An air source heat pump, sometimes referred to as an air-to-water source heat pump, transfers heat from the outside air to water. This in turn heats your rooms via radiators or underfloor heating. It can also heat water stored in a hot water cylinder for your hot taps, showers and baths.
Heat from the air is absorbed into a fluid. This fluid then passes through a heat exchanger into the heat pump, which raises the temperature and then transfers that heat to water.
For more information on how a heat pump works, including details on typical savings, system design and control, see our in depth guide to heat pumps.