Trench containing pipes for ground source heat pump
Ground source heat pumps require extensive digging to install

As we move away from our reliance on fossil fuels, we need to find new ways to heat our homes and businesses – and one way that can both reduce your carbon footprint and your energy bills is by installing a Ground Source Heat Pump. It has never been a better time to investigate it either, as thanks to the Government you could be entitled to a grant which can help pay for it.

Ground source heat pumps have been touted as a greener form of central heating, although it might not be the best possibility for everyone.

In this article, we will look at what exactly a ground source heat pump is, how it works, and how it needs to be installed. We will also examine some of the considerations you will have to make when you are deciding whether a ground source heat pump is right for you.

So, what is a Ground Source Heat Pump?

A ground source heat pump is designed to harness the natural heat from the ground, which is then transferred to your home in a similar way to a gas central heating system.

To make this happen, pipes need to be installed beneath the ground, either in trenches or in boreholes. Liquid is passed through this network of pipes, and then it is compressed using electricity to raise the temperature before that water is passed through the radiators or underfloor heating in your home.

The heated water that is left over is then stored in a hot water cylinder for use in hot taps, for showers, and for baths.

How Does a Ground Source Heat Pump Work?

As with other central heating systems, a ground source system is a closed loop system. Instead of a combustion event heating the water that goes to the radiators, it is the ambient heat generated from the ground that is compressed and then pumped around the house.

The pipes are filled with Thermic Transfer Fluid, also known as a ‘brine’, and this is a mixture of anti-freeze and water. As this passes through the network of pipes under the ground, it warms to the temperature around it – which can be much warmer than the air temperature.

The TTF solution is then compressed before going through the heat exchanger. This uses electricity, which can be made more environmentally friendly by choosing electricity from renewable sources. The compression raises the temperature of the water mixture, which can reach about 50° – just about 10° lower than the temperature tends to be in a gas boiler (but at a fraction of the cost).

After the compression, the mixture is then sent around all the radiators and through the underfloor heating to heat the house, while the rest is stored safely in the hot water cylinder, ready to be used for your shower or bath.

Things to Think About When Considering a Ground Source Heat Pump

There are a couple of things that you need to consider when you are comparing heating systems, and especially with ground source heat pumps.

Space

Although it might sound obvious, the more ground area that the network of pipes can cover, the better it will work. The pipes are usually laid in trenches close to the house, and a 3 or 4-bed new build house with good insulation would need at least two trenches dug, at 30-40m in length.

This means that to get the most out of ground source heating, you need a lot of outside space that can be dug up.

Another possibility is to create a borehole and dig down instead of along. This choice takes up less room and usually provides more heat (the earth is warmer the deeper you go), but they are more costly to install.

Access

Initial installation requires access to your (large) garden for digging machinery, whether you are going to make trenches or boreholes.

Upgrading and Insulation

The better insulated your home is, the less work the heat pump must do. In many cases, it is worth installing the ground source heat pump during the building stage or if you are already planning to renovate the property.

Experts recommend using a ground source heat pump on a new build house that has plenty of garden space, because then you can install underfloor heating and ensure that you have the best insulation possible.

Cost

There is no simple way to put this – but the biggest obstacle for most people when it comes to installing a ground source heat pump is the cost.

At the moment, the cost of installing a ground source heat pump is about £28,000 for trenches, and £57,000 for the boreholes.

Many people consider this an investment and expect to recoup some of the costs through savings in energy bills.

However, it can be difficult to accurately predict what the payback period is because it depends on several factors, including:

  • System efficiency
  • Insulation
  • Type of system replaced.
  • Using the controls properly
  • How you are using the heat produced,

While ground source heat pumps are more expensive to install, they are considered to be more efficient than air source heat pumps – mainly because the soil temperature does not go below 5° throughout the year, which means there is less efficiency variance.

What to Expect from a Ground Source Heat Pump

There are a few differences you might find when you are using a ground source heat pump.

  • Your home might take longer to heat up.
  • You might need to have the heating on for longer periods during the day.
  • If you have extra heating needs, or hot water needs, you might find you need an electric heater to meet demand.
  • The controls are not usually too intuitive, which means you need to ensure that the installer gives you a full demonstration and you keep the user manual handy.

Are There Any Schemes to Help with the Installation Costs?

There are different ways that you can get some help towards the installation costs of a ground source heat pump. In England and Wales, this is through the Boiler Upgrade Scheme (BUS).

If you meet the criteria, you will be awarded a grant of £7.500 towards the cost of your installation. This will be claimed on your behalf by the installation team and the value taken off of the invoice.

There are similar schemes available in Scotland and Ireland.

Is it Worth Installing a Ground Source Heat Pump?

This is where the decision really comes down to you. For many people, the lack of garden space and the cost of the installation are the deciding factor, but if you have acres of land and can afford to get the diggers in, you could find that it is way more efficient than other heating systems.

If you want to discuss your options, the best people to talk to are the Renewables team at GMS. We have the knowledge and experience you can rely on to help you make the right decision.