Air source heat pumps

An air source heat pump (ASHP) absorbs heat from outside air at low temperature into a fluid, then boosts it to a higher temperature by passing the fluid through a compressor, and transfers its higher temperature heat to the heating and hot water circuits of the house. The pump needs some electricity to run, but it should use less electrical energy than the heat it produces. Alternatively you could consider using solar photovoltaic panels or a wind turbine (if you are in a suitable area) for a greener source of electricity.

There are two main types of ASHP systems.

1. Air-to-water
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.

2. Air-to-air
An air-to-air system produces warm air which is circulated by fans to heat your home. They are unlikely to provide you with hot water as well.

Depending on the type of system you install, this heat can then be used:

• To heat radiators
• Provide heat for underfloor heating systems
• To warm air which is circulated using fans
• To heat water in your home.

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 Incentive (RHI)
• 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
• Easy to install
• Some can be used for air conditioning in the summer

Image: Which