The basic principles of a closed-loop GSHP system begins with the absorption of heat from the ground heat source. This is typically an array of pipes buried underground horizontally, vertically in a bore-hole, or even laid in a lake.

Heat absorption is achieved by circulating water mixed with antifreeze (Glycol) through a closed collector pipework system. The temperature of the earth at one metre below ground level remains fairly consistent between approximately 6 – 12ºC throughout the year depending on geographical location and soil type. Contrary to popular belief this is stored solar energy, energy from rainfall and (in some circumstances) energy from migrating groundwater, not geothermal exchange heat from the centre of the earth.

The stages of the Ground Source Heat Pump

1. The energy in the form of heat is absorbed from the heat source (rock, ground or lake) through a closed collector system containing water mixed with vegetable-based antifreeze.
2. The collector fluid then transfers this energy to the refrigerant in the heat pump’s evaporator heat exchanger.
3. The refrigerant vaporises and is then compressed in the compressor which is where most of the electricity is consumed. When a gas is compressed its temperature increases to around 50°C (this is the core scientific principle behind the gas compression cycle).
4. The refrigerant, with its increased temperature, enters the condenser heat exchanger where it transfers its energy to the heat medium circuit. This then provides spatial heating to the wet radiator or underfloor heating circuits, the hot water cylinder or a combination of heat emitters…