Vol. 80 Tuesday, 

No. 71 April 14, 2015 

Part III 

Department of Energy 

10 CFR Parts 429, 430, and 431 

Energy Conservation Program for Consumer Products and Certain 

Commercial and Industrial Equipment: Test Procedures for Consumer and 

Commercial Water Heaters; Proposed Rule 


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20116 Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 

DEPARTMENT OF ENERGY 

10 CFR Parts 429, 430, and 431 

[EERE–2015–BT–TP–0007] 

RIN 1904–AC91 

Energy Conservation Program for 

Consumer Products and Certain 

Commercial and Industrial Equipment: 

Test Procedures for Consumer and 

Commercial Water Heaters 

AGENCY: Office of Energy Efficiency and 

Renewable Energy, Department of 

Energy. 

ACTION: Notice of proposed rulemaking. 

SUMMARY: As required by the Energy 

Policy and Conservation Act of 1975 

(EPCA), as amended, the U.S. 

Department of Energy (DOE) proposes to 

establish a mathematical conversion 

factor for the purpose of translating 

efficiency ratings for water heaters 

under the test method currently in effect 

to the ratings under the amended test 

method promulgated by DOE in a final 

rule published on July 11, 2014 

(hereinafter referred to as the ‘‘the July 

2014 final rule’’). Compliance with the 

amended test procedure is required 

beginning on the later of: one year after 

the publication of a final rule that 

establishes a mathematical conversion 

factor, or December 31, 2015. This 

rulemaking document proposes a 

mathematical conversion factor which 

may be used to convert the existing 

efficiency ratings under the current 

Federal test procedure to efficiency 

ratings under the test procedure adopted 

in the July 2014 final rule for water 

heater basic models manufactured, 

tested and certified prior to the 

compliance date of the amended test 

procedure. The amended test procedure 

applies to all covered consumer water 

heaters and the covered commercial 

water heating equipment with 

residential applications defined in the 

July 2014 final rule as a ‘‘residentialduty commercial water heater.’’ In 

addition, this document proposes 

amendments to the minimum energy 

conservation standards for consumer 

water heaters and residential-duty 

commercial water heaters to account for 

the impact of the new metric, but does 

not alter the stringency of the existing 

energy conservation standards. While 

DOE has not planned a public meeting 

to discuss this proposal, DOE is willing 

to consider a request to hold a meeting. 

DATES: Comments: DOE will accept 

comments, data, and information 

regarding this notice of proposed 

rulemaking (NOPR) no later than May 

14, 2015. See section V, ‘‘Public 

Participation,’’ for details. 

ADDRESSES: All comments submitted 

must identify the NOPR for the 

Conversion Factor for Test Procedures 

for Consumer and Certain Commercial 

Water Heaters, and provide docket 

number EERE–2015–BT–TP–0007 and/

or RIN 1904–AC91. Interested persons 

are encouraged to submit comments 

using the Federal eRulemaking Portal at 

www.regulations.gov. Follow the 

instructions for submitting comments. 

Alternatively, interested persons may 

submit comments by any of the 

following methods: 

• Email: ConsumerCommWaterHtrs

2015TP0007@ee.doe.gov. Include the 

docket number and/or RIN in the 

subject line of the message. Submit 

electronic comments in WordPerfect, 

Microsoft Word, PDF, or ASCII file 

format, and avoid the use of special 

characters or any form of encryption. 

• Postal Mail: Ms. Brenda Edwards, 

U.S. Department of Energy, Building 

Technologies Office, Mailstop EE–5B, 

1000 Independence Avenue SW., 

Washington, DC 20585–0121. If 

possible, please submit all items on a 

compact disc (CD), in which case it is 

not necessary to include printed copies. 

• Hand Delivery/Courier: Ms. Brenda 

Edwards, U.S. Department of Energy, 

Building Technologies Office, 950 

L’Enfant Plaza SW., 6th Floor, 

Washington, DC 20024. Telephone: 

(202) 586–2945. If possible, please 

submit all items on a CD, in which case 

it is not necessary to include printed 

copies. 

No telefacsimilies (faxes) will be 

accepted. For detailed instructions on 

submitting comments and additional 

information on the rulemaking process, 

see section V of this document (Public 

Participation). 

Docket: The docket is available for 

review at www.regulations.gov, 

including Federal Register notices, 

comments, and other supporting 

documents/materials. 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. 

A link to the docket Web page can be 

found at: http://www.regulations.gov/

#!docketDetail;D=EERE-2015-BT-TP0007. This Web page contains a link to 

the docket for this notice of proposed 

rulemaking on the www.regulations.gov 

site. The www.regulations.gov Web page 

contains simple 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 information on how to submit a 

comment or review other public 

comments and the docket, contact Ms. 

Brenda Edwards at (202) 586–2945 or by 

email: Brenda.Edwards@ee.doe.gov. 

FOR FURTHER INFORMATION CONTACT: Ms. 

Ashley Armstrong, 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) 586–6590. Email: 

Ashley.Armstrong@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) 586–9507. Email: 

Eric.Stas@hq.doe.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Authority and Background 

II. Summary of the Notice of Proposed 

Rulemaking 

III. Discussion 

A. Stakeholder Comments on Other 

Rulemakings 

B. Scope 

1. Test Procedure and Energy Conservation 

Standards Coverage 

2. Units on the Market 

C. Potential Approaches for Developing 

Conversions 

1. Background Regarding Changes to 

Existing Test Procedures 

2. Analytical Methods 

3. Empirical Regression 

D. Testing Conducted for the Mathematical 

Conversion 

1. Consumer Water Heater Testing 

2. Residential-Duty Commercial Water 

Heater Testing 

E. Testing Results and Analysis of Test 

Data 

1. Impact of Certain Water Heater 

Attributes on Efficiency Ratings 

2. Conversion Factor Derivation 

3. Energy Conservation Standard 

Derivation 

F. Certification and Labeling Issues 

IV. Procedural Issues and Regulatory Review 

A. Review Under Executive Order 12866 

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 


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Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 20117 

1For editorial reasons, upon codification in the 

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

2All references to EPCA in this document refer 

to the statute as amended through the American 

Energy Manufacturing Technical Corrections Act 

(AEMTCA), Public Law 112–210 (Dec. 18, 2012). 

3For editorial reasons, upon codification in the 

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

L. Review Under Section 32 of the Federal 

Energy Administration Act of 1974 

V. Public Participation 

A. Submission of Comments 

B. Issues on Which DOE Seeks Comment 

VI. Approval of the Office of the Secretary 

I. Authority and Background 

Title III Part B1 of the Energy Policy 

and Conservation Act of 1975 (‘‘EPCA’’ 

or, ‘‘the Act’’), Public Law 94–163 (42 

U.S.C. 6291–6309, as codified) sets forth 

a variety of provisions designed to 

improve energy efficiency and 

established the Energy Conservation 

Program for Consumer Products Other 

Than Automobiles.2 These include 

consumer water heaters, one subject of 

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

Title III, Part C 3 of EPCA, Public Law 

94–163 (42 U.S.C. 6311–6317, as 

codified), added by Public Law 95–619, 

Title IV, Sec. 441(a), established the 

Energy Conservation Program for 

Certain Industrial Equipment, which 

includes the commercial water heating 

equipment that is another subject of this 

rulemaking. (42 U.S.C. 6311(1)(K)) 

Under EPCA, energy conservation 

programs generally consist of four parts: 

(1) Testing; (2) labeling; (3) establishing 

Federal energy conservation standards; 

and (4) certification and enforcement 

procedures. The testing requirements 

consist of test procedures that 

manufacturers of covered products and 

equipment must use as the basis for 

certifying to DOE that their products 

and equipment comply with the 

applicable energy conservation 

standards adopted under EPCA, and for 

making other representations about the 

efficiency of those products. (42 U.S.C. 

6293(c); 42 U.S.C. 6295(s); 42 U.S.C. 

6314) Similarly, DOE must use these 

test procedures to determine whether 

such products and equipment comply 

with any relevant standards 

promulgated under EPCA. (42 U.S.C. 

6295(s)) 

EPCA, as codified, contains what is 

known as an ‘‘anti-backsliding’’ 

provision, which prevents the Secretary 

from prescribing any amended standard 

that either increases the maximum 

allowable energy use or decreases the 

minimum required energy efficiency of 

a covered product. (42 U.S.C. 

6295(o)(1)) Also, the Secretary may not 

prescribe an amended or new standard 

if interested persons have established by 

a preponderance of the evidence that 

the standard is likely to result in the 

unavailability in the United States of 

any covered product type (or class) of 

performance characteristics (including 

reliability), features, sizes, capacities, 

and volumes that are substantially the 

same as those generally available in the 

United States. (42 U.S.C. 6295(o)(4)) 

EPCA prescribed energy conservation 

standards for consumer water heaters 

(42 U.S.C. 6295(e)(1)), and directed DOE 

to conduct further rulemakings to 

determine whether to amend these 

standards (42 U.S.C. 6295(e)(4)(A)–(B)). 

DOE notes that under 42 U.S.C. 

6295(m), the agency must periodically 

review its already established energy 

conservation standards for a covered 

product. Under this requirement, the 

next review that DOE would need to 

conduct must occur no later than six 

years from the issuance of a final rule 

establishing or amending a standard for 

a covered product. 

On April 16, 2010, DOE published a 

final rule (hereinafter referred to as the 

‘‘April 2010 final rule’’) that amended 

the energy conservation standards for all 

classes of consumer water heaters, 

except for tabletop and electric 

instantaneous water heaters, for which 

the existing energy conservation 

standards were left in place. 75 FR 

20112. The standards adopted by the 

April 2010 final rule are shown below 

in Table I.1. These standards will apply 

to all water heater products listed in 

Table I.1 and manufactured in, or 

imported into, the United States on or 

after April 16, 2015, for all classes, 

except for tabletop and electric 

instantaneous. For these latter two 

classes, compliance with these 

standards has been required since April 

15, 1991. 55 FR 42162 (Oct. 17, 1990). 

Current energy conservation standards 

for consumer water heaters can be found 

in DOE’s regulations at 10 CFR 

430.32(d). 

TABLE I.1—ENERGY CONSERVATION STANDARDS FOR CONSUMER WATER HEATERS

Product class Rated storage volume *** Energy factor ** 

Gas-fired Storage ................................ ≥20 gal and ≤55 gal ........................................................................................ 0.675¥(0.0015 × Vs) 

>55 gal and ≤100 gal ..................................................................................... 0.8012¥(0.00078 × Vs) 

Oil-fired Storage .................................. ≤50 gal ............................................................................................................ 0.68¥(0.0019 × Vs) 

Electric Storage ................................... ≥20 gal and ≤55 gal ........................................................................................ 0.96¥(0.0003 × Vs) 

>55 gal and ≤120 gal ..................................................................................... 2.057¥(0.00113 × Vs) 

Tabletop * ............................................ ≥20 gal and ≤120 gal ...................................................................................... 0.93¥(0.00113 × Vs) 

Gas-fired Instantaneous ...................... <2 gal .............................................................................................................. 0.82¥(0.0019 × Vs) 

Electric Instantaneous * ....................... <2 gal .............................................................................................................. 0.93¥(0.00132 × Vs) 

*Tabletop and electric instantaneous standards were not updated by the April 2010 final rule. 

** Vs is the ‘‘Rated Storage Volume’’ which equals the water storage capacity of a water heater (in gallons), as specified by the manufacturer. 

*** Rated Storage Volume limitations result from either a lack of test procedure coverage or from divisions created by DOE when adopting 

standards. The division at 55 gallons for gas-fired and electric storage water heaters was established in the April 16, 2010 final rule amending 

energy conservation standards. 75 FR 20112. The other storage volume limitations shown in this table are a result of test procedure applicability, 

and are discussed in the July 2014 final rule. 79 FR 40542 (July 11, 2014). 

The initial Federal energy 

conservation standards and test 

procedures for commercial water 

heating equipment were added to EPCA 

as an amendment made by the Energy 

Policy Act of 1992 (EPACT). (42 U.S.C. 

6313(a)(5)) These initial energy 

conservation standards corresponded to 

the efficiency levels contained in the 

American Society of Heating, 

Refrigerating and Air-Conditioning 

Engineers (ASHRAE) Standard 90.1 

(ASHRAE Standard 90.1) in effect on 

October 24, 1992. The statute provided 

that if the efficiency levels in ASHRAE 

Standard 90.1 were amended after 

October 24, 1992, the Secretary must 

establish an amended uniform national 

standard at new minimum levels for 

each equipment type specified in 

ASHRAE Standard 90.1, unless DOE 

determines, through a rulemaking 

supported by clear and convincing 

evidence, that national standards more 


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stringent than the new minimum levels 

would result in significant additional 

energy savings and be technologically 

feasible and economically justified. (42 

U.S.C. 6313(a)(6)(A)(ii)(I)–(II)) DOE 

issued the most recent final rule for 

commercial water heating equipment on 

January 12, 2001 (hereinafter, the 

‘‘January 2001 final rule’’), which 

adopted the amended energy 

conservation standards at levels 

equivalent to efficiency levels in 

ASHRAE Standard 90.1, as it was 

revised in October 1999. 66 FR 3336. 

The current standards for commercial 

water heating equipment are presented 

in Table I.2 and may be found in DOE’s 

regulations at 10 CFR 431.110. 

TABLE I.2—ENERGY CONSERVATION STANDARDS FOR COMMERCIAL WATER HEATING EQUIPMENT

Equipment Size 

Energy conservation standard * 

Minimum thermal efficiency 

(%) 

Maximum standby loss c

Electric storage water heaters ............................................... All ........................................... N/A 0.30 + 27/Vm (%/hr) 

Gas-fired storage water heaters ............................................ ≤155,000 Btu/hr ..................... 80 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

>155,000 Btu/hr ..................... 80 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

Oil-fired storage water heaters .............................................. ≤155,000 Btu/hr ..................... 78 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

>155,000 Btu/hr ..................... 78 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

Gas-fired instantaneous water heaters and hot water supply 

boilers **.

<10 gal ................................... 80 N/A 

≥10 gal ................................... 80 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

Oil-fired instantaneous water heaters and hot water supply 

boilers **.

<10 gal ................................... 80 N/A 

≥10 gal ................................... 78 Q/800 + 110(Vr) 1, 2 (Btu/hr) 

Equipment Size Minimum thermal insulation 

Unfired hot water storage tank .............................................. All ........................................... R–12.5 

* Vm is the measured storage volume, and Vr is the rated volume, both in gallons. Q is the nameplate input rate in Btu/hr. 

** For hot water supply boilers with a capacity of less than 10 gallons: (1) The standards are mandatory for products manufactured on and 

after October 21, 2005, and (2) products manufactured prior to that date, and on or after October 23, 2003, must meet either the standards listed 

in this table or the applicable standards in subpart E of this part for a ‘‘commercial packaged boiler.’’ 

*** Water heaters and hot water supply boilers having more than 140 gallons of storage capacity need not meet the standby loss requirement 

if: (1) The tank surface area is thermally insulated to R–12.5 or more; (2) a standing pilot light is not used; and (3) for gas or oil-fired storage 

water heaters, they have a fire damper or fan-assisted combustion. 

On December 18, 2012, the American 

Energy Manufacturing Technical 

Corrections Act (AEMTCA), Public Law 

112–210, was signed into law. In 

relevant part, it amended EPCA to 

require that DOE publish a final rule 

establishing a uniform efficiency 

descriptor and accompanying test 

methods for covered consumer water 

heaters and commercial water heating 

equipment within one year of the 

enactment of AEMTCA. (42 U.S.C. 

6295(e)(5)(B)) The final rule must 

replace the current energy factor, 

thermal efficiency, and standby loss 

metrics with a uniform efficiency 

descriptor. (42 U.S.C. 6295(e)(5)(C)) The 

July 2014 final rule fulfilled these 

requirements. AEMTCA requires that, 

beginning one year after the date of 

publication of DOE’s final rule 

establishing the uniform descriptor (i.e., 

July 13, 2015), the efficiency standards 

for the consumer water heaters and 

residential-duty commercial water 

heaters identified in the July 2014 final 

rule must be denominated according to 

the uniform efficiency descriptor 

established in that final rule (42 U.S.C. 

6295(e)(5)(D)), and that DOE must 

develop a mathematical conversion 

factor for converting the measurement of 

efficiency for those water heaters from 

the test procedures and metrics 

currently in effect to the new uniform 

energy descriptor. (42 U.S.C. 

6295(e)(5)(E)(i)–(ii)) Consumer water 

heaters and residential-duty commercial 

water heaters manufactured prior to the 

effective date of the final rule (i.e., July 

13, 2015) that comply with the 

efficiency standards and labeling 

requirements in effect prior to the final 

rule shall be considered to comply with 

the final rule and with any revised 

labeling requirements established by the 

Federal Trade Commission (FTC) to 

carry out the final rule. (42 U.S.C. 

6295(e)(5)(K)) 

AEMTCA also requires that the 

uniform efficiency descriptor and 

accompanying test method apply, to the 

maximum extent practicable, to all 

water-heating technologies currently in 

use and to future water-heating 

technologies. (42 U.S.C. 6295(e)(5)(H)) 

AEMTCA allows DOE to provide an 

exclusion from the uniform efficiency 

descriptor for specific categories of 

otherwise covered water heaters that do 

not have residential uses, that can be 

clearly described, and that are 

effectively rated using the current 

thermal efficiency and standby loss 

descriptors. (42 U.S.C. 6295(e)(5)(F)) 

AEMTCA outlines DOE’s various 

options for establishing a new uniform 

efficiency descriptor for water heaters. 

The options that AEMTCA provides to 

DOE include: (1) A revised version of 

the energy factor descriptor currently in 

use; (2) the thermal efficiency and 

standby loss descriptors currently in 

use; (3) a revised version of the thermal 

efficiency and standby loss descriptors; 

(4) a hybrid of descriptors; or (5) a new 

approach. (42 U.S.C. 6295(e)(5)(G)) 

Lastly, AEMTCA requires that DOE 

invite stakeholders to participate in the 

rulemaking process, and that DOE 

contract with the National Institute of 

Standards and Technology (NIST), as 

necessary, to conduct testing and 

simulation of alternative descriptors 

identified for consideration. (42 U.S.C. 

6295(e)(5)(I)–(J)) 

As noted previously, in the July 2014 

final rule, DOE amended its test 

procedure for consumer and certain 

commercial water heaters. 79 FR 40542 

(July 11, 2014). The July 2014 final rule 

for consumer and certain commercial 

water heaters satisfied the AEMTCA 

requirements to develop a uniform 

efficiency descriptor to replace the 

existing energy factor, thermal 

efficiency and standby loss metrics. The 

amended test procedure includes 


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4 DOE published a final rule on April 16, 2010, 

that will require compliance with amended energy 

conservation standards beginning on April 16, 

2015. 75 FR 20112. DOE focused the testing of 

consumer water heaters on units that would comply 

with the amended standards. 

provisions for determining the uniform 

energy factor (UEF), as well as the 

annual energy consumption of these 

products. Furthermore, the uniform 

descriptor test procedure can be applied 

to: (1) Most consumer water heaters 

(including certain consumer water 

heaters that are covered products under 

EPCA’s definition of ‘‘water heater’’ at 

42 U.S.C. 6291(27), but that are not 

addressed by the existing test method); 

and (2) to commercial water heaters that 

have residential applications. The major 

modifications to the existing DOE test 

procedure to establish the uniform 

descriptor test method included the use 

of multiple draw patterns and different 

draw patterns, and changes to the setpoint temperature. In addition, DOE 

expanded the scope of the test method 

to include test procedure provisions that 

are applicable to water heaters with 

storage volumes between 2 gallons (7.6 

L) and 20 gallons (76 L), and to clarify 

applicability to electric instantaneous 

water heaters. DOE also established a 

new equipment class and corresponding 

definition for ‘‘residential-duty 

commercial water heater.’’ 

This rulemaking will satisfy the 

requirements of AEMTCA to develop a 

mathematical conversion factor for 

converting the measurement of 

efficiency for covered water heaters 

from the test procedures and metrics 

currently in effect to the new uniform 

energy descriptor. (42 U.S.C. 

6295(e)(5)(E)) 

II. Summary of the Notice of Proposed 

Rulemaking 

This notice of proposed rulemaking 

proposes to establish a mathematical 

conversion factor between the current 

rated values under the existing water 

heaters test procedures (i.e., energy 

factor, first-hour rating, maximum 

gallons per minute (GPM) rating, 

thermal efficiency, standby loss), and 

the amended test procedure for the 

uniform efficiency descriptor (i.e., UEF 

and first-hour rating or maximum GPM 

rating), which was established in the 

July 2014 final rule. As discussed 

previously, the water heater test 

procedure was updated to be more 

representative of conditions 

encountered in the field (including 

modifications to both the test conditions 

and the draw patterns) and to expand 

the scope of the test procedure to apply 

to certain commercial and consumer 

water heaters that are currently not 

addressed by the test procedure. 

The mathematical conversion factor 

required by AEMTCA is a bridge 

between the efficiency ratings obtained 

through testing under the existing test 

procedures and those obtained under 

the uniform efficiency descriptor test 

procedure published in the July 2014 

final rule. Therefore, the mathematical 

conversion factor will only apply to 

products and equipment covered by the 

existing test procedure, as products and 

equipment that are not covered by the 

existing test method would not have 

ratings to be converted. Certain water 

heater types are not covered by the 

mathematical conversion factor, either 

because they are not covered by the 

uniform efficiency descriptor 

established by the July 2014 final rule 

(e.g., commercial heat pump water 

heaters), or because they are not covered 

by DOE’s existing test procedure (e.g., 

water heaters with storage volumes 

between 2 and 20 gallons). The water 

heater types that are and are not covered 

by the mathematical conversion factor 

are discussed in detail in section III.B of 

this notice of proposed rulemaking. 

To help develop the mathematical 

conversion factor, DOE conducted a 

series of tests on the types of water 

heaters included within the scope of 

this rulemaking (i.e., those described in 

section III.B and that pass the minimum 

standards for consumer 4 and 

commercial water heaters). An 

investigation of DOE’s Compliance 

Certification Management System 

(CCMS) and the Air-Conditioning, 

Heating, and Refrigeration Institute’s 

(AHRI) water-heating databases found 

that certain types of water heaters are 

not available for purchase on the 

market; these units are discussed in 

section III.B. As there are no existing 

water heaters in these product classes, 

and the purpose of the conversion factor 

is to convert the efficiency ratings of 

existing water heaters, DOE did not 

include these water heaters in its 

analysis for the mathematical 

conversion factor. 

DOE selected 72 water heaters for 

testing, including: 43 consumer storage 

units, 22 consumer instantaneous units, 

and 7 commercial residential-duty 

storage units. Units were selected to 

represent the range of rated values 

available on the market (i.e., storage 

volume, input rate, first-hour rating, 

maximum GPM, recovery efficiency, 

energy factor, thermal efficiency, and 

standby loss). DOE used data obtained 

from testing, along with analytical 

methods described in section III.C, to 

calculate the conversion factors 

described in this document. DOE 

investigated several approaches to 

derive these conversion factors, which 

are discussed in detail in section III.C of 

this notice of proposed rulemaking. 

DOE developed different conversion 

factors for determining first-hour rating, 

maximum GPM, and UEF based on the 

existing ratings for consumer and 

residential-duty commercial water 

heaters, which can be found in section 

III.E. 

DOE then used the conversion factors 

to derive minimum energy conservation 

standards based on the UEF, as shown 

in Table II.1 and Table II.2. The 

proposed standards based on UEF are 

neither more nor less stringent than the 

existing standards for consumer water 

heaters based on energy factor (as 

amended by the April 2010 final rule) 

and for commercial water-heating 

equipment based on the thermal 

efficiency and standby loss metrics. The 

methodology for deriving the proposed 

UEF standards is discussed in detail in 

section III.E.3 of this notice of proposed 

rulemaking. 

TABLE II.1—PROPOSED CONSUMER WATER HEATER ENERGY CONSERVATION STANDARDS

Product class Rated storage volume Draw pattern Uniform energy factor * 

Gas-fired Storage ............................................ ≥20 gal and ≤55 gal ........................................ Very Small ............ 0.3263¥(0.0019 × Vr) 

Low ....................... 0.5891¥(0.0019 × Vr) 

Medium ................. 0.6326¥(0.0013 × Vr) 

High ....................... 0.7128¥(0.0025 × Vr) 

>55 gal and ≤100 gal ...................................... Very Small ............ 0.5352¥(0.0007 × Vr) 

Low ....................... 0.7375¥(0.0009 × Vr) 

Medium ................. 0.7704¥(0.0010 × Vr) 

High ....................... 0.7980¥(0.0010 × Vr) 

Oil-fired Storage .............................................. ≤50 gal ............................................................ Very Small ............ 0.2267¥(0.0014 × Vr) 


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TABLE II.1—PROPOSED CONSUMER WATER HEATER ENERGY CONSERVATION STANDARDS—Continued 

Product class Rated storage volume Draw pattern Uniform energy factor * 

Low ....................... 0.4867¥(0.0006 × Vr) 

Medium ................. 0.6016¥(0.0012 × Vr) 

High ....................... 0.6529¥(0.0005 × Vr) 

Electric Storage ............................................... ≥20 gal and ≤55 gal ........................................ Very Small ............ 0.8268¥(0.0002 × Vr) 

Low ....................... 0.9393¥(0.0004 × Vr) 

Medium ................. 0.9683¥(0.0007 × Vr) 

High ....................... 0.9656¥(0.0004 × Vr) 

>55 gal and ≤120 gal ...................................... Very Small ............ 1.2701¥(0.0011 × Vr) 

Low ....................... 1.9137¥(0.0011 × Vr) 

Medium ................. 2.0626¥(0.0011 × Vr) 

High ....................... 2.1858¥(0.0011 × Vr) 

Tabletop Storage ............................................. ≥20 gal and ≤100 gal ...................................... Very Small ............ 0.6808¥(0.0022 × Vr) 

Low ....................... 0.8770¥(0.0012 × Vr) 

Medium ................. 0.9063¥(0.0009 × Vr) 

High ....................... 0.9302¥(0.0006 × Vr) 

Gas-fired Instantaneous .................................. <2 gal .............................................................. All .......................... 0.8036¥(0.0019 × Vr) 

Electric Instantaneous ..................................... <2 gal .............................................................. All .......................... 0.9192¥(0.0013 × Vr) 

* Vr is the rated storage volume which equals the water storage capacity of a water heater (in gallons), as specified by the manufacturer. 

TABLE II.2—PROPOSED RESIDENTIAL-DUTY COMMERCIAL WATER HEATER ENERGY CONSERVATION STANDARDS

Product class Draw pattern Uniform energy factor 

Gas-fired Storage .......................................................................................................................... Very Small ............ 0.3261 ¥ (0.0006 × Vr) 

Low ....................... 0.5219 ¥ (0.0008 × Vr) 

Medium ................. 0.5585 ¥ (0.0006 × Vr) 

High ....................... 0.6044 ¥ (0.0005 × Vr) 

Oil-fired Storage ............................................................................................................................ Very Small ............ 0.3206 ¥ (0.0006 × Vr) 

Low ....................... 0.5577 ¥ (0.0019 × Vr) 

Medium ................. 0.6027 ¥ (0.0019 × Vr) 

High ....................... 0.6446 ¥ (0.0018 × Vr) 

*Vr is the rated storage volume which equals the water storage capacity of a water heater (in gallons), as specified by the manufacturer. 

EPCA requires that a covered water 

heater be considered to comply with the 

July 2014 final rule on and after July 13, 

2015 (the effective date of the July 2014 

final rule) and with any revised labeling 

requirements established by the Federal 

Trade Commission to carry out the July 

2014 final rule if the covered water 

heater was manufactured prior to July 

13, 2015, and complied with the 

efficiency standards and labeling 

requirements in effect prior to July 13, 

2015. (42 U.S.C. 6295(e)(5)(K)) Upon the 

effective date of the final rule 

establishing the mathematical 

conversion factor (this rulemaking), 

compliance with energy conservation 

standards will be exclusively 

determined based on the standards as 

defined in terms of UEF, which will be 

established by this rulemaking. DOE has 

tentatively concluded that there will be 

three possible compliance paths 

available to manufacturers for basic 

models of consumer water heaters that 

were certified before July 13, 2015: 

(1) Convert the certified rating for 

energy factor obtained using the test 

procedure contained in Appendix E to 

subpart B of 10 CFR part 430 of the 

January 1, 2015 edition of the CFR along 

with the applicable sampling provisions 

in 10 CFR part 429 from energy factor 

to uniform energy factor using the 

applicable mathematical conversion 

factor; or 

(2) Conduct testing using the test 

procedure contained at Appendix E to 

subpart B of 10 CFR part 430, effective 

July 13, 2015, along with the applicable 

sampling provisions in 10 CFR part 429; 

or 

(3) Where permitted, apply an 

alternative efficiency determination 

method (AEDM) pursuant to 10 CFR 

429.70 to determine the represented 

efficiency of basic models for those 

categories of consumer water heaters 

where the ‘‘tested basic model’’ was 

tested using the test procedure 

contained at Appendix E to subpart B of 

10 CFR part 430, effective July 13, 2015. 

Similarly, DOE has tentatively 

concluded that there will be three 

possible compliance paths available to 

manufacturers for basic models of 

commercial residential-duty water 

heaters that were certified before July 

13, 2015: 

(1) Convert the certified rating for 

thermal efficiency and standby loss 

obtained using the test procedure 

contained in 10 CFR 431.106 of the 

January 1, 2015 edition of the CFR along 

with the applicable sampling provisions 

in part 429 from thermal efficiency and 

standby loss to uniform energy factor 

using the applicable mathematical 

conversion factor; or 

(2) Conduct testing using the test 

procedure at 10 CFR 431.106, effective 

July 13, 2015, along with the applicable 

sampling provisions in part 429; or 

(3) Where permitted, apply an 

alternative efficiency determination 

method (AEDM) pursuant to 10 CFR 

429.70 to determine the represented 

efficiency of basic models for those 

categories of commercial water heaters 

where the ‘‘tested basic model’’ was 

tested using the test procedure at 10 

CFR 431.106, effective July 13, 2015. 

After July 13, 2015, all new basic 

models (previously uncertified) must be 

rated using the new test procedure 

either by testing or by an AEDM, where 

allowed. All water heaters subject to the 

new test procedure adopted by the July 

2014 final rule must be rated and 

certified in terms of UEF. DOE will 

assess compliance based upon the 

energy conservation standards 

expressed in terms of UEF as developed 

in this rulemaking. One year after the 

final rule in this rulemaking is 

published, all water heaters subject to 

the new UEF test procedure must be 


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5 78 FR 2340. 

6ACEEE submitted a joint comment on behalf of 

ACEEE, the Appliance Standards Awareness Project 

(ASAP), the Alliance to Save Energy (ASE), the 

National Consumer Law Center (NCLC), the 

National Resources Defense Council (NRDC), the 

Northwest Power and Conservation Council 

(NPCC), and the Northeast Energy Efficiency 

Partnerships (NEEP). 

7Lutz, Jim, Camilla D. Whitehead, Alex Lekov, 

David Winiarski, and Greg Rosenquist, WHAM: A 

Simplified Energy Consumption Equation for Water 

Heaters, Proc. of 1998 ACEEE Summer Study on 

Energy Efficiency in Buildings. Vol. 1. 171–83. 

Print. 

8 78 FR 66202. 

9ACEEE submitted a joint comment on behalf of 

ACEEE, ASAP, ASE, Consumers Union (CU), NCLC, 

NRDC and NEEP. 

rated and certified based on testing 

using the UEF test procedure or an 

AEDM, which is based on the UEF test 

procedure, where allowed. A summary 

of the options and requirements at 

various key dates is shown in the table 

below. 

TABLE II.3—SUMMARY OF KEY DATES AND REQUIREMENTS

Description of date Date Requirements 

Test Procedure Effective Date ........................... July 13, 2015 ................................................... For new basic models introduced into commerce on or after July 13, 2015, manufacturers must begin to test and represent efficiency using the UEF metric pursuant to the 

UEF test procedure and sampling plan (or 

an AEDM that is based on the UEF test 

procedure, where allowed). 

Conversion Factor Effective Date ...................... Date of publication of the conversion factor 

final rule in the Federal Register.

For basic models certified using the EF metric 

or thermal efficiency and/or standby loss 

metrics prior to July 13, 2015, manufacturers must transition all of their representations to UEF either by applying the conversion equations or by using the UEF test 

procedure and sampling plan (or an AEDM 

that is based on the UEF test procedure, 

where allowed). 

Conversion Factor Ending Date ......................... One year after publication of conversion factor 

final rule.

All basic models must be rated in terms of 

UEF using the UEF test procedure and 

sampling plan or an AEDM that is based on 

the UEF test procedure, where allowed. 

III. Discussion 

A. Stakeholder Comments on Other 

Rulemakings 

During the rulemaking process to 

develop the uniform efficiency 

descriptor test procedure, comments 

were received from stakeholders in 

reference to the derivation and 

applicability of the conversion factor. 

DOE deferred discussion of and 

response to those comments until such 

time as they could be addressed in this 

rulemaking. 

In response to the test procedure 

request for information (RFI 5) published 

on January 11, 2013, DOE received 

seven written comments related to the 

conversion factor from the following 

interested parties: AHRI, A.O. Smith 

Corporation (A.O. Smith), Edison 

Electric Institute (EEI), Heat Transfer 

Products Inc. (HTP), the National 

Renewable Energy Laboratory (NREL), 

the Northwest Energy Efficiency 

Alliance (NEEA), and a joint comment 

on behalf of a number of environmental 

groups and efficiency advocates 

submitted by the American Council for 

an Energy-Efficient Economy (ACEEE).6

These comments are discussed 

immediately below. 

NREL stated that there is not a simple 

conversion factor that will work across 

all systems, but suggested an 

application of the Water Heater Analysis 

Model (WHAM) 7 to assist DOE in 

developing the conversion factor for 

storage water heaters. (NREL, EERE– 

2011–BT–TP–0042–0029 at p. 4) The 

joint commenters supported the use of 

a ‘‘good-enough’’ mathematical 

conversion method to express existing 

ratings in terms of the new uniform 

descriptor and urged DOE to test a 

sample of existing products to validate 

the algorithmic conversion method. 

(Joint comment, EERE–2011–BT–TP– 

0042–0035 at p. 4) HTP commented that 

the most exact approach would be to 

conduct an empirical analysis using 

curve fitting to actual test data, although 

the commenter acknowledged that there 

is not sufficient time for manufacturers 

to obtain this information and for the 

Department to then correlate and 

analyze the data. (HTP, EERE–2011–BT– 

TP–0042–0041 at p. 3) 

Regarding the derivation of updated 

energy conservation standards using the 

new uniform descriptor, AHRI and A.O. 

Smith commented that DOE should not 

simply test multiple units to determine 

an average difference between the 

current and new ratings and use that 

value to convert the ratings. (AHRI, 

EERE–2011–BT–TP–0042–0033 at p. 4; 

A.O. Smith, EERE–2011–BT–TP–0042– 

0034 at p. 3) NEEA commented that 

considering the limited laboratory 

capacity to test all water heaters under 

the revised method of test, DOE should 

assume that all water heaters that 

comply with current standards will also 

comply after the implementation of the 

new metrics. (NEEA, EERE–2011–BT– 

TP–0042–0037 at p. 6) EEI commented 

that the conversion factor should not 

make currently existing standards more 

stringent and should only be based on 

point-of-use metrics to be consistent 

with Federal law. (EEI, EERE–2011–BT– 

TP–0042–0040 at p. 2) 

In response to the test procedure 

NOPR8 published on November 4, 2013, 

DOE received three additional written 

comments related to the conversion 

factor from: AHRI, Bradford White 

Corporation (BWC) and a joint comment 

submitted on behalf of a number of 

environmental groups and efficiency 

advocates by ACEEE.9 AHRI and BWC 

suggested model types to test and urged 

DOE to release a schedule and process 

for the development of the conversion 

factor as soon as possible. (AHRI, EERE– 

2011–BT–TP–0042–0075 at p. 6–7; 

BWC, EERE–2011–BT–TP–0042–0061 at 

p. 7) AHRI suggested two categories to 

be considered in the conversion factor 

rulemaking: water heater type and 

storage volume. BWC expanded on the 

list of categories supplied by AHRI by 


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including considerations for input 

capacity, venting options, tank 

configuration, NOX emissions, and 

mobile home certification. The joint 

comment suggested that the sensitivity 

of the energy factor to draw pattern be 

investigated and that systematic 

differences between ‘‘old’’ and ‘‘new’’ 

values should be expected for several 

technologies. (Joint Comment, EERE– 

2011–BT–TP–0042–0077 at p. 2) 

DOE has considered these comments 

fully in the development of this 

proposed rule. Although discussed in 

overview here, these comments are 

discussed in more detail later in this 

document as applicable to DOE’s 

specific decisions regarding the 

mathematical conversion factor. In 

regards to the method of developing the 

conversion factor, DOE agrees in 

principle with the HTP comment that 

the most exact approach would be an 

empirical analysis using a curve-fitting 

method and actual test data, because 

such approach would account for all the 

changes made in the new test 

procedure, without having to make 

assumptions. However, DOE notes that 

the confidence in this empirical 

approach is dependent upon sample 

size and has considered whether the 

approach can feasibly be tested and 

implemented within the time 

constraints set forth by AEMTCA. (The 

curve-fitting method investigated is 

discussed in section III.C.3.) 

In addition, as suggested by NREL, 

DOE investigated the use of the WHAM 

model to predict water heater efficiency 

under the new test procedure 

parameters, and used the results in the 

conversion factor analysis. The 

methodology for applying WHAM and 

the results are found in section III.C.2.c. 

As suggested in the NOPR joint 

comment, the sensitivity of the UEF to 

draw pattern was investigated by 

including the drawn volume in the 

conversion factor calculations; this 

approach is discussed further in section 

III.C. 

In an effort to develop a mathematical 

conversion factor, DOE commissioned 

testing of 72 individual water heaters 

from various easily distinguishable 

water-heating categories under the 

updated test procedure. All of the water 

heaters chosen were found using either 

the Compliance Certification 

Management System (CCMS) or AHRI 

water heater databases, where the water 

heaters included in the databases were 

further distinguished based on the 

suggestions made by AHRI and BWC in 

response to the November 2013 water 

heaters NOPR (78 FR 66202 (Nov. 4, 

2013)). The models selected for testing 

and the parameters examined are 

described in more detail in section III.D. 

These test data were used to investigate 

all of the potential conversion factor 

methods described in section III.C. 

DOE has also carefully considered the 

comments regarding the establishment 

of energy conservation standards using 

the uniform efficiency descriptor metric 

(i.e., UEF). Those comments are 

discussed further in section III.E.3. 

B. Scope 

The purpose of this section is to 

describe DOE’s process for categorizing 

water heaters and establishing the range 

of units to be considered in this 

mathematical conversion factor 

rulemaking. DOE seeks comment on the 

scope of the conversion factor. This is 

identified as issue 1 in section V.E, 

‘‘Issues on Which DOE Seeks 

Comment.’’ 

1. Test Procedure and Energy 

Conservation Standards Coverage 

To determine the appropriate scope of 

coverage for the mathematical 

conversion factor, DOE first considered 

the scope of its existing test procedures 

and energy conservation standards for 

consumer and commercial water 

heaters. Water heaters that are not 

currently subject to the DOE test 

procedures or standards were not 

included in the scope of the conversion 

factor, as they are not required to be 

tested and rated for efficiency under the 

DOE test method. 

a. Consumer Water Heaters 

Under the existing regulatory 

definitions, DOE’s current consumer 

water heater test procedures and energy 

conservation standards are not 

applicable to gas or electric water 

heaters with storage tanks that are at or 

above 2 gallons (7.6 L) and less than 20 

gallons (76 L). In terms of the high end 

of the capacity range, the current DOE 

test procedure for consumer water 

heaters only applies to gas-fired water 

heaters with storage volumes less than 

or equal to 100 gallons (380 L), electric 

resistance and heat pump storage water 

heaters with storage volumes less than 

or equal to 120 gallons (450 L), and oilfired water heaters with storage volumes 

less than or equal to 50 gallons (190 L). 

10 CFR part 430, subpart B, appendix E, 

sections 1.12.1, 1.12.2, and 1.12.4. 

In the July 2014 final rule, DOE 

expanded the scope of the water heater 

test procedure for the uniform efficiency 

descriptor to include water heaters with 

storage volumes between 2 and 20 

gallons and up to 120 gallons. 79 FR 

40542, 40547–48 (July 11, 2014). 

DOE’s current consumer water heater 

test procedure and energy conservation 

standards are not applicable to gas-fired 

instantaneous water heaters with input 

capacities at or below 50,000 Btu/h or 

at or above 200,000 Btu/h. 10 CFR part 

430, subpart B, appendix E, section 

1.7.2. In addition, the existing test 

procedure and energy conservation 

standards are not applicable to gas-fired 

storage water heaters with input 

capacities above 75,000 Btu/h, electric 

storage water heaters with input ratings 

above 12 kW, and oil-fired storage water 

heaters with input ratings above 105,000 

Btu/h, as models exceeding those limits 

would not be classified as consumer 

water heaters under EPCA. (42 U.S.C. 

6291(27)); 10 CFR part 430, subpart B, 

appendix E, sections 1.12.1, 1.12.2, and 

1.12.4. 

In the July 2014 final rule, DOE 

designed the test procedure so it is 

applicable to water heaters with any 

input capacity. Therefore, the lower 

limit for instantaneous water heaters no 

longer applies. 79 FR 40542, 40548 (July 

11, 2014). 

As discussed in the July 2014 final 

rule, definitions were added for 

‘‘electric instantaneous water heater,’’ 

‘‘gas-fired heat pump water heater,’’ and 

‘‘oil-fired instantaneous water heater,’’ 

and the July 2014 test procedure is 

applicable to these types of appliances. 

79 FR 40542, 40549 (July 11, 2014). 

Although there is no definition for 

‘‘electric instantaneous water heater’’ in 

the current test procedure in 10 CFR 

part 430, subpart B, Appendix E, an 

energy conservation standard exists for 

this type of water heater. In addition, 

the current test procedure can be 

applied to electric instantaneous water 

heaters, and manufacturers report 

energy factor ratings for these products. 

For these reasons, DOE has decided to 

include electric instantaneous water 

heaters with rated storage volumes <2 

gallons and rated inputs ≤12 kW in the 

conversion factor analysis. 

DOE has tentatively excluded the 

consumer water heater products listed 

in Table III.1 from consideration for the 

mathematical conversion factor due to 

the lack of an existing Federal test 

procedure and rating to be converted. 


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10 In a condensing water heater, the combustion 

gases are cooled such that the temperature is 

reduced below the dew point and condensation 

occurs, allowing the latent heat of vaporization to 

be captured and improving the efficiency of the 

heat exchange between the combustion gases and 

the water. 

TABLE III.1—CONSUMER WATER HEATERS NOT COVERED BY THE MATHEMATICAL CONVERSION FACTOR

Product class Description of criteria for exclusion from conversion rulemaking 

Gas-fired Storage ..................................................................................... Rated Storage Volume ≥2 gal and <20 gal or >100 gal and ≤120 gal. 

Oil-fired Storage ....................................................................................... Rated Storage Volume >50 gal. 

Electric Storage ........................................................................................ Rated Storage Volume ≥2 gal and <20 gal. 

Tabletop .................................................................................................... Rated Storage Volume ≥2 gal and <20 gal. 

Gas-fired Instantaneous ........................................................................... Rated Input ≤ 50,000 Btu/h; Rated Storage Volume >2 gal. 

Electric Instantaneous .............................................................................. Rated Storage Volume >2 gal. 

b. Commercial Water Heaters 

As stated in the July 2014 final rule, 

DOE excluded from the uniform 

efficiency descriptor any specific 

category of water heater that does not 

have a residential use, can be clearly 

described, and can be effectively rated 

using the current thermal efficiency and 

standby loss descriptors. 79 FR 40542, 

40545 (July 11, 2014). DOE determined 

that certain commercial water heaters 

met these criteria to be excluded from 

the uniform efficiency descriptor, and 

distinguished them from water heaters 

that do not meet the criteria by 

establishing equipment classes for 

residential-duty commercial water 

heaters. Commercial water heaters 

meeting the definition of ‘‘residentialduty commercial water heater’’ do not 

meet the criteria for exclusion, and thus, 

are included in the uniform efficiency 

descriptor while all other commercial 

water heaters are not. DOE determined 

that three criteria would be used to 

distinguish residential-duty commercial 

water heaters from other commercial 

water heaters (79 FR 40542, 40547 (July 

11, 2014)): 

(1) For models requiring electricity, 

uses single-phase external power 

supply; 

(2) Is not designed to provide outlet 

hot water at temperatures greater than 

180 °F; and 

(3) Is not excluded by the limitations 

regarding rated input and storage 

volume presented in Table III.2. 

TABLE III.2—CAPACITY LIMITATIONS FOR DEFINING COMMERCIAL WATER HEATERS WITHOUT RESIDENTIAL APPLICATIONS

(i.e., NON-RESIDENTIAL-DUTY) 

Water heater type Indicator of non-residential application 

Gas-fired Storage ..................................................................................... Rated input >105 kBtu/h; Rated storage volume >120 gallons. 

Oil-fired Storage ....................................................................................... Rated input >140 kBtu/h; Rated storage volume >120 gallons. 

Electric Storage ........................................................................................ Rated input >12 kW; Rated storage volume >120 gallons. 

Heat Pump with Storage .......................................................................... Rated input >15 kW; Rated current >24 A at a rated voltage of not 

greater than 250 V; Rated storage volume >120 gallons. 

Gas-fired Instantaneous ........................................................................... Rated input >200 kBtu/h; Rated storage volume >2 gallons. 

Electric Instantaneous .............................................................................. Rated input >58.6 kW; Rated storage volume >2 gallons. 

Oil-fired Instantaneous ............................................................................. Rated input >210 kBtu/h; Rated storage volume >2 gallons. 

DOE did not include commercial 

water-heating equipment that does not 

meet the definition of a ‘‘residentialduty commercial water heater’’ in its 

consideration of the mathematical 

conversion factor, as the equipment is 

not subject to the uniform efficiency 

descriptor test procedure. Additionally, 

DOE notes that there are no electric 

storage water heaters that would be 

considered to be residential-duty 

commercial since the qualifications 

shown in Table II.2 would place an 

electric storage water heater in the 

consumer category. Since there are no 

such units, and could not be such units 

under the applicable definition, a 

conversion is unnecessary. DOE is, 

therefore, not proposing a conversion 

factor for residential-duty electric 

storage water heaters. DOE also notes 

that a water heater that meets the 

definition of a consumer electric storage 

water heater must be tested and rated as 

a consumer electric storage water heater 

even if it is marketed as part of a 

commercial product line. 

As stated in the July 2014 final rule, 

DOE has determined that certain 

commercial equipment including 

unfired storage tanks, add-on heat pump 

water heaters, and hot water supply 

boilers are not appropriately rated using 

the uniform descriptor applicable to 

other water heaters, and, thus, will 

continue to be rated using the existing 

metrics. 79 FR 40542, 40547. 

Electric instantaneous water heaters 

are currently subject to the commercial 

water heating equipment test 

procedures but do not have an 

associated energy conservation 

standard. 10 CFR 431.106; 10 CFR 

431.110. Because there is no commercial 

energy conservation standard for 

electric instantaneous water heaters, a 

conversion to the UEF cannot be made. 

2. Units on the Market 

As stated in section II, DOE undertook 

an investigation into the water-heating 

units on the market at the time of the 

publication of the final rule establishing 

the UEF test procedure. The AHRI 

commercial water heater database along 

with the CCMS consumer water heater 

database were examined to select 

representative units for testing and 

analysis. 

DOE’s analysis focused on the models 

that meet the energy conservation 

standards contained in the April 2010 

final rule, which will require 

compliance on April 16, 2015. The 

storage volume divisions at 55 gallons 

in the gas-fired and electric storage 

product classes, as established in the 

April 16, 2010 final rule, represent a 

divide in technology. For gas-fired 

storage units above 55 gallons 

manufactured on and after April 16, 

2015, the energy conservation standard 

will be high enough that current designs 

can only achieve the required efficiency 

through the use of condensing 

technology.10 For electric storage units 

with storage volumes above 55 gallons, 

only heat pump water heaters currently 


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have the ability to reach the April 16, 

2015 energy conservation standard 

levels. While the UEF test procedure 

will apply to both electric and gas units 

in this range, DOE found that for gasfired storage water heaters, there are 

currently no consumer water heaters 

above 55 gallons that would be 

compliant with the updated standard, so 

no units were tested for development of 

a conversion factor. For electric storage 

water heaters, heat pump water heaters 

meet or exceed the amended energy 

conservation standards and, thus, were 

candidates for inclusion in the test plan 

for the conversion factor. There are no 

oil-fired instantaneous or oil-fired 

storage water heaters above 50 gallons 

available on the market. 

In reviewing the commercial water 

heating market, DOE found that 

commercial oil-fired instantaneous 

water heaters are available on the 

market but do not meet the definition of 

‘‘residential-duty commercial water 

heater,’’ as they have storage volumes 

greater than 2 gallons. DOE found that 

all commercial gas-fired instantaneous 

units exceeded the maximum delivery 

temperature of 180 °F for residentialduty commercial water heaters, and, 

thus, would be regulated using the 

existing thermal efficiency and standby 

loss metrics. DOE also found that 

commercial electric instantaneous units 

which meet the definition of 

‘‘residential-duty commercial water 

heater’’ exist, however, as stated in 

section III.B.1.b, no energy conservation 

standard exists for these units; therefore 

a conversion factor was not developed. 

Consequently, none of the commercial 

water heaters identified above could be 

tested or examined for use in this 

rulemaking. In addition, a conversion 

factor for these water heaters is not 

needed because there are no units in 

existence with efficiency ratings that 

can be converted. However, because a 

manufacturer may want to design and 

produce products in these equipment 

classes in the future, DOE must 

establish energy conservation standards 

in terms of the UEF metric. Accordingly, 

DOE used information gained from 

other product classes to establish these 

energy conservation standards, as 

discussed in section III.E. 

C. Potential Approaches for Developing 

Conversions 

1. Background Regarding Changes to 

Existing Test Procedures 

a. Consumer Water Heater Test 

Procedures 

Both the current test procedure and 

the uniform efficiency descriptor test 

procedure consist of a delivery capacity 

test and a 24-hour simulated-use test. 

The delivery capacity tests for storage 

and instantaneous water heaters are the 

first-hour rating and maximum GPM 

tests, respectively. These tests are 

largely unchanged from the current to 

the new test procedure, except for 

modifications to account for the 

decrease in delivered water temperature 

from a nominal value of 135 °F to 125 

°F. The results of those tests, however, 

have implications on the 24-hour 

simulated-use test under the new test 

procedure that are absent under the 

current test procedure. 

In the current test procedure, the 

delivery capacity has no effect on the 

24-hour simulated-use test, which 

consists of six hot water draws, of 

equivalent volumes, at the start of the 

test and each of the first five subsequent 

hours. The water heater is then in 

standby mode for the remainder of the 

test. In the July 2014 final rule, 

however, the delivery capacity 

determines the draw pattern for the 24- 

hour simulated-use test. According to 

the new test procedure, a water heater’s 

delivery capacity can be categorized as 

either very small, low, medium, or high; 

these usages are shown below in Table 

III.3. 79 FR 40542, 40572 (July 11, 2014). 

These usage categories have an 

associated draw pattern prescribed to 

them during the 24-hour simulated-use. 

Depending on the delivery capacity 

associated with a water heater, between 

9 and 14 hot water draws of various 

volumes and flow rates are required. 

TABLE III.3—DELIVERY CAPACITY CATEGORIZATION CRITERIA

Draw Pattern 

First-Hour Rating, gal Maximum GPM, gpm Drawn 

Volume, gal ≥ < ≥ < 

Very Small ............................. 0 18 .......................................... 0 1.7 ......................................... 10 

Low ........................................ 18 51 .......................................... 1 .7 2.8 ......................................... 38 

Medium .................................. 51 75 .......................................... 2 .8 4 ............................................ 55 

High ....................................... 75 No upper limit ....................... 4 No upper limit ....................... 84 

In the existing DOE consumer water 

heater test procedure, a temperature of 

135 °F ± 5 °F is used for the set-point 

temperature for storage water heaters 

(measured as the mean tank 

temperature) and the delivery 

temperature for instantaneous water 

heaters. In the uniform efficiency 

descriptor test procedure set forth in the 

July 2014 final rule, a temperature of 

125 °F ± 5 °F is used for the set-point 

temperature for storage water heaters 

(measured as the delivery temperature) 

and the delivery temperature of 

instantaneous water heaters. 79 FR 

40542, 40554 (July 11, 2014). 

b. Commercial Water Heater Test 

Procedure 

The current test procedure for rating 

commercial water heaters consists of a 

steady-state test to determine thermal 

efficiency and a test lasting between 24 

and 48 hours to measure the standby 

loss. 77 FR 28996 (May 16, 2012); 10 

CFR 431.106. For electric resistance 

water heaters, the thermal efficiency is 

assigned a value of 98 percent in lieu of 

testing. The set-point temperature of the 

water heater is 140 °F ± 5 °F, and the 

unit sits in an environment with an 

ambient temperature of 75 °F ± 10 °F. 

Water is supplied to the water heater at 

a temperature of 70 °F ± 2 °F. 

Instantaneous water heaters are not 

required to undergo a standby loss test. 

Under the uniform efficiency 

descriptor test procedure, commercial 

water heaters falling under the 

‘‘residential-duty’’ category will now be 

subject to the first-hour rating or 

maximum GPM test and simulated-use 

tests specified in the previous section 

(III.C.1.a), with the same set-point 

temperature, ambient temperature, and 

inlet water temperature as is applied to 

consumer water heaters. 

2. Analytical Methods 

For converting existing ratings to 

ratings under the uniform efficiency 

descriptor test method, DOE considered 

equations based on a water heater’s 

physical characteristics; these 

approaches will be termed analytical 

methods. The sections below describe 


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potential analytical methods for the 

three key metrics that result from the 

uniform efficiency descriptor test 

method: (1) The maximum GPM; (2) the 

first-hour rating; and (3) the UEF. In the 

discussion immediately below, DOE 

introduces key factors that it expects 

will change ratings from the existing 

consumer and commercial water heater 

test procedures to the new uniform 

efficiency descriptor test procedure. 

a. Maximum GPM 

For flow-activated water heaters, the 

delivery capacity is determined by the 

10-minute maximum GPM rating test. 

During this test, the water heater runs at 

maximum firing rate to raise the 

temperature from its nominal value of 

58 °F to the prescribed delivery 

temperature. This flow rate is 

determined by the following equation: 

where V ̇ is the volumetric flow rate of 

water, Q is the firing rate, hr is the 

recovery efficiency, r is the density of 

the delivered water, cp is the specific 

heat of the delivered water, Tdel is the 

delivered water temperature, and Tin is 

the inlet water temperature. If it is 

assumed that the firing rate and 

recovery efficiency are the same with 

water delivered at 125 °F and 135 °F, 

then the ratio of the maximum GPM at 

125 °F versus that at 135 °F is 

determined by the following equation: 

Therefore, an analytical conversion 

from the existing maximum GPM rating 

(V ̇ ex) for consumer water heaters to the 

rating under the test conditions in the 

uniform efficiency descriptor test 

method (V ̇ UED) is: 

V ̇ UED = 1.147V ̇ ex

As discussed in detail in section 

III.E.2, tests on flow-activated water 

heaters showed a change in maximum 

GPM rating under the uniform 

efficiency descriptor test method that 

correlated well with the above equation. 

b. First-Hour Rating 

For water heaters that have a heat 

source controlled by means other than 

sensing flow (e.g., thermostaticallycontrolled), the delivery capacity is 

determined through a first-hour rating 

test. During this test, the water heater 

begins in its fully heated state, and 

water is drawn from it at a specified 

flow rate until the temperature of the 

delivered water drops a specified 

amount. The water heater is then 

allowed to recover, and subsequent 

draws are initiated when the controller 

acts to reduce the heat input to 

particular burners or heating elements 

specified in the test procedure. These 

subsequent draws are terminated based 

on the same criterion that is used for the 

first draw, namely that the outlet water 

temperature drops a set amount of 

degrees from its maximum value during 

that draw. When the test reaches a 

duration of one hour from the start of 

the first draw, the test concludes after 

the draw termination criterion is 

reached for the draw taking place at one 

hour from the start of the test. If no draw 

is occurring at the one hour duration, a 

draw is initiated and terminated when 

the outlet water temperature reaches the 

termination temperature of the previous 

draw, and the test is concluded upon 

termination of that draw. 

In the uniform efficiency descriptor 

test procedure, the primary change that 

will affect the first-hour rating is the 

shift from a nominal delivery 

temperature of 135 °F to 125 °F and the 

accompanying adjustment to the draw 

termination criterion to a decrease in 

delivered water temperature from 25 °F 

in the current consumer water heater 

test method to 15 °F in the uniform 

efficiency descriptor test method. 

Because the initial set-point temperature 

is reduced in the uniform efficiency 

descriptor as compared to the existing 

consumer water heater test procedure, 

less stored thermal energy will be 

available at the start of the test. 

However, this effect is countered 

because the lower set-point temperature 

allows the water heater to recover 

quicker (as the water only needs to be 

heated to a 15 °F temperature rise rather 

than a 25 °F temperature rise), thereby 

allowing subsequent draws to start 

sooner than they would under the 

current test procedure. Thus, due to 

these offsetting effects, DOE has 

observed through testing that sometimes 

the first-hour rating is increased when 

tested under the uniform efficiency 

descriptor, and sometimes the rating is 

decreased. DOE is not aware of any 

analytical models that would 

mathematically represent this behavior, 

so it has chosen not to pursue such an 

approach for converting existing firsthour ratings to first-hour ratings under 

the uniform efficiency descriptor. 

Rather, as discussed in section III.C.3, 

DOE chose an approach based on an 

empirical regression for converting the 

first-hour ratings. 

Likewise, DOE is not aware of any 

analytical method that will convert 

rated values of thermal efficiency and 

standby loss for residential-duty 

commercial storage water heaters to a 

first-hour rating. Therefore, DOE chose 

an approach based on empirical 

regression for converting existing ratings 

of residential-duty commercial water 

heaters to first-hour ratings. 

c. Uniform Energy Factor 

A number of changes to the 24-hour 

simulated-use test will alter the water 

heater energy efficiency ratings from the 

existing water heater test procedures as 

compared to the ratings obtained under 

the uniform efficiency descriptor test 

method. Among the key changes that are 

expected to alter the efficiency metric 

for consumer water heaters are: (1) A 

different volume of water withdrawn 

per test; (2) a change in the draw pattern 

(i.e., number of draws, flow rates during 

draws, timing of draws) applied during 

the test; (3) reduction of the test 

temperature from an average stored 

temperature of 135 °F to a delivered 

water temperature of 125 °F; and (4) 

removal of the stipulation to normalize 

the energy consumption to maintain a 

prescribed average water temperature 

within the storage tank. Residentialduty commercial water heaters will see 

a change from the thermal efficiency 

and standby loss metrics currently in 

place to the UEF, which consists of an 

entirely new approach for rating 

efficiency. 

i. Consumer Storage Water Heaters 

A simple theoretical model for 

determining the energy consumption of 

a storage-type water heater based on key 

test parameters, termed the Water 

Heater Analysis Model (WHAM), was 


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11Lutz, Jim, Camilla Dunham Whitehead, Alex 

Lekov, David Winiarski, and Greg Rosenquist. 

‘‘WHAM: A Simplified Energy Consumption 

Equation for Water Heaters’’ In Proceedings of the 

1998 ACEEE Summer Study on Energy Efficiency in 

Buildings (1998) (Available at: http://

cgec.ucdavis.edu/ACEEE/1998/pdffiles/papers/

0114.pdf) (Last accessed October 1, 2014). 

12Sparn, B., K. Hudon, and D. Christensen, 

Laboratory Performance Evaluation of Residential 

Integrated Heat Pump Water Heaters. National 

Renewable Energy Laboratory (September 2011) 

(Available at: http://www.nrel.gov/docs/fy11osti/

52635.pdf) (Last accessed October 1, 2014). 

presented by Lutz et al.11 The equation 

for the energy input (Q) over a 24-hour 

period is determined using the 

following equation: 

where r is the density of water, cp is the 

specific heat of water, hr is the recovery 

efficiency, V is the volume of water 

delivered per day, UA is the heat loss 

factor, Ttank is the average temperature of 

the water stored within the tank of a 

storage water heater, P is the input 

power to the water heater in Btu/h, Tamb

is the average ambient temperature 

during the test, and 24 is the number of 

hours in the test. This equation 

considers the energy required to heat 

the water that is delivered by the water 

heater from the inlet water temperature 

up to the delivery temperature and the 

energy required to make up the heat lost 

from the water heater to the surrounding 

environment. The time over which this 

standby energy loss is determined is 

corrected by the term with the power in 

the denominator to account for the fact 

that hr, as calculated in the test, 

accounts for standby energy loss during 

periods when heat input to the water is 

activated. 

This calculated energy can then be 

used to estimate the daily efficiency, Eff, 

under a given daily water demand (e.g., 

that required during the current EF test 

or that required during the UEF test): 

Currently, directories of water heater 

ratings provide the Eff (i.e., Energy 

Factor), P, and hr. Since the EF testing 

entails a prescribed Tdel (135 °F), Tin (58 

°F), Ttank (135 °F), Tamb (67.5 °F), and V 

(64.3 gallons), the two equations can be 

solved for the two remaining unknowns, 

Q and UA. The exception to this 

approach is heat pump water heaters. 

For these units, the reported recovery 

efficiency (hr) is that of the resistance 

element inside the water heater. Since it 

is expected that the heat pump unit 

would provide the majority of the 

heating during the simulated-use test as 

opposed to the resistance element, the 

required data to use the WHAM model 

for heat pump water heaters is not 

readily available in publicly accessible 

directories. For these units, DOE 

proposes to base the conversion 

equation purely on experimental data. 

After the equations are solved to 

determine UA, if one assumes that the 

UA and hr do not change under the new 

test approach, then the two equations 

can be solved again (this time inserting 

the UA value obtained from solving the 

previous set of equations) to determine 

the values for Q and Eff (i.e., UEF) under 

the uniform efficiency descriptor test 

method using the prescribed values for 

the uniform efficiency descriptor test 

procedure of Tdel (125 °F), Tin (58 °F), 

Ttank (125 °F), Tamb (67.5 °F), and V 

(varies depending upon draw pattern). 

This formulation entails a number of 

assumptions. A major assumption is 

that the average tank temperature is 

approximately equal to the delivered 

water temperature. As previously noted, 

the new procedure does not normalize 

the average stored water temperature to 

a prescribed value, so this estimate may 

not be completely accurate. Some water 

heaters have demonstrated that average 

tank temperature is below the typical 

delivered temperature because of 

stratification. This effect is believed to 

be most pronounced with condensing 

water heaters. Other water heaters show 

some stratification, but the average 

water temperature within the tank is 

typically closer to the delivered water 

temperature. Another assumption in 

this formulation is that the recovery 

efficiency and UA values do not change 

when the water heater stores water for 

delivery at 135 °F compared to storing 

it at 125 °F. While electric resistance 

water heaters have a prescribed recovery 

efficiency of 98 percent, other 

technologies may see changes in the 

recovery efficiency as the temperature 

drops. For example, the study by Sparn 

et al. shows plots of the Coefficient of 

Performance (COP), which is one aspect 

of the recovery efficiency, for heat pump 

water heaters.12 Their data suggest an 

increase in COP of approximately 15 

percent with the average tank 

temperature at 125 °F compared to 135 

°F. Data obtained by DOE indicate an 

increase in recovery efficiency obtained 

during the same draw profile of between 

3 and 13 percent, with an average of 8 

percent. Data collected on fossil-fuelfired water heaters show negligible 

dependency of the recovery efficiency 

on the prescribed tank temperature. The 

UA value may change slightly based on 

higher heat transfer coefficients at 

higher temperatures or changes in the 

thermal conductivity of insulating 

materials at higher temperatures. Data 

collected by DOE suggest that the UA 

value decreases 7 percent from 135 °F 

to 125 °F. 

For an initial estimate, DOE 

considered the situation where the UA 

and recovery efficiency do not change 

with temperature. The equations above 

can estimate the effects of two key 

factors that have changed in the test 

procedure, namely the volume drawn 

per day and the delivery temperature. 

As more water is delivered, the fraction 

of energy required to make up the 

standby losses compared to the overall 

energy required by the water heater is 

diminished, thereby increasing the 

fraction of energy going towards hot 

delivered water and increasing the 

efficiency. The change in set-point 

temperature appears to have less of an 

effect on water heater efficiency, since 

two competing factors are at play. With 

a lower stored water temperature, the 

standby losses are decreased, thereby 

increasing the overall efficiency of the 

water heater. The lower delivery 

temperature, however, means that less 

energy is delivered per gallon, so the 

energy delivered for a given volume 

delivered per day is less than that when 

the water is delivered at 135 °F, thereby 

decreasing the efficiency of the water 

heater. 

As noted, direct use of this model 

may not properly account for changes to 

the recovery efficiency, UA value, or 

normalization procedure for standby 

heat loss. Therefore, DOE has chosen a 

two-step process to convert the existing 

Energy Factor ratings for consumer 

storage water heaters to the UEF. First, 

using the equations and assumptions 

described above, a prediction of the 


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Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 20127 

efficiency given by WHAM is 

determined, termed UEFWHAM. This 

value is then considered as part of a 

regression analysis (see section III.C.3) 

to obtain a relationship that will convert 

from EF to UEF. DOE believes that the 

use of WHAM will capture the primary 

effects of changes in the volume of 

water delivered per day along with 

changes in the set-point temperature. 

Regression with experimental data will 

then capture the effects that may not be 

fully accounted for by WHAM, such as 

differences in the UA value, recovery 

efficiency, and the change to the 

normalization calculation procedure for 

standby heat loss. 

To establish a clear method of 

applying the analytical model, the 

WHAM-based UEF equation and Table 

III.4, comprising the coefficients based 

on draw bin, are presented below. This 

equation incorporates the equations and 

assumptions presented above, where hr

and EF are the recovery efficiency and 

energy factor, respectively, based on the 

current DOE test procedure, and P is the 

nameplate input rate in Btu/h. As 

shown in Table III.4, constants ‘‘a,’’ ‘‘b,’’ 

‘‘c,’’ and ‘‘d’’ are dependent on the 

volume of water being drawn. 

TABLE III.4—COEFFICIENTS FOR WHAM-BASED UEF CONVERSION FACTOR

Draw bin a b c d 

Very Small ....................................................................................................... 56095146 12884892499 8930623 15125743368 

Low .................................................................................................................. 56095146 48962591496 33936368 57477824799 

Medium ............................................................................................................ 56095146 70866908744 49118427 83191588525 

High .................................................................................................................. 56095146 108233096990 75017235 127056244293 

ii. Consumer Instantaneous Water 

Heaters 

WHAM is not directly applicable to 

instantaneous water heaters because it 

assumes that the water heater loses heat 

at a constant rate throughout the day 

when the heating element is not 

energized. For instantaneous water 

heaters, this modeling approach is 

inappropriate since the unit does not 

store water at an elevated temperature 

throughout the day, rather heating water 

as it flows through the unit. 

Instantaneous water heaters instead 

experience a separate type of heat loss 

to the surroundings that sometimes 

result in Energy Factors that are below 

the steady-state thermal efficiency. This 

loss occurs when heat that is present in 

the water heater at the end of a draw 

dissipates to the ambient. If a draw is 

not initiated shortly after the end of a 

draw, then most of this heat is lost. If, 

however, a subsequent draw starts 

shortly after a previous draw, some of 

that heat is captured in the hot water 

that is delivered. 

DOE attempted to capture these 

effects in a modified equation that 

separately accounts for energy 

consumption that goes towards 

supplying heat to the delivered water 

and energy consumption that goes 

towards heating up the materials 

making up the water heater: 

where LF is a loss factor related to the 

amount of energy stored in the materials 

of the water heater and N* is the 

number of draws from which heat loss 

occurs to the environment. LF is 

approximately equal to the mass of the 

material within the water heater times 

its heat capacity. N* is not simply the 

number of draws during the day, since 

some draws may occur close together 

and do not result in total energy loss. To 

determine the fraction of energy from a 

draw that is lost, DOE examined data 

from testing that suggested that most 

heat is lost from tankless water heaters 

after about one hour. Using this value, 

DOE scaled the energy loss for a draw 

by the length of the standby time 

following the draw. For example, a draw 

followed by over one hour of standby 

time would contribute a value of 1 to N* 

for that test. A draw followed by 30 

minutes of standby time prior to the 

next draw would contribute a value of 

(30 min)/(60 min) = 0.5 to N*. 

Contributions from each draw in a test 

pattern are added to obtain a value for 

N* for each draw pattern. For the 

existing DOE consumer water heater 

test, N* is 5.64, as the standby time 

following each draw is slightly under 60 

minutes. The values for N* for all draw 

patterns are provided in Table III.5. 

TABLE III.5—ESTIMATE OF NUMBER OF

DRAWS FROM WHICH ALL ENERGY

FROM WATER HEATER IS LOST TO

SURROUNDINGS

Draw pattern N* 

Existing Consumer Water Heater 

Draw Pattern ................................. 5.64 

Very-Small-Use ................................. 4.36 

Low-Use ............................................ 6.72 

Medium-Use ..................................... 7.45 

TABLE III.5—ESTIMATE OF NUMBER OF

DRAWS FROM WHICH ALL ENERGY

FROM WATER HEATER IS LOST TO

SURROUNDINGS—Continued 

Draw pattern N* 

High-Use ........................................... 7.53 

DOE attempted this approach by 

obtaining an estimate of LF from data 

obtained during testing of 17 gas 

instantaneous water heaters according 

to the current simulated-use test. (LF 

could theoretically be determined for 

each unit, but some test results showed 

a recovery efficiency equal to EF, which 

would mathematically lead to an 

infinite value of LF). A regression of the 

energy consumption data during these 

tests with the quantity multiplying LF 

in the previous model equation resulted 

in a value of LF of 0.679 Btu/°F. Using 


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this value to then estimate the energy 

consumption during the new simulateduse test resulted in predictions of the 

UEF. This approach resulted in a root 

mean squared error between predicted 

values and measured values of 0.027. 

Alternatively, a set of regressions, 

based solely on test data, were 

examined to determine the impact of 

other factors as discussed in section 

III.C.3. The best regressions resulted in 

a mean squared error of 0.032. 

As discussed for consumer storage 

water heaters in section III.C.2.c.i, DOE 

also considered a two-step process to 

convert the existing EF ratings to the 

UEF—first using the equations and 

assumptions described above to obtain 

an analytical prediction of UEF, then 

using a regression analysis to obtain a 

relationship that will convert from EF to 

UEF. Based on these results, DOE has 

chosen to use the analytical model plus 

a regression approach for converting EFs 

for consumer instantaneous water 

heaters to UEF. DOE has tentatively 

concluded that the assumptions made in 

the analytical model capture some key 

operating characteristics of the 

instantaneous units, and the further step 

to use measured data captures 

unforeseen issues. Details on this 

approach are provided in section III.C.3. 

iii. Residential-Duty Commercial Water 

Heaters 

DOE investigated a modified version 

of WHAM for converting the thermal 

efficiency and standby loss metrics for 

residential-duty commercial storage 

water heaters to UEF. The AHRI 

certification directory includes the 

thermal efficiency (Et) and standby loss 

(SL). The equation below estimates the 

energy consumption of a water heater 

based on these efficiency metrics: 

where 70 represents the nominal 

temperature difference in degrees 

Fahrenheit between the tank and 

ambient during the standby loss test. By 

assuming that Ttank equals Tdel, all 

variables in the equation above are 

known, since Et and SL can be obtained 

from current ratings and all other 

variables are specified in the UEF test 

procedure for a given projected firsthour rating. The equation above can be 

used in combination with the one below 

to estimate the UEF for residential-duty 

storage water heaters (UEFrd): 

These equations can be combined to 

yield the following equation for 

converting Et and SL to UEF using the 

coefficient C1, which is dependent upon 

the draw pattern applied during the 

UEF test, as provided in Table III.6. 

TABLE III.6—COEFFICIENT FOR CONVERSION OF COMMERCIAL WATER

HEATER RATINGS TO UEF 

Draw pattern C1

Very Small ............................ 3.575 × 10¥3

Low ....................................... 9.408 × 10¥4

Medium ................................. 6.500 × 10¥4

High ...................................... 4.256 × 10¥4

As was done with consumer water 

heaters, DOE decided to account for 

unforeseen effects observed during 

testing by combining this analytical 

prediction with a regression of the 

predicted values of UEF to the measured 

UEF. 

DOE seeks comments on the use of 

analytical methods to convert existing 

metrics to the ones described in the July 

2014 test procedure final rule. This is 

identified as issue 2 in section V.E, 

‘‘Issues on Which DOE Seeks 

Comment.’’ 

3. Empirical Regression 

An alternative to the analytical 

approaches described in section III.C.2 

is to develop empirical equations from 

measured metrics under the uniform 

efficiency descriptor test procedure to 

those obtained using the existing 

consumer and commercial water heater 

test procedures. This approach has the 

benefit of capturing the effects of factors 

that are not addressed in analytical 

models. The drawbacks of this approach 

are that it is susceptible to measurement 

errors and that it may not be easily 

extended to water heaters that were not 

part of the test program. 

To derive the conversion factors from 

an empirical regression, DOE first used 

a step regression method. The step 

regression method produces a linear 

equation which uses a set of observed 

independent variables, such as storage 

volume, input rate, delivery capacity, 

recovery efficiency, energy factor, 

thermal efficiency, or standby loss, and 

seeks to mathematically derive an 

equation using these variables to relate 

to a set of observed dependent variables, 

such as new delivery capacity (under 

the updated test method) and UEF. The 

step regression method systematically 

recombines the set of independent 

variables to produce an equation for 

each possible set. Each set’s equation is 

compared to the others and the equation 

with the best fit is chosen. This 

approach eliminates factors that are not 

significant in converting existing 

metrics to the new metrics. DOE also 

considered simpler regression forms to 

reduce confusion in converting from old 

metrics to new metrics and to ensure 

that the regressions were applicable 

over the broad range of water heaters 

available on the market. In these 

circumstances, DOE examined the 

deviations between measured values 

and predicted values from the 

correction equations. When those 

deviations were comparable, DOE opted 

for simplified models that would be 

expected to capture the major 

phenomena that would affect the new 

metrics. The regression tool found in the 

Analysis ToolPak of Microsoft Excel 

(2010) was used to calculate the 

equation for each set of independent 

variables. 

As noted previously, because DOE has 

tentatively concluded that an empirical 

regression methodology would be more 

accurate than the analytical method 

described in section III.C.2 for 

determining first-hour rating for storage 

water heaters, DOE has proposed 

conversion factors for those metrics and 

product types based on the use of the 

empirical regression methodology. DOE 

seeks comment on the use of the 

regression method for the conversion 

factor analysis. This is identified as 

issue 3 in section V.E, ‘‘Issues on Which 

DOE Seeks Comment.’’ 

D. Testing Conducted for the 

Mathematical Conversion 

1. Consumer Water Heater Testing 

For its analysis of a mathematical 

conversion factor between the existing 

efficiency metrics and the uniform 

efficiency descriptor, DOE tested 43 

consumer storage water heaters to both 

the existing and updated test 

procedures. Table III.7 and Table III.8 


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below summarize the units that have 

been tested. Table III.7 summarizes the 

units that have been tested according to 

heating type. Table III.8 provides an 

estimate of the distribution of those 

units across draw pattern categories by 

using their first-hour ratings under the 

current test (although it is 

acknowledged that the applied draw 

pattern for a particular water heater 

could change under the new first-hour 

rating test). 

TABLE III.7—CONSUMER STORAGE

WATER HEATER TEST DISTRIBUTION

BY PRODUCT TYPE

Product type Number of 

units tested 

Gas-fired ............................... 22 

Oil-fired ................................. 2 

Electric .................................. 11 

Heat Pump ............................ 6 

Tabletop ................................ 2 

TABLE III.8—CONSUMER STORAGE

WATER HEATER TEST DISTRIBUTION

BY DRAW PATTERN

Draw pattern * Number of 

units tested 

Very Small ** ......................... 0 

Low ....................................... 3 

Medium ................................. 27 

High ...................................... 13 

* The draw pattern shown is based on the 

current rated values; actual draw patterns are 

dependent upon amended test procedure firsthour rating discussed in section III.C.1. 

** No very small consumer storage water 

heaters covered under the existing test procedure were found on the market. 

DOE also tested 22 consumer 

instantaneous water heaters to develop 

the mathematical conversion for these 

products. Table III.9 below summarizes 

the units that have been tested. Table 

III.10 provides an estimate of the 

distribution of those units across draw 

patterns by using their maximum GPM 

ratings under the current test (although 

it is acknowledged that the applied 

draw pattern for a particular water 

heater could change under the new 

maximum GPM test). 

TABLE III.9—CONSUMER INSTANTANEOUS WATER HEATER TEST DISTRIBUTION BY PRODUCT TYPE

Product type Number of 

units tested 

Gas-fired * ............................. 17 

Oil-fired ** .............................. 0 

TABLE III.9—CONSUMER INSTANTANEOUS WATER HEATER TEST DISTRIBUTION BY PRODUCT TYPE— 

Continued 

Product type Number of 

units tested 

Electric .................................. 5 

* Gas-fired water heaters include both natural gas and propane water heaters, as well 

as water heaters capable of using either natural gas or propane. DOE tested 10 natural 

gas water heaters, 1 propane water heaters, 

and 6 water heaters capable of using either 

natural gas or propane. Water heaters capable 

of using either fuel were tested with natural 

gas. 

** No oil-fired consumer instantaneous water 

heaters were found to be on the market. 

TABLE III.10—CONSUMER INSTANTANEOUS WATER HEATER TEST DISTRIBUTION BY DRAW PATTERN

Draw pattern * Number of 

units tested 

Very Small ............................ 5 

Low ....................................... 1 

Medium ................................. 7 

High ...................................... 9 

* Draw pattern profiles are based on the 

rated values; actual draw patterns are dependent upon tested value discussed in section 

III.C.1. 

2. Residential-Duty Commercial Water 

Heater Testing 

DOE tested 7 residential-duty 

commercial storage water heaters to 

develop the mathematical conversion 

for this equipment. Table III.11 

summarizes the units that have been 

tested. A table showing the distribution 

of draw pattern within the residentialduty commercial water heater test list is 

not available, because commercial water 

heaters currently do not have first-hour 

ratings. 

TABLE III.11—RESIDENTIAL-DUTY

COMMERCIAL STORAGE WATER

HEATER TEST DISTRIBUTION BY

PRODUCT TYPE

Product type * Number of 

units tested 

Gas-fired ............................... 7 

Oil-fired ** .............................. 0 

* Heat pump and tabletop water heaters 

were not found on the market and, therefore, 

were not tested. 

** One oil-fired unit failed during testing. 

As discussed in section III.B.2, DOE 

did not analyze a mathematical 

conversion for residential-duty 

commercial electric storage water 

heaters or residential-duty commercial 

instantaneous water heaters. 

E. Testing Results and Analysis of Test 

Data 

1. Impact of Certain Water Heater 

Attributes on Efficiency Ratings 

After conducting testing on all of the 

selected water heaters according to both 

the existing test procedures and the 

uniform efficiency descriptor test 

procedure, DOE examined how 

particular attributes of water heaters 

might affect the conversion factors and 

investigated the approaches discussed 

in section III.C for obtaining conversion 

factors. The goal of this analysis was to 

determine whether or not particular 

attributes necessitated separate 

conversion equations. Separate 

conversions were created for subsets of 

the tested units based on water heater 

attributes such as NOX emission level, 

short or tall configuration, vent type, 

standing pilot or electric ignition, if 

condensing or heat pump technology is 

used, and if the unit is tabletop. 

Additionally, conversion equations 

were also generated based on the full set 

of water heaters. To determine whether 

it was necessary to develop separate 

conversion factors for a particular 

attribute, the root-mean-square (RMS) of 

the difference between the measured 

values and the values obtained through 

various conversion methods was 

compared. The conversion approach 

with the lowest cumulative RMS value 

for a particular fuel type was considered 

to be the best candidate for the 

conversion equation. 

The three levels of NOX emissions 

currently available in water heaters on 

the market include standard (greater 

than or equal to 40 nanograms per joule 

(ng/J)), low (less than 40 ng/J and greater 

than or equal to 10 ng/J for storage water 

heaters and greater than or equal to 14 

ng/J for instantaneous water heaters) 

and ultra-low (less than 10 ng/J for 

storage water heaters and less than 14 

ng/J for instantaneous water heaters). 

Most units that are short or tall have 

been labeled as such by the 

manufacturer; however, some units do 

not have this designation. DOE has 

found that some units labeled as small 

are actually taller than units labeled as 

tall. DOE is interested in how 

manufacturers determine whether a unit 

is short or tall. This is identified as issue 

4 in section V.E, ‘‘Issues on Which DOE 

Seeks Comment.’’ 

The four venting configurations 

currently available in water heaters on 

the market include atmospheric, direct, 

power, and power-direct. Atmospheric 

and power vent units intake air from the 

area surrounding the water heater, while 

direct and power-direct vents intake air 

from outdoors. Atmospheric and direct 


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vent units use natural convection to 

circulate combustion air, while power 

and power-direct vents use some 

additional method to force circulation of 

combustion air. Concentric inlet and 

outlet piping is a unique configuration 

that can be used in directly venting 

water heaters to preheat incoming air 

using exhaust gas. For these tests, 

concentric inlet and outlet piping was 

not used; inlet air for the direct and 

power-direct vent units was delivered to 

the water heater in separate pipes from 

that used for exhaust. As these tests 

were conducted under identical 

controlled conditions, DOE determined 

that there is very little difference 

between atmospheric and direct vent 

water heaters and also between power 

and power-direct vent. For these reasons 

DOE has grouped atmospheric and 

direct into the atmospheric 

configuration and power and powerdirect into the power configuration. 

As an example of the process that was 

taken to examine the effect of these 

factors, Table III.12 shows the 

cumulative RMS values for the firsthour rating conversions for consumer 

storage water heaters. The rows in the 

table indicate how the conversion 

equations were separated out, and the 

columns provide the RMS for each class 

of consumer storage water heaters. For 

gas water heaters, these values show 

that the conversion approach that 

differentiates between condensing or 

non-condensing technology and 

between NOX levels appears to provide 

the best approach considering its low 

RMS values. No other factors (e.g., short 

vs. tall, vent type, pilot type) were 

shown to have any significance on the 

effectiveness of the conversion factor. 

For oil-fired water heaters and electric 

water heaters, the lowest RMS 

deviations occurred when all units of 

that fuel type were considered, 

indicating that separating the 

conversion equations by tank shape was 

not necessary. The findings presented 

here for first-hour rating conversions are 

consistent with those for UEF. From 

these results, DOE proposes to develop 

conversion equations for consumer 

storage water heaters based on fuel type, 

with the gas units being further 

differentiated by whether or not they are 

condensing units and by their NOx 

emissions level ratings. 

For consumer instantaneous water 

heaters and residential-duty commercial 

water heaters, DOE found no 

dependence on factors such as 

condensing operation or vent type. 

Conversion factors for these classes of 

water heaters are, thus, based simply on 

fuel type. 

TABLE III.12—FIRST-HOUR RATING RMS VALUES BY WATER HEATER ATTRIBUTE FOR CONSUMER WATER HEATERS

Gas-fired Oil-fired Electric 

All Units (All fuel types) .................................................................................................................... 6.99 6.89 ............. 4.47. 

All Units Short or Tall ....................................................................................................................... 6.87 5.79 ............. 3.67. 

Fuel Type (Gas, Oil or Electric) ....................................................................................................... 7.16 Not enough 

units.

3.88. 

Fuel Type Short or Tall .................................................................................................................... 6.91 No short 

units.

Not enough 

short units. 

Fossil Fuel (Gas and Oil) ................................................................................................................. 6.59 5.73 ............. N/A. 

Fossil Fuel Short or Tall ................................................................................................................... 6.52 5.82 ............. N/A. 

Condensing or Non-Condensing ...................................................................................................... 6.66 N/A .............. N/A. 

NOX Type (Standard, Low or Ultra Low) ......................................................................................... 4.61 N/A .............. N/A. 

Vent Type (Atmospheric or Power) .................................................................................................. 5.53 N/A .............. N/A. 

Standing Pilot or Electric Ignition ..................................................................................................... 5.53 N/A .............. N/A. 

Non-Condensing NOX Type and Separate Condensing .................................................................. 3.98 N/A .............. N/A. 

All Electric Types Separate .............................................................................................................. N/A N/A .............. 3.43. 

Heat Pump Separate ........................................................................................................................ N/A N/A .............. 3.59. 

2. Conversion Factor Derivation 

DOE used the methods described in 

section III.C to derive the mathematical 

conversion factor for the different types 

of water heaters covered within the 

scope of this rulemaking (as discussed 

in section III.B). This section describes 

the methodology that was applied to 

develop a conversion factor for each 

type of water heater. 

a. Consumer Storage Water Heaters 

i. Test Results 

As stated in section III.D.1, DOE has 

conducted testing of 43 consumer 

storage water heaters using both the 

current and new test procedures. Table 

III.13 below presents the test data used 

to derive the consumer storage water 

heater conversion factors. Table III.14 

shows the water heater attributes by 

unit described in section III.D.1. 

TABLE III.13—CONSUMER STORAGE WATER HEATER TEST DATA

Unit No. Type 

Storage 

volume 

(gal) 

Input 

rate 

(Btu/h) 

Current 

FHR 

(gal) 

Updated 

FHR 

(gal) 

Current 

recovery 

efficiency 

(%) 

EF UEF 

CS–1 ................................ Heat Pump 45.2 13,600 59.1 48.2 264.7 2.260 2.069 

CS–2 ................................ Heat Pump 45.5 8,500 57.3 57.0 269.0 2.272 2.575 

CS–3 ................................ Heat Pump 58.9 6,800 71.5 68.6 290.1 2.406 2.493 

CS–4 ................................ Heat Pump 77.6 6,800 90.5 87.1 285.0 2.315 2.641 

CS–5 ................................ Heat Pump 80.8 1,800 57.0 58.0 288.0 2.330 2.540 

CS–6 ................................ Electric ....... 36.2 15,400 54.0 49.7 98.0 0.941 0.905 

CS–7 ................................ Electric ....... 44.9 14,300 64.1 64.3 98.0 0.855 0.840 

CS–8 ................................ Electric ....... 46.1 14,000 64.8 61.7 98.0 0.901 0.919 

CS–9 ................................ Electric ....... 27.4 13,000 38.7 43.1 98.0 0.912 0.906 

CS–10 .............................. Electric ...... 34.1 14,000 50.7 52.0 98.0 0.902 0.907 

CS–11 .............................. Electric ...... 35.9 15,400 52.4 51.8 98.0 0.931 0.920 


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TABLE III.13—CONSUMER STORAGE WATER HEATER TEST DATA—Continued 

Unit No. Type 

Storage 

volume 

(gal) 

Input 

rate 

(Btu/h) 

Current 

FHR 

(gal) 

Updated 

FHR 

(gal) 

Current 

recovery 

efficiency 

(%) 

EF UEF 

CS–12 .............................. Electric ...... 36.1 15,400 53.2 54.8 98.0 0.912 0.927 

CS–13 .............................. Electric ...... 44.9 15,400 64.9 59.4 98.0 0.960 0.926 

CS–14 .............................. Electric ...... 45.8 15,400 62.7 64.2 98.0 0.922 0.936 

CS–15 .............................. Electric ...... 49.7 18,800 68.5 73.2 98.0 0.924 0.940 

CS–16 .............................. Electric ...... 72.2 14,700 88.7 80.9 98.0 0.848 0.883 

CS–17 .............................. Tabletop .... 25.7 15,400 37.5 45.3 98.0 0.905 0.857 

CS–18 .............................. Tabletop .... 35.1 15,400 52.9 47.8 98.0 0.878 0.804 

CS–19 .............................. Gas ............ 38.4 39,800 67.0 81.1 80.5 0.601 0.630 

CS–20 .............................. Gas ............ 49.5 44,100 97.4 86.6 80.5 0.610 0.634 

CS–21 .............................. Gas ............ 37.8 39,700 70.1 86.9 83.8 0.608 0.641 

CS–22 .............................. Gas ............ 47.6 49,900 90.2 81.0 81.1 0.674 0.675 

CS–23 .............................. Gas ............ 37.9 39,400 74.4 81.6 80.3 0.691 0.705 

CS–24 .............................. Gas ............ 38.0 32,600 66.9 58.5 69.0 0.574 0.566 

CS–25 .............................. Gas ............ 38.0 39,800 80.2 63.8 83.6 0.711 0.669 

CS–26 .............................. Gas ............ 38.1 40,800 73.5 75.2 83.6 0.702 0.716 

CS–27 .............................. Gas ............ 38.2 39,300 71.9 77.6 77.4 0.607 0.635 

CS–28 .............................. Gas ............ 27.9 31,600 58.8 64.4 80.7 0.620 0.606 

CS–29 .............................. Gas ............ 38.1 40,200 74.7 70.6 80.5 0.622 0.569 

CS–30 .............................. Gas ............ 38.3 37,900 71.9 64.6 78.5 0.616 0.434 

CS–31 .............................. Gas ............ 47.3 50,600 95.1 87.0 78.8 0.606 0.640 

CS–32 .............................. Gas ............ 38.6 40,100 70.2 67.2 80.4 0.673 0.647 

CS–33 .............................. Gas ............ 38.9 32,400 68.6 65.2 78.1 0.666 0.624 

CS–34 .............................. Gas ............ 27.9 59,000 96.9 94.5 78.2 0.702 0.709 

CS–35 .............................. Gas ............ 38.5 36,000 66.0 68.0 85.0 0.699 0.670 

CS–36 .............................. Gas ............ 47.8 64,600 107.9 108.8 79.5 0.649 0.672 

CS–37 .............................. Gas ............ 45.7 39,800 91.0 84.8 96.3 0.830 0.828 

CS–38 .............................. Gas ............ 38.2 40,300 68.2 64.8 79.7 0.606 0.595 

CS–39 .............................. Gas ............ 38.2 38,300 71.3 64.6 75.2 0.625 0.596 

CS–40 .............................. Gas ............ 47.8 40,500 94.2 83.8 74.0 0.550 0.641 

CS–41 .............................. Gas ............ 48.1 36,000 92.4 88.2 81.4 0.631 0.662 

CS–42 .............................. Oil .............. 29.8 105,300 104.8 111.7 71.4 0.518 0.478 

CS–43 .............................. Oil .............. 30.1 105,300 112.5 127.4 89.4 0.605 0.641 

TABLE III.14—CONSUMER STORAGE WATER HEATER ATTRIBUTES

Unit No. NOX emission 

level Condensing Vent type Short or tall 

Standing pilot 

or electric 

ignition 

CS–1 ..................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–2 ..................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–3 ..................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–4 ..................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–5 ..................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–6 ..................................................................... N/A ................... N/A ................... N/A ................... Short ................. N/A. 

CS–7 ..................................................................... N/A ................... N/A ................... N/A ................... Short ................. N/A. 

CS–8 ..................................................................... N/A ................... N/A ................... N/A ................... Short ................. N/A. 

CS–9 ..................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–10 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–11 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–12 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–13 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–14 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–15 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–16 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–17 ................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–18 ................................................................... N/A ................... N/A ................... N/A ................... N/A ................... N/A. 

CS–19 ................................................................... Standard ........... No ..................... Atmospheric ...... Short ................. Yes. 

CS–20 ................................................................... Standard ........... No ..................... Atmospheric ...... Short ................. Yes. 

CS–21 ................................................................... Standard ........... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–22 ................................................................... Standard ........... No ..................... Power ............... Tall .................... No. 

CS–23 ................................................................... Low ................... No ..................... Atmospheric ...... Short ................. No. 

CS–24 ................................................................... Low ................... No ..................... Atmospheric ...... Short ................. Yes. 

CS–25 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... No. 

CS–26 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... No. 

CS–27 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... No. 

CS–28 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–29 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–30 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... Yes. 


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TABLE III.14—CONSUMER STORAGE WATER HEATER ATTRIBUTES—Continued 

Unit No. NOX emission 

level Condensing Vent type Short or tall 

Standing pilot 

or electric 

ignition 

CS–31 ................................................................... Low ................... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–32 ................................................................... Low ................... No ..................... Power ............... Short ................. No. 

CS–33 ................................................................... Low ................... No ..................... Power ............... Short ................. No. 

CS–34 ................................................................... Low ................... No ..................... Power ............... Tall .................... No. 

CS–35 ................................................................... Low ................... No ..................... Power ............... Tall .................... No. 

CS–36 ................................................................... Low ................... No ..................... Power ............... Tall .................... No. 

CS–37 ................................................................... Low ................... Yes ................... Power ............... Tall .................... No. 

CS–38 ................................................................... Ultra-Low .......... No ..................... Atmospheric ...... Short ................. Yes. 

CS–39 ................................................................... Ultra-Low .......... No ..................... Atmospheric ...... Short ................. Yes. 

CS–40 ................................................................... Ultra-Low .......... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–41 ................................................................... Ultra-Low .......... No ..................... Atmospheric ...... Tall .................... Yes. 

CS–42 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

CS–43 ................................................................... N/A ................... N/A ................... N/A ................... Tall .................... N/A. 

ii. Conversion Factor Results 

For consumer storage water heaters, 

DOE proposes to use the regression 

method described in section III.C.3 to 

develop new first hour ratings. Of the 

factors considered, DOE found that the 

existing first hour rating was the best 

overall predictor of the new first hour 

rating. These findings were based on the 

root mean squared errors between 

predictions and measured values. In 

some cases, addition of other factors in 

the regressions (e.g., input rate, storage 

volume) led to predictions with slightly 

better RMS values, but DOE chose to be 

consistent in its formulations by using 

the same factor, existing first hour 

ratings. In these cases, DOE found that 

addition of extra terms improved the 

RMS value by less than 1 gallon, so it 

tentatively concluded that the added 

potential for confusion is not warranted. 

The resulting equations for determining 

the FHRnew of consumer storage water 

heaters are: 

New FHRGas,Non-Condensing,Standard NOx = 

1.0085 * FHREx

New FHRGas,Non-Condensing,Low NOx = 4.6894 

+ 0.9112 * FHREx

New FHRGas,Non-Condensing,Ultra–Low NOx = 

2.9267 + 0.8882 * FHREx

New FHRGas,Condensing = ¥0.7072 + 

0.9724 * FHREx

New FHROil = 1.1018 * FHREx

New FHRElectric,Conventional&Tabletop = 

11.9239 + 0.7879 * FHREx

New FHRElectric,Heat Pump = ¥2.3440 + 

0.9856 * FHREx

where FHRnew is the new first hour 

rating, FHRex is the existing first hour 

rating, and the slope and intercept are 

constants obtained from a linear 

regression. While most of the data 

allowed for such a regression fit, in two 

cases (oil, non-condensing gas with 

standard level NOX burners) the 

available data were too limited to 

produce reliable regressions. In these 

cases, the intercepts of the regressions 

were assigned a value of zero, meaning 

that a water heater with an FHRex of 

zero would also have an FHRnew of zero. 

The next step in the conversion is to 

determine which draw pattern is to be 

applied to convert from EF to UEF. After 

the first-hour rating under the uniform 

efficiency descriptor is determined 

through the conversion factor above, the 

value can be applied to determine the 

appropriate draw pattern bin (i.e., very 

small, low, medium, or high) using 

Table III.3 of this NOPR or Table 1 of 

the uniform efficiency descriptor test 

procedure. 79 FR 40542, 40572 (July 11, 

2014). With the draw bin known, the 

UEF value based on the WHAM 

analytical model can be calculated using 

the process described in section 

III.C.2.c.i for all types except for heat 

pump water heaters. Alternatively, DOE 

investigated the step regression 

approach described in section III.C.3 to 

convert EF to UEF. DOE found that a 

third technique, a combination of these 

approaches in which the results of the 

WHAM analytical model are used as the 

independent variable in a standard 

linear regression analysis, produced the 

best results. Separate conversion 

equations were developed for the same 

categories as used for first-hour rating. 

The results of the first-hour regression, 

the WHAM analytical model, the step 

regression model, and the combined 

WHAM-regression model are presented 

below in Table III.16. The RMS errors 

for the classes range from 0.0014 to 

0.0495 when using a combined WHAMregression model. For heat pump water 

heaters, a linear regression in which the 

UEF is estimated solely from the 

existing EF results in an RMS error of 

0.187. Considering the larger magnitude 

of UEFs for heat pump water heaters, 

DOE has tentatively concluded that this 

relatively high RMS error is acceptable 

for heat pump water heaters. DOE has, 

therefore, tentatively decided to use the 

combined WHAM-regression approach 

to calculate the consumer storage water 

heater conversion factor for non-heat 

pump water heaters and to apply a 

regression that relates UEF to EF for 

heat pump water heaters. The WHAMregression approach accounts for the 

test procedure changes in terms of daily 

volume delivered and storage tank 

temperature, and it corrects for the 

unaccounted changes using a regression 

with actual test data. Because the data 

are not believed to be publicly available 

to compute the WHAM estimate for heat 

pump water heaters, DOE proposes to 

base this conversion on an empirical 

regression. The resulting equations for 

determining the UEF of consumer 

storage water heaters are: 

UEFGas,Non-Condensing,Standard NOx = 0.2726 * 

UEFWHAM + 0.4736 

UEFGas,Non-Condensing,Low NOx = 0.9966 * 

UEFWHAM ¥ 0.0126 

UEFGas,Non-Condensing,Ultra-Low NOx = 0.5811 

*UEFWHAM + 0.2673 


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UEFGas,Condensing = 0.9164 * UEFWHAM + 

0.0409 

UEFOil = 1.1185 * UEFWHAM ¥ 0.0945 

UEFElectric,Conventional&Tabletop = 0.8673 * 

UEFWHAM + 0.1227 

UEFElectric,Heat Pump = 1.5485 * EF ¥ 

1.1235 

where UEFWHAM is the conversion factor 

calculated using the WHAM analytical 

model and the coefficient values shown 

in Table III.15, P is the nameplate input 

rate in Btu/h, and hr is the recovery 

efficiency expressed in decimal form 

(e.g., 0.98 instead of 98 [%]). 

TABLE III.15—COEFFICIENTS FOR WHAM-BASED UEF CONVERSION FACTOR

Draw bin a b c d 

Very Small ....................................................................................................... 56095146 12884892499 8930623 15125743368 

Low .................................................................................................................. 56095146 48962591496 33936368 57477824799 

Medium ............................................................................................................ 56095146 70866908744 49118427 83191588525 

High .................................................................................................................. 56095146 108233096990 75017235 127056244293 

TABLE III.16—CONSUMER STORAGE WATER HEATER CONVERSION FACTOR RESULTS

Unit No. Tested FHR 

(gal) 

Regression 

FHR 

(gal) 

Tested 

UEF 

WHAM 

UEF 

Regression 

UEF 

WHAMRegression 

UEF 

CS–1 .................................................................... 48.2 55.9 2.069 2.209 2.375 2.384 

CS–2 .................................................................... 57.0 54.1 2.575 2.215 2.395 2.391 

CS–3 .................................................................... 68.6 68.1 2.493 2.339 2.603 2.525 

CS–4 .................................................................... 87.1 86.9 2.641 2.435 2.461 2.630 

CS–5 .................................................................... 58.0 53.8 2.540 2.213 2.484 2.388 

CS–6 .................................................................... 49.7 54.4 0.905 0.935 0.930 0.933 

CS–7 .................................................................... 64.3 62.4 0.840 0.836 0.875 0.847 

CS–8 .................................................................... 61.7 62.9 0.919 0.888 0.904 0.893 

CS–9 .................................................................... 43.1 42.4 0.906 0.866 0.911 0.874 

CS–10 .................................................................. 52.0 51.8 0.907 0.888 0.905 0.893 

CS–11 .................................................................. 51.8 53.2 0.920 0.923 0.923 0.923 

CS–12 .................................................................. 54.8 53.9 0.927 0.901 0.911 0.904 

CS–13 .................................................................. 59.4 63.0 0.926 0.956 0.941 0.952 

CS–14 .................................................................. 64.2 61.4 0.936 0.912 0.917 0.914 

CS–15 .................................................................. 73.2 65.9 0.940 0.915 0.919 0.916 

CS–16 .................................................................. 80.9 81.8 0.883 0.880 0.871 0.885 

CS–17 .................................................................. 45.3 41.5 0.857 0.855 0.896 0.864 

CS–18 .................................................................. 47.8 53.6 0.804 0.862 0.873 0.870 

CS–19 .................................................................. 81.1 67.5 0.630 0.578 0.632 0.631 

CS–20 .................................................................. 86.6 98.3 0.634 0.651 0.637 0.651 

CS–21 .................................................................. 86.9 70.7 0.641 0.583 0.636 0.632 

CS–22 .................................................................. 81.0 91.0 0.675 0.705 0.675 0.666 

CS–23 .................................................................. 81.6 72.5 0.705 0.676 0.683 0.661 

CS–24 .................................................................. 58.5 65.6 0.566 0.558 0.571 0.544 

CS–25 .................................................................. 63.8 77.8 0.669 0.739 0.702 0.724 

CS–26 .................................................................. 75.2 71.6 0.716 0.685 0.694 0.670 

CS–27 .................................................................. 77.6 70.2 0.635 0.587 0.603 0.572 

CS–28 .................................................................. 64.4 58.3 0.606 0.598 0.616 0.583 

CS–29 .................................................................. 70.6 72.8 0.569 0.600 0.617 0.585 

CS–30 .................................................................. 64.6 70.2 0.434 0.595 0.611 0.580 

CS–31 .................................................................. 87.0 91.4 0.640 0.645 0.602 0.630 

CS–32 .................................................................. 67.2 68.6 0.647 0.656 0.666 0.641 

CS–33 .................................................................. 65.2 67.2 0.624 0.651 0.660 0.636 

CS–34 .................................................................. 94.5 93.0 0.709 0.721 0.694 0.706 

CS–35 .................................................................. 68.0 64.8 0.670 0.679 0.690 0.664 

CS–36 .................................................................. 108.8 103.0 0.672 0.681 0.643 0.666 

CS–37 .................................................................. 84.8 87.8 0.828 0.861 0.824 0.830 

CS–38 .................................................................. 64.8 63.5 0.595 0.583 0.592 0.606 

CS–39 .................................................................. 64.6 66.3 0.596 0.609 0.599 0.621 

CS–40 .................................................................. 83.8 86.6 0.641 0.589 0.653 0.610 

CS–41 .................................................................. 88.2 85.0 0.662 0.670 0.649 0.656 

CS–42 .................................................................. 111.7 115.5 0.478 0.557 0.537 0.529 

CS–43 .................................................................. 127.4 123.9 0.641 0.659 0.613 0.643 

b. Consumer Instantaneous 

i. Test Results 

As stated in section III.D.1, DOE has 

tested 22 consumer instantaneous water 

heaters to both the current and new test 

procedures. Table III.17 presents the test 

data used to derive the consumer 

instantaneous water heater conversion 

factors. It is noted that test results show 

measured recovery efficiencies above 

100 percent and EFs and UEFs above 1 

for electric instantaneous units; DOE 

acknowledges that these results appear 

to violate theoretical limits and believes 

that these results are an artifact of 

measurement uncertainty. Table III.18 

shows the water heater attributes by 

unit described in section III.D.1. 


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TABLE III.17—CONSUMER INSTANTANEOUS WATER HEATER TEST DATA

Unit No. Type Input rate 

(Btu/h) 

Current 

max GPM 

Updated 

max GPM 

Current 

recovery 

efficiency 

(%) 

EF UEF 

CI–1 .................................. Electric ...... 8,200 0.20 0.23 101.2 1.012 0.982 

CI–2 .................................. Electric ...... 32,400 0.82 0.93 101.5 1.017 0.981 

CI–3 .................................. Electric ...... 34,100 0.87 0.99 101.8 1.018 1.001 

CI–4 .................................. Electric ...... 27,300 0.68 0.80 102.0 1.019 1.004 

CI–5 .................................. Electric ...... 20,500 0.52 0.59 102.3 1.021 1.005 

CI–6 .................................. Gas ............ 179,900 4.01 4.58 82.4 0.821 0.832 

CI–7 .................................. Gas ............ 178,500 4.08 4.71 83.8 0.837 0.828 

CI–8 .................................. Gas ............ 120,900 2.69 3.07 84.1 0.839 0.814 

CI–9 .................................. Gas ............ 199,000 4.61 4.86 87.0 0.876 0.841 

CI–10 ................................ Gas ............ 151,900 3.47 3.96 88.3 0.891 0.815 

CI–11 ................................ Gas ............ 141,100 3.11 3.61 81.4 0.810 0.824 

CI–12 ................................ Gas ............ 190,400 4.23 4.81 83.4 0.829 0.818 

CI–13 ................................ Gas ............ 142,500 2.96 3.43 80.9 0.801 0.795 

CI–14 ................................ Gas ............ 197,200 5.19 5.80 96.7 0.966 0.958 

CI–15 ................................ Gas ............ 199,800 4.80 4.10 93.8 0.932 0.931 

CI–16 ................................ Gas ............ 151,500 3.24 3.88 84.3 0.837 0.805 

CI–17 ................................ Gas ............ 180,400 3.92 4.60 85.0 0.853 0.827 

CI–18 ................................ Gas ............ 175,800 3.67 4.30 84.5 0.838 0.830 

CI–19 ................................ Gas ............ 199,200 4.30 5.07 75.0 0.743 0.799 

CI–20 ................................ Gas ............ 154,100 3.98 4.47 91.6 0.913 0.922 

CI–21 ................................ Gas ............ 201,300 4.90 5.70 88.0 0.851 0.884 

CI–22 ................................ Gas ............ 199,900 5.12 4.91 89.9 0.888 0.943 

TABLE III.18—CONSUMER INSTANTANEOUS WATER HEATER ATTRIBUTES

Unit No. NOX emission level Condensing Vent type 

CI–1 ......................................................... N/A ......................................................... N/A ......................................................... N/A. 

CI–2 ......................................................... N/A ......................................................... N/A ......................................................... N/A. 

CI–3 ......................................................... N/A ......................................................... N/A ......................................................... N/A. 

CI–4 ......................................................... N/A ......................................................... N/A ......................................................... N/A. 

CI–5 ......................................................... N/A ......................................................... N/A ......................................................... N/A. 

CI–6 ......................................................... Low ......................................................... No ........................................................... Atmospheric. 

CI–7 ......................................................... Low ......................................................... No ........................................................... Atmospheric. 

CI–8 ......................................................... Low ......................................................... No ........................................................... Atmospheric. 

CI–9 ......................................................... Low ......................................................... No ........................................................... Atmospheric. 

CI–10 ....................................................... Low ......................................................... No ........................................................... Atmospheric. 

CI–11 ....................................................... Low ......................................................... No ........................................................... Power. 

CI–12 ....................................................... Low ......................................................... No ........................................................... Power. 

CI–13 ....................................................... Low ......................................................... No ........................................................... Power. 

CI–14 ....................................................... Low ......................................................... Yes ......................................................... Atmospheric. 

CI–15 ....................................................... Low ......................................................... Yes ......................................................... Atmospheric. 

CI–16 ....................................................... Ultra-Low ................................................ No ........................................................... Atmospheric. 

CI–17 ....................................................... Ultra-Low ................................................ No ........................................................... Atmospheric. 

CI–18 ....................................................... Ultra-Low ................................................ No ........................................................... Atmospheric. 

CI–19 ....................................................... Ultra-Low ................................................ No ........................................................... Atmospheric. 

CI–20 ....................................................... Ultra-Low ................................................ Yes ......................................................... Atmospheric. 

CI–21 ....................................................... Ultra-Low ................................................ Yes ......................................................... Atmospheric. 

CI–22 ....................................................... Ultra-Low ................................................ Yes ......................................................... Power. 

ii. Conversion Factor Results 

As stated in section III.C.2, DOE 

developed an analytical model to 

convert the existing maximum GPM 

rating for consumer instantaneous water 

heaters to ratings under the uniform 

efficiency descriptor test procedure. 

DOE also attempted to develop an 

analytical method based on the WHAM 

equation to estimate the change in 

existing energy factor ratings under the 

existing consumer water heater test 

procedure to values under the uniform 

efficiency descriptor test procedure. 

Along with this analytical model, step 

regression and combined analytical 

model-regression approaches were 

conducted. The results of the analytical 

model, step regression, and combined 

analytical model-regression approaches 

for the maximum GPM and UEF 

conversions are presented in Table 

III.20. For the maximum GPM 

conversions, the RMS errors for the 

three approaches are 0.38, 0.35, and 

0.38, respectively. For the UEF 

conversions, the three approaches have 

RMS errors of 0.024, 0.028, and 0.023, 

respectively. DOE has tentatively 

decided to use the analytical model 

approach to calculate the consumer 

instantaneous maximum GPM 

conversion factor owing to the fact that 

the model predicts the resultant data 

very closely and that it will broadly 

apply to those units not tested. DOE has 

also tentatively decided to use the 

combined analytical model-regression 

approach to convert from EF to UEF 

since the RMS errors are low, and it has 

tentatively concluded that the use of the 

model and regression will capture key 


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effects that may not be captured with 

either approach by itself. For the electric 

instantaneous water heaters, DOE 

imposed a zero intercept on the 

regression since the regression with an 

intercept resulted in UEFs above the 

theoretical limit of 1. DOE has 

tentatively concluded that this step is 

technically acceptable, as it effectively 

states that a water heater with an EF of 

zero should also have a UEF of zero. 

The resulting conversion factors for both 

first hour rating and UEF are: 

MaxGPMnew = 1.147 * MaxGPMEx

UEFgas = 0.9059 * UEFmodel + 0.0783 

UEFelectric = 1.0079 * UEFmodel

where MaxGPMEx is the maximum GPM 

rating based on the current DOE test 

procedure and UEFmodel is the predicted 

UEF determined using the following 

analytical model: 

Values for the coefficients A and B are 

dependent upon the draw pattern 

applied during the simulated-use test 

and are provided in Table III.19. 

TABLE III.19—COEFFICIENTS TO DETERMINE UEFmodel FOR CONSUMER

INSTANTANEOUS WATER HEATERS

Draw bin A B 

Very Small ................ 5514.2 170.2 

Low ........................... 20954 262.4 

Medium ..................... 30328 290.9 

High .......................... 46319 294.0 

TABLE III.20—CONSUMER INSTANTANEOUS WATER HEATER CONVERSION FACTOR RESULTS

Unit No. Tested max 

GPM 

Analytical 

max 

GPM 

Regression 

max GPM 

Combined 

analyticalregression 

max GPM 

Tested 

UEF 

Analytical 

UEF 

Regression 

UEF 

Analyticalregression 

UEF 

CI–1 .................. 0.23 0.23 0.24 0.23 0.982 0.982 0.980 0.989 

CI–2 .................. 0.93 0.94 0.94 0.94 0.981 0.984 0.987 0.992 

CI–3 .................. 0.99 1.00 1.00 1.00 1.001 0.987 0.995 0.995 

CI–4 .................. 0.80 0.78 0.78 0.78 1.004 0.989 1.001 0.997 

CI–5 .................. 0.59 0.59 0.60 0.59 1.005 0.991 1.008 0.999 

CI–6 .................. 4.58 4.60 4.58 4.60 0.832 0.820 0.816 0.820 

CI–7 .................. 4.71 4.68 4.66 4.68 0.828 0.834 0.829 0.833 

CI–8 .................. 3.07 3.08 3.17 3.08 0.814 0.834 0.830 0.834 

CI–9 .................. 4.86 5.28 5.22 5.28 0.841 0.865 0.859 0.861 

CI–10 ................ 3.96 3.98 4.01 3.98 0.815 0.878 0.871 0.873 

CI–11 ................ 3.61 3.56 3.62 3.56 0.824 0.808 0.807 0.810 

CI–12 ................ 4.81 4.85 4.82 4.85 0.818 0.829 0.822 0.829 

CI–13 ................ 3.43 3.39 3.46 3.39 0.795 0.803 0.800 0.805 

CI–14 ................ 5.80 5.95 5.84 5.95 0.958 0.961 0.931 0.948 

CI–15 ................ 4.10 5.50 5.43 5.50 0.931 0.933 0.904 0.923 

CI–16 ................ 3.88 3.71 3.76 3.71 0.805 0.836 0.829 0.835 

CI–17 ................ 4.60 4.49 4.49 4.49 0.827 0.845 0.841 0.844 

CI–18 ................ 4.30 4.21 4.22 4.21 0.830 0.840 0.829 0.839 

CI–19 ................ 5.07 4.93 4.90 4.93 0.799 0.746 0.754 0.754 

CI–20 ................ 4.47 4.56 4.55 4.56 0.922 0.911 0.889 0.903 

CI–21 ................ 5.70 5.62 5.54 5.62 0.884 0.875 0.840 0.870 

CI–22 ................ 4.91 5.87 5.77 5.87 0.943 0.894 0.869 0.887 

c. Residential-Duty Commercial Storage 

Testing 

i. Test Data 

As stated in section III.D.2, DOE has 

tested 7 residential-duty commercial 

storage water heaters to both the current 

and new test procedures. Table III.21 

below presents the test data used to 

derive the residential-duty commercial 

storage water heater conversion factors. 

Table III.22 shows the water heater 

attributes by unit described in section 

III.D.2. 

TABLE III.21—RESIDENTIAL-DUTY COMMERCIAL STORAGE WATER HEATER TEST DATA

Unit No. Type 

Storage 

volume 

(gal) 

Input rate 

(Btu/h) 

Tested thermal 

efficiency 

(%) 

Tested 

standby loss 

(Btu/h) 

Updated FHR 

(gal) UEF 

RD–1 .............................. Gas ............. 95.4 79,100 80.4 1,178.2 109.8 0.514 

RD–2 .............................. Gas ............. 72.7 67,400 67.9 721.0 90.3 0.585 

RD–3 .............................. Gas ............. 71.3 69,700 75.5 839.4 119.3 0.619 

RD–4 .............................. Gas ............. 48.3 76,500 93.6 328.0 137.0 0.816 

RD–5 .............................. Gas ............. 48.4 75,300 88.9 338.1 126.5 0.725 

RD–6 .............................. Gas ............. 47.8 75,700 90.0 358.4 103.3 0.621 

RD–7 .............................. Gas ............. 71.0 63,800 67.1 1,546.8 111.5 0.470 


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TABLE III.22—RESIDENTIAL-DUTY COMMERCIAL STORAGE WATER HEATER ATTRIBUTES

Unit No. NOX

emission level Condensing Vent type Short or tall 

Standing pilot 

or electric 

ignition 

RD–1 ..................................................................... Standard ........... No ..................... Atmospheric ...... Tall .................... Yes. 

RD–2 ..................................................................... Standard ........... No ..................... Power ............... Tall .................... No. 

RD–3 ..................................................................... Standard ........... No ..................... Power ............... Tall .................... No. 

RD–4 ..................................................................... Low ................... Yes ................... Atmospheric ...... Short ................. No. 

RD–5 ..................................................................... Low ................... Yes ................... Power ............... Tall .................... No. 

RD–6 ..................................................................... Low ................... Yes ................... Power ............... Tall .................... No. 

RD–7 ..................................................................... Ultra-Low .......... No ..................... Atmospheric ...... Tall .................... Yes. 

ii. Conversion Factor Results 

As stated in section III.C.2.b, DOE is 

not aware of an analytical model to 

convert the thermal efficiency and 

standby loss ratings under the current 

test procedure to first-hour rating values 

under the new test procedure. 

Therefore, the step regression method 

described in section III.C.3 along with 

the best combination of water heater 

attributes were used to determine the 

following first-hour rating conversion 

factors: 

New FHRFossil Fuel = 1.0226 * Q + 39.81 

Where Q is the input rate of the burner 

in kBtu/h. For this regression, DOE 

decided to group both oil and gas water 

heaters because of the lack of oil water 

heaters identified. DOE has tentatively 

concluded that this grouping is the best 

approach to convert ratings for any 

residential-duty oil water heater on the 

market. 

The next step in the conversion is to 

determine which draw pattern is to be 

applied to convert to UEF. After the 

first-hour rating under the uniform 

efficiency descriptor is determined 

through the conversion factor above, the 

value can be applied to determine the 

appropriate draw pattern bin (i.e., very 

small, low, medium, or high) using 

Table III.3 of this NOPR or Table 1 of 

the uniform efficiency descriptor test 

procedure. 79 FR 40542, 40572 (July 11, 

2014). With the draw bin known, the 

UEF value based on the analytical 

model can be calculated using the 

process described in section III.C.2.c.iii. 

The analytical results, along with the 

results of the step regression and 

analytical-regression are shown in Table 

III.23 and have RMS values of 0.074, 

0.055, and 0.053, respectively. Based on 

these results, DOE has tentatively 

decided to use the combined analyticalregression approach to calculate the 

residential-duty commercial storage 

water heater conversion factor. While 

the regression approach yields a slightly 

better RMS error, DOE has tentatively 

concluded that the use of the analytical 

model will make the conversion more 

robust over the entire family of 

residential-duty commercial storage 

water heaters since it captures the 

effects of water temperature, draw 

volume per day, thermal efficiency, and 

standby loss that are expected to be 

valid for any water heater. Thus, the use 

of an analytical model is expected to be 

less prone to error should a model have 

some unexpected characteristic that was 

not captured in the water heaters tested 

as part of this NOPR. The resulting 

equations for determining the UEF of 

consumer storage water heaters are: 

UEFfossil fuel = 0.7300 * UEFrd + 0.1413 

Where UEFrd is the estimate of the UEF 

for residential-duty water heaters 

computed with the following equation: 

where C1 is a constant dependent upon 

the draw pattern given in Table III.6, Et

is the thermal efficiency in fractional 

form (i.e., 0.85 instead of 85 (%)), and 

SL is the standby loss in BTU/h. 

TABLE III.23—RESIDENTIAL-DUTY COMMERCIAL CONVERSION FACTOR RESULTS

Unit No. Tested FHR 

(gal) 

Regression 

FHR 

(gal) 

Tested UEF Analytical UEF Regression 

UEF 

Analyticalregression 

UEF 

RD–1 ............................................ 109.8 120.7 0.514 0.573 0.530 0.560 

RD–2 ............................................ 90.3 108.8 0.585 0.562 0.629 0.551 

RD–3 ............................................ 119.3 111.1 0.619 0.595 0.604 0.575 

RD–4 ............................................ 137.0 118.0 0.816 0.828 0.715 0.746 

RD–5 ............................................ 126.5 116.9 0.725 0.788 0.713 0.717 

RD–6 ............................................ 103.3 117.3 0.621 0.791 0.709 0.719 

RD–7 ............................................ 111.5 105.0 0.470 0.466 0.449 0.481 

d. Residential-Duty Instantaneous 

Testing 

As discussed in section III.B.2, no 

instantaneous residential-duty 

commercial water heaters exist on the 

market. Therefore, a conversion factor is 

not needed. 

3. Energy Conservation Standard 

Derivation 

After developing the mathematical 

conversion factors to convert from the 

existing efficiency ratings to the 

efficiency ratings under the UEF metric, 

DOE sought to update its energy 

conservation standards for covered 

water heater products so as to be in 

terms of UEF. DOE investigated several 

possible methods to determine the 

appropriate energy conservation 

standards in terms of UEF. 

First, DOE considered the ‘‘percent 

difference’’ method, which is the 

method DOE ultimately has proposed 

for updating the energy conservation 

standards so as to be based on the UEF 

metric. The percent difference method 

was conducted as follows: 

1. Apply conversion factor to convert 

the current efficiency metrics provided 

in the relevant consumer or commercial 

database to the calculated UEF value for 

each water heater on the market. 

2. Calculate the current efficiency 

standard for each water heater in the 

database, as follows: 


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a. For consumer water heaters, find 

the minimum EF. 

b. For residential-duty commercial 

water heaters, find the minimum 

thermal efficiency. 

3. Find the percent difference 

between the rated efficiency value and 

the standard for each water heater in the 

database, as follows: 

4. Find the new energy conservation 

standard for each water heater in the 

database, as follows: 

a. UEFmin = UEF (1 ¥ PD) 

5. Find a line through their minimum 

UEF values. 

The advantage of using a ‘‘percent 

difference’’ is that the updated energy 

conservation standard is a function of 

the UEF conversion for all water heaters 

rather than a subset. It also allows for 

conversions of standards for classes or 

groupings of water heaters where no 

minimally compliant models are 

currently available on the market. The 

proposed standards in terms of uniform 

energy factor are shown below by 

product class and draw pattern. 

TABLE III.24—UPDATED CONSUMER WATER HEATER ENERGY CONSERVATION STANDARDS

Product class Rated storage volume Draw pattern Uniform energy factor 

Gas-fired Storage ............................................ ≥20 gal and ≤55 gal ........................................ Very Small ............ 0.3263 ¥ (0.0019 × Vr) 

Low ....................... 0.5891 ¥ (0.0019 × Vr) 

Medium ................. 0.6326 ¥ (0.0013 × Vr) 

High ....................... 0.7128 ¥ (0.0025 × Vr) 

>55 gal and ≤100 gal ...................................... Very Small ............ 0.5352 ¥ (0.0007 × Vr) 

Low ....................... 0.7375 ¥ (0.0009 × Vr) 

Medium ................. 0.7704 ¥ (0.0010 × Vr) 

High ....................... 0.7980 ¥ (0.0010 × Vr) 

Oil-fired Storage .............................................. ≤50 gal ............................................................ Very Small ............ 0.2267 ¥ (0.0014 × Vr) 

Low ....................... 0.4867 ¥ (0.0006 × Vr) 

Medium ................. 0.6016 ¥ (0.0012 × Vr) 

High ....................... 0.6529 ¥ (0.0005 × Vr) 

Electric Storage ............................................... ≥20 gal and ≤55 gal ........................................ Very Small ............ 0.8268 ¥ (0.0002 × Vr) 

Low ....................... 0.9393 ¥ (0.0004 × Vr) 

Medium ................. 0.9683 ¥ (0.0007 × Vr) 

High ....................... 0.9656 ¥ (0.0004 × Vr) 

>55 gal and ≤120 gal ...................................... Very Small ............ 1.2701 ¥ (0.0011 × Vr) 

Low ....................... 1.9137 ¥ (0.0011 × Vr) 

Medium ................. 2.0326 ¥ (0.0011 × Vr) 

High ....................... 2.1858 ¥ (0.0011 × Vr) 

Tabletop Storage ............................................. ≥20 gal and ≤100 gal ...................................... Very Small ............ 0.6808 ¥ (0.0022 × Vr) 

Low ....................... 0.8770 ¥ (0.0012 × Vr) 

Medium ................. 0.9063 ¥ (0.0009 × Vr) 

High ....................... 0.9302 ¥ (0.0006 × Vr) 

Gas-fired Instantaneous .................................. <2 gal .............................................................. All .......................... 0.8036 ¥ (0.0019 × Vr) 

Electric Instantaneous ..................................... <2 gal .............................................................. All .......................... 0.9192 ¥ (0.0013 × Vr) 

* Vr is the rated storage volume which equals the water storage capacity of a water heater (in gallons), as specified by the manufacturer. 

TABLE III.25—UPDATED RESIDENTIAL-DUTY COMMERCIAL WATER HEATER ENERGY CONSERVATION STANDARDS

Product class Draw pattern Uniform energy factor 

Gas-fired Storage .......................................................................................................................... Very Small ............ 0.3261 ¥ (0.0006 × Vr) 

Low ....................... 0.5219 ¥ (0.0008 × Vr) 

Medium ................. 0.5585 ¥ (0.0006 × Vr) 

High ....................... 0.6044 ¥ (0.0005 × Vr) 

Oil-fired Storage ............................................................................................................................ Very Small ............ 0.3206 ¥ (0.0006 × Vr) 

Low ....................... 0.5577 ¥ (0.0019 × Vr) 

Medium ................. 0.6027 ¥ (0.0019 × Vr) 

High ....................... 0.6446 ¥ (0.0018 × Vr) 

* Vr is the rated storage volume which equals the water storage capacity of a water heater (in gallons), as specified by the manufacturer. 

As stated in section III.A, EEI 

commented in response to the 

November 2013 NOPR, that the updated 

energy conservation standards should 

be not more stringent than they are 

currently. The percent difference from 

the current rated energy factors and 

energy conservation standards are used 

to derive the new energy conservation 


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standards; therefore, the updated 

standards are no more stringent than 

those currently in existence. A.O. Smith 

and AHRI suggested that the average 

difference between the current and new 

ratings should not be used to convert 

the energy conservation standards. At 

no point in the conversion factor 

derivation or energy conservation 

standard analysis is a simple average 

taken, but rather, the trends of all the 

traditional factors affecting water 

heaters are considered. 

DOE also investigated a second 

method of determining the energy 

conservation standards where only test 

data from minimally-compliant water 

heaters would be used to develop a 

conversion factor using the analytical 

and regression methods described in 

section III.C. Then, this set of 

conversion factors could be applied to 

the minimum energy conservation 

standards to determine the appropriate 

energy conservation standards in terms 

of the UEF metric. This method would 

remove from consideration any factors 

that are present in more-efficient water 

heaters, so the resulting change in the 

standard would not be skewed at all by 

the inclusion of higher-efficiency 

products in the mathematical 

conversion. However, the conversion 

factors developed through such a 

methodology would potentially not be 

applicable for converting the efficiency 

ratings of products above the baseline. 

Therefore, DOE chose to pursue a 

methodology that was applicable to all 

water heaters and perform the 

conversion of standards based on the 

‘‘percent difference’’ method described 

above. 

DOE seeks comment on the most 

appropriate method for determining the 

energy conservation standards based on 

the updated test procedure. This is 

identified as issue 5 in section V.E, 

‘‘Issues on Which DOE Seeks 

Comment.’’ 

F. Certification and Labeling Issues 

Consumer water heaters and 

residential-duty commercial water 

heaters manufactured prior to the 

effective date of the uniform energy 

factor test procedure final rule (i.e., July 

13, 2015) that comply with the 

efficiency standards and labeling 

requirements in effect prior to that final 

rule will be considered to comply with 

the converted UEF standards and with 

any revised labeling requirements 

established by the Federal Trade 

Commission (FTC) to carry out the final 

rule. (42 U.S.C. 6295(e)(5)(K)) The 

statute requires that the standard be in 

terms of UEF as of July 13, 2015. 

Accordingly, DOE proposes to require 

manufacturers to provide EF and UEF 

for consumer water heaters (or thermal 

efficiency and standby loss and UEF for 

commercial residential-duty water 

heaters) in certification reports filed 

between July 13, 2015, and the 

compliance date determined by the final 

rule in this rulemaking. Manufacturers 

would not be required to submit revised 

certification reports for previously 

certified basic models until the next 

annual certification date (May 1). 

Allowing manufacturers to submit 

both EF and UEF data would allow 

manufacturers to fulfill the statutory 

requirement to begin using UEF for 

purposes of compliance with standards 

but would also allow manufacturers to 

provide the necessary information to 

determine costs under the current FTC 

labeling requirements. This would also 

allow a transition period for FTC to 

pursue a rulemaking to determine 

whether changes are needed to the 

water heater EnergyGuide label due to 

changes in the water heater test 

procedure. DOE expects that the 

conversion factors proposed in this 

notice could be used to convert EF to 

UEF for previously certified basic 

models or to convert UEF values 

‘‘backwards’’ to EF to determine the 

appropriate costs for labeling of new 

basic models until FTC has determined 

whether to make changes to the label. 

DOE has proposed a methodology for 

calculating costs based on UEF testing 

that could be used in future FTC 

labeling requirements. DOE requests 

comment on whether DOE should adopt 

such a provision in the final rule in this 

rulemaking or postpone adoption until 

FTC has had an opportunity to evaluate 

the ENERGY GUIDE label. 

IV. Procedural Issues and Regulatory 

Review 

A. Review Under Executive Order 12866 

The Office of Management and Budget 

(OMB) has determined that test 

procedure rulemakings do not constitute 

‘‘significant regulatory actions’’ under 

section 3(f) of Executive Order 12866, 

Regulatory Planning and Review, 58 FR 

51735 (Oct. 4, 1993). Accordingly, this 

action was not subject to review under 

the Executive Order by the Office of 

Information and Regulatory Affairs 

(OIRA) in the Office of Management and 

Budget. 

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 (IFRA) 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 Web site: http://energy.gov/

gc/office-general-counsel. 

This proposed rule would prescribe a 

mathematical conversion that would be 

used to determine compliance with 

energy conservation standards for 

consumer water heaters and certain 

commercial water heaters. For consumer 

water heaters and certain commercial 

water heaters, the mathematical 

conversion would establish a bridge 

between the rated values based on the 

results under the current test procedures 

and the uniform efficiency descriptor of 

the new test procedure. Furthermore, 

the conversion factor will ensure that no 

products which currently pass energy 

conservation standards fail to meet the 

energy conservation standards after the 

conversion factor has been applied. DOE 

reviewed this proposed rule under the 

provisions of the Regulatory Flexibility 

Act and the policies and procedures 

published on February 19, 2003. 68 FR 

7990. 

For the manufacturers of the covered 

water heater products, the Small 

Business Administration (SBA) has set a 

size threshold, which defines those 

entities classified as ‘‘small businesses’’ 

for the purposes of the statute. DOE 

used the SBA’s small business size 

standards to determine whether any 

small entities would be subject to the 

requirements of the rule. 65 FR 30836, 

30849 (May 15, 2000), as amended at 65 

FR 53533, 53545 (Sept. 5, 2000) and at 

77 FR 49991, 50008–11 (August 20, 

2012) and codified at 13 CFR part 121. 

The size standards are listed by North 

American Industry Classification 

System (NAICS) code and industry 

description and are available at http:// 

www.sba.gov/content/table-smallbusiness-size-standards. Consumer 

water heater manufacturing is classified 

under NAICS code 335228—‘‘Other 

Major Household Appliance 

Manufacturing.’’ The SBA sets a 

threshold of 500 employees or less for 

an entity to be considered as a small 

business. Commercial water heater 

manufacturing is classified under 

NAICS code 333318—‘‘Other 


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Commercial and Service Industry 

Machinery Manufacturing,’’ for which 

SBA sets a size threshold of 1,000 

employees or fewer as being considered 

a small business. 

DOE has identified 19 manufacturers 

of consumer water heaters (including 

manufacturers of products that fall 

under the expanded scope) that can be 

considered small businesses. DOE 

identified seven manufacturers of 

‘‘residential-duty’’ commercial water 

heaters that can be considered small 

businesses. Six of the ‘‘residential-duty’’ 

commercial water heater manufacturers 

also manufacture consumer water 

heaters, so the total number of water 

heater manufacturers impacted by this 

rule would be 20. DOE’s research 

involved reviewing several industry 

trade association membership 

directories (e.g., AHRI), product 

databases (e.g., AHRI, CEC, and 

ENERGY STAR databases), individual 

company Web sites, and marketing 

research tools (e.g., Hoovers reports) to 

create a list of all domestic small 

business manufacturers of products 

covered by this rulemaking. 

For the reasons explained below, DOE 

has concluded that the test procedure 

amendments contained in this proposed 

rule would not have a significant 

economic impact on any manufacturer, 

including small manufacturers. 

For consumer water heaters that were 

covered under the old test procedure 

and energy conservation standards, the 

conversion factor in this proposed rule 

would convert the rated values based on 

the current test procedure to equivalent 

values based on the new uniform 

descriptor test procedure. Although the 

energy conservation standards for 

consumer water heaters will be 

denominated using the uniform 

descriptor, the statute provides that all 

units that are on the market as of July 

13, 2015, that meet the April 16, 2015 

energy factor standard will be deemed 

to meet the converted standards. 

For certain commercial water heaters, 

defined under the term ‘‘residentialduty commercial water heater,’’ the 

conversion factor in this proposed rule 

would convert the rated values based on 

the current test procedure to the 

uniform descriptor which is based on 

the new test procedure. The energy 

conservation standards for commercial 

water heating equipment will be 

denominated using the uniform 

descriptor. The statute provides that all 

units that are on the market as of July 

13, 2015, that meet the thermal 

efficiency and standby losses standards 

will be deemed to meet the converted 

standards. 

At the date that compliance is 

required with the new test procedure, 

all water heating units with residential 

applications (i.e., consumer units and 

residential-duty commercial units) must 

meet the applicable energy conservation 

standards. These units will be re-rated 

to the uniform descriptor based on the 

new test procedure. This conversion 

will not result in any increase in 

stringency of the energy conservation 

standards. Therefore, no units that are 

on the market at the time of this 

rulemaking will be made illegal 

(noncompliant) by this action. 

Accordingly, DOE concludes and 

certifies that this final rule would not 

have a significant economic impact on 

a substantial number of small entities, 

so DOE has not prepared a regulatory 

flexibility analysis for this rulemaking. 

DOE will provide its certification and 

supporting statement of factual basis to 

the Chief Counsel for Advocacy of the 

SBA for review under 5 U.S.C. 605(b). 

C. Review Under the Paperwork 

Reduction Act of 1995 

Manufacturers of water heaters must 

certify to DOE that their products 

comply with any applicable energy 

conservation standards. In certifying 

compliance, manufacturers must test 

their products according to the DOE test 

procedures for water heaters, including 

any amendments adopted for those test 

procedures. DOE has established 

regulations for the certification and 

recordkeeping requirements for all 

covered consumer products and 

commercial equipment, including 

consumer and commercial water 

heaters. 76 FR 12422 (March 7, 2011); 

79 FR 25486 (May 5, 2014). The 

collection-of-information requirement 

for the certification and recordkeeping 

is subject to review and approval by 

OMB under the Paperwork Reduction 

Act (PRA). This requirement has been 

approved by OMB under OMB control 

number 1910–1400. Public reporting 

burden for the certification is estimated 

to average 30 hours per response, 

including the time for reviewing 

instructions, searching existing data 

sources, gathering and maintaining the 

data needed, and completing and 

reviewing the collection of information. 

Notwithstanding any other provision 

of the law, no person is required to 

respond to, nor shall any person be 

subject to a penalty for failure to comply 

with, a collection of information subject 

to the requirements of the PRA, unless 

that collection of information displays a 

currently valid OMB Control Number. 

D. Review Under the National 

Environmental Policy Act of 1969 

In this proposed rule, DOE proposes 

conversion factors to convert results 

from existing efficiency and delivery 

capacity metrics (and related energy 

conservation standard requirements) for 

consumer and certain commercial water 

heaters to the uniform energy 

descriptor. 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, this proposed rule would 

amend the existing rule without 

affecting the amount, quality or 

distribution of energy usage, and, 

therefore, would not result in any 

environmental impacts. Thus, this 

rulemaking is covered by Categorical 

Exclusion A5 under 10 CFR part 1021, 

subpart D, which applies to any 

rulemaking that interprets or amends an 

existing rule without changing the 

environmental effect of that rule. 

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 10, 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 


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20140 Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 

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. Regarding the 

review required by section 3(a), 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 them. On March 18, 1997, DOE 

published a statement of policy on its 

process for intergovernmental 

consultation under UMRA. 62 FR 

12820. (This policy is also available at 

http://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 by State, local, and Tribal 

governments, in the aggregate, or by the 

private sector, of $100 million or more 

in any year. Accordingly, no further 

assessment or analysis is required under 

UMRA. 

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 

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 

Pursuant to Executive Order 12630, 

‘‘Governmental Actions and Interference 

with Constitutionally Protected Property 

Rights,’’ 53 FR 8859 (March 18, 1988), 

DOE has determined that this regulation 

would not result in any takings that 

might require compensation under the 

Fifth Amendment to the U.S. 

Constitution. 

J. Review Under Treasury and General 

Government Appropriations Act, 2001 

Section 515 of the Treasury and 

General Government Appropriations 

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

for agencies to review most 

disseminations of information to the 

public under information quality 

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). 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 OIRA at 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 

promulgates 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. 

This regulatory action, which would 

develop a conversion factor to amend 

the energy conservation standards for 

consumer and certain commercial water 

heaters in light of new test procedures 

is not a significant regulatory action 

under Executive Order 12866 or any 

successor order. 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 for this 

rulemaking. 

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 et seq.), DOE must 

comply with all laws applicable to the 

former Federal Energy Administration, 

including section 32 of the Federal 

Energy Administration Act of 1974 

(Pub. L. 93–275), as amended by the 

Federal Energy Administration 

Authorization Act of 1977 (Pub. L. 95– 

70). (15 U.S.C. 788; FEAA) Section 32 

essentially provides in relevant part 


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Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 20141 

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. 

This proposed rule to implement 

conversion factors between the existing 

water heaters test procedure and the 

amended test procedure does not 

incorporate testing methods contained 

in commercial standards. 

V. Public Participation 

A. Submission of Comments 

DOE will accept comments, data, and 

information regarding this proposed 

rule no later than the date provided in 

the DATES section at the beginning of 

this proposed rule. Interested parties 

may submit comments, 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 

Web site 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, hand 

delivery/courier, or mail. Comments and 

documents submitted via email, hand 

delivery/courier, or mail 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. 

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. If you 

submit via mail or hand delivery/

courier, please provide all items on a 

CD, if feasible, in which case it is not 

necessary to submit printed copies. No 

telefacsimiles (faxes) will be accepted. 

Comments, data, and other 

information submitted to DOE 

electronically should be provided in 

PDF (preferred), Microsoft Word or 

Excel, WordPerfect, or text (ASCII) file 

format. Provide documents that are not 

secured, that are written in English, and 

that are 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, postal mail, or hand 

delivery/courier 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. 

Submit these documents via email or on 

a CD, if feasible. DOE will make its own 

determination about the confidential 

status of the information and treat it 

according to its determination. 

Factors of interest to DOE when 

evaluating requests to treat submitted 

information as confidential include: (1) 

A description of the items; (2) whether 

and why such items are customarily 

treated as confidential within the 

industry; (3) whether the information is 

generally known by or available from 

other sources; (4) whether the 

information has previously been made 

available to others without obligation 

concerning its confidentiality; (5) an 

explanation of the competitive injury to 

the submitting person which would 

result from public disclosure; (6) when 

such information might lose its 

confidential character due to the 

passage of time; and (7) why disclosure 

of the information would be contrary to 

the public interest. 

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). 

B. Issues on Which DOE Seeks Comment 

Although DOE welcomes comments 

on any aspect of this proposal, DOE is 

particularly interested in receiving 

comments and views of interested 

parties concerning the following issues: 

1. Has DOE identified all of the water 

heaters requiring a conversion from the 

old test procedures for consumer and 

commercial water heaters to the new 

test procedure for the uniform test 

method for measuring the energy 

consumption of water heaters? 

2. Are the proposed analytical 

methods appropriate for the conversion 

factor analysis? 

3. Is the proposed regression method 

appropriate for the conversion factor 

analysis? 

4. How do manufacturers specify 

whether a water heater is short or tall? 

Is there any criteria that could be 

applied to compare short and tall 

designs across all manufacturers? 

5. Is the proposed percentage 

difference method appropriate for the 

derivation of energy conservation 


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20142 Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 

standards based on the updated test 

procedure? 

VI. Approval of the Office of the 

Secretary 

The Secretary of Energy has approved 

publication of this notice of proposed 

rulemaking. 

List of Subjects 

10 CFR Part 429 

Confidential business information, 

Energy conservation, Household 

appliances, Imports, Reporting and 

recordkeeping requirements. 

10 CFR Part 430 

Administrative practice and 

procedure, Confidential business 

information, Energy conservation, 

Household appliances, Imports, 

Incorporation by reference, 

Intergovernmental relations, Small 

businesses. 

10 CFR Part 431 

Administrative practice and 

procedure, Confidential business 

information, Test procedures, 

Incorporation by reference, Reporting 

and recordkeeping requirements. 

Issued in Washington, DC, on March 27, 

2015. 

Kathleen B. Hogan, 

Deputy Assistant Secretary for Energy 

Efficiency, Energy Efficiency and Renewable 

Energy. 

For the reasons stated in the 

preamble, DOE is proposing to amend 

parts 429, 430, and 431 of Chapter II, 

Subchapter D of Title 10, Code of 

Federal Regulations, as set forth below: 

PART 429—CERTIFICATION, 

COMPLIANCE, AND ENFORCEMENT 

FOR CONSUMER PRODUCTS AND 

COMMERCIAL AND INDUSTRIAL 

EQUIPMENT 

■ 1. The authority citation for part 429 

continues to read as follows: 

Authority: 42 U.S.C. 6291–6317. 

■ 2. Section 429.17 is revised to read as 

follows: 

§ 429.17 Water heaters. 

(a) Determination of represented 

value. 

(1) As of July 13, 2015, manufacturers 

must determine the represented value 

for each new basic model of water 

heater by applying an AEDM in 

accordance with 10 CFR 429.70 or by 

testing for the uniform energy factor, in 

conjunction with the applicable 

sampling provisions as follows: 

(i) If the represented value is 

determined through testing, the general 

requirements of 10 CFR 429.11 are 

applicable; and 

(ii) For each basic model selected for 

testing, a sample of sufficient size shall 

be randomly selected and tested to 

ensure that— 

(A) Any represented value of the 

estimated annual operating cost or other 

measure of energy consumption of a 

basic model for which consumers would 

favor lower values shall be greater than 

or equal to the higher of: 

(1) The mean of the sample, where: 

and, x is the sample mean; n is the 

number of samples; and xi is the ith

sample; 

Or, 

(2) The upper 95-percent confidence 

limit (UCL) of the true mean divided by 

1.10, where: 

And xis the sample mean; s is the 

sample standard deviation; n is the 

number of samples; and t0.95 is the t 

statistic for a 95-percent one-tailed 

confidence interval with n-1 degrees of 

freedom (from Appendix A). 

and 

(B) Any represented value of the 

uniform energy factor, energy factor, or 

other measure of energy consumption of 

a basic model for which consumers 

would favor higher values shall be less 

than or equal to the lower of: 

(1) The mean of the sample, where: 

and, x is the sample mean; n is the 

number of samples; and xi is the ith

sample; 

Or, 

(2) The lower 95-percent confidence 

limit (LCL) of the true mean divided by 

0.90, where: 

And xis the sample mean; s is the 

sample standard deviation; n is the 

number of samples; and t0.95 is the t 

statistic for a 95-percent one-tailed 

confidence interval with n-1 degrees of 

freedom (from Appendix A). 

(2) For basic models initially certified 

before July 13, 2015 (using either the 

energy factor test procedure contained 

in Appendix E to Subpart B of 10 CFR 

part 430 of the January 1, 2015 edition 

of the Code of Federal Regulations or 

the thermal efficiency and standby loss 

test procedures contained in 10 CFR 

431.106 of the January 1, 2015 edition 

of the Code of Federal Regulations, in 

conjunction with applicable sampling 

provisions), manufacturers must: 

(i) Conduct testing for the uniform 

energy factor, in conjunction with the 

applicable sampling provisions of this 

paragraph; 

(ii) Apply an AEDM in accordance 

with 10 CFR 429.70; or 

(iii) Calculate the uniform energy 

factor by applying the following 

mathematical conversion factors to the 

previously certified value of energy 

factor as follows. Representations of 

uniform energy factor based on a 

calculation using this mathematical 

conversion factor must be equal to the 

uniform energy factor value resulting 

from the application of the appropriate 

equation below. 

(A) The applicable mathematical 

conversion factors are as follows: 

Product class Distinguishing criteria Conversion factor * 

Consumer Gas-fired Water Heater ......................... Non-Condensing, Standard NOX .......................... New FHR = 1.0085 * FHREx

UEF = 0.4736 + 0.2726 * UEFWHAM

Non-Condensing, Low NOX .................................. New FHR = 4.6894 = 0.9112 * FHREx

UEF = ¥0.0126 + 0.9966 * UEFWHAM

Non-Condensing, Ultra-Low NOX ......................... New FHR = 2.9267 + 0.8882 * FHREx

UEF = 0.2673 + 0.5811 * UEFWHAM

Condensing ........................................................... New FHR = ¥0.7072 + 0.9724 * FHREx

UEF = 0.0409 + 0.9164 * UEFWHAM

Consumer Oil-fired Water Heater ........................... N/A ......................................................................... New FHR = 1.1018 * FHREx

UEF = ¥0.0945 + 1.1185 * UEFWHAM

Consumer Electric Water Heater ............................ Electric Resistance ................................................ New FHR = 11.9239 + 0.789 * FHREx

UEF = 0.1227 + 0.8673 * UEFWHAM


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Product class Distinguishing criteria Conversion factor * 

Heat Pump ............................................................ New FHR = ¥2.3440 + 0.9856 * FHREx

UEF = ¥1.1235 + 1.5485 * EF 

Tabletop Water Heater ........................................... N/A ......................................................................... New FHR = 11.9239 + 0.7879 * FHREx

UEF = 0.1227 + 0.8673 * UEFWHAM

Instantaneous Gas-fired Water Heater ................... N/A ......................................................................... New Max GPM = 1.1467 * Max GPMEx

UEF = 0.0783 + 0.9052 * UEFmodel

Instantaneous Electric Water Heater ...................... N/A ......................................................................... New Max GPM = 1.1467 * Max GPMEx

UEF = 1.0079 * UEFmodel

Residential-Duty Commercial Gas-fired Water 

Heater.

N/A ......................................................................... New FHR = 39.8144 + 1.0226 * Q 

UEF = 0.1413 + 0.7300 * UEFWHAM

Residential-Duty Commercial Oil-fired Water Heater.N/A ......................................................................... New FHR = 39.8144 + 1.0226 * Q 

UEF = 0.1413 + 0.7300 * UEFWHAM

*FHREX = current first-hour rating. 

Max GPMEX = current max GPM rating. 

Q = nameplate input rate, in kBtu/hr. 

UEFWHAM = the UEF predicted based on either the WHAM equation (for consumer storage water heaters) or the modified WHAM (for residential-duty commercial water heaters, as defined in the sub-paragraphs below). 

UEFmodel = the UEF predicted based on the analytical model developed by DOE (for consumer instantaneous water heaters). 

(B) Calculate UEFWHAM (for consumer 

storage water heaters and residentialduty commercial storage water heaters) 

and UEFmodel (for consumer 

instantaneous water heaters) as follows: 

(1) For consumer storage water 

heaters: 

Where a, b, c, and d are coefficients 

based on the applicable draw pattern as 

specified in the table below; EF is the 

current energy factor rating; hr is the 

current recovery efficiency rating in 

decimal form; and P is the input rating 

in Btu/h. 

Draw pattern a b c d 

Very Small ............................................................................... 56095146 12884892499 8930623 15125743368 

Low .......................................................................................... 56095146 48962591496 33936368 57477824799 

Medium .................................................................................... 56095146 70866908744 49118427 83191588525 

High .......................................................................................... 56095146 108233096990 75017235 127056244293 

(2) For consumer instantaneous water 

heaters: 

Where hr is the current recovery 

efficiency rating expressed in decimal 

form and A and B are coefficients 

dependent upon the applicable draw 

pattern as specified in the table below. 

Draw pattern A B 

Very 

Small ... 5514 .2 170.2 

Low ......... 20954 262.4 

Medium ... 30328 290.9 

High ........ 46319 294.0 

(3) For residential-duty commercial 

water heaters: 

Where, Et is the existing thermal 

efficiency rating; SL is the existing 

standby loss rating in Btu/h; and C1 is 

a coefficient as specified in the table 

below based on the applicable draw 

pattern. 

Draw pattern C1

Very Small ............................ 3.575 x 10¥3

Low ....................................... 9.408 x 10¥4

Medium ................................. 6.500 x 10¥4

High ...................................... 4.256 x 10¥4

(3) Any represented value of the rated 

storage volume must be equal to the 

mean of the measured storage volumes 

of all the units within the sample. 

(4) Any represented value of first-hour 

rating or maximum gallons per minute 

(GPM) must be equal to the mean of the 

measured first-hour ratings or measured 

maximum GPM ratings, respectively, of 

all the units within the sample. 

(b) Certification reports. (1) The 

requirements of 10 CFR 429.12 are 

applicable to water heaters; and 

(2) Pursuant to 10 CFR 429.12(b)(13), 

a certification report shall include the 

following public product-specific 

information: 

(i) For storage-type water heater basic 

models tested for energy factor and 

rated pursuant to 10 CFR 

429.17(a)(2)(iii): Energy factor, uniform 

energy factor, rated storage volume (gal), 

first-hour rating (gal), and recovery 

efficiency (percent); 

(ii) For storage-type water heater basic 

models tested for uniform energy factor 

and rated pursuant to 10 CFR 

429.17(a)(1) or 10 CFR 429.17(a)(2)(i) 

through (ii): Uniform energy factor, 

rated storage volume in gallons (gal), 

first-hour rating (gal), and recovery 

efficiency (percent); 

(iii) For instantaneous-type water 

heater basic models tested for energy 

factor and rated pursuant to 10 CFR 

429.17(a)(2)(iii): Energy factor, uniform 

energy factor, rated storage volume (gal), 

maximum gallons per minute, and 

recovery efficiency (percent); and 


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20144 Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 

(iv) For instantaneous-type water 

heater basic models tested for uniform 

energy factor and rated pursuant to 10 

CFR 429.17(a)(1) or 10 CFR 

429.17(a)(2)(i) through (ii): Uniform 

energy factor, rated storage volume (gal), 

maximum gallons per minute, and 

recovery efficiency (percent). 

■ 3. Section 429.17 is further revised, 

effective [date one year after publication 

of final rule], to read as follows: 

§ 429.17 Water heaters. 

(a) Determination of represented 

value. (1) Manufacturers must 

determine the represented value for 

each water heater by applying an AEDM 

in accordance with 10 CFR 429.70 or by 

testing for the uniform energy factor, in 

conjunction with the applicable 

sampling provisions as follows: 

(i) If the represented value is 

determined through testing, the general 

requirements of 10 CFR 429.11 are 

applicable; and 

(ii) For each basic model selected for 

testing, a sample of sufficient size shall 

be randomly selected and tested to 

ensure that— 

(A) Any represented value of the 

estimated annual operating cost or other 

measure of energy consumption of a 

basic model for which consumers would 

favor lower values shall be greater than 

or equal to the higher of: 

(1) The mean of the sample, where: 

and, x is the sample mean; n is the 

number of samples; and xi is the ith

sample; 

Or, 

(2) The upper 95-percent confidence 

limit (UCL) of the true mean divided by 

1.10, where: 

And, x is the sample mean; s is the 

sample standard deviation; n is the 

number of samples; and t0.95 is the t 

statistic for a 95-percent one-tailed 

confidence interval with n-1 degrees of 

freedom (from Appendix A). 

and 

(B) Any represented value of the 

uniform energy factor, energy factor, or 

other measure of energy consumption of 

a basic model for which consumers 

would favor higher values shall be less 

than or equal to the lower of: 

(1) The mean of the sample, where: 

and, x is the sample mean; n is the 

number of samples; and xi is the ith

sample; 

Or, 

(2) The lower 95-percent confidence 

limit (LCL) of the true mean divided by 

0.90, where: 

And x is the sample mean; s is the 

sample standard deviation; n is the 

number of samples; and t0.95 is the t 

statistic for a 95-percent one-tailed 

confidence interval with n-1 degrees of 

freedom (from Appendix A). 

(2) Any represented value of the rated 

storage volume must be equal to the 

mean of the measured storage volumes 

of all the units within the sample. 

(3) Any represented value of first-hour 

rating or maximum gallons per minute 

(GPM) must be equal to the mean of the 

measured first-hour ratings or measured 

maximum GPM ratings, respectively, of 

all the units within the sample. 

(b) Certification reports. (1) The 

requirements of 10 CFR 429.12 are 

applicable to water heaters; and 

(2) Pursuant to 10 CFR 429.12(b)(13), 

a certification report shall include the 

following public product-specific 

information: 

(i) For storage-type water heater basic 

models: Uniform energy factor, rated 

storage volume in gallons (gal), firsthour rating (gal), and recovery efficiency 

(percent); 

(ii) For instantaneous-type water 

heater basic models: Uniform energy 

factor, rated storage volume (gal), 

maximum gallons per minute, and 

recovery efficiency (percent); and 

(iii) For instantaneous-type water 

heater basic models: Uniform energy 

factor, rated storage volume (gal), 

maximum gallons per minute, and 

recovery efficiency (percent). 

■ 4. Section 429.44 is amended by: 

■ a. Revising paragraph (a) introductory 

text; 

■ b. Adding new paragraphs (c)(2)(vii) 

and (viii); 

The revisions and additions read as 

follows: 

§ 429.44 Commercial water heating 

equipment. 

(a) For residential-duty commercial 

water heaters, determine representations 

as provided in 10 CFR 429.17(a). 

* * * * * 

(c) * * * 

(2) * * * 

(vii) Residential-duty commercial gasfired and oil-fired storage water heaters 

tested for thermal efficiency and 

standby loss and rated pursuant to 10 

CFR 429.17(a)(2)(iii): Thermal efficiency 

in percent (%), maximum standby loss 

in British thermal units per hour (Btu/ 

h), uniform energy factor, rated storage 

volume (gal), and the nameplate input 

rate in British thermal units per hour 

(Btu/h). 

(viii) Residential-duty commercial 

gas-fired and oil-fired storage water 

heaters tested for uniform energy factor 

and rated pursuant to 10 CFR 

429.17(a)(1) or 10 CFR 429.17(a)(2)(i) 

through (ii): Uniform energy factor, 

rated storage volume (gal), first-hour 

rating (gal), and recovery efficiency 

(percent). 

* * * * * 

■ 5. Section 429.44 is further revised, 

effective [date one year after publication 

of final rule], to read as follows: 

■ a. Removing paragraph (c)(2)(vii); 

■ b. Redesignating paragraph (c)(2)(viii) 

as (c)(2)(vii); and 

■ c. Revising newly redesignated 

paragraph (c)(2)(vii) to read as follows: 

§ 429.44 Commercial water heating 

equipment. 

* * * * * 

(c) * * * 

(2) * * * 

(vii) Residential-duty commercial gasfired and oil-fired storage water heaters: 

Uniform energy factor, rated storage 

volume (gal), first-hour rating (gal), and 

recovery efficiency (percent). 

* * * * * 

PART 430—ENERGY CONSERVATION 

PROGRAM FOR CONSUMER 

PRODUCTS 

■ 6. The authority citation for part 430 

continues to read as follows: 

Authority: 42 U.S.C. 6291–6309; 28 U.S.C. 

2461 note. 

■ 7. Section 430.23 is amended by 

revising paragraph (e) to read as follows: 

§ 430.23 Test procedures for the 

measurement of energy and water 

consumption. 

* * * * * 

(e) Water Heaters. (1) For water 

heaters tested using energy factor: 

(i) The estimated annual operating 

cost for water heaters tested in terms of 

energy factor shall be— 

(A) For a gas or oil water heater, the 

product of the annual energy 

consumption, determined according to 

section 6.1.8 or 6.2.5 of appendix E to 

subpart B of 10 CFR part 430 of the 

January 1, 2015 edition of the Code of 

Federal Regulations, times the 

representative average unit cost of gas or 

oil, as appropriate, in dollars per Btu as 

provided by the Secretary. The resulting 

product shall be rounded off to the 

nearest dollar per year. 


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Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 20145 

(B) For an electric water heater, the 

product of the annual energy 

consumption, determined according to 

section 6.1.8 or 6.2.5 of appendix E to 

subpart B to 10 CFR part 430 of the 

January 1, 2015 edition of the Code of 

Federal Regulations, times the 

representative average unit cost of 

electricity in dollars per kilowatt-hour 

as provided by the Secretary, divided by 

3412 Btu per kilowatt-hour. The 

resulting quotient shall be rounded off 

to the nearest dollar per year. 

(ii) For an individual test, the tested 

energy factor for a water heater shall be 

determined by section 6.1.7 or 6.2.4 of 

appendix E to subpart B of 10 CFR part 

430 of the January 1, 2015 edition of the 

Code of Federal Regulations, rounded 

off to the nearest 0.01. 

(2) For water heaters tested using 

uniform energy factor: 

(i) The estimated annual operating 

cost shall be: 

(A) For a gas or oil water heater, the 

sum of: The product of the annual gas 

or oil energy consumption, determined 

according to section 6.1.10 or 6.2.7 of 

appendix E of this subpart, times the 

representative average unit cost of gas or 

oil, as appropriate, in dollars per Btu as 

provided by the Secretary; plus the 

product of the annual electric energy 

consumption, determined according to 

section 6.1.9 or 6.2.6 of appendix E of 

this subpart, times the representative 

average unit cost of electricity in dollars 

per kilowatt-hour as provided by the 

Secretary. The resulting sum shall be 

rounded off to the nearest dollar per 

year. 

(B) For an electric water heater, the 

product of the annual energy 

consumption, determined according to 

section 6.1.9 or 6.2.6 of appendix E of 

this subpart, times the representative 

average unit cost of electricity in dollars 

per kilowatt-hour as provided by the 

Secretary. The resulting product shall be 

rounded off to the nearest dollar per 

year. 

(ii) For an individual test, the tested 

uniform energy factor for a water heater 

shall be determined by section 6.1.7 or 

6.2.4 of appendix E of this subpart, 

rounded to the nearest 0.01. 

* * * * * 

■ 8. Section 430.32 is amended by 

revising paragraph (d) to read as 

follows: 

§ 430.32 Energy and water conservation 

standards and their compliance dates. 

* * * * * 

(d) Water heaters. The energy factor of 

each basic model of water heater shall 

not be less than the following: 

Product class Rated storage 

volume Draw pattern Uniform energy factor as of July 13, 2015* 

Gas-fired Storage ............................................ ≥ 20 gal and ≤ 55 gal ...................................... Very Small ............ 0.3263–(0.0019 × Vr) 

Low ....................... 0.5891–(0.0019 × Vr) 

Medium ................. 0.6326–(0.0013 × Vr) 

High ....................... 0.7128–(0.0025 × Vr) 

< 55 gal and ≤ 100 gal ................................... Very Small ............ 0.5352–(0.0007 × Vr) 

Low ....................... 0.7375–(0.0009 × Vr) 

Medium ................. 0.7704–(0.0010 × Vr) 

High ....................... 0.7980–(0.0010 × Vr) 

Oil-fired Storage .............................................. ≤ 50 gal ........................................................... Very Small ............ 0.2267–(0.0014 × Vr) 

Low ....................... 0.4867–(0.0006 × Vr) 

Medium ................. 0.6016–(0.0012 × Vr) 

High ....................... 0.6529–(0.0005 × Vr) 

Electric Storage ............................................... ≥ 20 gal and ≤ 55 gal ...................................... Very Small ............ 0.8268–(0.0002 × Vr) 

Low ....................... 0.9393–(0.0004 × Vr) 

Medium ................. 0.9683–(0.0007 × Vr) 

High ....................... 0.9656–(0.0004 × Vr) 

< 55 gal and ≤ 120 gal ................................... Very Small ............ 1.2701–(0.0011 × Vr) 

Low ....................... 1.9137–(0.0011 × Vr) 

Medium ................. 2.0626–(0.0011 × Vr) 

High ....................... 2.1858–(0.0011 × Vr) 

Tabletop Storage ............................................. ≥ 20 gal and ≤ 100 gal .................................... Very Small ............ 0.6808–(0.0022 × Vr) 

Low ....................... 0.8770–(0.0012 × Vr) 

Medium ................. 0.9063–(0.0009 × Vr) 

High ....................... 0.9302–(0.0006 × Vr) 

Gas-fired Instantaneous .................................. < 2 gal ............................................................. All .......................... 0.8036–(0.0019 × Vr) 

Electric Instantaneous ..................................... < 2 gal ............................................................. All .......................... 0.9192–(0.0013 × Vr) 

*Vr is rated storage volume. 

* * * * * 

PART 431—ENERGY EFFICIENCY 

PROGRAM FOR CERTAIN 

COMMERCIAL AND INDUSTRIAL 

EQUIPMENT 

■ 9. The authority citation for part 431 

continues to read as follows: 

Authority: 42 U.S.C. 6291–6317. 

■ 10. In § 431.106 revise paragraph (b) 

to read as follows: 

§ 431.106 Uniform test method for the 

measurement of energy efficiency of 

commercial water heaters and hot water 

supply boilers (other than commercial heat 

pump water heaters). 

* * * * * 

(b) Testing and Calculations. 

Determine the energy efficiency of each 

class of equipment by conducting the 

applicable test procedure(s), set forth in 

the three rightmost columns of the 

following table: 


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20146 Federal Register / Vol. 80, No. 71 / Tuesday, April 14, 2015 / Proposed Rules 

TABLE 1 TO § 431.106—TEST PROCEDURES FOR COMMERCIAL WATER HEATERS AND HOT WATER SUPPLY BOILERS

(OTHER THAN COMMERCIAL HEAT PUMP WATER HEATERS) 

Equipment type Energy efficiency 

descriptor Test procedure 

Test procedure 

required for compliance on and after With these additional stipulations 

Residential-Duty Commercial Water Heater.Uniform Energy Factor 10 CFR Part 430, 

Subpart B, Appendix E.

July 13, 2015.

Gas-fired Storage and 

Instantaneous 

Water Heaters and 

Hot Water Supply 

Boilers.

Thermal Efficiency ..... Use test set-up, 

equipment, and procedures in subsection labeled 

‘‘Method of Test’’ of 

ANSI Z21.10.3– 

2011**, Exhibit G1.

May 13, 2013 ............. A. For all products, the duration of the standby loss test shall be until whichever of the 

following occurs first after you begin to 

measure the fuel and/or electric consumption: (1) The first cut-out after 24 hours or 

(2) 48 hours, if the water heater is not in 

the heating mode at that time. 

Standby Loss ............. Use test set-up, 

equipment, and procedures in subsection labeled 

‘‘Method of Test’’ of 

ANSI Z21.10.3– 

2011**, Exhibit G2.

May 13, 2013 ............. B. For oil and gas products, the standby loss 

in Btu per hour must be calculated as follows: SL (Btu per hour) = S (% per hour) × 

8.25 (Btu/gal-F) × Measured Volume (gal) 

× 70 (degrees F). 

Oil-fired Storage and 

Instantaneous 

Water Heaters and 

Hot Water Supply 

Boilers.

Thermal Efficiency ..... ANSI Z21.10.3– 

2011**, Exhibit G1.

May 13, 2013 ............. C. For oil-fired products, apply the following 

in conducting the thermal efficiency and 

standby loss tests: (1) Venting Requirements—Connect a vertical length of flue 

pipe to the flue gas outlet of sufficient 

height so as to meet the minimum draft 

specified by the manufacturer. (2) Oil Supply—Adjust the burner rate so that: (a) 

The hourly Btu input rate lies within ±2 

percent of the manufacturer’s specified 

input rate, (b) the CO2 reading shows the 

value specified by the manufacturer, (c) 

smoke in the flue does not exceed No. 1 

smoke as measured by the procedure in 

ASTM–D2156–80 (reference for guidance 

only, see § 431.104), and (d) fuel pump 

pressure lies within ±10 percent of manufacturer’s specifications. 

Standby Loss ............. Use test set-up, 

equipment, and procedures in subsection labeled 

‘‘Method of Test’’ of 

ANSI Z21.10.3– 

2011**, Exhibit G2.

May 13, 2013.

Electric Storage and 

Instantaneous 

Water Heaters.

Standby Loss ............. Use test set-up, 

equipment, and procedures in subsection labeled 

‘‘Method of Test’’ of 

ANSI Z21.10.3– 

2011**, Exhibit G2.

May 13, 2013 ............. D. For electric products, apply the following 

in conducting the standby loss test: (1) Assume that the thermal efficiency (Et) of 

electric water heaters with immersed heating elements is 98 percent. (2) Maintain 

the electrical supply voltage to within ±5 

percent of the center of the voltage range 

specified on the water heater nameplate. 

(3) If the set up includes multiple adjustable thermostats, set the highest one first 

to yield a maximum water temperature in 

the specified range as measured by the 

topmost tank thermocouple. Then set the 

lower thermostat(s) to yield a maximum 

mean tank temperature within the specified range. 

E. Install water-tube water heaters as shown 

in Figure 2, ‘‘Arrangement for Testing 

Water-tube Type Instantaneous and Circulating Water Heaters.’’ 

** Incorporated by reference, see § 431.105. 


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1Any packaged boiler that provides service water, 

that meets the definition of ‘‘commercial packaged 

boiler’’ in subpart E of this part, but does not meet 

the definition of ‘‘hot water supply boiler’’ in 

subpart G, must meet the requirements that apply 

to it under subpart E. 

■ 11. Section 431.110 is revised to read 

as follows: 

§ 431.110 Energy conservation standards 

and their effective dates. 

Each commercial storage water heater, 

instantaneous water heater, unfired hot 

water storage tank and hot water supply 

boiler 1 (except for residential-duty 

commercial water heaters) must meet 

the applicable energy conservation 

standard level(s) as follows: 

Product Size 

Energy conservation standard a (products manufactured 

on and after October 29, 2003) b

Minimum thermal efficiency Maximum standby loss c

Electric storage water heaters ......................................... All ....................................... N/A ..................................... 0.30 + 27/Vm (%/hr) 

Gas-fired storage water heaters ...................................... ≤155,000 Btu/hr ................. 80% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

>155,000 Btu/hr ................. 80% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

Oil-fired storage water heaters ........................................ ≤155,000 Btu/hr ................. 78% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

>155,000 Btu/hr ................. 78% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

Gas-fired instantaneous water heaters and hot water 

supply boilers.

<10 gal .............................. 80% ................................... N/A 

≥10 gal ............................... 80% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

Oil-fired instantaneous water heaters and hot water 

supply boilers.

<10 gal .............................. 80% ................................... N/A 

≥10 gal ............................... 78% ................................... Q/800 + 110(Vr)1⁄2 (Btu/hr) 

Product Size Minimum thermal insulation 

Unfired hot water storage tank ........................................ All ....................................... R–12.5.

aVm is the measured storage volume and Vr is the rated volume, both in gallons. Q is the nameplate input rate in Btu/hr. bFor hot water supply boilers with a capacity of less than 10 gallons: (1) the standards are mandatory for products manufactured on and after 

October 21, 2005, and (2) products manufactured prior to that date, and on or after October 23, 2003, must meet either the standards listed in 

this table or the applicable standards in subpart E of this part for a ‘‘commercial packaged boiler.’’ cWater heaters and hot water supply boilers having more than 140 gallons of storage capacity need not meet the standby loss requirement if 

(1) the tank surface area is thermally insulated to R–12.5 or more, (2) a standing pilot light is not used and (3) for gas or oil-fired storage water 

heaters, they have a fire damper or fan assisted combustion. 

Each residential-duty commercial 

water heater, as defined in 10 CFR 

431.102, must meet the applicable 

energy conservation standard level as 

follows: 

Product class Draw pattern Uniform energy factor* 

Gas-fired Storage .......................................................................................................................... Very Small ............ 0.3261–(0.0006 x Vr) 

Low ....................... 0.5219–(0.0008 x Vr) 

Medium ................. 0.5585–(0.0006 x Vr) 

High ....................... 0.6044–(0.0005 x Vr) 

Oil-fired Storage ............................................................................................................................ Very Small ............ 0.3206–(0.0006 x Vr) 

Low ....................... 0.5577–(0.0019 x Vr) 

Medium ................. 0.6027–(0.0019 x Vr) 

High ....................... 0.5446–(0.0018 x Vr) 

* Vr is the rated storage volume. 

[FR Doc. 2015–07932 Filed 4–13–15; 8:45 am] 

BILLING CODE 6450–01–P 


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