Different from a ground source heat pump, an air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside.
It can get heat from the air even when the temperature is as low as -15° C.
Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.
An air-to-water system distributes heat via your wet central heating system. Heat pumps work much more efficiently at a lower temperature than a standard boiler system would. This makes them more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.