A heat pump is an electrically powered, reversible-cycle refrigeration unit capable of both heating and
cooling the interior of a structure.
The heat source is commonly
either outside air (in the air-to-air type heat pump) or a closed loop of circulating water (in the water-to-air type heat pump). The former is the most popular type heat pump used for single family dwellings. The water-to-air heat pump
system is most often
found in multifamily structures.
These are essentially central
heating systems, with the heat pump replacing the
central furnace or boiler as the heat generating unit.
Operating valves in the heat pump unit control the reversal of the refrigeration cycle. It removes heat from the interior of the
structure and discharges it
outside during hot weather, and supplies heat to the interior spaces during
period of cold weather.
The basic components of a heat pump
installation are: the compressor, the condenser, the evaporator, and a low-voltage thermostat.