Air Source Heat Pumps

Air source heat pumps (ASHPs) absorb heat from the outside air. This heat can then be used to heat radiators, underfloor heating systems, or warm air convectors and hot water in your home.

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.

The benefits of air source heat pumps

  • Lower fuel bills, especially if you are replacing conventional electric heating

  • potential income through the UK government’s Renewable Heat Initiative

  • lower home carbon emissions, depending on which fuel you are replacing

  • no fuel deliveries needed

  • can heat your home as well as your water

  • minimal maintenance required

  • can be easier to install than a ground source heat pump.

Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods.

During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won't feel as hot to the touch as they might do when you are using a gas or oil boiler.

Hybrid heat pumps

In a well-insulated property, air-source heat pumps can provide all your heating needs by themselves. However, in older properties where it is not possible to insulate to a high enough standard for heat pumps to be fully effective on their own, you can have another heating system in place alongside the heat pump, usually a traditional gas or oil-fired boiler.

This set up is called a hybrid heat pump* or a bivalent system. With these systems, most of the time the heat pump will provide all your heating needs, and the gas or oil boiler will be switched off. However, on occasions when the heat pump is not able to provide enough heat on its own, such as when outdoor temperatures are very low and your heating demand is high, the fossil fuel boiler turns on.

The system can either be set up so that the heat pump then switches off, allowing the boiler to provide all your heat, or it can be set up for both systems to run at the same time. This will depend on the design of your particular system and which set-up is likely to be more cost-effective for you.