(a) Scope. This section prescribes the test requirements used to measure the energy efficiency of commercial warm air furnaces with a rated maximum input of 225,000 Btu per hour or more.

(b) Testing and calculations—(1) Thermal efficiency. Test in accordance with appendix A to subpart D of this part when making representations of thermal efficiency.

(2) Thermal efficiency two. Test in accordance with appendix B to subpart D of this part when making representations of thermal efficiency two.