Air-to-water heat pumps

Air-to-water heat pumps are air source heat pumps that extract heat from outside air and transfer it into a water-based heating circuit for space heating and domestic hot water. In home energy paperwork, the phrase usually points to the outdoor heat pump unit and its connected wet central heating system, including radiators, underfloor heating, fan coil units or a hot water cylinder. The term is separate from air-to-air heat pumps, ground or water source heat pumps, heat-loss calculations, emitter sizing, planning permission, Boiler Upgrade Scheme eligibility, MCS certification, DNO approval and any promise of running cost, noise or comfort performance.