Early this year we installed a dual fuel 15 SEER2 heat pump with a 96 AFUE backup furnace. It was also our first A2L system since the refrigerant changeover. Today, I finally got a chance to dial in the refrigerant charge and fully commission the cooling system.

We designed everything from system selection to ductwork. And finally getting to test everything is very gratifying, because we can now confirm the BTU/hr delivered and SEER in real time. Below is what we designed for and the results after installation.

-load calculation for home: 19,407 BTU/hr required

-equipment rated capacity: 21,795 BTU/hr

-final BTU/hr delivered: 21,393 BTU/hr @ 15.9 SEER2

The results emphasize 2 things: (1) We cannot go by nominal tonnage when sizing equipment. (2) Proper commissioning is the only way to truly verify that you get the efficiency you paid for.