How do Air Source Heat Pumps Work?

How do they work?

Air source heat pumps are fitted on the outside of your home, preferably in an area that has a good circulation of air. Whilst they range in size depending on the dimensions of the system you choose, most are about the size of a large air-conditioning unit. There are two main varieties (air and water) although how they operate is principally the same.

how air source heatpumps work

Air-air systems

In an air-air system the heat extracted from the outside air is boosted to the appropriate temperature by the compressor in the heat pump and then fed directly into the house. This system can only be used to supply space heating to your home.

Air-water systems

For the air-water model, the heat extracted from the outside air is boosted to a higher temperature and then used to heat water in a tank. This water is then used to run a conventional central heating system either based on radiators or underfloor heating.

Flow cycle for air source heat pump

The steps below outline the key parts of the process for an air-water system. The same process applies for an air-air system, except that after step two a fan blows air over the high temperature pipes which heats the room:

  1. A special anti-freeze solution is cycled through a pipe system, which collects heat from the outside as air is drawn over it by a fan
  2. A compressor then boosts the temperature of the solution to the required level, depending on your heating system
  3. The high temperature solution is run through sealed pipes contained in a water tank, which heats the water ready for use
  4. The heated water from the tank is circulated through your central heating system to heat your home
  5. The cooled solution flows back around the system where, again, it collects heat from the outside air.