An air source heat pump (ASHP) is a system which transfers heat from outside to inside a building, or vice versa. Under the principles of vapor compression refrigeration, an ASHP uses a refrigerant system involving a compressor and a condenser to absorb heat at one place and release it at another. They can be used as a space heater or cooler, and are sometimes called "reverse-cycle air conditioners".

In domestic heating use, an ASHP absorbs heat from outside air and releases it inside the building, as hot air, hot water-filled radiators, underfloor heating and/or domestic hot water supply.


On average, air source systems offer savings of around 38% when compared to traditional gas fired central heating systems, and offer far more flexibility than other types of electric heating systems. Free Air Source Heating is accredited to install Air Source Heat Pumps under the Low Carbon Building Programme, and installs only accredited equipment.