How do Air source heat pumps work?

An air source pump is an alternative way to heat your home. It will allow you to create your own renewable heat and save money on your ever-increasing energy bills.

An Air Source Heat Pump delivers heat at lower temperatures than gas and oil boilers.

Heat pumps can save you more on your heating bills if you're replacing an expensive system such as electric storage heaters, oil, LPG (liquefied petroleum gas) or coal, rather than gas (a well-insulated home is essential thou – otherwise the heat the pump is generating escapes) .

An air source heat pump takes heat from the 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 uses less electrical energy than the heat it produces. This makes them an energy-efficient way to warm your home.

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

Ground source heat pumps also harness natural heat and increase the temperature to warm your home.   Looking similar to an air-conditioning unit their size depends on how much heat they'll need to generate for your home - the more heat, the bigger the heat pump.

There are two main types of air source heat pumps: air-to-water and air-to-air. They work in different ways and are compatible with different types of heating systems.


Air-to-water heat pumps

Air-to-water heat pumps take heat from the outside air and feed it into your wet central heating system, again suitable for larger radiators or underfloor heating, they are most effective with a  large surface area to release the heat.


Air-to-air heat pumps

Air-to-air heat pumps take heat from the outside air and feed it into your home through fans. You need a warm air circulation system to move the heat around your home.

These systems cannot produce hot water, so you'll need a separate immersion heater or other water heating system.

In the summer, an air-to-air heat pump can operate in reverse. In other words, you can use it like an air-conditioning unit to provide cool air for your home.


Air source heat pump installation

Air source heat pumps are usually positioned outdoors at the side or back of a property. They need plenty of space around them for air to circulate.

Inside, you'll usually have a unit containing pumps and hot water.

They are less disruptive to install than ground source heat pumps, as they do not require any digging in your garden.

You won't normally need planning permission for an air source heat pump, but if you live in a listed building or conservation area, then you'll usually need the consent of your local authority. Also check that your installation will meet the building regulations in your area.

Speak to your home insurance provider too to check if your policy will cover the changes to your heating system.


If you're getting an air source heat pump it's important to make sure that your home is well-insulated to retain the heat. Underfloor heating or larger radiators are often installed alongside heat pumps to disperse the heat better.

At N10 Plumbing we show how to use the controls for your heat pump to help you use it most effectively. You will probably need to heat your home for more hours but at a lower temperature.

When your system is completed, No10 will supply a Commissioning Certificate and a MCS installation certificate once the system has been registered. You'll need this to qualify for most funding schemes.


  • Energy efficient and low carbon - air source heat pumps generate less CO2 than many conventional heating systems
  • Less disruptive than installing a ground source heat pump, especially if you're retrofitting
  • You will save money on heating compared with some older systems.


  • You'll need enough space in your garden for the external condenser unit
  • Condenser units can be noisy and blow colder air into the area immediately around them
  • Electricity is needed to drive the pump so they're not zero-carbon (unless the electricity comes from a renewable source such as solar panels or a wind turbine).


Are air source heat pumps efficient?

An air source heat pump system can help to lower your carbon footprint as it uses a renewable, natural source of heat – air. How much CO2 you'll save depends on the fuel you are replacing. For example, the figure will be higher if you are replacing coal or an oil boiler rather than natural gas.

A heat pump needs a power source, usually electricity, to power the heat pump, so there will still be some resulting CO2 emissions.

You should have your heat pump serviced every two to three years. Checking that any grills are free of leaves and debris on a regular basis and follow any other maintenance checks advised by N10 Plumbing.