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Ground source heat pumps explained

By drawing on the natural heat of the earth, ground source heat pumps can provide a fantastic alternative heat source for your home. They can also reduce your home’s carbon output, as well as save you money on your heating bills.

What is a ground source heat pump?

Ground source heat pumps (GSHPs), also known as geothermal heat pumps, use a network of pipes that are buried in your garden to extract heat from the ground.

This heat is increased further by the pump at ground level and is used to heat everything from radiators in your home to underfloor heating and even hot water.

The heat pumps themselves differ in shape and size, with some requiring a hot water cylinder which can sometimes be the size of a filing cabinet. However, smaller sized pumps can be fitted neatly in the kitchen sink cupboard.

How do ground source heat pumps work?

The heat from the ground is absorbed at low temperatures into a mixture of water and antifreeze inside pipework, which is buried outside your property. This fluid is then passed on to a compressor, or pump, which increases its temperature to around 50°C before it is used to provide heating and hot water in your home.

The system completes a continuous circuit by passing the cooled fluid back into the ground where it begins absorbing heat up once again.

What are the benefits of ground source heat pumps?

There are a host of benefits, with the biggest being the money you could save on your heating bills.

The Energy Saving Trust (EST) says an average ground source heat pump could save you up to £1,090 a year if you currently have an electric heating system. However, the savings are less impressive when replacing the average gas heating system at between £25 and £30 each year.

However, this could be significantly topped up with the help of the Government’s Renewable Heat Incentive (RHI) scheme. For an average four-bedroom detached home with a fitted ground source heat pump, the scheme provides payments of between £2,335 and £2,750 a year.

Ground source heat pumps also require less maintenance than combustion-based heating systems such as gas boilers and have a longer life span of around 20 years or more.

As a carbon reduction solution, the amount of CO2 you’ll save will again depend on the type of system you’re replacing. If you’re replacing a typical electric system, savings will be between 3.8 and 4.1 tonnes a year. Replacing the average gas heating system will save 2.4 to 2.6 tonnes a year.

However, for those looking for a net-zero carbon solution, a ground source heat pump will need to be combined with another green energy source such as solar panels, as the heat pump needs to be powered by a small supply of electricity.

How much do ground source heat pumps cost?

Given the more complex installation processes involved (mainly burying the pipe loop in your garden), ground source heat pumps are a more expensive choice than other alternative heating solutions, including air source heat pumps.

Installing a typical system costs around £14,000 to £19,000. However, this could be paid for over seven years by the RHI alone.

Are there any grants for ground source heat pumps?

There are a number of ground source heat pump grants available that can cover a substantial part of what can otherwise be an expensive installation. The main one being the Energy Company Obligation (ECO) grant.

What are ECO Grants?

The Government’s Energy Company Obligation (ECO) is a government-backed energy efficiency scheme that obligates the UK’s big energy companies to help customers on certain benefits afford energy-saving home improvements. As well as providing funding for a free boiler, it also covers a long list of other energy-saving measures, including ground source heat pumps.