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 | Et | = | 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 | Ec | = | 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. |