system
Tdb = dry bulb temperature of the test room in, [deg]F
Ti,k,in = inlet air temperature at time of the electrical 
power measurement, in [deg]F, in airflow-control setting i and heat 
setting k, where i can be ``Circ'' to represent constant-circulation 
(or minimum airflow) mode, ``Heat'' to represent heating mode, or 
``Max'' to represent maximum airflow (typically designated for 
cooling) mode. If i = Heat, k can be ``H'' to represent high heat 
setting or ``R'' to represent the reduced heat setting. If i = Max 
or Circ, k is not needed.
Ti,k,out = average outlet air temperature as measured by 
the outlet thermocouple grid at time of the electrical power 
measurement, in [deg]F, in airflow-control setting i and heat 
setting k, where i can be ``Circ'' to represent constant-circulation 
(or minimum airflow) mode, ``Heat'' to represent heating mode, or 
``Max'' to represent maximum airflow (typically designated for 
cooling) mode. If i = Heat, k can be ``H'' to represent high heat 
setting or ``R'' to represent the reduced heat setting. If i = Max 
or Circ, k is not needed.
[Delta]Ti,k = Ti,k,Out minus 
Ti,k,in, which is the air throughput temperature rise in 
setting i and heat setting k, in [deg]F
Qi,k = airflow in airflow-control setting i and heat setting k, in 
cubic feet per minute (CFM)
MH = annual furnace fan maximum airflow hours
QIN,k = nameplate fuel energy input rate, in Btu/h, at 
specified operating conditions k, based on the fuel's high heating 
value (``HHV'') determined as required in section 8.2.1.3 or 8.2.2.3 
of ASHRAE 103-2017, where k can be ``H'' for the maximum heat 
setting or ``R'' for the reduced heat setting.
W = humidity ratio in pounds water vapor per pounds dry air
vair = specific volume of dry air at specified operating 
conditions per the 2021 ASHRAE Handbook, in ft\3\/lb

    10. Calculation of derived results from test measurements for a 
single unit. Calculations shall be as specified in section 11 of 
ASHRAE 103-2017, except for appendices B and C; and as specified in 
sections 10.1 through 10.10 and Figure 1 of this appendix.
    10.1. Fan Energy Rating (FER)

[[Page 25804]]

[GRAPHIC] [TIFF OMITTED] TR12AP24.000

Where: QMax = QHeat for products for which the 
maximum airflow-control setting is a specified heat setting, or
[GRAPHIC] [TIFF OMITTED] TR12AP24.001

    For products for which the maximum airflow control setting is 
only designated for cooling; and
[GRAPHIC] [TIFF OMITTED] TR12AP24.002

    The estimated national average operating hours presented in 
table 2 to this appendix shall be used to calculate FER.

                  Table 2--Estimated National Average Operating Hour Values for Calculating FER
----------------------------------------------------------------------------------------------------------------
                                                                    Single-stage     Multi-stage or modulating
            Operating mode                       Variable              (hours)                (hours)
----------------------------------------------------------------------------------------------------------------
Heating...............................  HH.......................             830  830/HCR.
Maximum Airflow.......................  MH.......................             640  640.
Constant Circulation..................  CCH......................             400  400.
----------------------------------------------------------------------------------------------------------------

Where:
[GRAPHIC] [TIFF OMITTED] TR12AP24.003


[FR Doc. 2024-07620 Filed 4-11-24; 8:45 am]
BILLING CODE 6450-01-P