Air Source Heat Pumps

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

How do air source heat pumps work?

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 extract heat from the air even when the outside temperature is as low as minus 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.

There are two main types:

An air-to-water system uses the heat to warm water. Heat pumps heat water to a lower temperature than a standard boiler system would, so they are more suitable for underfloor heating systems than radiator systems.
An air-to-air system produces warm air which is circulated by fans to heat your home.
Heat from the air is absorbed into a fluid which is pumped through a heat exchanger in the heat pump. Low grade heat is then extracted by the refrigeration system and, after passing through the heat pump compressor, is concentrated into a higher temperature useful heat capable of heating water for the heating and hot water circuits of the house.

The efficiency of air source heat pump systems is measured by a coefficient of performance (CoP) - the amount of heat they produce compared to the amount of electricity needed to run them. A typical CoP for an air source heat pump is around 2.5 when used with under floor heating; it can be less when used with radiators. The COP means that for every unit of electricity used to power the pump, 2.5 units of heat could be generated.

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The benefits of air source heat pumps

  • Reduce your fuel bills: air source heat pumps run on electricity, so there's no need to pay for gas, oil or solid fuels to heat your home. Emissions can be reduced further if the heat pump is powered by another renewable technology, such as solar electricity (PV)
  • No fuel deliveries required.
  • Can provide space heating and hot water
  • Can lower fuel bills, depending on what heating fuel you are replacing
  • It’s often classed as a ‘fit and forget’ technology because it needs little maintenance.
  • Can be easier to install than a ground source heat pump, but efficiencies are often lower.