How does a heat pump work? It may be valuable to review the “How does an air conditioner work?” blog first, since most of the principles are the same, and a heat pump functions as an air conditioner during warm weather. Both functions depend on the transfer of heat by coils. When operating as an AC, heat is transferred from inside to outside through the properties of a refrigerant cycling from a high-pressure liquid to a low-pressure gas. In the heating mode the situation is basically reversed, with the available heat in the outside air being transferred to the inside coil and released into the ductwork. In both situations the desired effect is accomplished by the ability of the refrigerant to absorb heat and of the coils to give up that heat to the surrounding air.

Although heat pumps are very efficient and environmentally friendly, there are limitations. If the outside temperature falls below a certain point, the amount of heat pulled from the air can’t keep up with the heating requirements. At that point an electric heat strip kicks in as a supplement, with a corresponding drop in efficiency. In our area the advantages far out weigh the occasional need to use the back up heat!

Just remember, a heat pump is basically an air conditioner working backwards.