A heat pump is a proven heating and cooling system that uses a refrigerant to transfer heat energy between indoor and outdoor environments. The refrigerant travels within a closed loop between an external unit and an internal unit.
When the temperature rises indoors the heat pump works like an air conditioner. When the temperature drops indoors, the cycle is reversed and the system works like a heater. In heating mode the refrigerant absorbs heat from the outside air and uses it to warm up the interior of your home, even in the middle of winter.