Wash. Admin. Code § 51-11C-403325 - Table C403.3.2(5)-Minimum efficiency requirements-Warm air furnaces and unit heaters

Table C403.3.2(5)

Warm Air Furnaces and Combination Warm Air Furnaces/Air-Conditioning Units, Warm Air Duct Furnaces and Unit Heaters-Minimum Efficiency Requirements

Equipment Type	Size Category (Input)	Subcategory or Rating Condition	Minimum Efficiencyd,c	Test Procedurea
Warm-air furnace, gas fired for application outside the U.S.	< 225,000 Btu/h	Maximum capacityc	80% AFUE (nonweatherized) or 1% AFUE (weatherized) or 80% Etb,d	DOE 10 C.F.R. 430 Appendix N or Section 2.39, Thermal Efficiency, ANSI Z21.47
Warm-air furnace, gas fired	< 225,000 Btu/h	Maximum capacityc	80% Etb,d before 1/1/2023 81% Etd after 1/1/2023	Section 2.39, Thermal Efficiency, ANSI Z21.47
Warm-air furnace, oil fired	< 225,000 Btu/h	Maximum capacityc	83% AFUE (nonweatherized) or 78% AFUE (weatherized) or 80% Etb,d	DOE 10 C.F.R. 430 Appendix N or Section 42, Combustion UL 727
Warm-air furnace, oil fired	< 225,000 Btu/h	Maximum capacityc	80% Et before 1/1/2023 82% Etd after 1/1/2023	Section 42, Combustion UL 727
Electric furnaces for applications outside the U.S.	< 225,000 Btu/h	All	96% AFUE	DOE 10 C.F.R. 430 Appendix N
Warm air duct furnaces, gas fired	All capacities	Maximum capacityc	80% Ece	Section 2.10, Efficiency, ANSI Z83.8
Warm air unit heaters, gas fired	All capacities	Maximum capacityc	80% Ece,f	Section 2.10, Efficiency, ANSI Z83.8
Warm air unit heaters, oil fired	All capacities	Maximum capacityc	80% Ece,f	Section 40, Combustion, UL 731

For SI: 1 British thermal unit per hour = 0.2931 W.

^a Chapter 6 contains a complete specification of the referenced standards, which include test procedures, including the referenced year version of the test procedure.

^b Combination units (i.e., furnaces contained within the same cabinet as an air conditioner) not covered by DOE 10 C.F.R. 430 (i.e., 3-phase power or with cooling capacity greater than or equal to 65,000 Btu/h) may comply with either rating. All other units greater than 225,000 Btu/h sold in the U.S. must meet the AFUE standards for consumer products and testing using U.S. DOE's AFUE test procedure at DOE 10 C.F.R. 430 Subpart B, Appendix N.

^c Compliance of multiple firing rate units shall be at the maximum firing rate.

^d E_t = Thermal efficiency. Units must also include an interrupted or intermittent ignition device (IID), have jacket losses not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.

^e E_c = Combustion efficiency (100% less flue losses). See test procedure for detailed discussion.

^f Units must also include an interrupted or intermittent ignition device (IID) and have either power venting or an automatic flue damper.

^g This table is a replica of ASHRAE 90.1 Table 6.8.1-5 Warm-Air Furnaces and Combination Warm-Air Furnaces/Air-Conditioning Units, Warm-Air Duct Furnaces, and Unit Heaters-Minimum Efficiency Requirements.

Notes

Wash. Admin. Code § 51-11C-403325

Adopted by WSR 22-14-091, Filed 7/1/2022, effective 7/1/2023