A heat pump uses air conditioning principles to extract heat from one place and deliver it to another, with one big difference: the system is reversible. In addition to expelling heat from indoors, the system can be reversed to warm rooms in the winter.
Split air-source systems have a compressor, coil, fan and reversing valve unit outdoors that is connected with refrigerant-filled tubing to an indoor unit that contains a fan, indoor coil and a supplemental resistance heating element.
A blower draws room air in through a filter and passes it across the indoor coil. Air passing by indoor coil either gathers or gives off heat- depending on whether the system is set to warm or cool. Ductwork and registers deliver warmed or cooled air to rooms.
Electrical power is supplied through fused disconnect. A thermostat turns heat pump off and on with changes in indoor air temperature. --Don Vandervort
