10 CFR 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 alternative efficiency determination method (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 energy consumption or other measure of energy use 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:
(2) The upper 95percent 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 95percent onetailed confidence interval with n1 degrees of freedom (from Appendix A).
(B) Any represented value of energy efficiency 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:
(2) The lower 95percent 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 95percent onetailed confidence interval with n1 degrees of freedom (from Appendix A).
(C) 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.
(D) Any represented value of firsthour rating or maximum gallons per minute (GPM) must be equal to the mean of the measured firsthour ratings or measured maximum GPM ratings, respectively, of all the units within the sample.
(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) Determine the represented value for each basic model 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 of paragraph (a)(1) of this section; or
(ii) Calculate the uniform energy factor for each test sample by applying the following mathematical conversion factors to test data previously obtained through testing according to 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. Represented values of uniform energy factor, firsthour rating, and maximum GPM rating based on a calculation using this mathematical conversion factor must be determined using the applicable sampling provisions in paragraphs (a)(1)(i) and (ii) of this section.
(A) Calculate the New First Hour Rating (New FHR) or New Max Gallons per Minute (New Max GPM), as applicable, using the equations presented in the table in this paragraph.
Product class  Distinguishing criteria  Conversion factor * 

Consumer Gasfired Water Heater  NonCondensing, Standard and Low NO 
New FHR = 7.9592 0.8752 × FHR 
NonCondensing, UltraLow NO 
New FHR = 25.0680 0.6535 × FHR 

Condensing  New FHR = 1.0570 × FHR 

Consumer Oilfired Water Heater  N/A  New FHR = 0.9102 × FHR 
Consumer Electric Water Heater  Electric Resistance  New FHR = 9.2827 0.8092 × FHR 
Heat Pump  New FHR = −4.2705 0.9947 × FHR 

Tabletop Water Heater  N/A  New FHR = 41.5127 0.1989 × FHR 
Instantaneous Gasfired Water Heater  N/A  New Max GPM = 1.1461 × Max GPM 
Instantaneous Electric Water Heater  N/A  New Max GPM = 1.1461 × Max GPM 
GridEnabled Water Heater  N/A  New FHR = 9.2827 0.8092 × FHR 
ResidentialDuty Commercial Gasfired Water Heater  N/A  New FHR = −35.8233 0.4649 × V 
ResidentialDuty Commercial Oilfired Water Heater  N/A  New FHR = −35.8233 0.4649 × V 
ResidentialDuty Commercial Electric Instantaneous Water Heater  N/A  New Max GPM = 0.0146 0.0295 × Q. 
FHRP = prior firsthour rating.
Max GPMP = prior maximum GPM rating.
Q = nameplate input rate, in kBtu/h.
Et = thermal efficiency rating.
Vm = measured storage volume in gallons.
(B) Determine the applicable draw pattern as follows:
(1) For consumer gasfired water heaters, consumer oilfired water heaters, consumer electric water heaters, tabletop water heaters, gridenabled water heaters, residentialduty commercial gas water heaters, residentialduty commercial oilfired water heaters: Use the New FHR (as defined in paragraph (a)(2)(ii)(A) of this section) to select the applicable draw pattern from the table in this paragraph:
New FHR greater than or equal to:  and new FHR less than:  Draw pattern 

0 gallons  18 gallons  Very Small. 
18 gallons  51 gallons  Low. 
51 gallons  75 gallons  Medium. 
75 gallons  No upper limit  High. 
(2) For instantaneous gasfired water heaters, instantaneous electric water heaters, and residentialduty commercial electric instantaneous water heaters: Use New Max GPM (as defined in paragraph (a)(2)(ii)(A) of this section) to select the applicable draw pattern from the table in this paragraph:
New max GPM greater than or equal to:  And new max GPM rating less than:  Draw pattern 

0 gallons/minute  1.7 gallons/minute  Very Small. 
1.7 gallons/minute  2.8 gallons/minute  Low. 
2.8 gallons/minute  4 gallons/minute  Medium. 
4 gallons/minute  No upper limit  High. 
(C) For consumer electric heat pump water heaters, use the draw pattern to determine the applicable drawn volume (DV) from the table in this paragraph:
Draw pattern  DV 

Very Small  10 gallons. 
Low  38 gallons. 
Medium  55 gallons. 
High  84 gallons. 
(D) For each class besides consumer electric heat pump water heaters, use the applicable equation to calculate: UEFWHAM (for consumer storage water heatersexcept heat pumps), UEFmodel (for consumer instantaneous water heaters), UEFrd (for residentialduty commercial storage water heaters), and UEFrd, model (for residentialduty commercial electric instantaneous water heaters) as follows:
(1) For consumer storage water heaters (except consumer electric heat pump 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 energy factor; ηr is the recovery efficiency in decimal form; and P is the input rate in Btu/h.
Draw pattern  a  b  c  d 

Very Small  0.250266  57.5  0.039864  67.5 
Low  0.065860  57.5  0.039864  67.5 
Medium  0.045503  57.5  0.039864  67.5 
High  0.029794  57.5  0.039864  67.5 
(2) For consumer instantaneous water heaters:
Where ηr is the recovery efficiency expressed in decimal form and A is dependent upon the applicable draw pattern and fuel type as specified in the table in this paragraph.
Draw pattern  A  

Electric  Gas  
Very Small  0.003819  0.026915 
Low  0.001549  0.010917 
Medium  0.001186  0.008362 
High  0.000785  0.005534 
(3) For residentialduty commercial storage water heaters:
Where P is the input rate in Btu/h; Et is the thermal efficiency; SL is the standby loss in Btu/h; and F and G are coefficients as specified in the table in this paragraph based on the applicable draw pattern.
Draw pattern  F  G 

Very Small  0.821429  0.0043520 
Low  0.821429  0.0011450 
Medium  0.821429  0.0007914 
High  0.821429  0.0005181 
(4) For residentialduty commercial electric instantaneous water heaters:
Where Et is the thermal efficiency expressed in decimal form and A is dependent upon the applicable draw pattern, as specified in the table in this paragraph.
Draw pattern  A 

Very Small  0.003819 
Low  0.001549 
Medium  0.001186 
High  0.000785 
(E) Calculate the “New UEF” (i.e., the converted UEF) using the applicable equation in the table in this paragraph.
Product class  Distinguishing criteria  Conversion factor 

Consumer Gasfired Water Heater  NonCondensing, Standard and Low NO 
New UEF = −0.0002 0.9858 × UEF 
NonCondensing, UltraLow NO 
New UEF = 0.0746 0.8653 × UEF 

Condensing  New UEF = 0.4242 0.4641 × UEF 

Consumer Oilfired Water Heater  N/A  New UEF = −0.0033 0.9528 × UEF 
Consumer Electric Water Heater  Electric Resistance  New UEF = 0.4774 0.4740 × UEF 
Heat Pump  New UEF = 0.1513 0.8407 × EF 0.0043 × DV.  
Tabletop Water Heater  N/A  New UEF = −0.3305 1.3983 × UEF 
Instantaneous Gasfired Water Heater  N/A  New UEF = 0.1006 0.8622 × UEF 
Instantaneous Electric Water Heater  N/A  New UEF = 0.9847 × UEF 
GridEnabled Water Heater  N/A  New UEF = 0.4774 0.4740 × UEF 
ResidentialDuty Commercial Gasfired Water Heater  N/A  New UEF = −0.0022 1.0002 × UEF 
ResidentialDuty Commercial Oilfired Water Heater  N/A  New UEF = −0.0022 1.0002 × UEF 
ResidentialDuty Commercial Electric Instantaneous Water Heater  N/A  New UEF = UEF 
New UEF = converted UEF.
EF = Energy Factor.
(b)Certification reports.
(1) The requirements of 10 CFR 429.12 apply; and
(2) Pursuant to 10 CFR 429.12(b)(13), a certification report must include the following public, productspecific information:
(i) For storagetype water heater basic models previously certified for energy factor pursuant to § 429.17(a) of the January 1, 2015 edition of the Code of Federal Regulations, and for which uniform energy factor is calculated pursuant to 10 CFR 429.17(a)(2)(ii): The energy factor (EF, rounded to the nearest 0.01), the uniform energy factor (UEF, rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the uniform energy factor test procedure firsthour rating in gallons (gal, rounded to the nearest 1 gal) as determined under paragraph (a)(2)(ii)(A) of this section, the previously certified firsthour rating under the energy factor test procedure in gallons (gal, rounded to the nearest 1 gal), and the recovery efficiency in percent (%, rounded to the nearest 1%);
(ii) For storagetype water heater basic models rated pursuant to 10 CFR 429.17(a)(1) or 10 CFR 429.17(a)(2)(i): The uniform energy factor (UEF, rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the firsthour rating in gallons (gal, rounded to the nearest 1 gal), and the recovery efficiency in percent (%, rounded to the nearest 1%);
(iii) For instantaneoustype water heater basic models previously certified for energy factor pursuant to § 429.17(a) of the January 1, 2015 edition of the Code of Federal Regulations, and for which uniform energy factor is calculated pursuant to 10 CFR 429.17(a)(2)(ii): The energy factor (EF, rounded to the nearest 0.01), the uniform energy factor (UEF. rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the uniform energy factor test procedure maximum gallons per minute (gpm, rounded to the nearest 0.1 gpm) as determined under paragraph (a)(2)(ii)(A) of this section, the previously certified maximum gallons per minute (gpm, rounded to the nearest 0.1 gpm) under the energy factor test procedure, and the recovery efficiency in percent (%, rounded to the nearest 1%);
(iv) For instantaneoustype water heater basic models rated pursuant to 10 CFR 429.17(a)(1) or 10 CFR 429.17(a)(2)(i): The uniform energy factor (UEF, rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the maximum gallons per minute (gpm, rounded to the nearest 0.1 gpm), and the recovery efficiency in percent (%, rounded to the nearest 1%);
(v) For gridenabled water heater basic models previously certified for energy factor pursuant to 10 CFR 429.17(a) of the January 1, 2015 edition of the Code of Federal Regulations, and for which uniform energy factor is calculated pursuant to 10 CFR 429.17(a)(2)(ii): The energy factor (EF, rounded to the nearest 0.01), the uniform energy factor (UEF, rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the uniform energy factor test procedure firsthour rating in gallons (gal, rounded to the nearest 1 gal) as determined under paragraph (a)(2)(ii)(A) of this section, the previously certified firsthour rating under the energy factor test procedure in gallons (gal, rounded to the nearest 1 gal), the recovery efficiency in percent (%, rounded to the nearest 1%), a declaration that the model is a gridenabled water heater, whether it is equipped at the point of manufacture with an activation lock, and whether it bears a permanent label applied by the manufacturer that advises purchasers and endusers of the intended and appropriate use of the product; and
(vi) For gridenabled water heater basic models rated pursuant to 10 CFR 429.17(a)(1) or 10 CFR 429.17(a)(2)(i): The uniform energy factor (UEF, rounded to the nearest 0.01), the rated storage volume in gallons (gal, rounded to the nearest 1 gal), the firsthour rating in gallons (gal, rounded to the nearest 1 gal), and the recovery efficiency in percent (%, rounded to the nearest 1%), a declaration that the model is a gridenabled water heater, whether it is equipped at the point of manufacture with an activation lock, and whether it bears a permanent label applied by the manufacturer that advises purchasers and endusers of the intended and appropriate use of the product.