Ground source heat pumps

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.

If there is enough space, the collector loop can be laid horizontally in a trench about a metre or so below ground. Where there isn’t room to do this, you can drill vertical boreholes to extract heat from much further down, typically between 90m and 160m deep.

The space you need for a horizontal loop, and the depth you need for a borehole, will depend on many factors. Your heat pump installer will design the collector array based on local conditions and the heat requirements of your home.

Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, the air, or water is constantly being renewed naturally.

Watch our explainer video below:

Here are a few key questions to consider to find out if a ground source heat pump is suitable for your home and needs:

Installing a typical system costs around £14,000 to £19,000. Running costs will depend on a number of factors including the size of your home and how well insulated it is.

How much you can save will depend on what system you use now, as well as what you are replacing it with. Your savings will be affected by:

You may be able to receive payments for the heat you generate using a heat pump through the UK Government’s Renewable Heat Incentive.

Domestic RHI is no longer available in Northern Ireland. Details of the previous scheme can be viewed at NI Direct.

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 Quality Assured National Warranties (QANW).

Many manufacturers also offer optional extensions of warranty for a fee.

You can expect them to operate for 20 years or more, but they do require regular scheduled maintenance.

A yearly check by you and a more detailed check by a professional installer every three to five years should be sufficient.

The installer should leave written details of any maintenance checks you should undertake to ensure everything is working properly. Consult with your supplier 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.

• in England – General Permitted Development Order (GPDO)
• in Scotland – Town and Country Planning (General Permitted Development) (Domestic Microgeneration) (Scotland) Amendment Order 2009
• in Wales – The Town and Country Planning (General Permitted Development) (Amendment) (Wales) Order 2009)