Ground source heat pumps (GSHPs) use pipes which are buried in the earth to extract heat from the ground. This heat can then be used to heat radiators, underfloor or warm air heating systems and hot water for your home or business.
A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe, called a ground loop, which is buried in your ground. Heat from the ground is absorbed into the fluid and then passes through a heat exchanger into the heat pump. The ground stays at a fairly constant temperature under the surface all year, so the heat pump can be used throughout the year.
The length of the ground loop depends on the size of your home or premises and the amount of heat you need. Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, a vertical borehole can be drilled instead.
Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won't feel as hot to the touch as they might do when you are using a gas or oil boiler.
Air source heat pumps are usually easier to install than ground source as they don't need any trenches or drilling, but they are often less efficient when the air temperature is at or below freezing because the air is much colder and the source of heat for ground source heat pumps is constant all year round. Water source heat pumps can be used to provide heating in homes/ businesses near to rivers, streams and lakes.
Heat from the ground is absorbed at low temperatures into a fluid inside a loop of pipe (a ground loop) buried underground. The fluid then passes through a compressor that raises it to a higher temperature, which can then heat water for the heating and hot water circuits of the house. The cooled ground-loop fluid passes back into the ground where it absorbs further energy from the ground in a continuous process as long as heating is required.
Normally the loop is laid flat or coiled in trenches about two metres deep, but if there is not enough space on your land you can install a vertical loop down into the ground to a depth of up to 100 metres for a typical domestic premises. Heat pumps have some impact on the environment as they need electricity to run, photovoltaic panels can help to offset this. The heat that heat pumps extract from the ground, air, or water is constantly being renewed naturally so it minimises the ecological impact.
To help decide whether a ground source heat pump is right for you, there are a few key questions to consider:
Heat pump systems typically come with a warranty of two to three years. Workmanship warranties for heat pumps can last up to 10 years, for example through IWA (Quality Assured National Warranties).
The installer should leave written details of any maintenance checks you should undertake to ensure everything is working properly. Consult with us for exact maintenance requirements before you commit to installing a heat pump.
The Ground Source Heat Pump Association says there is no need for safety checks for ground source heat pumps and routine maintenance requirements are very low. These may include pre-heating season checks of the water pump, external pipes and fittings and electronics.
Domestic ground source heat pumps are generally allowed as permitted developments, but check with your local authority to find out whether you need planning permission or not.