Air Source Heat Pump

Heat your home with energy absorbed from the air around you.

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

An ashp extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat from the air even when the  temperature is as low as -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.

In tests we have found that for every 1kWh of electricity put in to run the ashp, you can get between 1.6kWh and 2.9kWh of heat/hot water output.

How do air source heat pumps work?
Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house. There are two main types of ashp system:
  • 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. So they are more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.
  • 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.

The higher the temperature of heating or hot water that you set, the less efficient the heat pump will be, the more it will cost to run.


Using an Air Source Heat Pump
There are a number of key differences in the way air source heat pumps work compared to other heating systems. For example, an ashp can vary the temperature of the circulating fluid in the radiator system to ensure that the ashp is working at its most efficient. This means that:
 
The ashp is working at its most efficient if the room is warm, but the radiators are only warm, not hot to touch.

Some important factors in using an ashp in the most efficient way:

Keep the ashp "on" all the time, using the programmable room thermostat to control the heating;

Keep the room temperature as low as is comfortable: the ashp gets proportionately more efficient the lower the temperature;

Keep the hot water temperature as low as you can cope with, as again the higher you increase the temperature the less efficient the ashp is working.