42270 Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 

DEPARTMENT OF ENERGY 

10 CFR Part 430 

[EERE–2019–BT–TP–0032] 

RIN 1904–AE77 

Energy Conservation Program: Test 

Procedure for Consumer Water 

Heaters and Residential-Duty 

Commercial Water Heaters 

AGENCY: Office of Energy Efficiency and 

Renewable Energy, Department of 

Energy. 

ACTION: Supplemental notice of 

proposed rulemaking and request for 

comment. 

SUMMARY: The U.S. Department of 

Energy (‘‘DOE’’) is publishing this 

supplemental notice of proposed 

rulemaking (‘‘SNOPR’’) to amend the 

test procedure for consumer water 

heaters and residential-duty commercial 

water heaters. This SNOPR updates the 

proposals presented in a notice of 

proposed rulemaking published in the 

Federal Register on January 11, 2022. In 

this SNOPR, DOE proposes additional 

amendments that would provide 

additional specificity regarding flow 

rate tolerances for water heaters with a 

rated storage volume of less than 2 

gallons; allow for voluntary 

representations at certain additionally 

specified test conditions for heat pump 

water heaters; revise the proposed 

specifications regarding separate storage 

tank requirements for certain types of 

water heaters; provide instructions for 

testing certain water heaters that store 

water at a temperature higher than the 

delivery setpoint; establish a metric and 

method for determining the effective 

storage volume of certain storage-type 

water heaters; and update the proposed 

methodology for estimating the internal 

tank temperature of water heaters which 

cannot be directly measured. DOE is 

seeking comment from interested parties 

on these proposals. 

DATES: DOE will accept comments, data, 

and information regarding this SNOPR 

no later than August 4, 2022. See 

section IV, ‘‘Public Participation,’’ for 

details. 

ADDRESSES: Comments: Interested 

persons are encouraged to submit 

comments using the Federal 

eRulemaking Portal at 

www.regulations.gov, under docket 

number EERE–2019–BT–TP–0032. 

Follow the instructions for submitting 

comments. Alternatively, interested 

persons may submit comments, 

identified by docket number EERE– 

2019–BT–TP–0032 and/or RIN 1904– 

AE77, by any of the following methods: 

(1) Email: WaterHeaters2019TP0032@

ee.doe.gov. Include docket number 

EERE–2019–BT–TP–0032 in the subject 

line of the message. 

(2) Postal Mail: Appliance and 

Equipment Standards Program, U.S. 

Department of Energy, Building 

Technologies Office, Mailstop EE–5B, 

1000 Independence Avenue SW, 

Washington, DC 20585–0121. 

Telephone: (202) 287–1445. If possible, 

please submit all items on a compact 

disc (‘‘CD’’), in which case it is not 

necessary to include printed copies. 

(3) Hand Delivery/Courier: Appliance 

and Equipment Standards Program, U.S. 

Department of Energy, Building 

Technologies Office, 950 L’Enfant Plaza 

SW, 6th Floor, Washington, DC 20024. 

Telephone: (202) 287–1445. If possible, 

please submit all items on a CD, in 

which case it is not necessary to include 

printed copies. 

No telefacsimiles (‘‘faxes’’) will be 

accepted. For detailed instructions on 

submitting comments and additional 

information on this process, see section 

V of this document (Public 

Participation). 

Docket: The docket for this activity, 

which includes Federal Register 

notices, public meeting/webinar 

attendee lists and transcripts, 

comments, and other supporting 

documents/materials, is available for 

review at www.regulations.gov. All 

documents in the docket are listed in 

the www.regulations.gov index. 

However, not all documents listed in 

the index may be publicly available, 

such as information that is exempt from 

public disclosure. 

The docket web page can be found at 

www.regulations.gov/docket?D=EERE2019-BT-TP-0032. The docket web page 

contains instructions on how to access 

all documents, including public 

comments, in the docket. See section V 

(Public Participation) for information on 

how to submit comments through 

www.regulations.gov. 

FOR FURTHER INFORMATION CONTACT: Ms. 

Julia Hegarty, U.S. Department of 

Energy, Office of Energy Efficiency and 

Renewable Energy, Building 

Technologies Office, EE–5B, 1000 

Independence Avenue SW, Washington, 

DC 20585–0121. Telephone: (202) 597– 

6737. Email: 

ApplianceStandardsQuestions@

ee.doe.gov. 

Mr. Eric Stas, U.S. Department of 

Energy, Office of the General Counsel, 

GC–33, 1000 Independence Avenue SW, 

Washington, DC 20585–0121. 

Telephone: (202) 586–5827. Email: 

Eric.Stas@hq.doe.gov. 

For further information on how to 

submit a comment, review other public 

comments and the docket, contact the 

Appliance and Equipment Standards 

Program staff at (202) 287–1445 or by 

email: ApplianceStandardsQuestions@

ee.doe.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Authority and Background 

A. Authority 

B. Background 

II. Synopsis of Proposed Amendments 

III. Discussion 

A. Flow Rate Tolerance Requirements 

B. Optional Test Conditions 

C. Storage Tank Over-Heating 

1. Testing in Over-Heated Mode 

2. Effective Storage Volume 

D. Separate Storage Tank Requirements 

E. Method for Determining Internal Tank 

Temperature for Certain Water Heaters 

IV. Procedural Issues and Regulatory Review 

A. Review Under Executive Orders 12866 

and 13563 

B. Review Under the Regulatory Flexibility 

Act 

C. Review Under the Paperwork Reduction 

Act of 1995 

D. Review Under the National 

Environmental Policy Act of 1969 

E. Review Under Executive Order 13132 

F. Review Under Executive Order 12988 

G. Review Under the Unfunded Mandates 

Reform Act of 1995 

H. Review Under the Treasury and General 

Government Appropriations Act, 1999 

I. Review Under Executive Order 12630 

J. Review Under Treasury and General 

Government Appropriations Act, 2001 

K. Review Under Executive Order 13211 

L. Review Under Section 32 of the Federal 

Energy Administration Act of 1974 

V. Public Participation 

VI. Approval of the Office of the Secretary 

I. Authority and Background 

Consumer water heaters are included 

in the list of ‘‘covered products’’ for 

which DOE is authorized to establish 

and amend energy conservation 

standards and test procedures. (42 

U.S.C. 6292(a)(4)) DOE’s energy 

conservation standards and test 

procedures for consumer water heaters 

are currently prescribed respectively at 

Title 10 of the Code of Federal 

Regulations (‘‘CFR’’), part 430 section 

32(d), and 10 CFR part 430, subpart B, 

appendix E (‘‘appendix E’’), Uniform 

Test Method for Measuring the Energy 

Consumption of Water Heaters. 

Residential-duty commercial water 

heaters, for which DOE is also 

authorized to establish and amend 

energy conservation standards and test 

procedures (42 U.S.C. 6311(1)(K)), must 

also be tested according to appendix E. 

10 CFR 431.106(b)(1) (See 42 U.S.C. 

6295(e)(5)(H)). DOE’s energy 

conservation standards for residentialduty commercial water heaters are 

currently prescribed at 10 CFR 


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Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 42271 

1All references to EPCA in this document refer 

to the statute as amended through Energy Act of 

2020, Pub. L. 116–260 (Dec. 27, 2020), which reflect 

the last statutory amendments that impact Parts A 

and A–1 of EPCA. 

2For editorial reasons, upon codification in the 

U.S. Code, Part B was redesignated Part A. 

3For editorial reasons, upon codification in the 

U.S. Code, Part C was redesignated Part A–1. 

4 IEC 62301, Household electrical appliances— 

Measurement of standby power (Edition 2.0, 2011– 

01). 

5 IEC 62087, Methods of measurement for the 

power consumption of audio, video, and related 

equipment (Edition 3.0, 2011–04). 

6The initial thermal efficiency and standby loss 

test procedures for commercial water heating 

equipment (including residential-duty commercial 

water heaters) were added to EPCA by the Energy 

Policy Act of 1992 (EPACT 1992), Public Law 102– 

486, and corresponded to those referenced in the 

ASHRAE and Illuminating Engineering Society of 

North America (IESNA) Standard 90.1–1989 (i.e., 

ASHRAE Standard 90.1–1989). (42 U.S.C. 

6314(a)(4)(A)) DOE subsequently updated the 

commercial water heating equipment test 

procedures on two separate occasions—once in a 

direct final rule published on October 21, 2004, and 

again in a final rule published on May 16, 2012. 

These rules incorporated by reference certain 

sections of the latest versions of American National 

Standards Institute (ANSI) Standard Z21.10.3, Gas 

Water Heaters, Volume III, Storage Water Heaters 

with Input Ratings Above 75,000 Btu Per Hour, 

Circulating and Instantaneous, available at the time 

(i.e., ANSI Z21.10.3–1998 and ANSI Z21.10.3–2011, 

respectively). 69 FR 61974, 61983 (Oct. 21, 2004) 

and 77 FR 28928, 28996 (May 16, 2012). 

431.110(b)(1). The following sections 

discuss DOE’s authority to establish and 

amend test procedures for consumer 

water heaters and residential-duty 

commercial water heaters, as well as 

relevant background information 

regarding DOE’s consideration of test 

procedures for these products and 

equipment. 

A. Authority 

The Energy Policy and Conservation 

Act, as amended (‘‘EPCA’’),1 authorizes 

DOE to regulate the energy efficiency of 

a number of consumer products and 

certain industrial equipment. (42 U.S.C. 

6291–6317, as codified) Title III, Part B 2

of EPCA established the Energy 

Conservation Program for Consumer 

Products Other Than Automobiles, 

which sets forth a variety of provisions 

designed to improve energy efficiency. 

(42 U.S.C. 6291–6309, as codified) 

These products include consumer water 

heaters, one of the subjects of this 

document. (42 U.S.C. 6292(a)(4)) Title 

III, Part C 3 of EPCA, added by Public 

Law 95–619, Title IV, section 441(a), 

established the Energy Conservation 

Program for Certain Industrial 

Equipment, which again sets forth a 

variety of provisions designed to 

improve energy efficiency. (42 U.S.C. 

6311–6317, as codified) This equipment 

includes residential-duty commercial 

water heaters, which are also the subject 

of this document. (42 U.S.C. 6311(1)(k)) 

The energy conservation program 

under EPCA consists essentially of four 

parts: (1) testing, (2) labeling, (3) Federal 

energy conservation standards, and (4) 

certification and enforcement 

procedures. Relevant provisions of 

EPCA specifically include definitions 

(42 U.S.C. 6291; 42 U.S.C. 6311), test 

procedures (42 U.S.C. 6293; 42 U.S.C. 

6314), labeling provisions (42 U.S.C. 

6294; 42 U.S.C. 6315), energy 

conservation standards (42 U.S.C. 6295; 

42 U.S.C. 6313), and the authority to 

require information and reports from 

manufacturers (42 U.S.C. 6296; 42 

U.S.C. 6316). 

The Federal testing requirements 

consist of test procedures that 

manufacturers of covered products and 

commercial equipment must use as the 

basis for: (1) certifying to DOE that their 

products/equipment comply with the 

applicable energy conservation 

standards adopted pursuant to EPCA (42 

U.S.C. 6295(s); 42 U.S.C. 6296; 42 U.S.C. 

6316(a)–(b)), and (2) making other 

representations about the efficiency of 

those consumer products (42 U.S.C. 

6293(c); 42 U.S.C. 6314(d)). Similarly, 

DOE must use these test procedures to 

determine whether the products comply 

with relevant standards promulgated 

under EPCA. (42 U.S.C. 6295(s)) 

Federal energy efficiency 

requirements for covered products and 

equipment established under EPCA 

generally supersede State laws and 

regulations concerning energy 

conservation testing, labeling, and 

standards. (42 U.S.C. 6297(a)–(c); 42 

U.S.C. 6316(a)–(b)) DOE may, however, 

grant waivers of Federal preemption in 

limited circumstances for particular 

State laws or regulations, in accordance 

with the procedures and other 

provisions of EPCA. (42 U.S.C. 6297(d); 

42 U.S.C. 6316(a); 42 U.S.C. 

6316(b)(2)(D)) 

Under 42 U.S.C. 6293, EPCA sets forth 

the criteria and procedures DOE must 

follow when prescribing or amending 

test procedures for covered products. 

Specifically, EPCA requires that any test 

procedures prescribed or amended shall 

be reasonably designed to produce test 

results which measure energy 

efficiency, energy use, or estimated 

annual operating cost of a covered 

product during a representative average 

use cycle or period of use and not be 

unduly burdensome to conduct. (42 

U.S.C. 6293(b)(3)) Under 42 U.S.C. 6314, 

the statute sets forth the criteria and 

procedures DOE must follow when 

prescribing or amending test procedures 

for covered equipment, reciting similar 

requirements at 42 U.S.C. 6314(a)(2). 

In addition, the Energy Independence 

and Security Act of 2007 (EISA 2007) 

amended EPCA to require that DOE 

amend its test procedures for all covered 

consumer products to integrate 

measures of standby mode and off mode 

energy consumption. (42 U.S.C. 

6295(gg)(2)(A)) Standby mode and off 

mode energy consumption must be 

incorporated into the overall energy 

efficiency, energy consumption, or other 

energy descriptor for each covered 

product unless the current test 

procedures already account for and 

incorporate standby and off mode 

energy consumption or such integration 

is technically infeasible. (42 U.S.C. 

6295(gg)(2)(A)(i)–(ii)) If an integrated 

test procedure is technically infeasible, 

DOE must prescribe a separate standby 

mode and off mode energy use test 

procedure for the covered product, if 

technically feasible. (42 U.S.C. 

6295(gg)(2)(A)(ii)) Any such amendment 

must consider the most current versions 

of the International Electrotechnical 

Commission (IEC) Standard 62301 4 and 

IEC Standard 62087,5 as applicable. (42 

U.S.C. 6295(gg)(2)(A)) 

The American Energy Manufacturing 

Technical Corrections Act (AEMTCA), 

Pub. L. 112–210, further amended EPCA 

to require that DOE establish a uniform 

efficiency descriptor and accompanying 

test methods to replace the energy factor 

(EF) metric for covered consumer water 

heaters and the thermal efficiency (TE) 

and standby loss (SL) metrics for 

commercial water-heating equipment 6

within one year of the enactment of 

AEMTCA. (42 U.S.C. 6295(e)(5)(B)–(C)) 

The uniform efficiency descriptor and 

accompanying test method were 

required to apply, to the maximum 

extent practicable, to all water-heating 

technologies in use at the time and to 

future water-heating technologies, but 

could exclude specific categories of 

covered water heaters that do not have 

residential uses, can be clearly 

described, and are effectively rated 

using the TE and SL descriptors. (42 

U.S.C. 6295(e)(5)(F) and (H)) In 

addition, beginning one year after the 

date of publication of DOE’s final rule 

establishing the uniform descriptor, the 

efficiency standards for covered water 

heaters were required to be 

denominated according to the uniform 

efficiency descriptor established in the 

final rule (42 U.S.C. 6295(e)(5)(D)); and 

for affected covered water heaters tested 

prior to the effective date of the test 

procedure final rule, DOE was required 

to develop a mathematical factor for 

converting the measurement of their 

energy efficiency from the EF, TE, and 

SL metrics to the new uniform energy 


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42272 Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 

7For covered, equipment, if the Secretary 

determines that a test procedure amendment is 

warranted, the Secretary must publish proposed test 

procedures in the Federal Register, and afford 

interested persons an opportunity (of not less than 

45 days’ duration) to present oral and written data, 

views, and arguments on the proposed test 

procedures. (42 U.S.C. 6314(b)) 

8ASHRAE Standard 41.1–2020, ‘‘Standard 

Methods for Temperature Measurement,’’ approved 

June 30, 2020. 

9ASHRAE Standard 41.6–2014, ‘‘Standard 

Method for Humidity Measurement,’’ ANSI 

approved July 3, 2014. 10ASHRAE Standard 118.2–2022, ‘‘Method of 

Testing for Rating Residential Water Heaters and 

Residential-Duty Commercial Water Heaters,’’ ANSI 

approved March 1, 2022. 11ASTM Standard D2156–09 (RA 2018), 

‘‘Standard Test Method for Smoke Density in Flue 

Gases from Burning Distillate Fuels,’’ reapproved 

October 1, 2018. 

12ASTM Standard E97–1987 (W 1991), ‘‘Standard 

Test Methods for Directional Reflectance Factor, 45- 

Deg 0-Deg, of Opaque Specimens by Broad-Band 

Filter Reflectometry,’’ approved January 1987, 

withdrawn 1991. Referenced by ASTM Standard 

D2156–09 (RA 2018). 

13A correction was published in the Federal 

Register on January 19, 2022, to properly reflect the 

date of the public meeting to discuss the test 

procedure NOPR. 87 FR 2731. 

descriptor. (42 U.S.C. 6295(e)(5)(E)(i)– 

(ii)) 

EPCA also requires that, at least once 

every 7 years, DOE evaluate test 

procedures for each type of covered 

product or equipment, including 

consumer water heaters and residentialduty commercial water heaters, to 

determine whether amended test 

procedures would more accurately or 

fully comply with the requirements for 

the test procedures to not be unduly 

burdensome to conduct and be 

reasonably designed to produce test 

results that reflect energy efficiency, 

energy use, and estimated operating 

costs during a representative average 

use cycle (or, additionally, period of use 

for consumer products). (42 U.S.C. 

6293(b)(1)(A); 42 U.S.C. 6314(a)(1)(A)) 

If the Secretary determines, on her 

own behalf or in response to a petition 

by any interested person, that a test 

procedure should be prescribed or 

amended, the Secretary shall promptly 

publish in the Federal Register 

proposed test procedures and afford 

interested persons an opportunity to 

present oral and written data, views, 

and arguments with respect to such 

procedures. (42 U.S.C. 6293(b)(2); 42 

U.S.C. 6314(b)) The comment period on 

a proposed rule to amend a test 

procedure shall be at least 60 days 7 and 

may not exceed 270 days. (42 U.S.C. 

6293(b)(2)) In prescribing or amending a 

test procedure, the Secretary shall take 

into account such information as the 

Secretary determines relevant to such 

procedure, including technological 

developments relating to energy use or 

energy efficiency of the type (or class) 

of covered products involved. (42 U.S.C. 

6293(b)(2)) If DOE determines that test 

procedure revisions are not appropriate, 

DOE must publish in the Federal 

Register its determination not to amend 

the test procedures. (42 U.S.C. 

6293(b)(1)(A)(ii) and 42 U.S.C. 

6314(a)(1)(A)(ii)) 

DOE is conducting this rulemaking in 

satisfaction of the 7-year-lookback 

review requirement specified in EPCA. 

(42 U.S.C. 6293(b)(1)(A) and 42 U.S.C. 

6314(a)(1)(A)) 

B. Background 

On January 11, 2022, DOE published 

in the Federal Register a notice of 

proposed rulemaking (‘‘January 2022 

NOPR’’) in which the Department 

proposed to update appendix E, and 

related sections of the CFR, as follows: 

(1) Incorporate by reference current 

versions of industry standards referenced by 

the current and proposed DOE test 

procedures: American Society of Heating, 

Refrigerating, and Air-Conditioning 

Engineers (ASHRAE) Standard 41.1,8

ASHRAE Standard 41.6,9 the pending update 

to ASHRAE Standard 118.2 10 (contingent on 

it being substantively the same as the draft 

which was under review), ASTM 

International (ASTM) D2156,11 and ASTM 

E97.12

(2) Add definitions for ‘‘circulating water 

heater,’’ ‘‘low temperature water heater,’’ and 

‘‘tabletop water heater.’’ 

(3) Specify how a mixing valve should be 

installed when the water heater is designed 

to operate with one. 

(4) Modify flow rate requirements during 

the FHR test for water heaters with a rated 

storage volume less than 20 gallons. 

(5) Modify timing of the first measurement 

in each draw of the 24-hour simulated-use 

test. 

(6) Clarify the determination of the first 

recovery period. 

(7) Clarify the mass of water to be used to 

calculate recovery efficiency. 

(8) Modify the terminology throughout 

appendix E to explicitly state ‘‘non-flow 

activated’’ and ‘‘flow-activated’’ water heater, 

where appropriate. 

(9) Clarify the descriptions of defined 

measured values for the standby period 

measurements. 

(10) Modify the test condition 

specifications and tolerances, including 

electric supply voltage tolerance, ambient 

temperature, ambient dry bulb temperature, 

ambient relative humidity, standard 

temperature and pressure definition, gas 

supply pressure, and manifold pressure. 

(11) Add provisions to address gas-fired 

water heaters with measured fuel input rates 

that deviate from the certified input rate. 

(12) Clarify provisions for calculating the 

volume or mass delivered. 

(13) Add specifications for testing for the 

newly defined ‘‘low temperature water 

heaters.’’ 

(14) Clarify testing requirements for the 

heat pump part of a split-system heat pump 

water heater. 

(15) Define the use of a separate unfired 

hot water storage tank for testing water 

heaters designed to operate with a separately 

sold hot water storage tank. 

(16) Clarify that any connection to an 

external network or control be disconnected 

during testing. 

(17) Add procedures for estimating internal 

stored water temperature for water heater 

designs in which the internal tank 

temperature cannot be directly measured. 

(18) Modify the provisions for untested 

water heater basic models within 10 CFR 

429.70(g) to include electric instantaneous 

water heaters. 

87 FR 1554, 1558.13

DOE received written comments in 

response to the January 2022 NOPR 

pertinent to the issues discussed in this 

SNOPR from the interested parties listed 

in Table III.1 of this document. In this 

SNOPR, DOE is maintaining the 

proposals from the January 2022 NOPR 

with modifications as discussed in this 

SNOPR and will address comments on 

any remaining topics in a future test 

procedure final rule. 

TABLE III.1—LIST OF COMMENTERS WITH WRITTEN SUBMISSIONS IN RESPONSE TO THE JANUARY 2022 NOPR RELEVANT

TO TOPICS COVERED IN THIS SNOPR 

Commenter(s) Reference in this 

SNOPR 

Comment No. 

in Docket Commenter type 

A.O. Smith Corporation .................................................................... A.O. Smith ............. 37 Manufacturer. 

Air Conditioning, Heating, and Refrigeration Institute ...................... AHRI ...................... 40 Trade Association. 

Appliance Standards Awareness Project, American Council for 

and Energy-Efficient Economy, National Consumer Law Center.

Joint Advocates ..... 34 Efficiency Advocacy Organizations. 

Bradford White Corporation .............................................................. BWC ...................... 33 Manufacturer. 


jspears on DSK121TN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 42273 

14The parenthetical reference provides a 

reference for information located in the docket of 

DOE’s rulemaking to develop test procedures for 

consumer water heaters and residential-duty 

commercial water heaters. (Docket No. EERE–2019– 

BT–TP–0032, which is maintained at 

www.regulations.gov). The references are arranged 

as follows: (commenter name, comment docket ID 

number, page of that document). 

TABLE III.1—LIST OF COMMENTERS WITH WRITTEN SUBMISSIONS IN RESPONSE TO THE JANUARY 2022 NOPR RELEVANT

TO TOPICS COVERED IN THIS SNOPR—Continued 

Commenter(s) Reference in this 

SNOPR 

Comment No. 

in Docket Commenter type 

Pacific Gas and Electric Company, San Diego Gas and Electric, 

and Southern California Edison; collectively, the California Investor-Owned Utilities.

CA IOUs ................ 36 Utilities. 

Jim Lutz ............................................................................................ Lutz ........................ 35 Individual. 

New York State Energy Research and Development Authority ...... NYSERDA ............. 32 State Agency. 

Northwest Energy Efficiency Alliance ............................................... NEEA ..................... 30 Efficiency Advocacy Organization. 

Rheem Manufacturing Company ...................................................... Rheem ................... 31 Manufacturer. 

As discussed, this SNOPR addresses 

only those comments related to the 

proposals laid out in this document; all 

other relevant comments will be 

addressed in a future stage of the 

rulemaking. A parenthetical reference at 

the end of a comment quotation or 

paraphrase provides the location of the 

item in the public record.14

II. Synopsis of Proposed Amendments 

DOE’s proposed actions in this 

SNOPR are summarized in Table II.1 of 

this document as compared to the 

January 2022 TP NOPR. Reasons for 

each proposed change are also 

explained in summary. 

TABLE II.1—SUMMARY OF PROPOSED CHANGES ADDRESSED IN THIS SNOPR 

January 2022 NOPR proposal SNOPR Attribution 

Proposed that flow rates for all water heaters 

with rated storage volume less than 2 gallons 

must be maintained within a tolerance of 

±0.25 gallons per minute.

Additionally proposes that for water heaters 

with rated storage volume less than 2 gallons and a rated Max GPM of less than 1 

gallon per minute, the flow rate tolerance 

shall be ±25 percent of the rated Max GPM.

Improve repeatability and reproducibility of the 

test procedure. 

Did not propose to allow for optional efficiency 

representations at alternative test conditions 

for heat pump water heaters.

Proposes to allow for optional efficiency representations at alternative test conditions 

for heat pump water heaters.

Harmonize with current industry testing practices. 

Did not propose a definition for split-system 

heat pump water heaters.

Proposes a definition for split-system heat 

pump water heaters to distinguish these 

from heat pump-only water heaters.

Provide additional clarity to application of test 

conditions for heat pump water heaters. 

Proposed to define ‘‘circulating water heaters’’ 

and require that such products be tested 

using an 80 gallon (±1 gallon) unfired hot 

water storage tank (‘‘UFHWST’’) that meets 

the energy conservation standards for an 

unfired hot water storage tank at 10 CFR 

431110(a).

Proposes that gas-fired circulating water heaters be tested using a UFHWST with a storage volume between 80 and 120 gallons 

and an R-value exactly at the minimum Rvalue required at 10 CFR 431110(a), and 

that heat pump circulating water heaters be 

tested using a 40-gallon electric resistance 

water heater at the minimum UEF standard 

required at 10 CFR 43032(d).

Improve representativeness of test methodology for circulating water heaters. 

Proposed to continue to specify that water 

heaters with multiple modes of operation be 

tested in the ‘‘default’’ or other similarly 

named mode as currently required by Appendix E.

Proposes that water heaters (with the exception of demand-response water heaters) 

with user-selectable modes to ‘‘over-heat’’ 

the water stored in the tank to increase effective capacity be tested at the highest internal tank temperature that can be 

achieved while maintaining the outlet water 

temperature at 125 ± 5 °F If no such overheated mode exists, the unit is to be tested 

in a default mode.

Improve representativeness of test methodology for water heaters with user-selectable 

overheated storage tank modes. 

Did not include a definition for ‘‘demand-response water heater’’.Proposes to define ‘‘demand-response water 

heater’’ based on the ENERGY STAR 

specification v5.0 definition for connected 

water heating product, with the additional 

requirement that demand-response water 

heaters cannot over-heat as a result of 

user-initiated operation.

Clarify the test methods for products with demand-response utility, 

Did not include any proposal related to the effective storage volume of storage-type water 

heaters.

Proposes to establish a metric and method for 

determining the effective storage volume of 

storage-type water heaters.

Adopt a metric to provide additional information to consumers on product performance. 


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42274 Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 

15 DOE consulted its public Certification 

Compliance Database (Available at: 

www.regulations.doe.gov/certification-data/CCMS– 

4-Water_Heaters.html#q=Product_Group_

s%3A%22Water%20Heaters%22). 

TABLE II.1—SUMMARY OF PROPOSED CHANGES ADDRESSED IN THIS SNOPR—Continued 

January 2022 NOPR proposal SNOPR Attribution 

Proposed a method of determining the internal 

storage tank temperature (for water heaters 

with rated storage volume greater than or 

equal to 2 gallons which cannot be directly 

measured) based on an assumption that the 

mean tank temperature is approximately the 

average of the inlet water temperature and 

the outlet water temperature.

Proposes a method of determining the internal storage tank temperature using draws 

at the beginning and end of the 24-hour 

simulated use test.

Adopt a test method for certain water heaters 

which cannot be directly measured. 

III. Discussion 

A. Flow Rate Tolerance Requirements 

In this SNOPR, DOE proposes to 

supplement the proposal presented in 

the January 2022 NOPR regarding 

specified flow rate tolerances for water 

heaters with a rated storage volume 

under 2 gallons. 

Section 5.4 of appendix E provides 

instructions for conducting the 24-hour 

simulated-use test for the determination 

of the uniform energy factor (‘‘UEF’’). 

Section 5.4.1 of appendix E specifies 

directions for determination of the draw 

pattern of the water heater under test; 

section 5.4.2 of appendix E specifies the 

test sequence for water heaters with 

rated storage volume greater than or 

equal to 2 gallons; and section 5.4.3 of 

appendix E specifies the test sequence 

for water heaters with rated storage 

volume less than 2 gallons. These test 

sequences specify the timings of each 

water draw during the 24-hour 

simulated-use test, the flow rates at 

which the draws must occur, and 

condition tolerances for these draws. 

In particular, section 5.4.2 of 

appendix E, Test Sequence for Water 

Heaters with Rated Storage Volumes 

Greater Than or Equal to 2 Gallons, 

provides that all draws during the 24- 

hour simulated-use test must be made at 

the flow rates specified in the applicable 

draw pattern table in section 5.5 of this 

appendix, within a tolerance of ±0.25 

gallons per minute (±0.9 liters per 

minute). Section 5.4.3 of appendix E, 

Test Sequence for Water Heaters with 

Rated Storage Volume Less Than 2 

Gallons, currently does not provide 

explicit instruction for the tolerance on 

the flow rate. 

Within the proposed amendments to 

the regulatory text provided in the 

January 2022 NOPR, DOE included a 

proposed amendment to section 5.4.3 of 

appendix E to specify that flow rates for 

water heaters with rated storage volume 

less than 2 gallons must be maintained 

within a tolerance of ±0.25 gallons per 

minute. 87 FR 1554, 1603 (Jan. 11, 

2022). The preamble to the January 2022 

NOPR did not include discussion of this 

topic, nor did DOE specifically request 

for comment on this topic. 

Adopting these proposed tolerances at 

section 5.4.3 of appendix E would 

ensure repeatability and reproducibility 

of test results for water heaters with 

rated storage volume less than 2 gallons. 

Most water heaters with storage volume 

less than 2 gallons are flow-activated 

devices, meaning that burner or heating 

element activation is controlled based 

on sensing the flow rate when hot water 

is called for. As such, significant 

variations in the flow rate from test to 

test could affect the measured efficiency 

of these products. 

In this SNOPR, DOE is updating its 

proposal to include additional 

specificity for water heaters with flow 

rates less than 1 gallon per minute. In 

section III.C.6 of the January 2022 

NOPR, DOE discussed water heaters on 

the market with maximum gallon per 

minute (‘‘Max GPM’’) delivery 

capacities below 1 gallon per minute. 87 

FR 1554, 1582 (Jan. 11, 2022). For these 

models, the ‘‘very small’’ draw pattern 

for the 24-hour simulated-use test 

would be applicable. Section 5.5 of 

appendix E states that, for the very 

small draw pattern, if the water heater 

has a Max GPM rating less than 1 gallon 

per minute (3.8 L/min), then all draws 

shall be implemented at a flow rate 

equal to the rated Max GPM. For 

products with Max GPM less than 1 

gallon per minute, an allowable flow 

rate tolerance of ±0.25 gallon per minute 

would represent a significant variation 

of flow rate in comparison to the rated 

Max GPM. For example, for a water 

heater with Max GPM of 0.5 gallon per 

minute, a tolerance of ±0.25 gallon per 

minute would represent a ±50 percent 

difference from the rated flow rate. 

Furthermore, in its review of publicly 

certified water heater ratings,15 DOE 

identified models with rated Max GPM 

delivery capacities as low as 0.20 gallon 

per minute. For such products, a flow 

rate tolerance of ±0.25 gallon per minute 

would allow for either flow rates close 

to zero or flow rates that are more than 

twice the rated Max GPM; either case 

would lead to results unrepresentative 

of actual product usage. Therefore, in 

this SNOPR, DOE proposes further 

amending section 5.4.3 of appendix E to 

specify that for water heaters with a 

rated Max GPM of less than 1 gallon per 

minute, the flow rate tolerance shall be 

±25 percent of the rated Max GPM. For 

such products, a flow rate tolerance of 

±25 percent would represent the same 

level of variation (on a percentage basis) 

as for products rated at 1.0 gallon per 

minute and subject to a tolerance of 

±0.25 gallon per minute. 

By way of example, under the 

proposal, for a water heater with a rated 

Max GPM flow rate of 0.5 gallon per 

minute, the required tolerance would be 

±0.125 gallon per minute. For a water 

heater with a rated Max GPM flow rate 

of 0.20 gallon per minute, the required 

tolerance would thus be ±0.05 gallon 

per minute. 

As discussed, EPCA requires that test 

procedures be reasonably designed to 

produce test results which measure 

energy efficiency, energy use, or 

estimated annual operating cost of a 

covered product during a representative 

average use cycle or period of use and 

not be unduly burdensome to conduct. 

(42 U.S.C. 6293(b)(3)) DOE expects that 

laboratories may require high-precision 

water flow rate instrumentation (e.g., 

Coriolis flow meters) in order to 

maintain the tolerances discussed, in 

particular for water heaters with rated 

Max GPM flow rates less than 1 gallon 

per minute. DOE is aware through its 

testing activities that multiple thirdparty laboratories already use Coriolis 

flow meters. In reviewing water heater 

test data previously collected, DOE has 

observed third-party laboratories 

maintaining flow rate condition 

tolerances as low as ±0.05 gallon per 

minute. For these reasons, DOE has 

initially determined that the proposed 

tolerances would generally not require 

additional capital investments for test 


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Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 42275 

16 DOE proposed amendments to the ambient air 

tolerance requirements in the January 2022 NOPR. 

87 FR 1554, 1577–1578 (Jan. 11, 2022). 

laboratories and, therefore, would not be 

unduly burdensome to conduct. 

DOE also has tentatively determined 

that the proposed amendment would 

not alter the measured efficiency of 

consumer water heaters and residentialduty commercial water heaters, nor 

require retesting or recertification solely 

as a result of DOE’s adoption of the 

proposed amendments to the test 

procedure, if made final. In the absence 

of an explicit instruction for the flow 

rate tolerance applicable to water 

heaters with rated storage volume under 

2 gallons, DOE expects that general 

industry best practice is to apply the 

flow rate tolerances being proposed for 

section 5.4.3 of appendix E for water 

heaters with rated storage volume less 

than 2 gallons (based on DOE’s review 

of third-party laboratory test data), such 

that this proposal is expected to be 

consistent with current methodology. 

With the addition of these proposed 

amendments to section 5.4.3 of 

appendix E, DOE maintains the 

proposals set forth in the January 2022 

NOPR. 

DOE seeks comment on the proposed 

amendment to specify flow rate 

tolerances for the 24-hour simulated use 

test for water heaters with rated storage 

volume under 2 gallons, and in 

particular to specify the tolerance as ±25 

percent for water heaters with a rated 

maximum flow rate of less than 1 gallon 

per minute. DOE is particularly 

interested in test data or information 

that would indicate the technical 

feasibility of maintaining the tolerances 

proposed with instrumentation that is 

used in general practice, as well as the 

potential impacts on test burden. 

B. Optional Test Conditions 

Section 2.2 of appendix E specifies 

that the ambient air temperature shall be 

maintained between 65.0 °F and 70.0 °F 

(18.3 °C and 21.1 °C) on a continuous 

basis during the test. Additionally, for 

heat pump water heaters, that test 

procedure provision provides that the 

dry-bulb temperature shall be 

maintained at 67.5 °F ±1 °F (19.7 °C ±0.6 

°C) and that the relative humidity shall 

be maintained at 50 percent ±2 percent 

throughout the test.16

In the January 2022 NOPR, DOE 

discussed comments previously 

received on the April 2020 RFI 

suggesting that DOE explore the usage of 

NEEA’s Advanced Water Heating 

Specification for voluntary climatespecific efficiency representations of 

heat pump water heaters. 87 FR 1554, 

1580 (Jan. 11, 2022). In response to 

those comments, DOE stated that it did 

not have data to indicate what 

conditions would be representative for 

regional representations, and, thus, DOE 

tentatively decided not to allow 

optional representations of additional 

efficiency ratings at test conditions 

other than those found in the DOE test 

procedure, such as those made in 

accordance with NEEA’s Advanced 

Water Heating Specification. Id. 

In response to the January 2022 

NOPR, DOE received additional 

comments regarding optional 

representations that have led the 

Department to reconsider its tentative 

decision not to allow optional 

representations. 

The CA IOUs stated that water heater 

installation practices vary regionally, 

and that similar units installed in the 

same region can experience different 

ambient conditions. The CA IOUs 

further stated that the direct 

relationship between the diverse 

ambient conditions and efficiency make 

it impossible to choose a single 

representative value for ambient 

conditions for the consumer water 

heaters test procedure that will yield 

useful energy consumption estimates for 

heat pump water heaters. The CA IOUs 

asserted that in the case of a splitsystem heat pump water heater, the 

condenser is almost always located in 

an unconditioned space (e.g., outdoors), 

such that the ambient conditions 

specified in the current DOE test 

procedure are not representative. The 

CA IOUs recommended that DOE clarify 

whether manufacturers may provide 

information on the performance of heat 

pump water heaters at ambient 

temperatures other than 67.5 °F ±1 °F. 

The CA IOUs reiterated their 

recommendation to allow manufacturers 

to provide representations for more than 

one ambient condition, stating that 

allowing manufacturers to state 

performance under different conditions 

would allow them to introduce heat 

pump water heater models optimized 

for different applications, would help 

keep performance claims consistent, 

and would help consumers select the 

most appropriate products. (CA IOUs, 

No. 36 at p. 2) 

The Joint Advocates stated that the 

value of having test data at both colder 

and warmer conditions than those 

specified in the current test procedure is 

that they would allow for calculating 

UEFs for any climate regardless of 

whether the specific optional test 

conditions are representative of any 

region. The Joint Advocates reiterated 

its recommendation that DOE allow 

voluntary reporting of ratings at two 

additional test conditions. The Joint 

Advocates asserted that allowing 

optional reporting would help provide a 

better understanding of the differences 

in heat pump water heater performance 

at various conditions without increasing 

test burden for manufacturers who do 

not wish to report these additional 

rating. (Joint Advocates, No. 34 at p. 1) 

NYSERDA requested that DOE require 

heat pump water heater performance 

data at a range of operating conditions. 

NYSERDA stated that demonstrating 

performance at different ambient 

temperatures is a commonly applied 

approach for heat pumps that serve 

HVAC loads, and that similar treatment 

for heat pump water heaters is 

appropriate. NYSERDA stated that in 

order for heat pump water heaters to 

provide utility in all climates, including 

the colder temperatures in New York, 

consumers and installers will need to 

understand the expected performance at 

a range of operating conditions. 

NYSERDA encouraged DOE to allow 

manufacturers to provide performance 

data at conditions representative of 

where heat pump water heaters will be 

installed throughout the country. 

NYSERDA specifically referenced 

NEEA’s Advanced Water Heating 

Specification as an example resource. 

(NYSERDA, No. 32 at p. 3) 

BWC stated that voluntary 

representations would potentially 

increase burden and not increase 

representativeness for performance on a 

national basis. BWC expressed its 

support for DOE’s tentative 

determination not to allow additional 

voluntary representations. (BWC, No. 33 

at p. 8) 

After considering these comments, the 

Department once again notes that EPCA 

requires that the DOE test procedure 

must be reasonably designed to produce 

test results which measure energy 

efficiency during a representative 

average use cycle or period of use. (42 

U.S.C. 6293(b)(3)) While the test 

conditions in the current appendix E 

test procedure must remain 

representative for the nation as a whole, 

comments from interested parties have 

demonstrated that allowing additional 

representations of efficiency at 

alternative ambient conditions could 

provide consumers with additional 

information about the expected 

performance of heat pump water heaters 

at conditions that are representative of 

their specific installation circumstances. 

For other types of covered products and 

equipment, DOE has adopted optional 

metrics for voluntary representations 

where it was determined that the 

primary efficiency metric would not be 

representative for certain installation 


jspears on DSK121TN23PROD with PROPOSALS2
42276 Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 

17Available at: neea.org/img/documents/ 

residential-unitary-HPWH-qualified-productslist.pdf (Last accessed on May 11, 2022). 

conditions common for the product or 

equipment. For heat pump water 

heaters, both the efficiency and the 

heating capacity of the product are 

sensitive to the ambient conditions, and 

in general will be lower at colder 

ambient temperatures and higher at 

warmer ambient temperatures. For 

example, at lower ambient 

temperatures, the reduction in heating 

capacity of the heat pump could result 

in back-up electric resistance heating 

elements operating more frequently than 

at the current DOE rating conditions. 

Differences in ambient conditions also 

would affect integrated heat pump water 

heaters installed in unconditioned 

spaces (e.g., garage or attic) and splitsystem heat pump water heaters for 

which the heat pump components are 

located outdoors. Depending on the 

installation location, the ambient 

conditions may vary significantly from 

the conditions in the DOE test method, 

thereby resulting in significantly 

different performance for such products. 

For these reasons, in this SNOPR, DOE 

has tentatively determined to allow for 

certain optional representations for 

additional ambient conditions, as 

described further in the following 

paragraphs. DOE understands this to be 

the intent in NYSERDA’s request 

(however, NYSERDA’s comment 

discusses both a requirement for 

optional representations as well as an 

allowance for optional representations). 

In response to BWC’s concerns 

regarding a potential increase in test 

burden, DOE proposes that any testing 

at multiple ambient conditions would 

be optional, and DOE is not proposing 

to require testing at the alternative 

ambient conditions. In summary, DOE is 

proposing to define new metrics for 

optional representations based primarily 

upon the test conditions provided in 

NEEA’s Advanced Water Heating 

Specification version 8.0 (‘‘AWHS 

v8.0’’). 

AWHS v8.0 was published by NEEA 

on March 1, 2022. Though early editions 

of the AWHS focused primarily on 

providing more representative 

performance metrics for heat pump 

water heaters in cold climates, the latest 

editions are now more broadly focused 

on providing representative 

performance metrics for heat pump 

water heaters across all climates. 

Performance metrics in the AWHS are 

generally calculated by measuring 

energy efficiency at multiple (two or 

more) ambient test conditions, linearly 

interpolating between the test results, 

and finally calculating an ambient 

temperature-weighted efficiency metric 

using temperature bin data. The metric 

is a cold climate efficiency (‘‘CCE’’) 

rating for integrated heat pump water 

heaters installed in semi-conditioned 

(i.e., garage, basement) spaces and a 

seasonal coefficient of performance 

(‘‘SCOP’’) for split-system heat pump 

water heaters (where the heat pump is 

separated from the storage tank and 

located outdoors). 

NEEA maintains a Qualified Products 

List for heat pump water heaters tested 

by manufacturers to the AWHS.17 As of 

February 2022, the Qualified Products 

List contains CCE and SCOP 

representations from seventeen heat 

pump water heater brands. As such, 

DOE notes that manufacturers are 

already conducting testing per the 

AWHS and are providing 

representations in accordance with its 

test methods. On this basis, DOE has 

tentatively determined that adopting 

these test points for voluntary testing 

and representations would not 

significantly increase test burden for 

manufacturers who choose to provide 

these ratings. 

In its review of the AWHS v8.0, DOE 

determined that there are several 

differences between the test conditions 

provided and those present in the 

appendix E test procedure. These 

differences include ambient dry bulb 

temperatures, relative humidity 

conditions, and supply water 

temperatures. 

For integrated heat pump water 

heaters, AWHS v8.0 determines CCE50

at ambient air conditions of 50 °F dry 

bulb temperature and 58 percent 

relative humidity, with a supply water 

temperature of 50 °F. An additional 

high-temperature condition of 95 °F is 

also included but noted as optional in 

appendix B.1.1 to AWHS v8.0. DOE is 

proposing adopt the low ambient air 

conditions (50 °F and 58 percent relative 

humidity) and the high ambient air 

conditions (95 °F and 40 percent relative 

humidity) for optional representations 

of integral heat pump water heaters. 

Additionally, AWHS v8.0 modifies the 

inlet water temperatures at these 

ambient conditions to reflect the 

corresponding mains water temperature 

expected at each outdoor air 

temperature. At the 50 °F ambient 

condition, the specified inlet water 

temperature is also 50 °F, and at the 

95 °F ambient condition, the specified 

inlet water temperature is 67 °F. 

Although NEEA’s AWHS v8.0 specifies 

these air and water conditions only for 

integrated heat pump water heaters, 

DOE has tentatively determined that 

these conditions could also be used for 

heat pump-only water heaters, which 

typically do not have any outdoor 

components. 

For split-system heat pump water 

heaters, Appendix B.4 to AWHS v8.0 

includes a note that the test method and 

calculation procedure is ‘‘in progress,’’ 

and test conditions are labeled as ‘‘draft 

testing conditions.’’ Appendix B.4 to 

AWHS v8.0 states, ‘‘broadly, the method 

will consist of calculating an efficiency 

for each test in Table 8 following the 

Uniform Energy Factor calculation 

method but substituting in appropriate 

temperature conditions.’’ For splitsystem heat pump water heaters, AWHS 

v8.0 determines SCOP at ambient air 

conditions ranging from 5 °F dry bulb 

temperature and 30 percent relative 

humidity to 95 °F dry bulb temperature 

and 25 percent relative humidity. 

Similar to the requirements in AWHS 

v8.0 for integrated heat pump water 

heaters, the supply water temperature 

requirement varies with ambient dry 

bulb temperature. The four standard test 

conditions for SCOP in AWHS v8.0 are 

shown in Table 8 of AWHS v8.0 and in 

Table III.1 in this SNOPR. 

TABLE III.1—AWHS V8.0 STANDARD TEST CONDITIONS FOR SPLIT-SYSTEM HEAT PUMP WATER HEATERS

Test point 

Outdoor conditions Water Indoor conditions 

Outdoor 

dry-bulb 

temperature 

Outdoor 

wet-bulb 

temperature 

Relative 

humidity 

(%) 

Supply water 

temperature 

Dry-bulb 

temperature Relative humidity 

A .......................................... 5 °F 2 °F 30 42 °F 67.5 °F Not specified. 

B .......................................... 34 °F 31 °F 72 47 °F 


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Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 42277 

TABLE III.1—AWHS V8.0 STANDARD TEST CONDITIONS FOR SPLIT-SYSTEM HEAT PUMP WATER HEATERS—Continued 

Test point 

Outdoor conditions Water Indoor conditions 

Outdoor 

dry-bulb 

temperature 

Outdoor 

wet-bulb 

temperature 

Relative 

humidity 

(%) 

Supply water 

temperature 

Dry-bulb 

temperature Relative humidity 

C .......................................... 68 °F 57 °F 50 58 °F 

D .......................................... 95 °F 69 °F 25 67 °F 

Test point C in AWHS v8.0 most 

closely resembles the current test 

condition in appendix E. In this SNOPR, 

DOE is proposing to adopt the three 

additional outdoor air conditions (A, B, 

and D in AWHS v8.0) for optional 

representations of split-system heat 

pump water heaters. Where indoor 

relative humidity is not currently 

specified in AWHS v8.0 for split-system 

heat pump water heaters, DOE is 

proposing to use the 50-percent relative 

humidity requirement from the current 

appendix E test procedure in order to 

maintain the consistency and 

comparability of results. Tolerances on 

these conditions would be the same as 

those required for the standard UEF test 

conditions. 

DOE proposes to adopt the optional 

test conditions as stand-alone metrics in 

sections 2.8 and 5.6 of appendix E. DOE 

proposes to adopt a new metric, EX

(where ‘‘X’’ represents the air 

temperature under which the test was 

conducted if not 67.5 °F), at sections 

1.16 and 6.5 of appendix E for optional 

representations only. The metric EX

would represent the result of a test done 

in accordance with the UEF test 

procedure but at a different set of 

ambient test conditions. With the 

exception of the different temperature 

(both air and water) and humidity 

conditions, all other aspects of the test 

procedure would remain identical to 

those used to determine the regulated 

metric, UEF. The draw pattern used to 

determine EX would be the same draw 

pattern used to determine UEF. The 

proposed optional test conditions for 

heat pump water heaters are shown in 

Table III.2. 

TABLE III.2—PROPOSED OPTIONAL TEST CONDITIONS FOR HEAT PUMP WATER HEATERS

Heat pump type Metric 

Outdoor air conditions Indoor air conditions 

Supply water 

Dry-bulb temperature 

temperature 

Relative 

humidity 

(%) 

Dry-bulb 

temperature 

Relative 

humidity 

(%) 

Split-System ............................................. E5 5.0 °F 30 67.5 °F 50 42.0 °F 

E34 34.0 °F 72 47.0 °F 

E95 95.0 °F 25 67.0 °F 

Integrated or Heat Pump-Only ................. E50 N/A N/A 50.0 °F 58 50.0 °F 

E95 N/A N/A 95.0 °F 40 67.0 °F 

DOE seeks information and comments 

on its proposal to allow optional 

representations of EX in the appendix E 

test procedure to indicate efficiency at 

different inlet air and water conditions. 

DOE also welcomes feedback on its 

proposal to use the same temperature 

measurement tolerances for optional Ex

conditions and the required UEF 

condition. DOE is interested in data 

which can be used to determine the 

range of indoor ambient air conditions 

typical in semi-conditioned spaces in 

different geographical regions in the 

United States, and how these conditions 

typically correlate to outdoor air 

conditions. DOE is also interested in 

data which may be used to correlate 

consumer hot water usage patterns with 

different seasonal conditions. 

In order to avoid any potential 

confusion between heat pump-only 

water heaters and split-system water 

heaters, DOE is also proposing to define 

‘‘split-system heat pump water heater’’ 

in section 1.14 of appendix E. 

Specifically, DOE proposes to adopt the 

definition in AWHS v8.0 with minor 

modifications: 

Split-system heat pump water heater 

means a heat pump-type water heater 

with an indoor storage tank and outdoor 

heat pump component. 

DOE welcomes comment on its 

proposed definition of ‘‘split-system 

heat pump water heater.’’ 

DOE has tentatively determined that 

this proposal would not lead to 

additional testing costs or burden for 

manufacturers or test labs because these 

optional metrics would remain 

voluntary for representations. 

C. Storage Tank Over-Heating 

As discussed in the January 2022 

NOPR, DOE proposed amendments 

pertaining to water heaters that are 

designed to, or have operational modes 

that, raise the temperature of the stored 

water significantly above the outlet 

water temperature requirements 

specified in section 2.4 of appendix E. 

87 FR 1554, 1580 (Jan. 11, 2022). These 

water heaters are meant to be used with 

a mixing valve (which may or may not 

be provided with, or be built into, the 

unit) to temper the outlet water to a 

typical outlet water temperature. 

Generally, raising the temperature of the 

water in the storage tank significantly 

above the target output temperature (i.e., 

‘‘over-heating’’ the water) would 

effectively increase the amount of hot 

water that a given size water heater can 

deliver (e.g., a 50-gallon water heater 

with an over-heated storage tank 

temperature could provide the same 

amount of hot water as an 80-gallon 

water heater with a more typical storage 

tank temperature). An FHR test 

performed at an over-heated storage 

tank temperature would result in a 

higher FHR than a test performed at a 

lower, more conventional storage tank 

temperature. The installation 

instructions in section 4 of appendix E 

do not address when a separate mixing 

valve should be installed, and the 

operational mode selection instructions 

in section 5.1 of appendix E do not 

specifically address when the water 

heater has an operational mode that can 

over-heat the water in the storage tank. 


jspears on DSK121TN23PROD with PROPOSALS2
42278 Federal Register / Vol. 87, No. 134 / Thursday, July 14, 2022 / Proposed Rules 

18The ENERGY STAR program published a Test 

Method to Validate Demand Response for 

connected residential water heaters on April 5, 

2021 (the ‘‘ENERGY STAR Connected Test 

Method’’). Section 4.1 of the ENERGY STAR 

Connected Test Method addresses the test set-up in 

which a separate mixing valve is required. The 

Energy Star Test Method to Validate Demand 

Response for connected residential water heaters is 

available at: www.energystar.gov/sites/default/files/ 

ENERGY%20STAR%20Connected%20

Residential%20Water%20Heaters%20Test%20

Method%20to%20Validate%20Demand%20

Response_0.pdf (Last accessed May 19, 2022). 

However, section 5.1 of appendix E 

requires that the water heater be tested 

in its default mode, and where a default 

mode is not specified, to test the unit in 

all modes and rate the unit using the 

results of the most energy-intensive 

mode. Id. 

For this type of water heater, DOE 

proposed in the January 2022 NOPR to 

add instructions for the installation of a 

mixing valve similar to what is 

published in section 4.1 of the ENERGY 

STAR Connected Test Method.18 87 FR 

1554, 1580 (Jan. 11, 2022). 

In response to the January 2022 

NOPR, several commenters requested 

that DOE consider further amendments 

to the appendix E test procedure to 

provide more representative efficiency 

results for such storage-type water 

heaters that ‘‘over-heat’’ the stored water 

beyond the delivery temperature. These 

comments are summarized and 

responded to in the paragraphs that 

follow. In consideration of these 

comments, DOE is proposing additional 

testing requirements to further address 

water heaters that have an operational 

mode (or modes) that over-heat the 

stored water. 

NYSERDA commented that DOE 

should ensure that all test procedure 

requirements surrounding FHR enable 

comparison between products and 

accurately reflect the in-field 

performance of water heaters, including 

those which may augment capacity 

through the use of a mixing valve or 

other approaches. (NYSERDA, No. 32 at 

p. 4) 

NEEA commented that it supports 

DOE’s proposal to specify instructions 

for the installation of a mixing valve, 

stating that the proposal would improve 

repeatability and comparability of test 

results by providing clarity on the pipe, 

valve, and measurement locations. 

(NEEA, No. 30 at p. 2) The commenter 

further asserted that ensuring that inlet 

temperature is measured before 

supplying cold water to the mixing 

valve and that outlet temperature is 

measured after heating and mixing 

would produce the most representative 

and repeatable test results. (Id.) NEEA 

also recommended that DOE consider 

ways to account for the increased 

effective capacity enabled by a mixing 

valve (either separate or integrated). (Id.) 

According to NEEA, products that store 

water at a higher temperature in a mode 

other than default would have an 

increased effective capacity and lower 

UEF in this high temperature mode. (Id.) 

NEEA encouraged DOE to consider 

ways to account for the increased 

effective capacity for products with 

integrated mixing valves and those 

designed to be used with a mixing 

valve. (Id.) 

The Joint Advocates expressed 

support for DOE’s proposal to include 

instructions for the installation of a 

mixing valve and encouraged DOE to 

amend the test procedure to capture the 

associated increase in effective hot 

water storage volume for water heaters 

designed to be used with a mixing 

valve. (Joint Advocates, No. 34 at pp. 1– 

2) The Joint Advocates stated that 

raising the temperature of the stored 

water above the outlet water 

temperature requirements essentially 

increases the amount of hot water 

delivered without increasing the size of 

the water heater, and that this is not 

reflected in the test procedure or 

standards because water heater ratings 

are calculated based on the rated storage 

volume, not the actual effective volume. 

(Id.) Therefore, the Joint Advocates 

recommended that DOE amend the test 

procedure to account for the additional 

effective storage volume enabled by a 

higher operating temperature and 

mixing valve. Specifically, the Joint 

Commenters encouraged DOE to 

consider specifying how to calculate the 

effective storage volume for water 

heaters designed to be installed with a 

mixing valved based on the highest 

possible temperature setpoint and 

requiring such water heaters to be tested 

at both 125 ±5 °F and at their highest 

setpoint. (Id.) Furthermore, the Joint 

Advocates commented that water 

heaters designed to be installed with a 

mixing valve should be subject to the 

DOE standards based on both their rated 

storage volume (and FHR at the 125 ± 

5 °F setpoint) and their effective storage 

volume (and FHR at their highest 

setpoint). (Id.) 

The CA IOUs stated that storage 

volume and first hour rating are often 

correlated; however, with the increased 

use of thermostatic mixing valves, this 

correlation has decreased, and FHR has 

become a better representation of hot 

water delivery than storage volume. (CA 

IOUs, No. 36 at p. 3) The CA IOUs 

asserted that the FHR metric best 

defines consumer amenity, and that the 

current standards—which are 

differentiated by storage volume—allow 

for less-efficient performance for larger 

volume tanks within a given test 

procedure bin despite delivering similar 

service to the consumer. (Id.) With 

regard to mixing valves specifically, the 

CA IOUs supported DOE’s proposal to 

require the fitting of thermostatic 

mixing valves between the inlet and 

outlet temperature measurement points 

when they are not an integral 

component of the water heater and in 

the absence of manufacturer 

instructions. (Id. at p. 5) The CA IOUs 

stated that this requirement would align 

with product designs, as manufacturers 

typically direct the integration of a valve 

or its installation, making it the correct 

choice to ensure comparability of results 

and to accurately represent real-world 

energy use. (Id.) 

In order to further examine the 

potential impact of storage tank overheating, DOE performed testing on one 

50-gallon electric resistance storage 

water heater that includes built-in 

mixing valve and multiple userselectable modes to boost the delivery 

capacity by over-heating the storage 

tank. DOE collected data at three 

different storage tank temperatures, each 

of which provided an outlet water 

temperature at 125 ±5 °F through the use 

of the built-in mixing valve. The 

maximum measured mean tank 

temperature after cut-out following the 

first draw of the 24-hour simulated use 

test (Tmax,1) and the average outlet water 

temperature during the second draw 

(Tdel,2) were used as indicators of overheating. Data from this testing is shown 

in Table III.3 of this document. The first 

row of data (with maximum mean tank 

temperature value of 124.3) represents 

the unit as tested according to the 

current test procedure. 


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19For example, DOE’s Compliance Certification 

Database includes a 107-gallon electric storage 

water heater with an FHR rating of 94 gallons. 

20 DOE is concurrently evaluating potential 

amended energy conservation standards for 

consumer water heaters (Docket No. EERE–2017– 

BT–STD–0019) and residential-duty commercial 

water heaters (Docket No. EERE–2021–BT–STD– 

0027). 

TABLE III.3—STORAGE TANK OVER-HEATING TEST DATA

Tmax,1 * (°F) Tdel,2 ** (°F) Corresponding 

FHR 

Corresponding 

UEF 

124.3 .......................................................................................................................... 121.3 77 gal 0.94 

144.5 .......................................................................................................................... 124.3 81 gal 0.90 

159.6 .......................................................................................................................... 124.3 95 gal 0.88 

*Tmax,1 represents the maximum measured mean tank temperature after cut-out following the first draw of the 24-hour simulated-use test.

**Tdel,2 represents the average outlet water temperature during the second draw of the 24-hour simulated-use test. 

The test results support NEEA’s 

assertion that storage tank over-heating 

could lead to reductions in UEF. The 

test configuration corresponding to the 

current DOE test procedure produced a 

UEF value of 0.94, which surpasses the 

threshold for compliance with the 

current minimum energy conservation 

applicable to this unit (minimum UEF 

of 0.93). The over-heated configurations 

with mean tank temperatures of 144.5 

and 159.6 produced UEF values of 0.90 

and 0.88, respectively, both of which are 

below the applicable minimum energy 

conservation standard for this unit. 

In addition, the test results indicate 

that storage tank over-heating leads to 

an increase in the measured FHR value. 

The test configuration corresponding to 

the current DOE test procedure 

produced an FHR value of 77 gallons. 

The over-heated configurations with 

mean tank temperatures of 144.5 and 

159.6 produced FHR values of 81 and 95 

gallons, respectively. DOE notes that an 

FHR of 95 gallons is comparable to that 

of a 100-gallon electric storage water 

heater.19 By comparison, the current 

minimum energy conservation standard 

that applies to 100-gallon consumer 

water heaters in the high draw pattern 

is a UEF of 2.13 (which currently can 

only be achieved through heat pump 

technology). 

From its review of publicly available 

product literature, products that utilize 

storage tank over-heating generally offer 

user-selectable operating modes that 

result in tank temperatures ranging from 

100 °F to 170 °F. Based on DOE’s test 

data, should consumers choose to 

operate these products to a highcapacity mode (which maintains the 

storage tank at, for example, 140 °F 

while delivering water at 125 °F), the 

water heater would likely perform 

significantly worse than a rating 

determined based on testing without 

storage tank over-heating (i.e., the rated 

efficiency at the rated delivery capacity 

would not be representative of an 

average use cycle or period of use when 

operated in a high-capacity mode). 

Hence, DOE has tentatively determined 

that revisions to the method for 

determination of UEF and FHR are 

necessary to yield results representative 

of an average use cycle for these 

products. These proposed amendments 

are discussed in detail in the following 

sections. 

1. Testing in Over-Heated Mode 

Most conventional storage-type water 

heaters do not include a mixing valve 

and offer a range of temperature 

setpoints that would, in typical 

installations, deliver outlet water at the 

temperature corresponding to the 

setpoint temperature (e.g., a 140 °F 

setting on the water heater will deliver 

a 140 °F outlet temperature). Whereas, 

as discussed previously, water heaters 

that include a mixing valve and provide 

‘‘over-heating’’ capability offer a range 

of internal temperature setpoints, 

although the outlet water remains at 

nominally at 125 °F regardless of 

internal setpoint. For the remainder of 

this discussion, DOE refers to a userinitiated mode that results in an 

elevated internal water temperature 

without increasing the delivered water 

temperature as ‘‘over-heated mode.’’ 

Currently, section 5.1 of appendix E 

states, ‘‘For water heaters that allow for 

multiple user-selected operational 

modes, all procedures specified in this 

appendix shall be carried out with the 

water heater in the same operational 

mode (i.e., only one mode). This 

operational mode shall be the default 

mode (or similarly-named, suggested 

mode for normal operation) as defined 

by the manufacturer in its product 

literature for giving selection guidance 

to the consumer.’’ An ‘‘overheated 

mode’’ in storage-type water heaters is 

distinct from a high-temperature 

setpoint because the outlet water 

temperature is unaffected by the 

internal temperature setpoint. DOE 

surmises that consumers who purchase 

a water heater that provides overheating capability would do so with the 

intent to use such capability; as such, 

these consumers would be expected to 

use the over-heated mode some portion 

of the time, ranging from occasional use 

(e.g., switching between the normal 

mode and the over-heated mode 

depending on the hot water capacity 

needed at any particular time) to regular 

use. Accordingly, for such products, 

DOE expects that a representative 

average use cycle would include some 

portion of time in over-heated mode. 

For this reason, DOE has tentatively 

concluded that testing only in the 

default mode would not produce results 

that are representative of an average use 

cycle or period of use for products with 

this capability if the default mode does 

not provide over-heat capability. 

Considering these factors, DOE has 

tentatively determined that testing 

storage-type water heaters that offer 

user-selectable over-heated modes in the 

over-heated mode would provide a more 

representative result than testing in the 

default mode. Therefore, DOE proposes 

to amend section 5.1 of appendix E to 

require that for water heaters that offer 

a user-selected operational mode(s) in 

which the storage tank is maintained at 

a temperature higher than the delivery 

temperature, the operational mode shall 

be that which results in the highest 

mean tank temperature while 

maintaining an outlet temperature of 

125 ±5 °F. 

DOE recognizes that the 

aforementioned proposal would likely 

cause UEF ratings for these products to 

decrease if they are currently certified 

using a default operational mode that 

does not initiate over-heating. In order 

to limit potential re-testing and recertification burden for manufacturers, 

DOE is proposing that the requirement 

to test these products in the over-heated 

mode go into effect only once DOE 

completes its ongoing review of 

potential amended energy conservation 

standards for consumer water heaters 

and residential-duty commercial water 

heaters.20

Electric storage water heaters with 

demand-response capabilities may 

undergo utility-initiated over-heating 

during certain periods in order to store 

additional energy in the water heater for 


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21The ENERGY STAR Version 5.0 Residential 

Water Heater Final Draft Specification was 

published on June 1, 2022 and is available online 

at: www.energystar.gov/products/spec/residential_

water_heaters_specification_version_5_0_pd (Last 

accessed on June 4, 2022). 

22ANSI/CTA–2045–B, ‘‘Modular 

Communications Interface for Energy 

Management,’’ published February 2021. 

use during peak demand periods. This 

over-heating, when initiated by the 

electric utility company, serves an 

important purpose for energy storage 

and grid flexibility. Products that offer 

the ability to respond to utility-initiated 

over-heating requests are distinct in 

function from products that offer userinitiated over-heating, because demandresponse water heaters do not over-heat 

to increase the overall daily capacity of 

the water heater. Instead, the capacity is 

only temporarily boosted to counteract 

the deactivation of the heating elements 

for extended periods of time when 

demand curtailment is occurring. As 

such, demand-response water heaters 

with the capability to undergo utilityinitiated over-heating would not be 

expected increase the capacity of the 

water heater over a typical average use 

cycle in the same way that a water 

heater with user-initiated over-heating 

would, so DOE has tentatively 

concluded that testing demand-response 

water heaters in the default/normal 

mode would be the most representative 

for demand-response water heaters. 

In order to clarify which products 

with over-heating capability should be 

tested in the operational mode that 

results in the highest mean tank 

temperature while maintaining an outlet 

temperature of 125 ±5 °F and which 

products with over-heating capability 

should be tested in default/normal 

mode, DOE is proposing to define 

‘‘demand-response water heater’’ in 

section 1.3 of appendix E. Products 

meeting that definition would be tested 

in normal/default mode, while all other 

products capable of over-heating the 

stored water in the tank would be tested 

in the in the operational mode that 

results in the highest mean tank 

temperature while maintaining an outlet 

temperature of 125 ±5 °F. The proposed 

definition for ‘‘demand-response water 

heater’’ is based on the ENERGY STAR 

definitions for ‘‘connected water heater 

product,’’ ‘‘demand response 

management system,’’ and ‘‘demand 

response’’ in specification version 5.0, 

with certain modifications made by 

DOE.21 More specifically, DOE proposes 

to define ‘‘demand-response water 

heater’’ as follows: 

Demand-response water heater means a 

storage-type water heater that— 

(1) Has integrated communications 

hardware and additional hardware and 

software required to enable connected 

functionality with a utility or third party, 

which dispatches signals with demand 

response instructions and/or price signals to 

the product and receives messages from the 

demand-response water heater; 

(2) Meets the communication and 

equipment standards for Consumer 

Technology Association Standard (CTA) 

2045–B (ANSI/CTA–2045–B); 22

(3) Automatically heats the stored water 

above the delivery temperature setpoint only 

in response to instructions received from a 

utility or third party. 

DOE welcomes comment on its 

proposed definition of ‘‘demandresponse water heater,’’ including the 

specification for ANSI/CTA–2045–B to 

demonstrate connected functionality (as 

it is the latest version of the CTA–2045 

standard). 

DOE seeks comment on the proposal 

to specify that water heaters, except 

demand-response water heaters, that 

offer an operational mode (or modes) 

causing water to be stored at a 

temperature higher than the delivery 

temperature must be tested in the ‘‘overheated mode’’ that results in the highest 

internal tank temperature while still 

while maintaining an outlet temperature 

of 125 ±5 °F. DOE also welcomes 

feedback on its proposal to require 

testing in this manner only after 

compliance with amended energy 

conservation standards for consumer 

water heaters and residential-duty 

commercial water heaters is required. 

DOE further seeks information and 

consumer use data to identify how often 

the over-heated mode is used in field 

installations. 

2. Effective Storage Volume 

As discussed in section III.C of this 

document, the Joint Advocates and the 

CA IOUs both recommended that the 

increase in water heating capacity 

attained through over-heating the 

storage tank be considered for energy 

conservation standards. The Joint 

Advocates suggested that compliance 

with standards should be based on an 

‘‘effective storage volume,’’ whereas the 

CA IOUs advocated for FHR to be used 

for standards instead of a representation 

of storage volume. 

The current energy conservation 

standards at 10 CFR 430.32(d) define the 

minimum required UEF as a function of 

rated storage volume. These standards 

have been amended over time but are 

based on the original standards 

prescribed by EPCA at 42 U.S.C. 

6295(e)(1), which also correlated the 

efficiency metric to storage volume. In 

doing so, these standards account for 

differences in standby losses (i.e., heat 

transfer from the hot, stored water to the 

ambient surroundings) for storage tanks 

of varying sizes. For storage-type water 

heaters, the amount of hot water 

immediately available for consumer use 

has typically been governed by the 

storage tank size, with increased tank 

size resulting in a corresponding 

increase in standby losses. Standby 

losses are primarily dependent upon 

three factors: (1) surface area of the tank; 

(2) temperature of the stored water, and 

(3) tank insulation. As storage tank 

volume increases, so do the expected 

standby losses (all else being equal). 

Similarly, an increased water 

temperature would also increase 

standby losses. The standards originally 

prescribed by EPCA and subsequently 

amended by DOE did not contemplate 

storage tank over-heating and its 

potential impact on standby losses and 

the amount of hot water that is 

immediately available for consumer use. 

Therefore, DOE has initially concluded 

that a capacity metric that combines 

information about the tank volume and 

storage temperature may be more 

appropriate. 

Similar to standby loss, the thermal 

energy stored in a water heater is a 

function of both the volume and the 

temperature of the water being stored in 

the tank. The ability to over-heat the 

tank increases the effective thermal 

energy storage of the tank to that 

equivalent to a larger tank that has been 

heated to a more conventional, lower 

temperature (i.e., approximately 125 

±5 °F). DOE has tentatively determined 

that a measure of ‘‘effective storage 

volume’’ (as suggested by the Joint 

Advocates) that reflects the thermal 

energy stored in the water heater would 

allow for a better comparison between a 

smaller water heater with over-heating 

and a larger water heater storing water 

at a lower temperature. 

Lutz stated that the test procedure 

should be able to distinguish and 

measure the ability of a water heater to 

deliver hot water with enough energy 

and to deliver a high enough 

temperature. Lutz provided the example 

of a bath, where the temperature at 

every point during the draw is not 

important; contrasted with a shower, 

where the temperature is crucial. (Lutz, 

No. 35 at p. 1) 

DOE notes that for activities such as 

filling a bathtub, consumers would 

benefit more from knowing the effective 

storage volume (i.e., the volume of 

immediately available hot water) of a 

water heater, whereas for activities such 

as taking a shower, consumers could 

benefit more from knowing the FHR 

(i.e., ability to deliver hot water for an 

extended period of time). In particular, 


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FHR represents one full hour of delivery 

and does not necessarily describe 

immediate hot water availability, as 

FHR is also impacted by the rate of 

recovery. Hence, in addition to FHR, 

DOE has tentatively determined that 

effective storage volume would be a 

meaningful performance metric for 

consumers. In this SNOPR, DOE 

proposes a method to determine 

effective storage volume, Veff (expressed 

in gallons or liters), at section 6.3.1.1 of 

appendix E. For water heaters storing 

water no higher than the delivery 

temperature, DOE proposes that the 

effective storage volume be equivalent 

to the measured storage volume. DOE 

proposes that to determine whether the 

stored water temperature is higher than 

the delivery temperature, the maximum 

mean tank temperature measured after 

cut-out following the first draw of the 

24-hour simulated-use test (Tmax,1) is to 

be compared to the average outlet water 

temperature during the second draw of 

the 24-hour simulated-use test (Tdel,2). If 

Tmax,1 is less than or equal to Tdel,2, then 

the unit would be determined to not be 

capable of over-heating the stored water, 

and the effective storage volume would 

be set equal to the measured storage 

volume. DOE has tentatively chosen 

Tmax,1 to represent the temperature of 

the stored water. Based on DOE’s review 

of its own test data, Tmax,1 is typically 

the highest mean tank temperature 

achieved by the water heater, and Tmax

values throughout the test (i.e., all 

maximum mean tank temperatures 

following element cut-out) typically do 

not vary significantly. DOE has 

tentatively chosen Tdel,2 to represent the 

delivered water temperature because it 

corresponds to the first draw after Tmax,1

is observed. 

By contrast, for water heaters capable 

of over-heating water (as determined by 

Tmax,1 being greater than Tdel,2), DOE 

proposes to calculate the effective 

storage volume based on a volume 

scaling factor and data already collected 

during the appendix E test. The volume 

scaling factor would be determined as 

follows, which is based on the relative 

heat transfer rates calculated from the 

temperature data collected during the 

test: 

Where: 

kV is the dimensionless volume scaling 

factor; 

r(T) is the density of water evaluated at 

temperature T; 

CP(T) is the heat capacity of water evaluated 

at temperature T, and 

67.5 °F is the average ambient temperature. 

DOE proposes to determine the 

effective storage volume by multiplying 

the measured storage volume by kV. 

DOE notes that this approach to 

calculating effective storage volume 

would allow all calculations to be based 

on data collected during a single 24- 

hour simulated use test, but it would 

yield meaningful results only if water 

heaters capable of over-heating are 

required to be tested in an over-heated 

mode, which is discussed in section 

III.C.1 of this document. 

This SNOPR does not propose to 

require representations of effective 

storage volume, but DOE may consider 

such requirements as part of a future 

energy conservation standards 

rulemaking, should this proposal be 

finalized. 

With respect to the comment from the 

CA IOUs suggesting that the energy 

conservation standards be based on FHR 

rather than storage volume, DOE notes 

that changes to the energy conservation 

standards are outside the scope of this 

test procedure rulemaking. However, 

this recommendation, along with the 

Joint Advocates’ recommendation that 

standards be based on an effective 

volume, will be considered further in 

DOE’s concurrent energy conservation 

standards rulemaking. 

DOE seeks comment on its tentative 

determination that effective storage 

volume would be a meaningful 

performance metric for consumers and 

is a more appropriate measure of 

thermal energy storage than FHR. 

DOE seeks comment on the proposed 

equations and approach to calculating 

effective storage volume for water 

heaters. 

D. Separate Storage Tank Requirements 

Some water heaters on the market 

require a volume of water, typically 

contained in either a storage tank (or 

tanks) or in a piping distribution system 

of sufficient volume, to operate. These 

products operate by circulating water 

stored either in the piping system or 

from a separate tank (or multiple 

separate tanks) to the water heater to be 

heated then back to the piping system 

or tank until hot water is needed. In the 

January 2022 NOPR, DOE identified two 

types of products that require a volume 

of water to operate—heat pump-only 

water heaters that require installation 

with a separate storage tank and 

circulating gas-fired instantaneous water 

heaters that require installation with a 

separate storage tank or a piping system 

of sufficient volume. 87 FR 1554, 1583– 

1585 (Jan. 11, 2022). Circulating gasfired instantaneous water heaters are 

distinct from other types of gas-fired 

instantaneous water heaters in that they 

are not designed to operate independent 

of a storage tank or hot water system, as 

other gas-fired instantaneous water 

heaters are. This applies generally to 

circulating water heaters; however, DOE 

has tentatively determined that there are 

no electric resistance or oil-fired 

circulating water heaters on the market 

today. 

The current test procedure does not 

have procedures in place to 

appropriately test circulating water 

heaters. As such, in the January 2022 

NOPR, DOE proposed to define 

‘‘circulating water heater’’ (including 

both heat pump-only and gas-fired 

instantaneous circulating water heaters) 

and to require that such products be 

tested using an 80 gallon (± 1 gallon) 

unfired hot water storage tank 

(‘‘UFHWST’’) that meets the energy 

conservation standards for an unfired 

hot water storage tank at 10 CFR 

431.110(a). 87 FR 1554, 1583–1585 (Jan. 

11, 2022). 

In response to the January 2022 

NOPR, DOE received a number of 

comments regarding the separate storage 

tank requirements, primarily related to 

the ± 1 gallon tolerance, the 

representativeness of an 80-gallon 

unfired hot water storage tank, and the 

lack of a specification for the upper 

bound on thermal insulation for the 

unfired hot water storage tank. These 

comments are summarized and 

addressed in the paragraphs that follow. 

NYSERDA commented that an 80- 

gallon UFHWST may not be the correct 

tank to use to increase repeatability and 

represent real world conditions. 

(NYSERDA, No. 32 at p. 2) 

Rheem commented that because a 

circulating water heater can be paired 

with multiple sizes of tanks (e.g., 40-, 

60-, and 80-gallon tanks), DOE should 

consider multiple tank sizes for testing 

circulating water heaters instead of just 

one 80-gallon storage tank. Rheem also 

suggested that DOE increase the 


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23 DOE understands this to be a reference to the 

10 percent by volume tolerances prescribed by UL 

Standard 174 (‘‘Household Electric Storage Tank 

Water Heaters’’) and UL Standard 1453 (‘‘Standard 

for Electric Booster and Commercial Storage Tank 

Water Heaters’’). These standards can be found 

online at www.shopulstandards.com (Last accessed 

on June 21, 2022). 

24See Figure 3A.2.8 of the Preliminary Analysis 

Technical Support Document for consumer water 

heaters (Docket No. EERE–2017–BT–STD–0019– 

0018). 

tolerance on the volume of the storage 

tank to match the tolerance prescribed 

by product safety standards,23 noting 

that a ±1 gallon tolerance on an 80- 

gallon storage volume is too tight. 

Rheem also requested clarification on 

whether the separately sold storage tank 

may have backup heating (e.g., if the 

circulating water heater is designed to 

be used with a tank that has backup 

heating) and whether the two products 

could be rated together as a system. 

(Rheem, No. 40 at pp. 3–4) 

AHRI recommended that DOE not 

adopt a ±1 gallon tolerance requirement 

for the storage tank used in the test for 

a heat pump-only water heater, stating 

that DOE should instead apply 10 

percent volume tolerance, consistent 

with UL standard 174 or UL standard 

1453. AHRI also suggested that 

manufacturers be allowed to specify the 

storage tank used to determine ratings 

for circulating and heat pump-only 

water heaters. (AHRI, No. 40 at pp. 3– 

5) 

A.O. Smith stated that it would not be 

unduly burdensome to use an 80-gallon 

tank for heat pump-only water heater 

testing. However, A.O. Smith stated that 

tank insulation, inlet and outlet 

connection locations, internal tank 

baffling, and inlet tube designs could 

impact the UEF result, and accordingly, 

these variables should be addressed in 

the DOE test procedure. A.O. Smith 

recommended that, to minimize as 

many variables as possible, 

manufacturers be required to provide 

the model number of the specific tank 

as part of its certification data, and that 

the test tank should be defined as a part 

of the test apparatus. (A.O. Smith, No. 

37 at p. 3) DOE understands this to 

mean that A.O. Smith recommends that 

the UFHWST model number used for 

testing UEF be certified to DOE by the 

manufacturer, and that appendix E 

should indicate that the specific 

UFHWST model certified to DOE must 

be used in the test set-up. 

The CA IOUs stated that the proposed 

80-gallon tank size may not reflect realworld applications. Additionally, the 

CA IOUs argued that because the 

proposed requirement would impose a 

minimum R-value for the tank, but no 

maximum, it could lead to variations in 

test outcomes. The CA IOUs suggested 

that heat pump-only water heater 

manufacturers should be allowed to test 

their products with a manufacturerspecified storage tank and certify the 

information about the tank used for 

testing. The CA IOUs also suggested that 

for heat-pump-only water heaters, DOE 

should specify a traditional consumer 

electric storage water heater tank, as it 

may be more representative of actual 

use. (CA IOUs, No. 36 at p. 5; CA IOUs, 

No. 27 at p. 31) 

BWC commented that not all storage 

tanks are designed identically, and 

differences in tank design may lead to 

differences in ratings for circulating and 

heat pump-only water heaters. BWC 

also urged DOE to not adopt a 1-gallon 

tolerance on the volume of an 80-gallon 

storage tank, but instead to use a 10- 

percent tolerance. BWC requested that 

DOE clarify whether the 80-gallon 

requirement would pertain to nominal 

capacity. (BWC, No. 33 at p. 9) 

After considering the issues raised by 

commenters, DOE is proposing several 

updates to its earlier proposals (in 

section 4.10 of appendix E) for testing 

circulating water heaters as initially 

presented in the January 2022 NOPR. 

First, after re-evaluating the market 

for heat-pump-only water heaters, DOE 

tentatively agrees with the CA IOUs that 

testing such products with a 

conventional electric storage water (i.e., 

an electric water heater that uses only 

electric resistance heating elements) 

would be more representative than 

testing with an UFHWST. Therefore, 

DOE is proposing that heat-pump-only 

water heaters be tested in the medium 

draw pattern using a 40-gallon 

traditional electric storage tank (i.e., that 

provides heat only with electric 

resistance heating elements) that has a 

UEF rating at the minimum required at 

10 CFR 430.32(d). DOE chose a 40- 

gallon tank in the medium draw pattern 

because that size and draw pattern 

combination has the highest number of 

models currently available on the 

market.24 DOE is also proposing that, for 

heat pump-only water heaters, the test 

be carried out using a tank that does not 

‘‘over-heat’’ the stored water (see 

discussion of over-heating in section 

III.C of this document; Tmax,1 (maximum 

measured mean tank temperature after 

the first recovery period of the 24-hour 

simulated-use test) must be less than or 

equal to Tdel,2 (average outlet water 

temperature during the 2nd draw of the 

24-hour simulated-use test)). This 

would ensure that the electric storage 

tanks are not overheating during the 

test, thereby ensuring consistency across 

tests. 

In contrast, DOE is maintaining its 

earlier proposal that a UFHWST be used 

for testing of circulating gas-fired water 

heaters, as those products are more 

likely to be installed with a UFHWST in 

the field. Therefore, DOE tentatively 

concludes that testing with an UFHWST 

would be representative for such units. 

In response to AHRI’s suggestion that 

DOE allow manufacturers to specify the 

storage tank used for testing, DOE notes 

that this approach could lead to 

additional test burden for third-party 

testing labs, who may need to acquire 

more than one storage tank if they are 

performing tests for multiple 

manufacturers, each of whom may 

specify a different storage tank for 

testing. In order to avoid creating the 

potential for additional test burden, 

DOE has tentatively determined not to 

allow manufacturers to specify the 

electric storage water heater or unfired 

hot water storage tank used respectively 

for testing the heat pump-only or gasfired instantaneous circulating water 

heaters. Additionally, DOE will 

consider relevant amendments to 

certification and reporting requirements 

in a separate rulemaking. 

After considering the comments 

regarding the tolerance on the storage 

tank initially proposed in the January 

2022 NOPR, DOE has tentatively 

determined that a wider tolerance 

would reduce potential testing burden 

while still providing representative and 

reproducible results. In other words, 

DOE tentatively concludes that a 10- 

percent tolerance would increase 

flexibility for manufacturers by 

increasing the number of tanks that 

could be used for testing, while not 

materially impacting the UEF test 

results. Therefore, consistent with the 

recommendations provided by 

commenters, DOE is proposing to adopt 

a 10 percent tolerance (±10 percent, 

allowing products with rated storage 

volumes between 36 gallons and 44 

gallons) for the electric storage water 

heater used for testing heat-pump-only 

water heaters. 

In addition, after further review of the 

market for circulating gas-fired 

instantaneous water heaters and unfired 

hot water storage tanks, DOE is 

proposing to allow testing with a tank 

at any storage volume between 80- and 

120-gallons. Based on further analysis, 

DOE has tentatively determined that 

variations in the tank size should not 

significantly impact the result of the 

test. During a water draw, the internal 

tank temperature decreases as hot water 

exits the tank and is replenished by 

colder water entering the tank. 


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25Currently, baseline energy conservation 

standards for UFHWSTs require a thermal 

insulation of R–12.5. 10 CFR 431.110(a). 

Generally, different tank sizes will 

result in different rates of internal 

temperature decrease during a water 

draw (e.g., during a specified water 

draw, a smaller tank will generally 

experience a faster decrease in 

temperature compared to a larger tank). 

During a test, any potential differences 

in the tank water temperature due to the 

use of different size tanks would be 

accompanied by a corresponding 

proportional difference in burner ontime, such that the impact on measured 

efficiency (i.e., the ratio of energy output 

to energy input) would be negligible. 

DOE also recognizes that a larger tank 

would likely have more standby losses 

than a smaller tank; however, DOE has 

tentatively determined that the impact 

this would have on measure efficiency 

would also not be significant. 

Providing a range of allowable tank 

volumes would reduce potential burden 

by providing manufacturers with more 

tank options, thereby allowing them to 

pair their circulating gas-fired 

instantaneous water heaters with an 

existing UFHWST model. This approach 

is also likely to be more representative 

of how the units would be installed in 

the field as opposed to testing with a 

custom-made tank for testing or a 

competitor’s tank that meets a specific 

volume requirement. 

DOE notes that, as suggested by the 

CA IOUs and A.O. Smith, the lack of an 

upper bound on the thermal insulation 

value for the UFHWST could lead to 

differences in measured efficiency that 

reflect differences in tank performance, 

rather than reflecting differences in 

water heater performance. Therefore, 

DOE has tentatively determined that 

more specific constraints on tank 

performance are warranted to ensure 

more comparable test results across the 

subject water heater models. Thus, DOE 

is proposing to require that UFHWSTs 

used for testing circulating gas-fired 

instantaneous water heaters exactly 

meet the baseline energy conservation 

standard for UFHWSTs.25 As stated 

previously, A.O. Smith raised the 

concern that differences in the 

UFHWST’s design (insulation, inlet and 

outlet connection locations, internal 

tank baffling, and inlet tube designs) 

could lead to variation in UEF results; 

however, A.O. Smith and other 

commenters did not provide suggestions 

on specific UFHWST designs which 

should be standardized in order to 

improve representativeness and 

repeatability of the test method. A.O. 

Smith did not provide any data to 

demonstrate these to be significant 

concerns. While the variations in 

insulation would most significantly 

impact the standby losses of the tank 

(and therefore the UEF rating of the 

circulating water heater), these 

variations would already be minimized 

by specifying the R-value of the 

UFHWST to be the baseline requirement 

in the energy conservation standards for 

UFHWSTs. Regarding the other design 

options, over-specifying the design of 

the UFHWST—given the impacts on the 

UEF rating are minimal—could result in 

a very narrow range of UFHWST models 

which can be used for testing circulating 

water heaters, thereby potentially 

introducing significant barriers to 

testing these products at third-party 

laboratories. Additionally, DOE does not 

currently have sufficient information on 

specifications for the inlet and outlet 

connection locations, internal tank 

baffling, and inlet tube designs for the 

UFHWST; therefore, DOE is not 

including these specifications in its 

proposed requirements. 

As noted previously, DOE is similarly 

proposing that the electric storage water 

heater used for testing heat-pump-only 

water heaters have a rated UEF 

corresponding to the minimum standard 

found at 10 CFR 430.32(d), thereby 

helping to ensure more comparable 

results. 

In summary, in this SNOPR, DOE 

proposes to further amend the separate 

storage tank requirements proposed in 

the January 2022 NOPR for heat pumponly and gas-fired circulating water 

heaters. DOE proposes that heat pumponly water heaters be tested with a 40- 

gallon (± 4 gallons) electric storage 

water heater that has a UEF value 

corresponding to the minimum standard 

for such products; and that gas-fired 

circulating water heaters be tested with 

an 80- to 120-gallon unfired hot water 

storage tank that is rated equal to the 

energy conservation standard for such 

equipment. 

DOE requests comment on its 

proposed separate tank requirements for 

heat pump-only and gas-fired 

circulating water heaters. DOE also 

seeks comment on whether any 

additional tank characteristics should be 

specified. 

For gas-fired circulating water heaters, 

these proposed changes could require a 

one-time purchase of an 80- to 120- 

gallon unfired hot water storage tank. 

DOE research indicates that such tanks 

are readily commercially available for 

approximately $2,000. For heat pumponly water heaters, the proposed 

changes could result in a one-time 

purchase of a 40-gallon (± 4 gallons) 

electric storage water heater. DOE 

research indicates that such water 

heaters are readily available for 

approximately $500. These estimates 

reflect costs for third-party laboratory 

testing (i.e., assuming these tanks would 

have to be purchased at retail price). 

DOE seeks comment on the estimated 

potential increase in costs for testing 

heat pump-only and gas-fired 

circulating water heaters according to 

this proposal. 

Finally, although this SNOPR does 

not propose changes to the certification 

requirements, DOE may consider a 

requirement to certify the UFHWST and 

electric storage water heater models 

and/or characteristics in a future 

rulemaking. 

E. Method for Determining Internal 

Tank Temperature for Certain Water 

Heaters 

As discussed in the January 2022 

NOPR, section 4.5 of appendix E 

specifies that the thermocouples be 

inserted into the storage tank of a water 

heater through either the anodic device 

opening, the temperature and pressure 

relief valve, or the outlet water line. 

DOE has identified consumer water 

heaters with physical attributes that 

make measuring internal storage tank 

temperature using any of these means 

difficult, such as water heaters that have 

a built-in mixing valve and no anodic 

device, or have a large heat exchanger 

that does not accommodate insertion of 

a thermocouple tree. 87 FR 1554, 1586 

(Jan. 11, 2022). Commenters on the 

April 2020 RFI suggested an approach 

whereby the tank would be drained 

down to measure the temperature of the 

water inside. Id. In the January 2022 

NOPR, DOE explained how draining 

down the tank would not be possible in 

the middle of the 24-hour simulated use 

test, when mean tank temperature data 

is required. Id. Therefore, DOE proposed 

that the internal tank temperature for 

these products would be approximated 

as the average between the inlet and 

outlet temperatures (i.e., a ‘‘linear 

temperature gradient’’ assumption). Id. 

Rheem agreed with DOE’s proposed 

methodology to estimate the mean tank 

temperature for products for which the 

internal tank temperature cannot be 

directly measured. (Rheem, No. 31 at p. 

4) 


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26Additionally, AHRI stated that the procedure 

should require measurements to be taken 15 

seconds after the initial draw to be consistent with 

other proposals. 

27Currently, mean tank temperature 

measurements are not required for consumer water 

heaters or residential-duty commercial water 

heaters less than 2 gallons in rated storage volume. 

However, several commenters 

indicated that the linear temperature 

gradient assumption inherent to the 

proposed methodology in the January 

2022 NOPR is incorrect. AHRI 

commented that the proposed procedure 

incorrectly assumes a linear temperature 

gradient in the tank, which can lead to 

inaccurate calculation of temperature 

and stored energy in the tank.26 (AHRI, 

No. 40 at p. 5) 

A.O. Smith commented that it has 

conducted testing using the proposed 

test method and has found that the 

assumption of a linear temperature 

gradient is inaccurate when compared 

to actual temperature readings 

conducted with thermocouples. 

Accordingly, A.O. Smith concluded that 

it would be premature to incorporate the 

proposed test method into the DOE test 

procedure at this time. (A.O. Smith, No. 

37 at pp. 5–6) BWC indicated that, 

based on its own testing, the proposed 

methodology could record artificially 

lower tank temperatures, with errors as 

high as 10 to 25 percent. (BWC, No. 33 

at p. 10) 

In the final rule that established the 

current test procedure for commercial 

water heaters, DOE noted that using the 

average of the supply and outlet water 

temperature as an estimate for the stored 

water temperature is only valid if the 

water temperature inside the heat 

exchanger has a linear increase in 

temperature as it moves from the inlet 

to the outlet. 81 FR 79261, 79295 (Nov. 

10, 2016). In order to estimate the 

internal tank temperature for 

commercial instantaneous water heaters 

and hot water supply boilers, DOE 

adopted a method that uses the outlet 

water temperature as an approximation, 

because it was consistent with the 

industry-adopted test method for flowactivated instantaneous water heaters, 

found at Annex E.3 of ANSI Standard 

Z21.10.3–2015. Id. 

However, as discussed in section III.C 

of this SNOPR, DOE is aware of 

consumer water heaters that can store 

water at temperatures that are 

significantly higher than the outlet 

temperature, so the method used for 

commercial instantaneous water heaters 

and hot water supply boilers would not 

be applicable to all types of products 

covered under this rulemaking. 

Furthermore, outlet water temperature 

would only be representative of the 

internal tank temperature for consumer 

water heaters and residential-duty 

commercial water heaters with very 

limited storage volume, where the small 

volume prevents internal temperature 

stratification.27

Based on further consideration of 

comments received in response to the 

January 2022 NOPR and at previous 

stages of this rulemaking, DOE is 

proposing in this SNOPR that, for water 

heaters with rated storage volumes 

greater than or equal to 2 gallons that 

are unable to have their internal tank 

temperatures measured using 

thermocouples, the internal tank 

temperature shall be estimated by 

removing water from the water heater, 

as described in detail in the following 

paragraphs. This method, proposed in a 

new section 5.4.2.2 of appendix E, is 

partially based on the approaches 

suggested by Rheem and BWC prior to 

the January 2022 NOPR (see Document 

No. EERE–2019–BT–TP–0032–0012 at 

p. 5 and Document No. EERE–2019–BT– 

TP–0032–0014 at p. 9), with certain 

modifications. 

As discussed in the January 2022 

NOPR, throughout the 24-hour 

simulated-use test, internal tank 

thermocouples are used to determine 

the mean tank temperature. Mean tank 

temperatures are required at the start 

and end of the test, the start and end of 

the standby period, and the after the 

first recovery period (i.e., T0, T24, Tsu,0, 

Tsu,f, and Tmax,1, respectively). Also, an 

average mean tank temperature 

throughout the standby period is 

required (i.e., Tt,stby,1). 87 FR 1554, 1586 

(Jan. 11, 2022). DOE performed an 

analysis on data collected from its own 

testing and has initially concluded that, 

for typical storage-type water heaters, 

T0, , Tsu,0, and Tmax,1 are similar in that 

they represent temperatures near the 

cut-out control temperature. Removing 

the heated water from the tank and 

measuring the temperature, as described 

in detail below, immediately after cutout may reasonably estimate these 

temperatures. The mean tank 

temperature at the end of the standby 

period, Tsu,f, can also be measured by 

removing water and measuring its 

temperature at the end of a sufficiently 

long standby period at the end of the 

test, and this value could also 

approximate T24. 

In this SNOPR, DOE is proposing the 

following methodology for water heaters 

with rated storage volumes greater than 

or equal to 2 gallons that are unable to 

have their internal tank temperatures 

measured using thermocouples: 

(1) After the FHR test (for non-flowactivated products) or Max GPM test (for 

flow-activated products), allow the 

water heater to fully recover. 

(2) When cut-out occurs, deactivate 

the burner, compressor, and/or 

electrical heating elements. 

(3) Remove the hot water from the 

tank by performing a continuous draw, 

while measuring the outlet water 

temperature at 3-second intervals, until 

the outlet water temperature is within 

2 °F of the inlet water temperature for 

five consecutive readings. Perform the 

draw at a flow rate of 3.0 gallons per 

minute (±0.25 gallons per minute). 

Compute the mean tank temperature, 

Tst, as follows and assign this value as 

T0, Tsu,0, and Tmax,1: 

Where: 

Tst = the estimated average internal storage 

tank temperature. 

Tp = the average of the inlet and the outlet 

water temperatures at the end of the 

period defined by tp. 

vout,p = the average flow rate during the 

period. 

Vst = the rated storage volume of the water 

heater. 

tp = the duration of the period, determined 

by the length of time taken for the outlet 

water temperature to be within 2 °F of 

the inlet water temperature for 15 

consecutive seconds. The duration of the 

period shall include the 15-second 

stabilization period. 

Tin,p = the average of the inlet water 

temperatures during the period. 

Tout,p = the average of the outlet water 

temperatures during the period. 

(4) Re-activate the burner, 

compressor, and/or electrical elements 

and perform the 24-hour simulated use 


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test as instructed in section 5.4 of 

appendix E. 

(5) The standby period will start at 

five minutes after the end of the first 

recovery period after the last draw of the 

simulated-use test. The standby period 

shall last eight hours, so testing will 

extend beyond the 24-hour duration of 

the simulated-use test. At the end of the 

final standby measurement, remove 

water from the tank once again as in 

step #3, including computing the value 

of mean tank temperature. This 

calculated mean tank temperature is 

then assigned as Tsu,f and T24. 

(6) Determine Tt,stby,1 as the average of 

Tsu,0 and Tsu,f. 

DOE seeks comment on its revised 

proposed test method to determine the 

internal tank temperature for water 

heaters that cannot be directly measured 

and are greater than or equal to 2 gallons 

in rated storage volume. 

DOE estimates that, at maximum, the 

proposed method for estimating the 

internal tank temperature would 

increase the test duration by 8 hours 

(corresponding to the final standby 

period appended to the current 24-hour 

simulated use test). DOE estimates that 

the testing a water heater to the 24-hour 

simulated use test currently costs $3,000 

for a fossil-fuel-fired or electric water 

heater and $4,500 for a heat pump water 

heater. By extending the duration of the 

test by up to 8 hours (or 33 percent), this 

amendment, if finalized, could increase 

testing costs by $1,000 to $1,500 per 

basic model for water heaters with rated 

storage volume greater than or equal to 

2 gallons which cannot have their 

internal storage tank directly measured. 

However, these products are designed in 

such a way that instruments for 

measuring the internal water 

temperature cannot be installed, and, 

thus, these products cannot be tested to 

the current version of appendix E. 

IV. Procedural Issues and Regulatory 

Review 

A. Review Under Executive Orders 

12866 and 13563 

Executive Order (‘‘E.O.’’)12866, 

‘‘Regulatory Planning and Review,’’ 58 

FR 51735 (Oct. 4, 1993), as 

supplemented and reaffirmed by E.O. 

13563, ‘‘Improving Regulation and 

Regulatory Review,’’ 76 FR 3821 (Jan. 

21, 2011), requires agencies, to the 

extent permitted by law, to: (1) propose 

or adopt a regulation only upon a 

reasoned determination that its benefits 

justify its costs (recognizing that some 

benefits and costs are difficult to 

quantify); (2) tailor regulations to 

impose the least burden on society, 

consistent with obtaining regulatory 

objectives, taking into account, among 

other things, and to the extent 

practicable, the costs of cumulative 

regulations; (3) select, in choosing 

among alternative regulatory 

approaches, those approaches that 

maximize net benefits (including 

potential economic, environmental, 

public health and safety, and other 

advantages; distributive impacts; and 

equity); (4) to the extent feasible, specify 

performance objectives, rather than 

specifying the behavior or manner of 

compliance that regulated entities must 

adopt; and (5) identify and assess 

available alternatives to direct 

regulation, including providing 

economic incentives to encourage the 

desired behavior, such as user fees or 

marketable permits, or providing 

information upon which choices can be 

made by the public. DOE emphasizes as 

well that E.O. 13563 requires agencies to 

use the best available techniques to 

quantify anticipated present and future 

benefits and costs as accurately as 

possible. In its guidance, the Office of 

Information and Regulatory Affairs 

(‘‘OIRA’’) in the Office of Management 

and Budget (‘‘OMB’’) has emphasized 

that such techniques may include 

identifying changing future compliance 

costs that might result from 

technological innovation or anticipated 

behavioral changes. For the reasons 

stated in the preamble, this proposed 

regulatory action is consistent with 

these principles. 

Section 6(a) of E.O. 12866 also 

requires agencies to submit ‘‘significant 

regulatory actions’’ to OIRA for review. 

OIRA has determined that this proposed 

regulatory action does not constitute a 

‘‘significant regulatory action’’ under 

section 3(f) of E.O. 12866. Accordingly, 

this action was not submitted to OIRA 

for review under E.O. 12866. 

B. Review Under the Regulatory 

Flexibility Act 

The Regulatory Flexibility Act (5 

U.S.C. 601 et seq.) requires preparation 

of an initial regulatory flexibility 

analysis (‘‘IRFA’’) for any rule that by 

law must be proposed for public 

comment, unless the agency certifies 

that the rule, if promulgated, will not 

have a significant economic impact on 

a substantial number of small entities. 

As required by Executive Order 13272, 

‘‘Proper Consideration of Small Entities 

in Agency Rulemaking,’’ 67 FR 53461 

(August 16, 2002), DOE published 

procedures and policies on February 19, 

2003, to ensure that the potential 

impacts of its rules on small entities are 

properly considered during the DOE 

rulemaking process. 68 FR 7990. DOE 

has made its procedures and policies 

available on the Office of the General 

Counsel’s website: www.energy.gov/gc/ 

office-general-counsel. DOE reviewed 

this test procedure SNOPR under the 

provisions of the Regulatory Flexibility 

Act and the policies and procedures 

previously published on February 19, 

2003. 

The following sections detail DOE’s 

IRFA for this test procedure rulemaking. 

1. Description of Reasons Why Action Is 

Being Considered 

DOE is proposing to amend test 

procedures for consumer water heaters 

and residential-duty commercial water 

heaters. DOE is publishing this 

rulemaking in satisfaction of the 7-yearlookback review requirement specified 

in EPCA. (42 U.S.C. 6293(b)(1)(A); 

6314(a)(1)) Further, amending test 

procedures for consumer and 

residential-duty commercial water 

heaters assists DOE in fulfilling its 

statutory deadline for amending energy 

conservation standards for products and 

equipment that achieve the maximum 

improvement in energy efficiency that is 

technologically feasible and 

economically justified. (42 U.S.C. 

6295(o)(2)(A); 42 U.S.C. 6313(a)(6)) 

Additionally, amending test procedures 

for consumer and residential-duty 

commercial water heaters allows 

manufacturers to produce 

measurements of energy efficiency that 

are representative of an average use 

cycle and uniform for all manufacturers. 

On January 11, 2022, DOE published 

a test procedure NOPR (‘‘January 2022 

NOPR’’) in the Federal Register 

proposing to amend the test procedure 

for consumer water heaters and 

residential-duty commercial gas water 

heaters. See 87 FR 1554, 1590–1592. In 

this SNOPR, DOE proposes 

modifications to the January 2022 

NOPR. 

2. Objectives of, and Legal Basis for, 

Rule 

EPCA authorizes DOE to regulate the 

energy efficiency of a number of 

consumer products and certain 

industrial equipment, including the 

consumer and residential-duty 

commercial water heaters that are the 

subject of this proposed rulemaking. (42 

U.S.C. 6292(a)(4) and 42 U.S.C. 

6311(1)(K)) 

3. Description and Estimate of Small 

Entities Regulated 

For manufacturers of consumer water 

heaters and residential-duty commercial 

water heaters, the Small Business 

Administration (SBA) has set a size 

threshold, which defines those entities 

classified as ‘‘small businesses’’ for the 


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28U.S. Department of Energy Compliance 

Certification Management System, available at: 

www.regulations.doe.gov/ccms. (Last accessed 

March 1, 2022). 

29AHRI Directory of Certified Product 

Performance, available at: www.ahridirectory.org/ 

Search/SearchHome. (Last accessed March 1, 2022). 

purposes of the statute. DOE used the 

SBA’s small business size standards to 

determine whether any small entities 

would be subject to the requirements of 

the rule. (See 13 CFR part 121.) The size 

standards are listed by North American 

Industry Classification System 

(‘‘NAICS’’) code and industry 

description and are available at: 

www.sba.gov/document/support—tablesize-standards. Manufacturing of 

consumer water heaters and residentialduty commercial water heaters is 

classified under NAICS 335220, ‘‘Major 

Household Appliance Manufacturing.’’ 

The SBA sets a threshold of 1,500 

employees or fewer for an entity to be 

considered as a small business for this 

category. DOE used available public 

information to identify potential small 

manufacturers. DOE accessed CCMS,28

the certified product directory of the 

AHRI,29 company websites, and 

manufacturer literature to identify 

companies that import, private label, or 

produce the consumer water heaters and 

residential-duty commercial water 

heaters covered by this proposal. Using 

these sources, DOE identified a total of 

27 manufacturers of consumer water 

heaters and residential-duty commercial 

water heaters. Of these 27 

manufacturers, DOE identified one 

domestic small business that 

manufactures products covered by the 

proposed test procedure amendments in 

this SNOPR. 

4. Description and Estimate of 

Compliance Requirements 

As noted previously, DOE conducted 

an initial regulatory flexibility analysis 

(‘‘IRFA’’) as part of the January 2022 

NOPR, in which it determined that there 

is one domestic, small business that 

manufactures residential water heaters 

impacted by the January 2022 NOPR. Id. 

at 87 FR 1591. Under the proposed 

amendments in the January 2022 NOPR, 

DOE anticipated the small business 

would incur third-party re-testing costs 

of $4,500 for one basic model as result 

of DOE’s proposal to require the use of 

a separate unfired hot water storage tank 

for testing water heaters designed to 

operate with a separately sold hot water 

storage tank. DOE estimated the 

compliance burden to represent less 

than 0.01 percent of the company’s 

revenue. Id. 

This SNOPR serves to: (1) provide 

additional specificity for the existing 

test procedure for water heaters with a 

rated storage volume of less than 2 

gallons; (2) propose optional rating 

conditions and associated metrics for 

voluntary representations of heat pump 

water heaters; (3) revise the separate 

storage tank requirements for circulating 

water heaters proposed in the January 

2022 NOPR; (4) provide instructions for 

testing water heaters which store water 

at a temperature higher than the 

delivery setpoint and for determining 

the effective storage volume of such 

products, and (5) revise the testing 

requirements for water heaters which 

are greater than or equal to 2 gallons in 

rated storage volume but cannot have 

the temperature of their internal storage 

tanks directly measured. Each of these 

proposed amendments will be discussed 

in turn to assess their potential impacts 

in light of the Regulatory Flexibility Act. 

First, DOE proposes to add flow rate 

tolerances for the 24-hour simulated-use 

test for water heaters with a rated 

storage volume of less than 2 gallons. 

DOE expects that laboratories may 

utilize high-precision water flow rate 

instrumentation (e.g., Coriolis flow 

meters) to meet the proposed flow rate 

tolerances. DOE is aware of multiple 

third-party laboratories which already 

incorporate Coriolis flow meters for 

DOE compliance testing. Further, DOE 

expects that general industry best 

practice is already applying the flow 

rate tolerances being proposed for 

section 5.4.3 of appendix E for water 

heaters with rated storage volume less 

than 2 gallons; therefore, this proposal 

is expected to be consistent with current 

methodology and practice. 

Additionally, DOE has tentatively 

determined that the proposed 

amendment would not alter the 

measured efficiency of consumer water 

heaters and residential-duty commercial 

water heaters, nor require retesting or 

recertification solely as a result of DOE’s 

adoption of the proposed amendments 

to the test procedure. For these reasons, 

DOE has initially determined that the 

proposed tolerances would generally 

not impose additional testing burden. 

Second, DOE is proposing to adopt 

optional test conditions and metrics for 

voluntary representations of heat pump 

water heater energy efficiency at test 

conditions other than the standard 

rating conditions. If adopted in a final 

rule, these metrics will not be required 

for reporting or compliance with 

standards for consumer water heaters 

and residential-duty commercial water 

heaters. Therefore, DOE has initially 

determined that testing for these 

optional metrics would not be unduly 

burdensome to conduct. 

Third, DOE previously proposed 

separate storage tank requirements for 

testing circulating water heaters in the 

January 2022 NOPR. 87 FR 1554, 1589 

(Jan. 11, 2022). In the January 2022 

NOPR, DOE proposed that circulating 

water heaters (including heat pumponly water heaters) be tested paired 

with 80-gallon unfired hot water storage 

tanks which meets the energy 

conservation standard requirements at 

10 CFR 431.110(a). Id. In this SNOPR, 

DOE is instead proposing to require 

circulating gas-fired instantaneous water 

heaters and heat pump-only water 

heaters to be paired with different types 

of tanks to be more representative of 

field installations. 

For circulating gas-fired instantaneous 

water heaters, DOE proposes that these 

products be paired with UFHWSTs that 

exactly meet baseline energy 

conservation standards (as required at 

10 CFR 431.110(a)) and rated at a 

capacity between 80 gallons and 120 

gallons. Compared to the January 2022 

NOPR, DOE applied additional 

specificity to the tank performance 

constraints to improve reproducibility 

of the test method and increased the 

range of acceptable capacities after 

reviewing market data on which 

capacities are commercially available at 

the baseline energy conservation 

standard level. 

DOE estimates that the cost of running 

the amended test procedure for 

circulating gas-fired instantaneous water 

heaters should be the same as testing a 

comparable water heater with storage 

volume (i.e., third-party testing of a 

fossil fuel-fired or electric storage water 

heater would cost approximately $3,000 

and third-party testing of an electric 

storage water heater which uses heat 

pump technology would cost 

approximately $4,500). However, DOE 

is not aware of any domestic small 

manufacturers of circulating gas-fired 

instantaneous water heaters at this time. 

For heat pump-only water heaters, 

DOE is updating its proposal to propose 

that these products be paired with 

electric storage water heaters that have 

a rated storage volume of 40 gallons ± 

4 gallons, have an FHR that results in 

classification at the medium draw 

pattern, and be rated at exactly the 

minimum required UEF. Compared to 

the January 2022 NOPR, DOE is 

proposing a different type and size of 

product to be paired with a heat pumponly water heater to better reflect how 

heat pump-only water heaters may be 

installed in the field. 

DOE estimates that the cost of running 

the amended test procedure for heat 

pump-only water heaters should be the 

same as testing a comparable water 


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heater with storage volume. For this 

estimate, DOE utilized a third-party test 

estimate of $4,500. DOE believes this to 

represent the high-end range of the 

testing cost burden compared to inhouse testing. 

DOE is aware of one domestic small 

manufacturer which has a single model 

that would be affected by this 

amendment. DOE expects the cost to 

test that model per the test method 

proposed in this SNOPR to be $4,500. 

This represents less than 0.01 percent of 

company revenue, and, therefore, DOE 

has tentatively determined that it would 

not be unduly burdensome to conduct. 

Fourth, DOE is proposing to require 

that water heaters, except for demandresponse water heaters, which can store 

water at a temperature higher than the 

delivery setpoint as a result of a userselected operating mode be tested using 

the setting that provides the highest 

internal mean tank temperature while 

delivering water at a temperature of 

125 °F ±5 °F, and that an ‘‘effective 

storage volume’’—which quantifies the 

increase in energy storage due to this 

mode of operation—be calculated for all 

storage water heaters based on data that 

is already being collected per the 

current appendix E test procedure. This 

proposal, if adopted, would improve 

representativeness and reproducibility 

for water heaters with such a capability. 

The proposed amendment to test in 

an ‘‘over-heated’’ mode could 

potentially lead to re-testing and recertification costs for manufacturers of 

such water heaters, as it would impact 

the UEF rating of such products. Should 

a manufacturer be required to re-testing, 

DOE estimates re-testing costs to be up 

to $4,500 per basic model using thirdparty testing. DOE believes this to 

represent the high-end range of the 

testing cost burden compared to inhouse testing. 

DOE is not proposing to require 

compliance with this provision until 

compliance with amended energy 

conservation standards is also required 

(after the date of a final rule amending 

the test procedure for consumer water 

heaters and residential-duty commercial 

water heaters). Therefore, DOE has 

tentatively determined that this 

proposed amendment, if adopted, 

would not impose additional costs for 

manufacturers until such time as 

potential amended standards would be 

required. DOE will consider these 

impacts in a separate rulemaking as part 

of its ongoing review of potential 

amended energy conservation 

standards. 

Lastly, there is currently no method to 

determine ratings for water heaters 

which have rated storage volumes of 2 

gallons or more but cannot have the 

internal storage tank temperature 

directly measured by means of the 

instrumentation required in the 

appendix E test procedure. The use of 

standard instrumentation is limited by 

the geometries of these products. 

Examples of such cases include 

products which have built-in mixing 

valves at the water outlet, products 

which do not use a sacrificial anode rod 

(and therefore do not have the 

associated opening for the anode rod), 

or products with complex heat 

exchanger geometries. DOE previously 

proposed to rely on inlet and outlet 

water temperatures to approximate the 

internal storage tank temperatures for 

these water heaters. 87 FR 1554, 1586 

(Jan. 11, 2022). However, in this 

SNOPR, DOE is revising its proposed 

methodology for determining the 

internal tank temperatures of such 

products to improve the accuracy as 

compared to the method originally 

proposed in the January 2022 NOPR. 

The method proposed in this SNOPR 

relies on drawing out water from the 

tank at the beginning and end of the 24- 

hour simulated use test and monitoring 

the temperature of the water as it is 

drawn out to estimate the internal tank 

temperature of the stored water prior to 

being drawn out of the water heater. 

This method may result in overall 

testing costs of $4,000 to $6,000 per 

basic model of water heater which 

cannot be directly measured. This is 

comparable to the average cost of $3,000 

to $4,500 per basic model of water 

heater which can be directly measured. 

DOE is currently not aware of any small 

businesses which produce water heaters 

which will have to be tested in this 

manner, and, thus, DOE has tentatively 

concluded that this amendment, if 

finalized, would not impact small 

manufacturers. 

DOE requests comment on its 

understanding of the cost impacts of the 

proposed amendments in this notice on 

small, domestic manufacturers. 

5. Duplication, Overlap, and Conflict 

With Other Rules and Regulations 

DOE is not aware of any rules or 

regulations that duplicate, overlap, or 

conflict with the rule being considered 

today. 

6. Significant Alternatives to the Rule 

The discussion in the previous 

section analyzes impacts on small 

businesses that would result from DOE’s 

proposed test procedure, if finalized. In 

reviewing alternatives to the proposed 

test procedure, DOE examined not 

establishing a performance-based test 

procedure for consumer and residentialduty commercial water heaters or 

establishing prescriptive-based test 

procedures. While not establishing 

performance-based test procedures or 

establishing prescriptive-based test 

procedures for consumer and 

residential-duty commercial water 

heaters would reduce the burden on 

small businesses, DOE must use test 

procedures to determine whether the 

products comply with relevant 

standards promulgated under EPCA. (42 

U.S.C. 6295(s)) Because establishing 

performance-based test procedures for 

consumer and residential-duty 

commercial water heaters is necessary 

prior to establishing performance-based 

energy conservation standards, DOE 

tentatively concludes that establishing 

performance-based test procedures, as 

proposed in this SNOPR, supports 

DOE’s authority to achieve the 

maximum improvement in energy 

efficiency that is technologically 

feasible and economically justified. (42 

U.S.C. 6295(o)(2)(A); 42 U.S.C. 

6313(a)(6)(A)(ii)(II)) 

The Department has tentatively 

determined that there are no better 

alternatives than the test procedures 

amendments proposed in this SNOPR, 

in terms of both meeting the agency’s 

objectives and reducing burden. 

Additionally, manufacturers subject to 

DOE’s test procedures may apply to 

DOE’s Office of Hearings and Appeals 

for exception relief under certain 

circumstances. Manufacturers should 

refer to 10 CFR part 430, subpart E, and 

10 CFR part 1003 for additional details. 

C. Review Under the Paperwork 

Reduction Act of 1995 

Manufacturers of consumer and 

residential-duty commercial water 

heaters must certify to DOE that their 

products comply with any applicable 

energy conservation standards. To 

certify compliance, manufacturers must 

first obtain test data for their products 

according to the DOE test procedures, 

including any amendments adopted for 

those test procedures. DOE has 

established regulations for the 

certification and recordkeeping 

requirements for all covered consumer 

products and commercial equipment, 

including consumer and residentialduty commercial water heaters. (See 

generally 10 CFR part 429.) The 

collection-of-information requirement 

for certification and recordkeeping is 

subject to review and approval by OMB 

under the Paperwork Reduction Act 

(‘‘PRA’’). This requirement has been 

approved by OMB under OMB control 

number 1910–1400. Public reporting 

burden for the certification is estimated 

to average 35 hours per response, 


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including the time for reviewing 

instructions, searching existing data 

sources, gathering and maintaining the 

data needed, and completing and 

reviewing the collection of information. 

DOE is not proposing to amend the 

certification or reporting requirements 

for consumer and residential-duty 

commercial water heaters in this 

SNOPR. Instead, DOE may consider 

proposals to amend the certification 

requirements and reporting for these 

products under a separate rulemaking 

regarding appliance and equipment 

certification. DOE will address changes 

to OMB Control Number 1910–1400 at 

that time, as necessary. 

Notwithstanding any other provision 

of the law, no person is required to 

respond to, nor shall any person be 

subject to a penalty for failure to comply 

with, a collection of information subject 

to the requirements of the PRA, unless 

that collection of information displays a 

currently valid OMB Control Number. 

D. Review Under the National 

Environmental Policy Act of 1969 

In this SNOPR, DOE proposes test 

procedure amendments that it expects 

will be used to develop and implement 

future energy conservation standards for 

consumer and residential-duty 

commercial water heaters. DOE has 

determined that this rule falls into a 

class of actions that are categorically 

excluded from review under the 

National Environmental Policy Act of 

1969 (42 U.S.C. 4321 et seq.) and DOE’s 

implementing regulations at 10 CFR part 

1021. Specifically, DOE has determined 

that adopting test procedures for 

measuring energy efficiency of 

consumer products and industrial 

equipment is consistent with activities 

identified in 10 CFR part 1021, 

appendix A to subpart D, A5 and A6. 

Accordingly, neither an environmental 

assessment nor an environmental 

impact statement is required. 

E. Review Under Executive Order 13132 

Executive Order 13132, ‘‘Federalism,’’ 

64 FR 43255 (August 4, 1999), imposes 

certain requirements on agencies 

formulating and implementing policies 

or regulations that preempt State law or 

that have federalism implications. The 

Executive order requires agencies to 

examine the constitutional and statutory 

authority supporting any action that 

would limit the policymaking discretion 

of the States and to carefully assess the 

necessity for such actions. The 

Executive order also requires agencies to 

have an accountable process to ensure 

meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications. On March 14, 2000, DOE 

published a statement of policy 

describing the intergovernmental 

consultation process it will follow in the 

development of such regulations. 65 FR 

13735. DOE has examined this proposed 

rule and has determined that it would 

not have a substantial direct effect on 

the States, on the relationship between 

the national government and the States, 

or on the distribution of power and 

responsibilities among the various 

levels of government. EPCA governs and 

prescribes Federal preemption of State 

regulations as to energy conservation for 

the products that are the subject of this 

proposed rule. States can petition DOE 

for exemption from such preemption to 

the extent, and based on criteria, set 

forth in EPCA. (42 U.S.C. 6297(d)) No 

further action is required by Executive 

Order 13132. 

F. Review Under Executive Order 12988 

Regarding the review of existing 

regulations and the promulgation of 

new regulations, section 3(a) of 

Executive Order 12988, ‘‘Civil Justice 

Reform,’’ 61 FR 4729 (Feb. 7, 1996), 

imposes on Federal agencies the general 

duty to adhere to the following 

requirements: (1) eliminate drafting 

errors and ambiguity; (2) write 

regulations to minimize litigation; (3) 

provide a clear legal standard for 

affected conduct rather than a general 

standard, and (4) promote simplification 

and burden reduction. Section 3(b) of 

Executive Order 12988 specifically 

requires that Executive agencies make 

every reasonable effort to ensure that the 

regulation: (1) clearly specifies the 

preemptive effect, if any; (2) clearly 

specifies any effect on existing Federal 

law or regulation; (3) provides a clear 

legal standard for affected conduct 

while promoting simplification and 

burden reduction; (4) specifies the 

retroactive effect, if any; (5) adequately 

defines key terms, and (6) addresses 

other important issues affecting clarity 

and general draftsmanship under any 

guidelines issued by the Attorney 

General. Section 3(c) of Executive Order 

12988 requires Executive agencies to 

review regulations in light of applicable 

standards in sections 3(a) and 3(b) to 

determine whether they are met or it is 

unreasonable to meet one or more of 

them. DOE has completed the required 

review and determined that, to the 

extent permitted by law, the proposed 

rule meets the relevant standards of 

Executive Order 12988. 

G. Review Under the Unfunded 

Mandates Reform Act of 1995 

Title II of the Unfunded Mandates 

Reform Act of 1995 (‘‘UMRA’’) requires 

each Federal agency to assess the effects 

of Federal regulatory actions on State, 

local, and Tribal governments and the 

private sector. Public Law 104–4, sec. 

201 (codified at 2 U.S.C. 1531). For a 

proposed regulatory action likely to 

result in a rule that may cause the 

expenditure by State, local, and Tribal 

governments, in the aggregate, or by the 

private sector of $100 million or more 

in any one year (adjusted annually for 

inflation), section 202 of UMRA requires 

a Federal agency to publish a written 

statement that estimates the resulting 

costs, benefits, and other effects on the 

national economy. (2 U.S.C. 1532(a), (b)) 

The UMRA also requires a Federal 

agency to develop an effective process 

to permit timely input by elected 

officers of State, local, and Tribal 

governments on a proposed ‘‘significant 

intergovernmental mandate,’’ and 

requires an agency plan for giving notice 

and opportunity for timely input to 

potentially affected small governments 

before establishing any requirements 

that might significantly or uniquely 

affect small governments. On March 18, 

1997, DOE published a statement of 

policy on its process for 

intergovernmental consultation under 

UMRA. 62 FR 12820; also available at 

www.energy.gov/gc/office-generalcounsel. DOE examined this proposed 

rule according to UMRA and its 

statement of policy and determined that 

the rule contains neither an 

intergovernmental mandate, nor a 

mandate that may result in the 

expenditure of $100 million or more in 

any year, so these requirements do not 

apply. 

H. Review Under the Treasury and 

General Government Appropriations 

Act, 1999 

Section 654 of the Treasury and 

General Government Appropriations 

Act, 1999 (Pub. L. 105–277) requires 

Federal agencies to issue a Family 

Policymaking Assessment for any rule 

that may affect family well-being. This 

proposed rule would not have any 

impact on the autonomy or integrity of 

the family as an institution. 

Accordingly, DOE has concluded that it 

is not necessary to prepare a Family 

Policymaking Assessment. 

I. Review Under Executive Order 12630 

DOE has determined, under Executive 

Order 12630, ‘‘Governmental Actions 

and Interference with Constitutionally 

Protected Property Rights,’’ 53 FR 8859 

(March 18, 1988), that this proposed 

regulation would not result in any 

takings that might require compensation 

under the Fifth Amendment to the U.S. 

Constitution. 


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J. Review Under the Treasury and 

General Government Appropriations 

Act, 2001 

Section 515 of the Treasury and 

General Government Appropriations 

Act, 2001 (44 U.S.C. 3516 note) provides 

for agencies to review most 

disseminations of information to the 

public under guidelines established by 

each agency pursuant to general 

guidelines issued by OMB. OMB’s 

guidelines were published at 67 FR 

8452 (Feb. 22, 2002), and DOE’s 

guidelines were published at 67 FR 

62446 (Oct. 7, 2002). Pursuant to OMB 

Memorandum M–19–15, Improving 

Implementation of the Information 

Quality Act (April 24, 2019), DOE 

published updated guidelines which are 

available at www.energy.gov/sites/prod/ 

files/2019/12/f70/DOE%20Final

%20Updated%20IQA%20Guidelines

%20Dec%202019.pdf. DOE has 

reviewed this proposed rule under the 

OMB and DOE guidelines and has 

concluded that it is consistent with 

applicable policies in those guidelines. 

K. Review Under Executive Order 13211 

Executive Order 13211, ‘‘Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use,’’ 66 FR 28355 (May 

22, 2001), requires Federal agencies to 

prepare and submit to OMB, a 

Statement of Energy Effects for any 

proposed significant energy action. A 

‘‘significant energy action’’ is defined as 

any action by an agency that 

promulgated or is expected to lead to 

promulgation of a final rule, and that: 

(1) is a significant regulatory action 

under Executive Order 12866, or any 

successor order; and (2) is likely to have 

a significant adverse effect on the 

supply, distribution, or use of energy; or 

(3) is designated by the Administrator of 

OIRA as a significant energy action. For 

any proposed significant energy action, 

the agency must give a detailed 

statement of any adverse effects on 

energy supply, distribution, or use 

should the proposal be implemented, 

and of reasonable alternatives to the 

action and their expected benefits on 

energy supply, distribution, and use. 

The proposed regulatory action to 

amend the test procedure for measuring 

the energy efficiency of consumer and 

residential-duty commercial water 

heaters is not a significant regulatory 

action under Executive Order 12866. 

Moreover, it would not have a 

significant adverse effect on the supply, 

distribution, or use of energy, nor has it 

been designated as a significant energy 

action by the Administrator of OIRA. 

Therefore, it is not a significant energy 

action, and, accordingly, DOE has not 

prepared a Statement of Energy Effects. 

L. Review Under Section 32 of the 

Federal Energy Administration Act of 

1974 

Under section 301 of the Department 

of Energy Organization Act (Pub. L. 95– 

91; 42 U.S.C. 7101), DOE must comply 

with section 32 of the Federal Energy 

Administration Act of 1974, as amended 

by the Federal Energy Administration 

Authorization Act of 1977. (15 U.S.C. 

788; ‘‘FEAA’’) Section 32 essentially 

provides in relevant part that, where a 

proposed rule authorizes or requires use 

of commercial standards, the notice of 

proposed rulemaking must inform the 

public of the use and background of 

such standards. In addition, section 

32(c) requires DOE to consult with the 

Attorney General and the Chairman of 

the Federal Trade Commission (‘‘FTC’’) 

concerning the impact of the 

commercial or industry standards on 

competition. 

As discussed in the January 11, 2022 

NOPR, the proposed modifications to 

the test procedure for consumer and 

residential-duty commercial water 

heaters would incorporate testing 

methods contained in certain sections of 

the following commercial standards: 

ASHRAE 41.1–2020, ASTM D2156–09 

(RA 2018), and a finalized version of 

ASHRAE 118.2. DOE has evaluated 

these standards and is unable to 

conclude whether they fully comply 

with the requirements of section 32(b) of 

the FEAA (i.e., whether they were 

developed in a manner that fully 

provides for public participation, 

comment, and review). DOE will 

consult with both the Attorney General 

and the Chairman of the FTC 

concerning the impact of these test 

procedures on competition, prior to 

prescribing a final rule. 

V. Public Participation 

DOE will accept comments, data, and 

information regarding this supplemental 

proposed rule no later than the date 

provided in the DATES section at the 

beginning of this SNOPR. Interested 

parties may submit comments, data, and 

other information using any of the 

methods described in the ADDRESSES

section at the beginning of this 

document. 

Submitting comments via 

www.regulations.gov. The 

www.regulations.gov web page will 

require you to provide your name and 

contact information. Your contact 

information will be viewable to DOE 

Building Technologies staff only. Your 

contact information will not be publicly 

viewable except for your first and last 

names, organization name (if any), and 

submitter representative name (if any). 

If your comment is not processed 

properly because of technical 

difficulties, DOE will use this 

information to contact you. If DOE 

cannot read your comment due to 

technical difficulties and cannot contact 

you for clarification, DOE may not be 

able to consider your comment. 

However, your contact information 

will be publicly viewable if you include 

it in the comment itself or in any 

documents attached to your comment. 

Any information that you do not want 

to be publicly viewable should not be 

included in your comment, nor in any 

document attached to your comment. 

Otherwise, persons viewing comments 

will see only first and last names, 

organization names, correspondence 

containing comments, and any 

documents submitted with the 

comments. 

Do not submit to www.regulations.gov 

information for which disclosure is 

restricted by statute, such as trade 

secrets and commercial or financial 

information (hereinafter referred to as 

Confidential Business Information 

(‘‘CBI’’)). Comments submitted through 

www.regulations.gov cannot be claimed 

as CBI. Comments received through the 

website will waive any CBI claims for 

the information submitted. For 

information on submitting CBI, see the 

Confidential Business Information 

section. 

DOE processes submissions made 

through www.regulations.gov before 

posting. Normally, comments will be 

posted within a few days of being 

submitted. However, if large volumes of 

comments are being processed 

simultaneously, your comment may not 

be viewable for up to several weeks. 

Please keep the comment tracking 

number that www.regulations.gov 

provides after you have successfully 

uploaded your comment. 

Submitting comments via email. 

Comments and documents submitted 

via email also will be posted to 

www.regulations.gov. If you do not want 

your personal contact information to be 

publicly viewable, do not include it in 

your comment or any accompanying 

documents. Instead, provide your 

contact information in a cover letter. 

Include your first and last names, email 

address, telephone number, and 

optional mailing address. With this 

instruction followed, the cover letter 

will not be publicly viewable as long as 

it does not include any comments. 

Include contact information each time 

you submit comments, data, documents, 

and other information to DOE. No 

telefacsimiles (faxes) will be accepted. 


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Comments, data, and other 

information submitted to DOE 

electronically should be provided in 

PDF (preferred), Microsoft Word or 

Excel, WordPerfect, or text (ASCII) file 

format. Provide documents that are not 

secured, written in English, and free of 

any defects or viruses. Documents 

should not contain special characters or 

any form of encryption, and, if possible, 

they should carry the electronic 

signature of the author. 

Campaign form letters. Please submit 

campaign form letters by the originating 

organization in batches of between 50 to 

500 form letters per PDF or as one form 

letter with a list of supporters’ names 

compiled into one or more PDFs. This 

reduces comment processing and 

posting time. 

Confidential Business Information. 

Pursuant to 10 CFR 1004.11, any person 

submitting information that he or she 

believes to be confidential and exempt 

by law from public disclosure should 

submit via email two well-marked 

copies: one copy of the document 

marked ‘‘confidential’’ including all the 

information believed to be confidential, 

and one copy of the document marked 

‘‘non-confidential’’ with the information 

believed to be confidential deleted. DOE 

will make its own determination about 

the confidential status of the 

information and treat it according to its 

determination. 

It is DOE’s policy that all comments 

may be included in the public docket, 

without change and as received, 

including any personal information 

provided in the comments (except 

information deemed to be exempt from 

public disclosure). 

VI. Approval of the Office of the 

Secretary 

The Secretary of Energy has approved 

publication of this supplemental notice 

of proposed rulemaking and request for 

comment. 

List of Subjects in 10 CFR Part 430 

Administrative practice and 

procedure, Confidential business 

information, Energy conservation, 

Household appliances, Imports, 

Intergovernmental relations, Reporting 

and recordkeeping requirements, Small 

businesses. 

Signing Authority 

This document of the Department of 

Energy was signed on July 1, 2022, by 

Kelly J. Speakes-Backman, Principal 

Deputy Assistant Secretary for Energy 

Efficiency and Renewable Energy, 

pursuant to delegated authority from the 

Secretary of Energy. That document 

with the original signature and date is 

maintained by DOE. For administrative 

purposes only, and in compliance with 

requirements of the Office of the Federal 

Register, the undersigned DOE Federal 

Register Liaison Officer has been 

authorized to sign and submit the 

document in electronic format for 

publication, as an official document of 

the Department of Energy. This 

administrative process in no way alters 

the legal effect of this document upon 

publication in the Federal Register. 

Signed in Washington, DC, on July 6, 2022. 

Treena V. Garrett, 

Federal Register Liaison Officer, U.S. 

Department of Energy. 

For the reasons stated in the 

preamble, DOE is proposing to amend 

part 430 of Chapter II of Title 10, Code 

of Federal Regulations, as set forth 

below: 

PART 430—ENERGY CONSERVATION 

PROGRAM FOR CONSUMER 

PRODUCTS 

■ 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. 

■ 2. Appendix E to subpart B of part 430 

is amended by: 

■ a. Revising the note at the beginning 

of the appendix; 

■ b. Revising section 1; 

■ c. Adding new sections 2.8, 4.10; 

■ d. Revising sections 5.1, 5.4.2; 

■ e. Adding sections 5.6, 6.3.1.1; 

■ f. Revising section 6.3.9; and 

■ g. Adding new section 6.5; 

The revisions and additions read as 

follows: 

Appendix E to Subpart B of Part 430— 

Uniform Test Method for Measuring the 

Energy Consumption of Water Heaters 

Note: Prior to [date 180 days after date of 

publication of the final rule in the Federal 

Register], representations with respect to the 

energy use or efficiency of consumer water 

heaters and residential-duty commercial 

water heaters covered by this test method, 

including compliance certifications, must be 

based on testing conducted in accordance 

with either this appendix as it now appears 

or appendix E as it appeared at 10 CFR part 

430, subpart B revised as of January 1, 2021. 

On and after [date 180 days after date of 

publication of the final rule in the Federal 

Register], representations with respect to 

energy use or efficiency of consumer water 

heaters and residential-duty commercial 

water heaters covered by this test method, 

including compliance certifications, must be 

based on testing conducted in accordance 

with this appendix. 

In addition, water heaters subject to section 

5.1.2 of this appendix may optionally apply 

the requirements in section 5.1.1 of this 

appendix in lieu of the requirements in 

section 5.1.2 of this appendix until the 

compliance date of a final rule reviewing 

potential amended energy conservation 

standards for these products published after 

[date of publication of the final rule in the 

Federal Register]. 

1. Definitions. 

1.1. Cut-in means the time when or water 

temperature at which a water heater control 

or thermostat acts to increase the energy or 

fuel input to the heating elements, 

compressor, or burner. 

1.2. Cut-out means the time when or water 

temperature at which a water heater control 

or thermostat acts to reduce to a minimum 

the energy or fuel input to the heating 

elements, compressor, or burner. 

1.3. Demand-response water heater means 

a storage-type water heater that— 

(1) Has integrated communications 

hardware and additional hardware and 

software required to enable connected 

functionality with a utility or third party, 

which dispatches signals with demand 

response instructions and/or price signals to 

the product and receives messages from the 

demand-response water heater; 

(2) Meets the communication and 

equipment standards for Consumer 

Technology Association Standard 2045–B 

(CTA–2045–B); 

(3) Automatically heats the stored water 

above the delivery temperature setpoint only 

in response to instructions received from a 

utility or third party. 

1.4. Design Power Rating means the power 

rating or input rate that a water heater 

manufacturer assigns to a particular design of 

water heater and that is included on the 

nameplate of the water heater, expressed in 

kilowatts or Btu (kJ) per hour as appropriate. 

For modulating water heaters, the design 

power rating is the maximum power rating or 

input rate that is specified by the 

manufacturer on the nameplate of the water 

heater. 

1.5. Draw Cluster means a collection of 

water draws initiated during the 24-hour 

simulated-use test during which no 

successive draws are separated by more than 

2 hours. 

1.6. First-Hour Rating means an estimate of 

the maximum volume of ‘‘hot’’ water that a 

non-flow activated water heater can supply 

within an hour that begins with the water 

heater fully heated (i.e., with all thermostats 

satisfied). 

1.7. Flow-Activated describes an 

operational scheme in which a water heater 

initiates and terminates heating based on 

sensing flow. 

1.8. Heat Trap means a device that can be 

integrally connected or independently 

attached to the hot and/or cold water pipe 

connections of a water heater such that the 

device will develop a thermal or mechanical 

seal to minimize the recirculation of water 

due to thermal convection between the water 

heater tank and its connecting pipes. 

1.9. Maximum GPM (L/min) Rating means 

the maximum gallons per minute (liters per 

minute) of hot water that can be supplied by 

flow-activated water heater when tested in 

accordance with section 5.3.2 of this 

appendix. 


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1.10. Modulating Water Heater means a 

water heater that can automatically vary its 

power or input rate from the minimum to the 

maximum power or input rate specified on 

the nameplate of the water heater by the 

manufacturer. 

1.11. Rated Storage Volume means the 

water storage capacity of a water heater, in 

gallons (liters), as certified by the 

manufacturer pursuant to 10 CFR part 429. 

1.12. Recovery Efficiency means the ratio of 

energy delivered to the water to the energy 

content of the fuel consumed by the water 

heater. 

1.13. Recovery Period means the time when 

the main burner of a water heater with a 

rated storage volume greater than or equal to 

2 gallons is raising the temperature of the 

stored water. 

1.14. Split-system heat pump water heater 

means a heat pump-type water heater with an 

indoor storage tank and outdoor heat pump 

component. 

1.15. Standby means the time, in hours, 

during which water is not being withdrawn 

from the water heater. 

1.16. Symbol Usage. The following identity 

relationships are provided to help clarify the 

symbology used throughout this procedure: 

Cp—specific heat of water 

Eannual—annual energy consumption of a 

water heater 

Eannual,e—annual electrical energy 

consumption of a water heater 

Eannual,f—annual fossil-fuel energy 

consumption of a water heater 

EX—energy efficiency of a heat pump-type 

water heater when the 24-hour simulated 

use test is optionally conducted at any of 

the additional air temperature conditions 

as specified in section 2.8 of this 

appendix, where the subscript ‘‘X’’ 

corresponds to the dry-bulb temperature 

at which the test is conducted. 

Fhr—first-hour rating of a non-flow activated 

water heater 

Fmax—maximum GPM (L/min) rating of a 

flow-activated water heater 

i—a subscript to indicate the draw number 

during a test 

kV—storage tank volume scaling ratio for 

water heaters with a rated storage 

volume greater than or equal to 2 gallons 

Mdel,i—mass of water removed during the ith 

draw of the 24-hour simulated-use test 

Min,i—mass of water entering the water heater 

during the ith draw of the 24-hour 

simulated-use test 

M*del,i—for non-flow activated water heaters, 

mass of water removed during the ith 

draw during the first-hour rating test 

M *in,i—for non-flow activated water heaters, 

mass of water entering the water heater 

during the ith draw during the first-hour 

rating test 

Mdel,10m—for flow-activated water heaters, 

mass of water removed continuously 

during the maximum GPM (L/min) rating 

test 

Min,10m—for flow-activated water heaters, 

mass of water entering the water heater 

continuously during the maximum GPM 

(L/min) rating test 

n—for non-flow activated water heaters, total 

number of draws during the first-hour 

rating test 

N—total number of draws during the 24-hour 

simulated-use test 

Nr—number of draws from the start of the 24- 

hour simulated-use test to the end to the 

first recovery period as described in 

section 5.4.2 of this appendix 

Q—total fossil fuel and/or electric energy 

consumed during the entire 24-hour 

simulated-use test 

Qd—daily water heating energy consumption 

adjusted for net change in internal 

energy 

Qda—Qd with adjustment for variation of tank 

to ambient air temperature difference 

from nominal value 

Qdm—overall adjusted daily water heating 

energy consumption including Qda and 

QHWD

Qe—total electrical energy used during the 

24-hour simulated-use test 

Qf—total fossil fuel energy used by the water 

heater during the 24-hour simulated-use 

test 

Qhr—hourly standby losses of a water heater 

with a rated storage volume greater than 

or equal to 2 gallons 

QHW—daily energy consumption to heat 

water at the measured average 

temperature rise across the water heater 

QHW,67 °F—daily energy consumption to heat 

quantity of water removed during test 

over a temperature rise of 67 °F (37.3 °C) 

QHWD—adjustment to daily energy 

consumption, QHW, due to variation of 

the temperature rise across the water 

heater not equal to the nominal value of 

67 °F (37.3 °C) 

Qr—energy consumption of water heater 

from the beginning of the test to the end 

of the first recovery period 

Qstby—total energy consumed during the 

standby time interval tstby,1, as 

determined in section 5.4.2 of this 

appendix 

Qsu,0—cumulative energy consumption, 

including all fossil fuel and electrical 

energy use, of the water heater from the 

start of the 24-hour simulated-use test to 

the start of the standby period as 

determined in section 5.4.2 of this 

appendix 

Qsu,f—cumulative energy consumption, 

including all fossil fuel and electrical 

energy use, of the water heater from the 

start of the 24-hour simulated-use test to 

the end of the standby period as 

determined in section 5.4.2 of this 

appendix 

T0—mean tank temperature at the beginning 

of the 24-hour simulated-use test as 

determined in section 5.4.2 of this 

appendix 

T24—mean tank temperature at the end of the 

24-hour simulated-use test as determined 

in section 5.4.2 of this appendix 

Ta,stby—average ambient air temperature 

during all standby periods of the 24-hour 

simulated-use test as determined in 

section 5.4.2 of this appendix 

Ta,stby,1—overall average ambient temperature 

between the start and end of the standby 

period as determined in section 5.4.2 of 

this appendix 

Tt,stby1—overall average mean tank 

temperature between the start and end of 

the standby period as determined in 

section 5.4.2 of this appendix 

Tdel—for flow-activated water heaters, 

average outlet water temperature during 

the maximum GPM (L/min) rating test 

Tdel,i—average outlet water temperature 

during the ith draw of the 24-hour 

simulated-use test 

Tin—for flow-activated water heaters, average 

inlet water temperature during the 

maximum GPM (L/min) rating test 

Tst—for water heaters which cannot have 

internal tank temperature directly 

measured, estimated average internal 

storage tank temperature 

Tp—for water heaters which cannot have 

internal tank temperature directly 

measured, average of the inlet and the 

outlet water temperatures at the end of 

the period defined by tp

Tin,p—for water heaters which cannot have 

internal tank temperature directly 

measured, average of the inlet water 

temperatures 

Tout,p—for water heaters which cannot have 

internal tank temperature directly 

measured, average of the outlet water 

temperatures 

Tin,i—average inlet water temperature during 

the ith draw of the 24-hour simulateduse test 

Tmax,1—maximum measured mean tank 

temperature after the first recovery 

period of the 24-hour simulated-use test 

as determined in section 5.4.2 of this 

appendix 

Tsu,0—maximum measured mean tank 

temperature at the beginning of the 

standby period as determined in section 

5.4.2 of this appendix 

Tsu,f—measured mean tank temperature at the 

end of the standby period as determined 

in section 5.4.2 of this appendix 

T*del,i—for non-flow activated water heaters, 

average outlet water temperature during 

the ith draw (i = 1 to n) of the first-hour 

rating test 

T*max,i—for non-flow activated water heaters, 

maximum outlet water temperature 

observed during the ith draw (i = 1 to n) 

of the first-hour rating test 

T*min,i—for non-flow activated water heaters, 

minimum outlet water temperature to 

terminate the ith draw (i = 1 to n) of the 

first-hour rating test 

UA—standby loss coefficient of a water 

heater with a rated storage volume 

greater than or equal to 2 gallons 

UEF—uniform energy factor of a water heater 

V—the volume of hot water drawn during the 

applicable draw pattern 

Vdel,i—volume of water removed during the 

ith draw (i = 1 to N) of the 24-hour 

simulated-use test 

Vin,i—volume of water entering the water 

heater during the ith draw (i = 1 to N) 

of the 24-hour simulated-use test 

V*del,i—for non-flow activated water heaters, 

volume of water removed during the ith 

draw (i = 1 to n) of the first-hour rating 

test 

V*in,i—for non-flow activated water heaters, 

volume of water entering the water 

heater during the ith draw (i = 1 to n) 

of the first-hour rating test 

Vdel,10m—for flow-activated water heaters, 

volume of water removed during the 

maximum GPM (L/min) rating test 


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Vin,10m—for flow-activated water heaters, 

volume of water entering the water 

heater during the maximum GPM (L/ 

min) rating test 

Vst—measured storage volume of the storage 

tank for water heaters with a rated 

storage volume greater than or equal to 

2 gallons 

Veff—effective storage volume of water 

heaters with a rated storage volume 

greater than or equal to 2 gallons 

vout,p—for water heaters which cannot have 

internal tank temperature directly 

measured, average flow rate 

Wf—weight of storage tank when completely 

filled with water for water heaters with 

a rated storage volume greater than or 

equal to 2 gallons 

Wt—tare weight of storage tank when 

completely empty of water for water 

heaters with a rated storage volume 

greater than or equal to 2 gallons 

hr—recovery efficiency 

r—density of water 

tp—for water heaters which cannot have 

internal tank temperature directly 

measured, duration of the temperature 

measurement period, determined by the 

length of time taken for the outlet water 

temperature to be within 2 °F of the inlet 

water temperature for 15 consecutive 

seconds (including the 15-second 

stabilization period) 

tstby,1—elapsed time between the start and 

end of the standby period as determined 

in section 5.4.2 of this appendix 

tstby,2—overall time of standby periods when 

no water is withdrawn during the 24- 

hour simulated-use test as determined in 

section 5.4.2 of this appendix 

1.17. Temperature Controller means a 

device that is available to the user to adjust 

the temperature of the water inside a water 

heater that stores heated water or the outlet 

water temperature. 

1.18. Uniform Energy Factor means the 

measure of water heater overall efficiency. 

1.19. Water Heater Requiring a Storage 

Tank means a water heater without a storage 

tank specified or supplied by the 

manufacturer that cannot meet the 

requirements of sections 2 and 5 of this 

appendix without the use of a storage water 

heater or unfired hot water storage tank. 

2. * * * 

2.8 Optional Test Conditions (Heat 

Pump-Type Water Heaters). 

The following test conditions may be used 

for optional representations of EX for heat 

pump-type water heaters. When conducting 

a 24-hour simulated use test to determine EX, 

the test conditions in section 2.1 and sections 

2.4 through 2.7 apply. The ambient air 

temperature and humidity conditions in 

section 2.2 and the supply water temperature 

in section 2.3 are replaced with the air 

temperature, humidity, and supply water 

temperature conditions as shown in the 

following table. Testing may optionally be 

performed at any or all of the conditions in 

the table. 

Heat pump type Metric 

Outdoor air conditions Indoor air conditions 

Supply water 

Dry-bulb temperature 

temperature 

Relative 

humidity 

(%) 

Dry-bulb 

temperature 

Relative 

humidity 

(%) 

Split-System ............................................. E5 5.0 °F 30 67.5 °F 50 42.0 °F 

E34 34.0 °F 72 47.0 °F 

E95 95.0 °F 25 67.0 °F 

Integrated or Heat Pump-Only ................. E50 N/A N/A 50.0 °F 58 50.0 °F 

E95 N/A N/A 95.0 °F 40 67.0 °F 

* * * * * 

4. * * * 

4.10 Storage Tank Requirement for 

Circulating Water Heaters. 

When testing a gas-fired, oil-fired, or 

electric resistance circulating water heater 

(i.e., any circulating water heater that does 

not use a heat pump), the tank to be used for 

testing shall be an unfired hot water storage 

tank having a certified volume between 80 

and 120 gallons (364–546 liters) that meets 

but does not exceed the minimum energy 

conservation standards required according to 

10 CFR 431.110. When testing a heat pump 

circulating water heater, the tank to be used 

for testing shall be an electric storage water 

heater that uses only electric resistance 

elements for heating, has a measured volume 

of 40 gallons (± 4 gallons), has a First-Hour 

Rating greater than or equal to 51 gallons and 

less than 75 gallons resulting in classification 

under the medium draw pattern, and has a 

rated UEF equal to the minimum UEF 

standard specified at § 430.32(d), rounded to 

the nearest 0.01. In addition, the water heater 

used for testing shall not be capable of ‘‘overheating’’ the stored water, as determined by 

Tmax,1 (maximum measured mean tank 

temperature after the first recovery period of 

the 24-hour simulated-use test) being less 

than or equal to Tdel,2 (average outlet water 

temperature during the 2nd draw of the 24- 

hour simulated-use test). 

5. * * * 

5.1 Operational Mode Selection. For 

water heaters that allow for multiple userselected operational modes, all procedures 

specified in this appendix shall be carried 

out with the water heater in the same 

operational mode (i.e., only one mode). 

Water heaters subject to section 5.1.2 of this 

appendix may optionally apply the 

requirements in section 5.1.1 in lieu of the 

requirements in section 5.1.2 of this 

appendix until the compliance date of a final 

rule reviewing potential amended energy 

conservation standards for these products 

published after [date of publication of the 

test procedure final rule in the Federal 

Register] 

5.1.1 Water Heaters Without Storage 

Tank Over-heating Capability. If a non-flowactivated water heater does not have any 

user-selectable operational modes where the 

mean temperature of the storage tank can be 

maintained at a temperature higher than the 

delivery setpoint temperature (e.g., by use of 

a mixing valve), the instructions in this 

section apply. The operational mode shall be 

the default mode (or similarly named, 

suggested mode for normal operation) as 

defined by the manufacturer in the I&O 

manual for giving selection guidance to the 

consumer. For heat pump water heaters, if a 

default mode is not defined in the product 

literature, each test shall be conducted under 

an operational mode in which both the heat 

pump and any electric resistance backup 

heating element(s) are activated by the unit’s 

control scheme, and which can achieve the 

internal storage tank temperature specified in 

this test procedure; if multiple operational 

modes meet these criteria, the water heater 

shall be tested under the most energyintensive mode. If no default mode is 

specified and the unit does not offer an 

operational mode that utilizes both the heat 

pump and the electric resistance backup 

heating element(s), the first-hour rating test 

and the 24-hour simulated-use test shall be 

tested in heat-pump-only mode. For other 

types of water heaters where a default mode 

is not specified, test the unit in all modes and 

rate the unit using the results of the most 

energy-intensive mode. 

5.1.2 Water Heaters With Storage Tank 

Over-heating Capability. If a non-flowactivated water heater that is not a demandresponse water heater (as defined in section 

1.3 of this appendix) has a user-selectable 

operational mode where the mean 

temperature of the storage tank can be 

maintained at a temperature higher than the 

delivery setpoint temperature (e.g., by use of 

a mixing valve), set the unit to maintain the 

highest mean tank temperature possible 

while delivering water at 125 °F ±5 °F. 

Maintain this setting throughout the entirety 

of the test. 

* * * * * 

5.4 * * * 

5.4.2 Test Sequence for Water Heater 

With Rated Storage Volume Greater Than or 

Equal to 2 Gallons. 

If the water heater is turned off, fill the 

water heater with supply water at the 

temperature specified in section 2.3 of this 

appendix and maintain supply water 

pressure as described in section 2.6 of this 

appendix. Turn on the water heater and 

associated heat pump unit, if present. If 

turned on in this fashion, the soak-in period 

described in section 5.2.4 of this appendix 

shall be implemented. If the water heater has 


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undergone a first-hour rating test prior to 

conduct of the 24-hour simulated-use test, 

allow the water heater to fully recover after 

completion of that test such that the main 

burner, heating elements, or heat pump 

compressor of the water heater are no longer 

raising the temperature of the stored water. 

In all cases, the water heater shall sit idle for 

1 hour prior to the start of the 24-hour test; 

during which time no water is drawn from 

the unit, and there is no energy input to the 

main heating elements, heat pump 

compressor, and/or burners. 

For water heaters that can have their 

internal storage tank temperature measured 

directly, perform testing in accordance with 

the instructions in section 5.4.2.1 of this 

appendix. For water heaters that cannot have 

their internal tank temperatures measured, 

perform testing in accordance with the 

instructions in section 5.4.2.2. of this 

appendix. 

5.4.2.1 Water Heaters which Can Have 

Internal Storage Tank Temperature 

Measured Directly. 

After the 1-hour period specified in section 

5.4.2 of this appendix, the 24-hour 

simulated-use test will begin. One minute 

prior to the start of the 24-hour test 

simulated-use test, record the mean tank 

temperature (T0). 

At the start of the 24-hour simulated-use 

test, record the electrical and/or fuel 

measurement readings, as appropriate. Begin 

the 24-hour simulated-use test by 

withdrawing the volume specified in the 

appropriate table in section 5.5 of this 

appendix (i.e., Table III.1, Table III.2, Table 

III.3, or Table III.4, depending on the firsthour rating or maximum GPM rating) for the 

first draw at the flow rate specified in the 

applicable table. Record the time when this 

first draw is initiated and assign it as the test 

elapsed time (t) of zero (0). Record the 

average storage tank and ambient 

temperature every minute throughout the 24- 

hour simulated-use test. At the elapsed times 

specified in the applicable draw pattern table 

in section 5.5 of this appendix for a 

particular draw pattern, initiate additional 

draws pursuant to the draw pattern, 

removing the volume of hot water at the 

prescribed flow rate specified by the table. 

The maximum allowable deviation from the 

specified volume of water removed for any 

single draw taken at a nominal flow rate of 

1.0 GPM or 1.7 GPM is ± 0.1 gallons (± 0.4 

liters). The maximum allowable deviation 

from the specified volume of water removed 

for any single draw taken at a nominal flow 

rate of 3.0 GPM is ± 0.25 gallons (0.9 liters). 

The quantity of water withdrawn during the 

last draw shall be increased or decreased as 

necessary such that the total volume of water 

withdrawn equals the prescribed daily 

amount for that draw pattern ±1.0 gallon 

(±3.8 liters). If this adjustment to the volume 

drawn during the last draw results in no 

draw taking place, the test is considered 

invalid. 

All draws during the 24-hour simulateduse test shall be made at the flow rates 

specified in the applicable draw pattern table 

in section 5.5 of this appendix, within a 

tolerance of ±0.25 gallons per minute (±0.9 

liters per minute). Measurements of the inlet 

and outlet temperatures shall be made 15 

seconds after the draw is initiated and at 

every subsequent 3-second interval 

throughout the duration of each draw. 

Calculate and record the mean of the hot 

water discharge temperature and the cold 

water inlet temperature for each draw Tdel,i

and Tin,i). Determine and record the net mass 

or volume removed (Mi or Vi), as appropriate, 

after each draw. 

The first recovery period is the time from 

the start of the 24-hour simulated-use test 

and continues during the temperature rise of 

the stored water until the first cut-out; if the 

cut-out occurs during a subsequent draw, the 

first recovery period includes the time until 

the draw of water from the tank stops. If, after 

the first cut-out occurs but during a 

subsequent draw, a subsequent cut-in occurs 

prior to the draw completion, the first 

recovery period includes the time until the 

subsequent cut-out occurs, prior to another 

draw. The first recovery period may continue 

until a cut-out occurs when water is not 

being removed from the water heater or a cutout occurs during a draw and the water 

heater does not cut-in prior to the end of the 

draw. 

At the end of the first recovery period, 

record the maximum mean tank temperature 

observed after cut-out (Tmax,1). At the end of 

the first recovery period, record the total 

energy consumed by the water heater from 

the beginning of the test (Qr), including all 

fossil fuel and/or electrical energy use, from 

the main heat source and auxiliary 

equipment including, but not limited to, 

burner(s), resistive elements(s), compressor, 

fan, controls, pump, etc., as applicable. 

The start of the portion of the test during 

which the standby loss coefficient is 

determined depends upon whether the unit 

has fully recovered from the first draw 

cluster. If a recovery is occurring at or within 

five minutes after the end of the final draw 

in the first draw cluster, as identified in the 

applicable draw pattern table in section 5.5 

of this appendix, then the standby period 

starts when a maximum mean tank 

temperature is observed starting five minutes 

after the end of the recovery period that 

follows that draw. If a recovery does not 

occur at or within five minutes after the end 

of the final draw in the first draw cluster, as 

identified in the applicable draw pattern 

table in section 5.5 of this appendix, then the 

standby period starts five minutes after the 

end of that draw. Determine and record the 

total electrical energy and/or fossil fuel 

consumed from the beginning of the test to 

the start of the standby period (Qsu,0). 

In preparation for determining the energy 

consumed during standby, record the reading 

given on the electrical energy (watt-hour) 

meter, the gas meter, and/or the scale used 

to determine oil consumption, as 

appropriate. Record the mean tank 

temperature at the start of the standby period 

(Tsu,0). At 1-minute intervals, record ambient 

temperature, the electric and/or fuel 

instrument readings and the mean tank 

temperature until the next draw is initiated. 

The end of the standby period is when the 

final mean tank temperature is recorded, as 

described. Just prior to initiation of the next 

draw, record the mean tank temperature 

(Tsu,f). If the water heater is undergoing 

recovery when the next draw is initiated, 

record the mean tank temperature (Tsu,f) at 

the minute prior to the start of the recovery. 

Determine the total electrical energy and/or 

fossil fuel energy consumption from the 

beginning of the test to the end of the standby 

period (Qsu,f). Record the time interval 

between the start of the standby period and 

the end of the standby period (tstby,1). 

Following the final draw of the prescribed 

draw pattern and subsequent recovery, allow 

the water heater to remain in the standby 

mode until exactly 24 hours have elapsed 

since the start of the 24-hour simulated-use 

test (i.e., since t = 0). During the last hour 

of the 24-hour simulated-use test (i.e., hour 

23 of the 24-hour simulated-use test), power 

to the main burner, heating element, or 

compressor shall be disabled. At 24 hours, 

record the reading given by the gas meter, oil 

meter, and/or the electrical energy meter as 

appropriate. Determine the fossil fuel and/or 

electrical energy consumed during the entire 

24-hour simulated-use test and designate the 

quantity as Q. 

In the event that the recovery period 

continues from the end of the last draw of the 

first draw cluster until the subsequent draw, 

the standby period will start after the end of 

the first recovery period after the last draw 

of the 24-hour simulated-use test, when the 

temperature reaches the maximum mean tank 

temperature, though no sooner than five 

minutes after the end of this recovery period. 

The standby period shall last eight hours, so 

testing may extend beyond the 24-hour 

duration of the 24-hour simulated-use test. 

Determine and record the total electrical 

energy and/or fossil fuel consumed from the 

beginning of the 24-hour simulated-use test 

to the start of the 8-hour standby period 

(Qsu,0). In preparation for determining the 

energy consumed during standby, record the 

reading(s) given on the electrical energy 

(watt-hour) meter, the gas meter, and/or the 

scale used to determine oil consumption, as 

appropriate. Record the mean tank 

temperature at the start of the standby period 

(Tsu,0). Record the mean tank temperature, the 

ambient temperature, and the electric and/or 

fuel instrument readings at 1-minute 

intervals until the end of the 8-hour period. 

Record the mean tank temperature at the end 

of the 8-hour standby period (Tsu,f). If the 

water heater is undergoing recovery at the 

end of the standby period, record the mean 

tank temperature (Tsu,f) at the minute prior to 

the start of the recovery, which will mark the 

end of the standby period. Determine the 

total electrical energy and/or fossil fuel 

energy consumption from the beginning of 

the test to the end of the standby period 

(Qsu,f). Record the time interval between the 

start of the standby period and the end of the 

standby period as tstby,1. Record the average 

ambient temperature from the start of the 

standby period to the end of the standby 

period (Ta,stby,1). Record the average mean 

tank temperature from the start of the 

standby period to the end of the standby 

period (Tt,stby,1). 

If the standby period occurred at the end 

of the first recovery period after the last draw 

of the 24-hour simulated-use test, allow the 

water heater to remain in the standby mode 


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until exactly 24 hours have elapsed since the 

start of the 24-hour simulated-use test (i.e., 

since t = 0) or the end of the standby period, 

whichever is longer. At 24 hours, record the 

mean tank temperature (T24) and the reading 

given by the gas meter, oil meter, and/or the 

electrical energy meter as appropriate. If the 

water heater is undergoing a recovery at 24 

hours, record the reading given by the gas 

meter, oil meter, and/or electrical energy 

meter, as appropriate, and the mean tank 

temperature (T24) at the minute prior to the 

start of the recovery. Determine the fossil fuel 

and/or electrical energy consumed during the 

24 hours and designate the quantity as Q. 

Record the time during which water is not 

being withdrawn from the water heater 

during the entire 24-hour period (tstby,2). 

When the standby period occurs after the last 

draw of the 24-hour simulated-use test, the 

test may extend past hour 24. When this 

occurs, the measurements taken after hour 24 

apply only to the calculations of the standby 

loss coefficient. All other measurements 

during the time between hour 23 and hour 

24 remain the same. 

5.4.2.2 Water Heaters which Cannot Have 

Internal Storage Tank Temperature 

Measured Directly. 

After the water heater has undergone a 1- 

hour idle period (as described in section 

5.4.2 of this appendix), deactivate the burner, 

compressor, or heating element(s). 

Remove the water from the storage tank by 

performing a continuous draw at a flow rate 

of 3.0 GPM (11.4 L/min) ± 0.25 GPM (0.9 L/ 

min) until the outlet water temperature is 

within ±2 °F (±1.1 °C) of the inlet water 

temperature for 15 consecutive seconds. 

While removing the hot water, measure the 

inlet and outlet temperature beginning 15 

seconds after initiating the draw and at 3- 

second intervals thereafter until the outlet 

condition has stabilized. Determine the mean 

tank temperature using section 6.3.9 of this 

appendix and assign this value of Tst for T0, 

Tmax,1, and Tsu,0. 

After completing the draw, reactivate the 

burner, compressor, or heating elements(s) 

and allow the unit to fully recover such that 

the main burner, heating elements, or heat 

pump compressor is no longer raising the 

temperature of the stored water. Let the water 

heater sit idle again for 1 hour prior to 

beginning the 24-hour test, during which 

time no water shall be drawn from the unit, 

and there shall be no energy input to the 

main heating elements. After the 1-hour 

period, the 24-hour simulated-use test will 

begin. 

At the start of the 24-hour simulated-use 

test, record the electrical and/or fuel 

measurement readings, as appropriate. Begin 

the 24-hour simulated-use test by 

withdrawing the volume specified in the 

appropriate table in section 5.5 of this 

appendix (i.e., Table III.1, Table III.2, Table 

III.3, or Table III.4, depending on the firsthour rating or maximum GPM rating) for the 

first draw at the flow rate specified in the 

applicable table. Record the time when this 

first draw is initiated and assign it as the test 

elapsed time (t) of zero (0). Record the 

average ambient temperature every minute 

throughout the 24-hour simulated-use test. At 

the elapsed times specified in the applicable 

draw pattern table in section 5.5 of this 

appendix for a particular draw pattern, 

initiate additional draws pursuant to the 

draw pattern, removing the volume of hot 

water at the prescribed flow rate specified by 

the table. The maximum allowable deviation 

from the specified volume of water removed 

for any single draw taken at a nominal flow 

rate of 1.0 GPM or 1.7 GPM is ± 0.1 gallons 

(± 0.4 liters). The maximum allowable 

deviation from the specified volume of water 

removed for any single draw taken at a 

nominal flow rate of 3.0 GPM is ± 0.25 

gallons (0.9 liters). The quantity of water 

withdrawn during the last draw shall be 

increased or decreased as necessary such that 

the total volume of water withdrawn equals 

the prescribed daily amount for that draw 

pattern ± 1.0 gallon (± 3.8 liters). If this 

adjustment to the volume drawn during the 

last draw results in no draw taking place, the 

test is considered invalid. 

All draws during the 24-hour simulateduse test shall be made at the flow rates 

specified in the applicable draw pattern table 

in section 5.5 of this appendix, within a 

tolerance of ±0.25 gallons per minute (±0.9 

liters per minute). Measurements of the inlet 

and outlet temperatures shall be made 15 

seconds after the draw is initiated and at 

every subsequent 3-second interval 

throughout the duration of each draw. 

Calculate and record the mean of the hot 

water discharge temperature and the cold 

water inlet temperature for each draw Tdel,i

and Tin,i). Determine and record the net mass 

or volume removed (Mi or Vi), as appropriate, 

after each draw. 

The first recovery period is the time from 

the start of the 24-hour simulated-use test 

and continues until the first cut-out; if the 

cut-out occurs during a subsequent draw, the 

first recovery period includes the time until 

the draw of water from the tank stops. If, after 

the first cut-out occurs but during a 

subsequent draw, a subsequent cut-in occurs 

prior to the draw completion, the first 

recovery period includes the time until the 

subsequent cut-out occurs, prior to another 

draw. The first recovery period may continue 

until a cut-out occurs when water is not 

being removed from the water heater or a cutout occurs during a draw and the water 

heater does not cut-in prior to the end of the 

draw. 

At the end of the first recovery period, 

record the total energy consumed by the 

water heater from the beginning of the test 

(Qr), including all fossil fuel and/or electrical 

energy use, from the main heat source and 

auxiliary equipment including, but not 

limited to, burner(s), resistive elements(s), 

compressor, fan, controls, pump, etc., as 

applicable. 

The standby period begins at five minutes 

after the first time a recovery ends following 

last draw of the simulated-use test and shall 

continue for 8 hours. At the end of the 8-hour 

standby period, record the total amount of 

time elapsed since the start of the 24-hour 

simulated-use test (i.e., since t = 0). 

Determine and record the total electrical 

energy and/or fossil fuel consumed from the 

beginning of the 24-hour simulated-use test 

to the start of the 8-hour standby period 

(Qsu,0). In preparation for determining the 

energy consumed during standby, record the 

reading(s) given on the electrical energy 

(watt-hour) meter, the gas meter, and/or the 

scale used to determine oil consumption, as 

appropriate. Record the ambient temperature 

and the electric and/or fuel instrument 

readings at 1-minute intervals until the end 

of the 8-hour period. At the 8-hour mark, 

deactivate the water heater and before 

drawing water from the tank. Remove water 

from the storage tank by performing a 

continuous draw at a flow rate of 3.0 GPM 

(11.4 L/min) ± 0.25 GPM (0.9 L/min) until the 

outlet water temperature is within ±2 °F (±1.1 

°C) of the inlet water temperature for 15 

consecutive seconds. While removing the hot 

water, measure the inlet and outlet 

temperature beginning 15 seconds after 

initiating the draw and at 3-second intervals 

thereafter until the outlet condition has 

stabilized. Determine the mean tank 

temperature using section 6.3.9 of this 

appendix and assign this value of Tst for Tsu,f

and T24. 

Determine the total electrical energy and/ 

or fossil fuel energy consumption from the 

beginning of the test to the end of the standby 

period (Qsu,f). Record the time interval 

between the start of the standby period and 

the end of the standby period as tstby,1. 

Record the average ambient temperature from 

the start of the standby period to the end of 

the standby period (Ta,stby,1). The average 

mean tank temperature from the start of the 

standby period to the end of the standby 

period (Tt,stby,1) shall be the average of Tsu,0

and Tsu,f.

5.4.3 Test Sequence for Water Heaters 

with Rated Storage Volume Less Than 2 

Gallons. 

Establish normal operation with the 

discharge water temperature at 125 °F ±5 °F 

(51.7 °C ±2.8 °C) and set the flow rate as 

determined in section 5.2 of this appendix. 

Prior to commencement of the 24-hour 

simulated-use test, the unit shall remain in 

an idle state in which controls are active but 

no water is drawn through the unit for a 

period of one hour. With no draw occurring, 

record the reading given by the gas meter 

and/or the electrical energy meter as 

appropriate. Begin the 24-hour simulated-use 

test by withdrawing the volume specified in 

Tables III.1 through III.4 of section 5.5 of this 

appendix for the first draw at the flow rate 

specified. Record the time when this first 

draw is initiated and designate it as an 

elapsed time, t, of 0. At the elapsed times 

specified in Tables III.1 through III.4 for a 

particular draw pattern, initiate additional 

draws, removing the volume of hot water at 

the prescribed flow rate specified in Tables 

III.1 through III.4. The maximum allowable 

deviation from the specified volume of water 

removed for any single draw taken at a 

nominal flow rate less than or equal to 1.7 

GPM (6.4 L/min) is ±0.1 gallons (±0.4 liters). 

The maximum allowable deviation from the 

specified volume of water removed for any 

single draw taken at a nominal flow rate of 

3.0 GPM (11.4 L/min) is ±0.25 gallons (0.9 

liters). The quantity of water drawn during 

the final draw shall be increased or decreased 

as necessary such that the total volume of 

water withdrawn equals the prescribed daily 

amount for that draw pattern ±1.0 gallon 


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(±3.8 liters). If this adjustment to the volume 

drawn in the last draw results in no draw 

taking place, the test is considered invalid. 

All draws during the 24-hour simulateduse test shall be made at the flow rates 

specified in the applicable draw pattern table 

in section 5.5 of this appendix within a 

tolerance of ± 0.25 gallons per minute (±0.9 

liters per minute) unless the unit being tested 

has a rated Max GPM of less than 1 gallon 

per minute, in which case the tolerance shall 

be ± 25% of the rated Max GPM. 

Measurements of the inlet and outlet water 

temperatures shall be made 15 seconds after 

the draw is initiated and at every 3-second 

interval thereafter throughout the duration of 

the draw. Calculate the mean of the hot water 

discharge temperature and the cold water 

inlet temperature for each draw. Record the 

mass of the withdrawn water or the water 

meter reading, as appropriate, after each 

draw. At the end of the first recovery period 

following the first draw, determine and 

record the fossil fuel and/or electrical energy 

consumed, Qr. Following the final draw and 

subsequent recovery, allow the water heater 

to remain in the standby mode until exactly 

24 hours have elapsed since the start of the 

test (i.e., since t = 0). At 24 hours, record the 

reading given by the gas meter, oil meter, 

and/or the electrical energy meter, as 

appropriate. Determine the fossil fuel and/or 

electrical energy consumed during the entire 

24-hour simulated-use test and designate the 

quantity as Q. 

* * * * * 

5.6 Optional Tests (Heat Pump-Type 

Water Heaters). 

Optional testing may be conducted on heat 

pump-type water heaters to determine EX. If 

optional testing is performed, conduct the 

additional 24-hour simulated use test(s) at 

one or multiple of the test conditions 

specified in section 2.8 of this appendix. 

Prior to conducting a 24-hour simulated use 

test at an optional condition, confirm the air 

and water conditions specified in section 2.8 

are met and re-set the outlet discharge 

temperature in accordance with section 5.2.2 

of this appendix. Perform the optional 24- 

hour simulated use test(s) in accordance with 

section 5.4 of this appendix using the same 

draw pattern used for the determination of 

UEF. 

* * * * * 

6.3 * * * 

6.3.1.1 Effective Storage Volume. The 

effective storage tank capacity, Veff, is 

computed as follows: 

Veff = kvVst

where: 

Vst = as defined in section 6.3.1 and 

kV = a dimensionless volume scaling factor 

determined as follows: 

where: 

Tmax,1 = the maximum measured mean tank 

temperature after cut-out following the 

first draw of the 24-hour simulated-use 

test, °F(°C). 

Tdel,2= the average outlet water temperature 

during the second draw of the 24-hour 

simulated-use test, °F(°C). 

r(Tmax,1) = the density of the stored hot water 

evaluated at the maximum measured 

mean tank temperature after cut-out 

following the first draw of the 24-hour 

simulated-use test (Tmax,1), lb/gal (kg/L). 

Cp(Tmax,1) = the specific heat of the stored hot 

water, evaluated at Tmax,1, Btu/(lb·°F) (kJ/ 

(kg·°C)). 

r(125 °F) = the density of the stored hot water 

at 125 °F, lb/gal (kg/L). 

Cp(125 °F) = the specific heat of the stored hot 

water at 125 °F, Btu/(lb·°F) (kJ/(kg·°C)). 

125 °F (51.7 °C) = the nominal maximum 

mean tank temperature for a storage tank 

that does not utilize a mixing valve to 

achieve a 125 °F delivery temperature. 

67.5 °F (19.7 °C) = the nominal average 

ambient air temperature. 

* * * * * 

6.3.9 Estimated Mean Tank Temperature 

for Water Heaters with Rated Storage 

Volumes Greater Than or Equal to 2 Gallons. 

If testing is conducted in accordance with 

section 5.4.2.2 of this appendix, calculate the 

mean tank temperature immediately prior to 

the internal tank temperature determination 

draw using the following equation: 

Where: 

Tst = the estimated average internal storage 

tank temperature, °F (°C) 

Tp = the average of the inlet and the outlet 

water temperatures at the end of the 

period defined by tp, °F (°C). 

vout,p = the average flow rate during the 

period, gal/min (L/min). 

Vst = the rated storage volume of the water 

heater, gal (L). 

tp = the number of minutes in the duration 

of the period, determined by the length 

of time taken for the outlet water 

temperature to be within 2 °F of the inlet 

water temperature for 15 consecutive 

seconds and including the 15-second 

stabilization period. 

Tin,p = the average of the inlet water 

temperatures during the period, °F (°C). 

Tout,p = the average of the outlet water 

temperatures during the period, °F (°C). 

* * * * * 

6.5 Energy Efficiency at Optional Test 

Conditions. If testing is conducted at optional 

test conditions in accordance with section 

5.6 of this appendix, calculate the energy 

efficiency at the test condition, EX, using the 

formulas section 6.3 or 6.4 of this appendix 

(as applicable), except substituting the 

applicable ambient temperature and supply 

water temperature used for testing (as 

specified in section 2.8 of this appendix) for 

the nominal ambient temperature and supply 

water temperature conditions used in the 

equations for determining UEF (i.e., 67.5 °F 

and 58 °F). 

[FR Doc. 2022–14687 Filed 7–13–22; 8:45 am] 

BILLING CODE 6450–01–P 


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