Ground source heat pumps (GSHPs) use pipes which are buried in the ground to extract heat from the earth. This heat can then be used to heat radiators, and hot water in your home.
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 the earth. Heat from the ground is absorbed into the fluid and then passes through a heat exchanger inside the heat pump. The ground stays at a fairly constant temperature under the surface, so the heat pump can be used throughout the year whilst maintaining a stable efficiency.
The length of the ground loop depends on the size of your home and the amount of heat you need. Longer loops can draw more heat from the ground, but require more space. If space is limited, a vertical borehole can be drilled instead although this carries a higher installation cost.
Unlike gas, oil and conventional electric 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, oil or electric boiler.
Air source heat pumps are the cheaper alternative to ground source as they don’t require a ground collector but they are often less efficient.
- lower your fuel bills when replacing gas, oil or electric
- lower your homes carbon emissions
- no fuel storage required, no fuel deliveries needed
- provides space heating and hot water throughout the year
- minimal maintenance required
Costs, savings and financial support
Installing a system varies depending on the size of the property, domestic costs vary around £12,000- £40,000. 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:
- Your heat distribution system. Underfloor heating can be more efficient than radiators because the water doesn’t need to be so hot. If underfloor heating isn’t possible, use the largest radiators you can. Your installer should be able to advise on this.
- Your fuel costs. You will still have to pay fuel bills with a heat pump because they are powered by electricity, but you will save on the fuel you are replacing. If the fuel you are replacing is expensive you are more likely to make a saving.
- Your old heating system. If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump.
- Water heating. If the heat pump is providing hot water then this could limit the overall efficiency. You might want to consider solar water heating to provide hot water in the summer and help maintain your heat pump efficiency.
Using the controls
Learn how to control the system so you can get the most out of it. You will probably need to set the heating to come on for longer hours, but you might be able to set the thermostat lower and still feel comfortable. Your installer should explain to you how to control the system so you can use it most effectively
Heat from the ground is absorbed at low temperatures (roughly 10 degrees) 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.
The ground loop is laid flat or coiled in trenches 1.2 meters deep. Which method you use depends on the manufacturer of the heat pump.
Is your garden suitable for a ground loop?
It doesn’t have to be particularly big, but the ground needs to be suitable for digging a trench or a borehole and accessible to digging machinery.
Is your home well insulated?
As the ground source heat pump produces lower temperatures than conventional methods you must make sure the heat is used efficiently.
What fuel will you be replacing?
The system will pay for itself much more quickly if it’s replacing an electricity, gas or oil heating systems.
What type of heating system will you use? Ground source heat pumps can perform better with underfloor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.
Is the system intended for a new development?
Combining the installation with other building work can reduce the cost of installing the system.