A heat pump is a mechanical device used for heating and cooling which operates by pumping heat from a cooler to a warmer location.
Heat pumps can extract heat from air, water or the earth.
You might think of the heat pump as an air conditioner that can operate in either direction. It consists of an inside and outside unit, each containing a coil. The outside unit has a compressor. Both coils are connected by tubing, and inside the tubing is liquid refrigerant, which has the ability to absorb and release heat. In the summer, warm air inside your home is absorbed by the refrigerant in the inside unit, which cools the air in the inside coil and then blows that cooled air into your home.