10 C.F.R. § 431.110

Current through September 30, 2024

Section 431.110 - Energy conservation standards and their effective dates

(a) Each commercial storage water heater, instantaneous water heater, and hot water supply boiler (excluding residential-duty commercial water heaters) must meet the applicable energy conservation standard level(s) as specified in the table to this paragraph. Any 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 of this part, must meet the requirements that apply to it under subpart E of this part.

Table 1 to § 431.110(a) -Commercial Water Heater Energy Conservation Standards

Equipment	Size	Energy conservation standards a
		Minimum thermal efficiency (equipment manufactured on and after October 9, 2015) (%)	Minimum thermal efficiency (equipment manufactured on and after October 6, 2026) (%)	Maximum standby loss (equipment manufactured on and after October 29, 2003) b	Maximum standby loss (equipment manufactured on and after October 6, 2026) b
Electric storage water heaters	All	N/A	N/A	0.30 + 27/V m (%/h)	0.30 + 27/V m (%/h)
Gas-fired storage water heaters and storage-type instantaneous water heaters	All	80	95	Q/800 + 110(V r )1/2 (Btu/h)	0.86 * [Q/800 + 110(V r )1/2 ] (Btu/h)
Oil-fired storage water heaters	All	80	80	Q/800 + 110(V r )1/2 (Btu/h)	Q/800 + 110(V r )1/2 (Btu/h)
Electric instantaneous water heaters c	10 gal [GREATER THAN EQUAL TO]10 gal	80 77	80 77	N/A 2.30 + 67/V m (%/h)	N/A 2.30 + 67/V m (%/h)
Gas-fired instantaneous water heaters and hot water supply boilers	10 gal [GREATER THAN EQUAL TO]10 gal	80 80	96 96	N/A Q/800 + 110(V r )1/2 (Btu/h)	N/A Q/800 + 110(V r )1/2 (Btu/h)
Oil-fired instantaneous water heater and hot water supply boilers	10 gal [GREATER THAN EQUAL TO]10 gal	80 78	80 78	N/A Q/800 + 110(V r )1/2 (Btu/h)	N/A Q/800 + 110(V r )1/2 (Btu/h)

^a V _m is the measured storage volume, and V _r is the rated storage volume, both in gallons. Q is the rated input in Btu/h, as determined pursuant to 10 CFR 429.44 .

^b Water heaters and hot water supply boilers with a rated storage volume greater than 140 gallons need not meet the standby loss requirement if:

(1) The tank surface area is thermally insulated to R-12.5 or more, with the R-value as defined in § 431.102

(2) A standing pilot light is not used; and

(3) For gas-fired or oil-fired storage water heaters, they have a flue damper or fan-assisted combustion.

^c The compliance date for energy conservation standards for electric instantaneous water heaters is January 1, 1994.

(b) Each unfired hot water storage tank manufactured on and after October 29, 2003, must have a minimum thermal insulation of R-12.5.

(c) Each residential-duty commercial water heater must meet the applicable energy conservation standard level(s) as follows:

Table 2 to § 431.110(c) -Residential-Duty Commercial Water Heater Energy Conservation Standards

Equipment	Specifications a	Draw pattern	Uniform energy factor b
			Equipment manufactured before October 6, 2026	Equipment manufactured after October 6, 2026
Gas-fired storage	75 kBtu/hr and [LESS THAN EQUAL TO]105 kBtu/hr and [LESS THAN EQUAL TO]120 gal	Very Small Low Medium High	0.2674-(0.0009 * V r ) 0.5362-(0.0012 * V r ) 0.6002-(0.0011 * V r ) 0.6597-(0.0009 * V r )	0.5374-(0.0009 * V r ) 0.8062-(0.0012 * V r ) 0.8702-(0.0011 * V r ) 0.9297-(0.0009 * V r )
Oil-fired storage	105 kBtu/hr and [LESS THAN EQUAL TO]140 kBtu/hr and [LESS THAN EQUAL TO]120 gal	Very Small Low Medium High	0.2932-(0.0015 * V r ) 0.5596-(0.0018 * V r ) 0.6194-(0.0016 * V r ) 0.6470-(0.0013 * V r )	0.2932-(0.0015 * V r ) 0.5596-(0.0018 * V r ) 0.6194-(0.0016 * V r ) 0.6470-(0.0013 * V r )
Electric instantaneous	12 kW and [LESS THAN EQUAL TO]58.6 kW and [LESS THAN EQUAL TO]2 gal	Very Small Low Medium High	0.80 0.80 0.80 0.80	0.80 0.80 0.80 0.80

^a Additionally, to be classified as a residential-duty commercial water heater, a commercial water heater must meet the following conditions: (1) If the water heater requires electricity, it must use a single-phase external power supply; and (2) The water heater must not be designed to heat water to temperatures greater than 180 °F.

^b V _r is the rated storage volume (in gallons), as determined pursuant to 10 CFR 429.44 .

10 C.F.R. §431.110

81 FR 96238, Dec. 29, 2016

81 FR 96238, 12/29/2016; 88 FR 69822, 12/5/2023