Ground Source Heat Pumps

Ground Source Heat Pumps

Ground Source Heat Pumps (GSHPs) use pipes buried in the ground to extract heat for use in radiators, underfloor heating systems and hot water in your home.

Depending on the suitability of the house and other multiple aspects, a GSHP can use around a third less electricity for heating than other forms of electrical heating, delivering heat at lower temperatures over a much longer period than a conventional boiler. When properly controlled, it can switch on and off with the heating requirements of your home.

How the technology works

The ground absorbs and stores heat from the sun, maintaining a constant temperature of around 10 to 14°C at a depth of about 10 meters, all year round. This energy is absorbed through fluid which is pumped through pipework, either in the form of a 'slinky' which are coiled plastic pipe lengths laid in trenches one or two metres deep or by using a borehole(s) where pipework can extend between 50 to 150 meters vertically into the ground.

The type of pipework collection system installed is determined by the area of land available compared to the heat demand of your house, its condition and accessibility

The low level heat collected in the fluid within the pipework is then collected, compressed and converted to useable temperatures of up to 50°C; then, via a heat exchanger, is distributed throughout the property via a wet central heating system, or underfloor heating.

You may be able access a grant to support the installation of a GSHP. The eligibility requirements and products supported under government-backed initiatives regularly change. Please get in touch for the latest advice on this.

Choosing your system

The heating requirement for most UK homes is around 6-8kW. A normal-sized home built within the last decade should only require around 4-5kW of heat. For every 3kW of heat provided, a GSHP will consume around 1kW of electricity – this is known as the technology’s Coefficient of Performance (COP). But this depends on the quality of the design and installation.

To obtain the maximum performance from a heat pump, you should ideally use an underfloor heating system. This is because a building can often be heated with water at a flow temperature of as little as 3540°C. Existing central heating radiators can be used, but may not be large enough to transfer heat at lower temperatures compared to fossil fuel boilers Heat loss calculations will be needed to decide if you need larger radiators.

TOP TIP

Heat pumps are always more effective when used in a well-insulated house. If you are considering this system, start with improving the insulation of walls and loft spaces as much as possible. (See our other factsheets on how to insulate your home.)

Comparison to Air Source Heat Pumps (ASHPs)

GSHPs typically cost as much to install as ASHPs, but come with other advantages. GSHPs are typically cheaper to operate because the ground is a constant temperature all year round, but ASHPs have to work harder, using more electricity in the winter when the air is coldest. GSHPs also require less maintenance because the heat pump unit is located inside and not exposed to the atmosphere. However, the lifetime costs of a GSHP may still be higher than an ASHP.

Domestic Hot Water

It is possible to supply domestic hot water with a GSHP. The water from the heat pump will be used for preheating water and then an immersion heater can bring to the required temperature for washing