Our Geothermal Systems circulate water through pipes buried in the ground to extract the heat stored below the earth’s surface. The average ground temperature just below the surface, in the UK is between 8ºC and 13ºC, this temperature remains constant throughout the year. The temperature of the water in the pipes is lower than the surrounding ground and so it warms up slightly. The returning water is chilled back down by the heat pump, where it is used to heat up a refrigerant. By compressing this 'warmed' refrigerant the temperature is further increased before being transferred to the building heating system. The heating water output from the heat pump is typically 45ºC - 65ºC.