Extracting Heat from Outside Air

An Air to Water Heating system uses the energy available in the air with a refrigerant circuit; the pumps absorb heat from the outside air. This heat can then be used for radiators, under floor heating systems, or warm air convectors and for hot water.

The system works by extracting heat from the outside air, in the same way that a fridge extracts heat from inside. A heat pump can extract heat from the air even when the temperature is far below 0. Heat in the air is absorbed at low temperature into a fluid (such as water with antifreeze), which is then passed through a compressor where the temperature is increased. The fluid is then transferred to the heating and hot water circuits of the house.

An Air to Water Heating system is just one type of Air Source heat pump system. There is also the Air to Air Heating system, which produces warm air that is circulated by fans to heat your home (these types of system do not provide hot water as well).

Heat pumps require electricity to run, so they are not completely environmentally friendly, but the heat they extract from the air is renewable and has no impact on the environment. If the electricity they run on is from solar panels or another renewable resource then they are completely green.

More Benefits

  • Lowers your energy bills
  • Reduces carbon footprint
  • Require very little maintenance
  • Easy to install

Heat pumps generate heat at lower temperatures over longer periods of time; in comparison to gas and oil boilers (you’ll notice radiators aren’t as hot to the touch). Through the winter they may need to be on constantly to heat your home.

Should I get an Air to Water Heating system?

Before you make a decision, you need to ask a few questions.

  • Do you have room for it? The system will require a place outside of your home where a unit can be mounted to a wall or placed on the ground. It will need plenty of space for airflow and should ideally be somewhere where it will get sunlight.
  • Is your home properly insulated? Before upgrading or installing any type of heating system, it’s best to check you’ll be getting the most out of them. Poorly insulated homes will easily lose the lower temperatures produced by an Air to Water Heating system.
  • What fuel do you currently use? Air to Water Heating systems pay for themselves quicker when replacing electricity or goal heating systems, but isn’t the best choice for a home using gas.
  • Is it a new development? If the property is a new development, combining a Water to Air Heating system with other building work can reduce the costs.


An Air to Water Heating system installation usually costs at least £6,000. Once the system is installed you should see a reduction in your bills right away, but it does depend on other factors, such as how we insulated the building is and your current energy costs.

It is a good idea to learn the controls on your new installation so you can get the most out of it. You will most likely need to set the heating to come on for longer hours, and you might be able to turn the system down and still be warm enough. Ask your installer how to use the system fully.

In Wales and Northern Ireland planning permission is usually required, in England and Scotland Air to Water Heat pumps can be considered Permitted Development, but it’s worth checking.