Air Source Heat Pumps(ASHP)

Air Source Heat Pump handling Unit located outside
Air Source Heat Pump handling Unit located outside

An Air Source Heat Pump (ASHP) extracts heat from the outside air in the same way that a fridge extracts heat from its inside. Heat from the air is absorbed into a fluid which is pumped through a heat exchanger in the heat pump. Low grade heat is then extracted by the refrigeration system and, after passing through a heat pump compressor, is concentrated into a higher temperature useful heat capable of heating water for the heating and hot water circuits.

There are two main types of air source heat pump system:

  • An air-to-water system distributes heat via wet central heating system either using underfloor heating coils or a traditional radiator system, although this is less appropriate;
  • An air-to-air system produces warm air which is circulated by fans to heat the space. This type of system is unlikely to provide hot water as well.

Air source heat pumps lose their efficiency as external temperatures fall, and are therefore not very cost effective in cold regions.

The external unit of an ASHP generates noise so care should be taken that schools' noise regulations are considered when siting this component and they are located away from classrooms and other quiet areas.

Without the need for expensive bore holes or large scale excavations Air Source Heat Pumps are considerably cheaper than Ground Source systems to install however tend to be less efficient.

Link to short examples

What should I do?

External temperatures at the site need to be carefully considered to ensure cost effectiveness.

WLGA - CLILC Llywodraeth Cynulliad Cymru / Welsh Assembly Government