What is a heat pump??

In summer a heat pump draws heat out of your home to cool it. In the winter, it draws heat from outside air into your home to warm it. Many heat pumps have a booster electrical-resistance heater that automatically heats outside air even more. Outside air always has heat in it -- even at very low outdoor temperatures.

The efficiency of heat pumps is rated using SEER (for cooling efficiency) and HSPF (for heating efficiency). A heat pump uses electricity as its power source.