Air Earth Energy - Ground Source Heat Pumps

GROUND SOURCE HEAT PUMPS

Ground Source Heat Pumps offer efficient heating and hot water supply for commercial and residential properties. They use pipes that are buried outdoors to harvest heat from the ground. This heat can then be used to provide hot water or heat radiators. Ground source heat pumps are powered by electricity, but the harvested heat is naturally renewed.

A ground source heat pump circulates antifreeze and water around a ground loop located below the ground. The size and length of the ground loop depends on several factors such as the amount of heat needed and the size of your facility. Longer loops are capable of absorbing more heat although they require more space to be buried in. If square footage is limited, a vertical borehole can be drilled instead.

Heat is then absorbed from the ground and goes through the heat exchanger found in the heat pump. Ground source heat pumps can be used all-year long since the ground maintains a fairly constant temperature under the surface. They also produce heat at much lower temperatures than regular boilers. To achieve better results, the building must be draught-proofed and well-insulated. While you don’t need a large amount of space to accommodate a ground source heat pump, the ground must be suitable for digging a borehole or trench.
With regular maintenance, your ground source heat pump can last up to 20 years. Regular tune-ups will ensure your heater operates safely and effectively while reducing costly repairs and energy bills.

Do you have somewhere suitable to put it?

You don’t necessarily need a large space, but you will need land near your home suitable for digging trenches or drilling boreholes.

Ground loop

The ground will need to be suitable for digging and accessible to machinery from a road entrance. The area will need to avoid trees, as roots will cause problems when digging trenches. The length of ground loop and trenches depend on the size of your home and the amount of heat you need.

Boreholes

If space is limited, it may be possible to drill vertical boreholes to gather heat. This is usually more expensive than digging trenches and usually needs a specialist ground (thermogeological) survey.

Larger houses may require more than one borehole. Borehole depth depends on the heat demand of a property and the underlying geology but is likely to be around 75-200 metres deep.

Inside the house

You will need space inside your home for the indoor heat pump unit, which contains key components. The inside unit often contains the hot water cylinder and is roughly the size of an American style fridge.

How will you heat the rooms in your house?

Most homes in the UK use radiators or underfloor heating to circulate hot water, which is known as a ‘wet system’. Ground source heat pumps need a wet system.

If you don’t currently have a wet system, you will have to decide whether you’d like to install one. This is a great opportunity to make sure the wet system is optimised for a heat pump, resulting in lower running costs.

How much does a ground source heat pump cost?

The cost of a ground source heat pump installation varies, influenced by:

Access to the ground and whether you choose trenches or a borehole to lay the ground loop.
The brand, model and size of heat pump chosen.
The size of the property and how much heat it needs.
Whether it’s a newbuild or an existing property.
Whether you’re opting to make any improvements to your radiators to improve the efficiency of the heat pump, or if you are installing radiators or underfloor heating for the first time.

Save on your energy bills

Installing a Ground Source Heat Pump can help you to reduce your monthly energy bills depending on your current system and the other alternatives available to you. Savings are more likely if you do not have access to mains gas. Savings are unlikely to be possible if your home is not well insulated.

The table below identifies the savings that the Energy Savings Trust suggested could be made by replacing an existing heating system with an average Ground Source Heat Pump in an average detached 4 bedroom home under the outgoing Domestic Renewable Heat Incentive Scheme*.

Government grants*

From 23 May 2022, you can apply for a one-off grant of up to £6000 towards the cost of installing any new ground-source heat pump whose installation commenced no earlier than 1 April 2022. This is under the terms of the government’s new Boiler Upgrade Scheme (BUS)*, which offers up to £6,000 as an incentive for ground-source heat pumps to homeowners who have first met the home insulation recommendations in an EPC report. Other eligibility criteria may apply; see here for details.

* The BUS scheme replaces the former Domestic Renewable Heat Incentive scheme. Successful applicants to the DRHI scheme before the deadline of March 31st, 2022 will remain eligible for payments under the scheme for seven years from the date of installation.

[Last updated April 12, 2022]