The basic components of a field erected heat pump system consist of a refrigeration compressor, a cooler to dissipate unwanted heat to the atmosphere when not required for storage, buried insulated water storage tank, chilled water and condenser water circulating pumps, heating and cooling coils and an emergency back-up boiler for heating. An automatic temperature control system must be provided employing three-way by-pass or diverting valves, heat sensors, limit controls and thermostats

Three types of compressors can be used for the construction of a heat pump system -- a reciprocating compressor, a centrifugal compressor or a screw type compressor. Historically, maintenance costs have been higher for reciprocating type compressors than for centrifugal compressors, while three stage centrifugal compressors have a higher KW per Ton operating cost utilizing 130°F (54.4°C) condensing water temperatures over single or two stage centrifugal machines saving 105°F (40.6°C) condensing water temperature.