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What is Geothermal Heating?

Becky Mckay
By: Becky Mckay
Updated: 19th September 2023

Alpha Boiler Warranty
Geothermal heating is a heating system which uses heat that has radiated from the core of the Earth. Geothermal heating is often confused with the heat extracted by ground source heat pumps to heat homes but there's actually a significant difference.

Geothermal vs Ground source heating

As both geothermal and ground source heating systems take heat from the ground, it's no surprise that there's some confusion around the difference between geothermal heat and ground source heat.

The word geothermal means 'earth's heat' as the heat comes from the Earth's core. To access this heat in the UK, geothermal heating systems have to be buried as low as 500 - 2,500 metres.

Ground source heat is much closer to the surface and that's because it's heat absorbed by the ground from the sun. Ground source heat pumps don't have to be buried as deep as their geothermal counterparts (often 15-150 metres) making them much more suitable for domestic installation.

How do geothermal heating systems work?

Geothermal heating systems work at temperatures up to 300°C and are typically used by large industrial plants or communities that have higher demands. This is unlike ground source heat pumps which can be installed in a garden.

How do ground source heat pumps work?

Ground source heat pumps are made up of 3 parts:

  1. Ground loop
  2. Heat pump
  3. Heat distribution system

The ground loop is buried underground either in a horizontal trench (2 metres deep) or a vertical borehole (15-150 metres). Circulated through these pipes is a combination of water and antifreeze which absorbs the heat and travels back round to the heat pump.

Once it arrives at the heat pump, the temperature of the liquid is increased further by a heat exchanger before being circulated around the central heating system. Alternatively, the hot fluid can be used to warm domestic water stored in a cylinder.

Pros and cons of ground source

Advantages of ground source heat pumps

The main advantage of a ground source heat pump over a geothermal heating system is that they're suitable for domestic installation.

  • Longer lifetime than traditional heating systems
  • Don't often require much maintenance
  • You could potentially lower the carbon emissions of your home by 2-8 tonnes annually
  • Quiet during operation
  • Could add value to your property
  • Receive payments through the Renewable Heat Incentive (RHI)

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Ground source heat pump considerations

To really feel the benefit of a ground source heat pump, your property will need to be well insulated and, as they operate at lower temperatures, they will be most effective when installed alongside large radiators or underfloor heating.

There are some important considerations to make before the ground source heat pump has even been installed too:

  • If there's enough room in your garden;
  • Whether there's plenty of space to give access for digging machinery; and
  • If you want your garden to be dug up to allow for the installation.

Ground source heat pump efficiency

Most UK homes are heated by a gas boiler which tend to have an efficiency rating of 93% but ground source heat pumps, on the other hand, use 3-4 kilowatts of energy for every kilowatt of electricity the use – giving an efficiency rating of around 300%.

Ground source heat pumps costs

While ground source heat pumps are highly efficient and could save you money on your energy bills, as well as earn you payments through the Renewable Heat Incentive, they are expensive.

A ground source heat pump is likely to cost between £8,000 and £12,000 with the price varying depending on the model and manufacturer.

Find out more about the different models in Ground Source Heat Pump Manufacturers.

What is an air source heat pump?

Like ground source heat pumps, air source heat pumps are also a renewable heating system but rather than taking heat from the ground they use the air outside.

Even in temperatures as low as -15C an air source heat pump is able to extract heat from the outside air and use it to heat your home.

Air source heat pumps tend to be more

Hybrid heating systems

When it comes to renewable heating systems, you don't have to go all in and remove your existing gas boiler to make for the heat pump. You might be better off with a hybrid heating system.

Hybrid heating systems incorporate a conventional gas boiler alongside a renewable system, such as a heat pump, and uses the most efficient system to meet the heating demands of your home at any time.

So, if there was little demand for heating then the heat pump would be called into action but if there was a very high demand then the gas boiler would probably be fired up to quickly and effectively heat up your property.

Get free heat pump quotes

If you're looking to lower your carbon footprint as well as your energy bills with a renewable heating system then your next step is to find an installer.

At Boiler Guide, we have a network of fully-qualified installers right across the UK and by taking a few moments to complete our simple online form we can match you with the installers based near you.

You'll get free quotes from up to 3 installers putting you in a position to compare them and be confident that you're getting the most competitive price available.

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Becky Mckay

About the author

Becky Mckay

Becky has been a writer at Boiler Guide since 2021. Her vast boiler knowledge means she’s ready to help with any home heating query, big or small!

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