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Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / Proposed Rules supply temperature in section 2.2 of Appendix J2 to between 130 F 54.4 C
and 135 F 57.2 C for all clothes washers, but maintained 135 F as the target temperature. 80 FR 46729, 46734
46735.
DOE analyzed household water temperatures as part of the test procedure final rule for residential and commercial water heaters published July 11, 2014. 79 FR 40541 July 2014
Water Heater Final Rule. In the July 2014 Water Heater Final Rule, DOE
revised the hot water delivery temperature from 135 F to 125 F based on an analysis of data showing that the average set point temperature for
consumer water heaters in the field is 124.2 F 51.2 C, which was rounded to the nearest 5 F, resulting in a test set point temperature of 125 F. 79 FR
40541, 40554. Additionally, a 2011
compilation of field data across the United States and southern Ontario by Lawrence Berkeley National Laboratory LBNL 17 found a median daily outlet water temperature of 122.7 F 50.4 C.
Id. Further, DOE noted in the July 2014
Water Heater Final Rule that water heaters are commonly set with temperatures in the range of 120 F to 125 F. Id.
Additionally, DOEs consumer dishwasher test procedure, codified at
49149

10 CFR part 430 subpart B, appendix C1
Appendix C1, specifies a hot water supply temperature of 120 F 2 F for water-heating dishwashers designed for heating water with a nominal inlet temperature of 120 F, which includes nearly all consumer dishwashers currently on the U.S. market. Section 2.3.2 of Appendix C1. This water supply temperature is intended to be representative of household hot water temperatures.
Table III.1 summarizes the various hot water temperature data considered for the present rulemaking.

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TABLE III.1SUMMARY OF FIELD SURVEYS OF WATER HEATER TEMPERATURE
Temperature F

Source
Description
May 2011 LBNL Report
July 2014 Water Heater Final Rule
July 2014 Water Heater Final Rule
Appendix C1

Median daily outlet water temperature
Average set point temperature for consumer water heaters in the field
Common water heater setpoints
Dishwasher test procedure supply temperature

122.7
124.2
120125
120

In the May 2020 RFI, DOE requested comments on whether DOE should consider updating the hot water supply temperature specification for the clothes washer test procedures to be within the range of 120 F to 125 F, providing better consistency with DOEs test procedures for dishwashers and consumer water heaters. 85 FR 31065, 31069.
AHAM suggested that product design changes may be required if DOE amends the clothes washer test procedures to harmonize the hot water supply temperature with the dishwasher test procedure. AHAM stated that changing the hot water supply temperature specification would impact measured efficiency, and DOE would thus need to address that change in the accompanying standards rulemaking.
AHAM, No. 5 at p. 6
GEA stated that there is little benefit to consumers by moving the target temperature to 120 F. If DOE does change the target temperature, GEA is concerned about the change in measured hot water energy usage. GEA, No. 13 at p. 2
The CA IOUs recommended keeping the target temperature at 135 F to prevent the growth of Legionella bacteria. The CA IOUs referenced the American Society of Sanitary Engineering ASSE Scald Awareness Task Group and Unified Plumbing Code UPC recommendations that hot water temperature should be 130140 F

to eliminate the risk of Legionella growth. CA IOUs, No. 8 at pp. 1415
The Joint Commenters stated that DOE should consider changing the target temperature to 120 F, because 120 F is the hot water supply temperature for the consumer dishwasher test procedure and is a common water heater set point. Joint Commenters, No. 10 at p. 3 However, the Joint Commenters also stated that the 135 F target temperature may be appropriate to maintain as average set points increase in the field due to Legionella concerns. The Joint Commenters encouraged DOE to investigate which hot water supply temperature would be most representative. Id.
UL supports specifying the hot water supply temperature to be consistent with hot water heater outlet temperatures, as supported by field data. UL, No. 9 at p. 1
Samsung recommended that DOE
specify a hot water supply temperature of 120 2 F, consistent with the temperature specified in the consumer dishwasher test procedure. Samsung also commented that the U.S. Consumer Product Safety Commission recommends this temperature to consumers as the safest set point for water heaters to avoid scalds. Samsung, No. 6 at p. 3
NEEA encouraged DOE to investigate the hot water supply temperature that would be most representative of field
use. NEEA added that water heater set points may increase closer to the Appendix J2-specified 135 F in the future, due to concerns about Legionella bacteria growth. NEEA, No. 12 at p. 26
NEEA also recommended that DOE
consider heat losses in the pipes and static water in the supply line in the field, which are likely to lower clothes washer inlet hot temperatures relative to water heater set points. Id.
Based on the analysis of recent water temperature data summarized in Table III.1, DOE is proposing to update the hot water supply temperature in the proposed new Appendix J from 130
135 F to 120125 F. DOE preliminarily concludes that an inlet temperature of 120125 F is more representative of consumer hot water temperatures than the range of 130135 F currently specified in Appendix J2.
In addition, section 4.1.2 of Appendix J2 calculates the hot water energy consumption for each tested load size, by multiplying the hot water consumption for each tested load size, by T, the temperature rise, and by K, the specific heat of water. In Appendix J2, T is defined as 75 F, which represents the nominal difference between the hot and cold water inlet temperatures. In this NOPR, DOE is proposing to use a value for T of 65 F
in the proposed new Appendix J, consistent with the differential between the nominal values for the proposed hot
17 Lutz, JD, Renaldi, Lekov A, Qin Y, and Melody M, Hot Water Draw Patterns in Single Family
Houses: Findings from Field Studies, LBNL Report
number LBNL4830E May 2011. Available at www.escholarship.org/uc/item/2k24v1kj.

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