A ground source heat pump is a renewable heating system which means that it uses a sustainable source of energy to run and contributes very little carbon to the atmosphere.
Ground source heat pumps run on a small amount of electricity to extract latent heat from underground which can then be used to produce hot water for taps and showers and central heating. There are four main parts to the system: ground loop, heat pump, hot water cylinder, and heat distribution system.
How Do Ground Source Heat Pumps Work?
1. When sunlight hits the earth, the heat is absorbed by the ground.
2. Pipes filled with water and antifreeze are buried underground outside the home in a closed circuit. The pipes are buried either in a vertical borehole (up to 160m below the ground) or horizontal trench (up to 2m below the ground).
3.The liquid is pumped around the ground loop by a heat pump absorbing the natural heat from underground.
4. An evaporator, compressor and condenser intensify the heat, raising its temperature, so it can heat water in a cylinder. The water for domestic use is stored in cylinders, which can then be boosted in temperature using an immersion heater.
5. Hot water is also sent to a heat distribution system, e.g., underfloor heating or radiators.
6. The ground-loop fluid is recirculated through the pipes so it can absorb more heat from the ground, and will continue to do so whenever hot water is required.
The temperature beneath the ground stays at a constant temperature all year round (10-15 degrees Celcius) so ground source heat pumps are effective even in winter.
Are Ground Source Heat Pumps Efficient?
The only traditional form of energy used is electricity to power the heat pump, but ground source heat pumps do not require much electricity. However, the level of thermal energy, or heat, emitted is 3-4 times the amount of electrical energy needed to power the pump.
In addition, by using ‘green electricity’ which has been generated via solar panels or wind farms, ground source heat pumps can be made even more environmentally friendly, as all your heating will be from sustainable sources with zero carbon emissions.
How much does a ground source heat pump cost?
Ground source heat pump systems do not come cheap and cost around £8000 – £12000. Here are some of the most popular models on the market.
Note: Until March 2021, homeowners can apply for a Green Homes Grant from the government to cover two-thirds of the installation cost of a ground source heat pump. Click here for more information.
| Manufacturer | Model | Available Outputs (kW) | ErP Energy Efficiency Rating | Potential Price |
|---|---|---|---|---|
| Vaillant | geoTHERM | 22, 30, 38, 46 | A++ | £8,000 – £12,000 |
| Viessman | Vitocal 222-G | 6.1 – 10.0 | A++ | £6,000 – £7,500 |
| Nibe | Nibe F1145 | 5 – 17 | A+++(17kW – A++) | £9,000 – £10,000 |
| Kensa | Evo | 7, 9, 13, 17 | A++ | £8,000 – £12,000 |
| Worcester-Bosch | Greenstore 6 System | 6, 7, 9, 11 | A+ | £4,500 – £8,000 |
However, with a potential annual saving of around £400 – £800 on heating bills, it is a good long-term investment, particularly as there are practically no maintenance costs and a life expectancy of over 50 years.
Depending on the type of fossil fuel you currently use for heating and hot water, changing to a ground source energy heating system can cut your households carbon dioxide emissions by 2 – 8 tonnes each year.
Running costs will depend on a number of factors including the size of your home and how well insulated it is. As heat pumps don’t burn fuel, you’re very likely to save money on your heating bills, but the amount of money you will save will depend on the heating system you are replacing. If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump, as well as a reduction in carbon emissions.
| Heating System to be Replaced by Ground Source Heat Pump | Potential Annual Savings (£) | Potential Annual Carbon Savings (tonnes) |
|---|---|---|
| Gas boiler | £25-£30 | 2.5-2.7 |
| Oil boiler | £20-30 | 3.9-4.2 |
| LPG boiler | £530-£570 | 3.1-3.3 |
| Electric heating | £1,000-£1,090 | 3.6-3.9 |
| Solid fuel heating, e.g. coal | £400-£440 | 9.9-10.6 |
Figures taken from the Energy Saving Trust based on April 2020 data.
Renewable Heat Incentive Payments
A significant benefit of installing a ground source heat pump is that you could receive payments through the Renewable Heat Incentive (RHI). The RHI is a government scheme designed to encourage homeowners to invest in renewable heating rather than a gas, oil, LPG, or electric boiler.
Through the RHI, you would receive quarterly payments over a 7 year period. Tariffs vary depending on the heating system being used and are reevaluated by Ofgem each quarter. Successful applications submitted between now and 31st March 2021 will receive 21.16p per kWh.
Note: The Renewable Heat Incentive is set to be replaced by the Clean Heat Grant from 2022.
Is a Ground Source Heat Pump Right for You?
Using ground source energy as a means of home heating will be more efficient in a fully insulated building. It is better suited to heating systems that have less variation between the heat source and the heat output such as underfloor heating as this operates at a much lower temperature, usually around 30 degrees compared to radiators, which normally function at around 70 degrees.
Ordinary radiators can still be used with ground source energy heating but you may need to install larger radiators.
The heat pump unit is typically housed in a cabinet around the size of a large fridge. In fact, the whole system can be likened to the way in which a fridge works, only in reverse. A fridge takes the warm air from inside and moves it outside whereas the heat pump takes the heat stored underground and brings it inside.
Some ground source heat pumps also have a cooling system, keeping the interior of your home cool in warm weather.
Get quotes for a ground source heat pump
When taking your next steps to find the right renewable heating system for your home, it’s important to seek professional advice.
To connect with ground source heat pump installers in your area, visit Boiler Guide where you can get free no-obligation quotes from up to 3 installers. By comparing quotes, you can be confident that you’re hiring the best person for the job at the most competitive price.
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