A Quick Guide to Ground Source Heat Pumps in the UK

Written-by

Janet Richardson

Reviewed-by

Richard Burdett-Gardiner

Updated on

Sep 05, 2024

A Quick Guide to Ground Source Heat Pumps in the UK

A major renewable source of heat for homes can actually be found in the ground. One of the best methods of extracting and harnessing this valuable energy is a Ground Source Heat Pump (GSHP) which can be used for producing hot water for domestic use, showers and hot taps as well as for central heating systems and, occasionally, for operating warm air heating systems. It sounds like a simple solution to all your heating problems but there are a few caveats you need to consider before you take the heat pump plunge.

How does a Ground Source Heat Pump Work?

The heat in the ground remains fairly constant in the UK, even through the winter months, producing small amounts of constant warmth that can be magnified by the appropriate machinery. Pipes are buried in the earth outside your house and a mixture of water and antifreeze is circulated around them. The ground heat gets absorbed into the surrounding mixture and is transported to a heat exchanger and from there into the heat pump that passes it to the heating sources in your home, such as radiators. While the heat produced from the ground is initially pretty low, it is compressed to produce higher temperatures.

The heat pump works as a continuous process with the mixture circulating back down into the ground to absorb more energy once it has been used to heat your property. A flat array can be buried about 2m deep throughout your garden, but a vertical one can be drilled down up to 100m. Whether it is a suitable method of heating your home depends on the size of garden you have and the depth of your soil. A larger array buried in the ground helps you to produce more heat. If space is limited, a vertical borehole can be drilled down into the earth. Another factor you need to consider is how you are currently heating your house.

• Ground Heat Exchanger: A network of pipes in the ground or a bore-hole. These 'coils' absorb heat from the ground using a refrigerant. 
• Heat Pump Unit: Located near your property, it transfers heat between the heat exchanger and your property's central heating system.
• Distribution System: The central heating system - underfloor/radiator water heating system that distributes the heat throughout the property. 

The Benefits of Ground Source Heat Pumps

• If you use it to replace your conventional heating, either by gas or electric boiler, it can dramatically reduce your energy bills. How much you will save will depend on the initial cost of installation and the type of fuel source being replaced.
• You might be able to benefit from the government’s Boiler Upgrade Scheme (BUS) which offers homeowners a grant of £7500 to help towards the upfront costs. You don't have to pay this money back and it's simple and easy to receive. 
• Although it is also dependent on the type of fuel you are replacing, you could significantly reduce your carbon emissions and contribute to halting global warming.
• Ground Source Heat Pumps (GSHPs) are very low maintenance and easy to run once installed, providing heat for radiators and hot water.
• The pumps deliver heat at much lower temperatures than normal gas or electric systems, so you may have to have them on for longer periods.
• GSHP systems offer the most efficient solution for heating your home or business. 
• GSHP systems have a long lifespan, some say up to 50 years

Deciding if a Ground Source Heat Pump is for you

There are several things to consider before you decide to take on something like a Ground Source Heat Pump. First of all, your house needs to be well insulated. GSHPs produce heat at much lower temperatures than normal systems so you would be well advised to have sufficient floor, wall cavity and loft insulation as well as double glazing, to make sure all that heat is kept in. How you are going to heat your house is another area to think about carefully. 

Ground Source Heat Pumps work better with things like underfloor or warm air heating rather than traditional radiators. Finally, the ground needs to be suitable. You need to check if you can get diggers and drills into the garden as well as find out about the nature of the ground. For example, if there is a lot of rock beneath the initial layer of soil then it might not benefit from a vertical bore.

Types of Ground Source Heat Pumps

Ground Source Heat Pumps can utilise the heat from both water and the earth, and there are some different varieties. A closed loop system is the most common, using a contained water and antifreeze mixture. An open loop system uses water from the surrounding area but this needs to meet certain requirements such as being low in chlorine.

• Open or Closed Loop Ground Source Heat Pump: Usually buried flat around 2m in a decent-sized garden.
• Single Borehole Open or Closed Loop GSHP: A vertical installation that can be drilled up to 100m down into the ground.
• Single Well Open or Closed Loop WSHP: If you have an underwater source such as a well, then the loop can be connected to this.
• Lake or Pond Source Open or Closed Loop WSHP: If you have a lake or large pond nearby, then it works the same as a Ground Source Heat Pump, but in water.

 

Single Borehole Closed Loop GSHP	Single Borehole Closed Loop GSHP	Single Well Open Loop WSHP
Lake or Pond Source Open Loop WSHP	Open Loop Dual Well WSHP	Closed Loop Single Well GSHP/WSHP
	Closed Loop Water Source GSHP/WSHP

Getting your GSHP Installed

Major work has to be undertaken if you want to install a Ground Source Heat Pump, including checking whether you need planning permission. Workmen and diggers (possibly even a crane) will need to be able to access the area where you are going to have the heat pump installed.

Remember, the first thing you need to consider, which may add cost to your conversion to a heat pump, is whether your house is ready for it – have you got the right central heating system installed and is your property insulated to a high enough standard? There are a number of companies that specialise in putting in heat pumps and they will be able to advise if your property and garden would suit such an installation.

You'll need to find a good, MCS accredited installation company to perform a full site survey and heat-loss survey. Not all properties are suitable, so make sure you're well-read on the technology before signing any contracts.

Maintenance 

As with any mechanical or complex device, annual inspections are important. A qualified engineer should visit your property to do a full check and service of your GSHP. This will certainly improve the lifespan. That said, there are some things you can do yourself. 

Filter Changes: Replace air filters regularly, especially if they look dirty. 
Fluid Check: Check the levels of the antifreeze solution in closed-loop systems. Directions for this should be explained by your installation company. 
Electrics: Check that controls and connections are clean and tight 

Conclusion

In this article we've covered the basics of ground-source heat pumps. They certainly aren't cheap, but are most likely, the most efficient and sustainable heating system available on the UK market. Not really that applicable for a mid-terrace property in a city (never say never), but if you're on oil or LPG, in a larger property, then the return on investment can be very attractive and you're certainly future proofing and doing your bit for the environment.

For more information check out our articles: 

Heat Pump information
Different types of heat pumps
Installation of a Ground Source Heat Pump

Search for heat pump installers in your area here.