Ground Source Heat Pump

Ground Source Heat Pump
Ground source heat pumps collect low-grade heat from the ground and increase it in temperature via a heat pump to supply heating loads. The ground source heat pump system consists of ground loops, which are loops of pipe buried at shallow depth in ground adjacent to the building and a heat pump, which is installed in the property replacing the boiler. The efficiency – or Coefficienct of Performance the ratio of useful energy out to energy into a system – of such systems can exceed 350% due to the relatively high temperature of the ground.

The average ground temperature just below the surface in the UK is between 8°C to 13°C and remains constant throughout the year. Water circulated through the ground loops is at lower temperature than the surrounding ground so warms up slightly, picking up energy from the ground. In the heat pump, this low grade heat is transferred to a refrigerant which is then compressed to increase the temperature, allowing a supply of heat to the building at approximately 50 – 55°C.

The temperature of heat supply from a heat pump is ideally suited for use with a wet underfloor heating system, but is lower than that traditionally provided by a boiler for a radiator based system. For this reason, it is important to plan for the installation of a ground-source system early in the design of the building’s heating system, so that appropriate emitters can be installed for the temperature of supply.