Here are some things to know about ASHPs: 

• How they work

ASHPs use electricity to power a fan that draws air through the heat pump, extracting heat into a refrigeration coil. The heat is then transferred to a fluid that's compressed to increase its temperature, which is then used to heat your home. 

• Types

There are two main types of ASHPs: air-to-water and air-to-air. Air-to-water ASHPs feed heat into your wet central heating system. 

• Sustainability

ASHPs are a low carbon way to heat your home and can be combined with other renewable and energy efficient technologies. 

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How does an air source heat pump work?

An air source heat pump takes heat from the outside air and boosts it to a higher temperature using a compressor. It then transfers the heat to the heating system in your home. They work a bit like refrigerators in reverse. 

1. The air source heat pump absorbs heat from the outside air into a liquid refrigerant at a low temperature.

2. Using electricity, the pump compresses the liquid to increase its temperature. It then condenses back into a liquid to release its stored heat.

3. Heat is sent to your radiators or underfloor heating. The remainder can be stored in your hot water cylinder.

4. You can use your stored hot water for showers, baths and taps.

The pump uses electricity to run, but it should use less electrical energy than the heat it produces. This makes it an energy efficient way to warm your home.

Air source heat pumps work even if the temperature is well below zero.

​​An air source heat pump is a low-carbon way of heating your home. They absorb latent heat from the outside air and use it to increase the temperature inside your home. 

Air source heat pumps look similar to air-conditioning units. Their size depends on how much heat they'll need to generate for your home – the more heat, the bigger the heat pump.

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Air-to-water heat pumps

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Air-to-water heat pumps take heat from the outside air and feed it into your wet central heating system. 

They're most suitable for homes with larger radiators or water underfloor heating because the heat they produce is cooler than that from a conventional gas or oil boiler. To be most effective, they need a large surface area to release the heat.

It is more straightforward to incorporate underfloor heating for a heat pump while you're extending your home or in a new-build property. It can also cost less than retrofitting underfloor heating later on.