Guide to Ground Source Heat Pumps

Ground source heat pumps are a greener alternative to conventional boilers, offering a more sustainable method of heating a home and providing hot water. These systems extract heat energy from the ground using a network of pipes buried beneath the surface (we’ll explore how they operate in greater detail below).

Last reviewed: September 2026.

This guide covers everything you need to know about ground source heat pumps. Along the way, we’ll explain:

• What ground source heat pumps are;
• How these devices work;
• The various types that can be installed;
• The pros and cons;
• The costs of installing and running them;
• The grants available for homeowners;
• Planning permission requirements;
• The installation process;
• Typical maintenance requirements.

What is a ground source heat pump?

A ground source heat pump is an eco-friendly setup that can be used to provide hot water whilst heating radiators and underfloor heating systems. These devices are similar to air source heat pumps. Instead of drawing heat from the air, however, they use a buried network of pipes known as a ‘ground loop’ to extract heat energy from beneath the surface.

There are several different types of ground source heat pump, each of which uses a unique type of ground loop (more on this below).

How do ground source heat pumps work?

Ground source heat pumps operate using the following process:

To extract heat from the ground, a liquid mixture of cold water and antifreeze is pumped through a network of pipes buried beneath the surface. The ground around the pipes has a year-round temperature of between 8 and 12°C due to energy from the Sun. As the liquid travels through the pipes, it absorbs this low-grade heat from the surrounding earth.

The warmed antifreeze mixture then passes up out of the ground and into a heat exchanger known as an evaporator. The refrigerant liquid within the heat exchanger absorbs heat energy from the mixture, evaporating to form a gas. The cooled liquid antifreeze mixture then returns to the ground loop system to extract more heat. Meanwhile, the warmed refrigerant gas rises.

The warmed gas is fed into a compressor, which increases its pressure and causes its temperature to rise even further. Hot refrigerant gas then feeds into a second heat exchanger known as a condenser. Once inside, the gas heats up water contained in pipes – the heated water then travels into the home, where it can be used to power radiators and underfloor heating systems and provide hot water to showers and taps.

Having transferred its heat to the water, the refrigerant gas reverts to a liquid. This liquid passes through an expansion valve at the end of the cycle to reduce its pressure and lower its temperature. Finally, the liquid refrigerant returns to the evaporator, ready to be heated up once more by the antifreeze mixture from the ground loop system (and the cycle continues).

For a visual explainer of how ground source heat pumps work, take a look at this useful video.

Types of ground loop system

Ground source heat pumps can use four different types of ground loop systems for exchanging heat:

• Horizontal
• Vertical
• Pond/lake
• Open loop

Let’s take a look at each of these varieties.

Horizontal

This is the standard type of ground loop system. A horizontal loop consists of a network of pipes buried in trenches around two metres beneath the ground, parallel to the surface – the antifreeze mixture travels through the pipes and draws heat from the adjacent earth.

Vertical

Vertical ground loops are used in cases where garden space is limited as they cover a much smaller area. As the name suggests, the pipes are buried in a vertical position perpendicular to the surface, requiring a borehole of up to 200 metres deep – the pipes gather heat energy from the ground surrounding the borehole.

Pond/lake

In some areas, you’ll find bodies of water underneath the ground. If there is a large enough underground lake available, then a pond/lake ground loop may be used. In this setup, the network of pipes goes down into the body of water at least three metres below the surface. The antifreeze mixture in the pipes absorbs heat energy from the water and carries it back to the heat exchanger.

Open loop

Open loop systems are the least common type and operate differently from the other setups. Instead of using an antifreeze mixture carried in pipes, water from an underground lake or well is circulated directly through the ground source heat pump system to the heat exchanger.

Pros and cons of ground source heat pumps

One of the main benefits of ground source heat pumps is their efficiency – as the temperature underground remains relatively constant throughout the year, they can produce three to four times as much heat energy as is required to operate them (providing greater efficiency levels than air source heat pumps).

Other advantages to ground source heat pumps include:

• They provide hot water as well as heating your home;
• Upfront grant funding is available in every part of Great Britain – £7,500 through the Boiler Upgrade Scheme in England and Wales, and £7,500 (or £9,000 in rural and island areas) through the Home Energy Scotland Grant and Loan in Scotland. See the grants section below;
• Minimal maintenance is required;
• Depending on which fuel you switch from, a ground source heat pump could lower your fuel bills;
• If a renewable energy source is used to power them, they produce zero carbon emissions;
• They produce much less noise than conventional boilers and air source heat pumps;
• The components last much longer than other heating systems (up to 25 years).

These systems are not without their drawbacks. It’s important to be aware of the following disadvantages:

• The high initial installation costs can be prohibitive;
• Installing a ground source heat pump causes disruption to your garden (horizontal ground loops require a large area of earth to be dug up);
• The antifreeze mixture can be damaging to the environment, so the ground loop system must adhere to regulations and be installed securely to prevent this from happening;
• Ground source heat pumps provide heating at lower temperatures than conventional systems, meaning large radiators or underfloor heating systems are required to provide the same heating effect.
• Certain types of ground loop system may not be suitable for the area: horizontal systems require a lot of garden space, vertical systems need a certain type of bedrock, and water-based systems require a large underground body of water to be present.

The cost of ground source heat pumps

When considering the overall cost of a ground source heat pump, it’s important to consider both the price of installation and running the system.

Installation costs

Installing a ground source heat pump accounts for the bulk of the cost. The Energy Saving Trust puts a typical ground source heat pump installation at around £15,000 where the ground loop can be buried in trenches. Where a borehole has to be drilled instead, the cost is considerably higher – the Energy Saving Trust puts the top end at around £57,000.

These are pre-grant figures. In England and Wales the Boiler Upgrade Scheme takes £7,500 off the price as an upfront discount on your installer’s quote; in Scotland the Home Energy Scotland grant does the same job (see the grants section below). Installation of a heat pump also carries 0% VAT until 31 March 2027.

The two key factors when calculating the installation cost are the size of the home that needs to be heated and the area of garden space that’s available. As you’d expect, the more rooms that require heating, the greater the size of the ground loop and the higher the costs.

Horizontal ground loops are the cheapest option from an installation standpoint. However, they usually require a substantial area of land. If a vertical ground loop is required due to limited space, the ground source heat pump borehole will cost significantly more than the groundwork for a horizontal system.

Running costs

Once the system is installed, a ground source heat pump still requires some energy input to pump the various heat-exchanging fluids around the system. That said, the running costs are typically lower than a conventional system if the home is insulated effectively.

The Energy Saving Trust’s current guidance is that for every unit of electricity a heat pump uses, it delivers three to four units of heat – an efficiency of 300-400%, against roughly 90% for an A-rated gas boiler. That efficiency gap is what creates the saving.

How much you actually save depends almost entirely on what you are replacing:

• Electric heating, LPG, solid fuel and oil – these are the expensive fuels, and this is where ground source heat pumps deliver their biggest annual savings.
• An old, inefficient gas boiler – a worthwhile saving is realistic.
• A newer, efficient gas or oil boiler – be realistic. Because electricity costs more per unit than gas or oil, the Energy Saving Trust is clear that a heat pump “won’t necessarily be cheaper to run” in this scenario. Moving onto a heat pump time-of-use tariff is usually what tips the balance back in favour of the heat pump.

Your installer must calculate a Seasonal Performance Factor (SPF) for the system they design for your home, and share it with you before work starts. That figure – not a generic national average – is the honest basis for estimating your running costs.

For an indication of typical annual savings by the fuel you are replacing, the Energy Saving Trust publishes a savings table on its ground source heat pump page, which you can filter for England, Scotland, Wales or Northern Ireland. Treat any national average as a starting point only — actual savings vary widely by property, insulation, system design and tariff, so get quotes and ask each installer for the SPF figure for the system they are proposing.

Grants for ground source heat pumps

There is no longer any scheme that pays you an ongoing income for running a ground source heat pump. The Domestic Renewable Heat Incentive, which did exactly that, closed to new applicants on 31 March 2022 — if you are not already on it, you cannot join it. Support today comes as an upfront discount on the installation instead, and which scheme applies depends on where you live.

England and Wales: the Boiler Upgrade Scheme

The Boiler Upgrade Scheme (BUS) is administered by Ofgem and gives:

• £7,500 off the cost and installation of a ground source heat pump (this includes water source heat pumps and pumps on shared ground loops);
• £9,000 off an air-to-water or ground source heat pump in eligible off-gas-grid properties — an enhanced rate available from 21 July 2026 until 31 March 2027;
• £7,500 for an air-to-water (air source) heat pump, £2,500 for an air-to-air heat pump and £5,000 for a biomass boiler, if you are weighing up the alternatives.

Biomass boilers carry extra conditions: they can only go into rural properties with no connection to the gas grid, and only as a standalone system providing both heating and hot water.

How it works. BUS is installer-led. Your MCS-certified installer makes the application on your behalf, deals with Ofgem, and passes the grant to you as an upfront discount on your quote — you never handle the money. Ofgem will contact you to confirm you consented to the application and that you meet the eligibility criteria; if you don’t respond within 14 calendar days the application may be rejected. Once approved, your installer has six months to complete a ground source installation (three months for other technologies).

Who qualifies. The scheme is open to residential and non-residential properties in England and Wales. Key conditions:

• Your installer and the products used must be certified under the Microgeneration Certification Scheme (MCS);
• The heat pump must be capable of meeting the full space heating and hot water requirements of the property, and must be sized to meet its full space heating need;
• It must replace an existing fossil fuel or electric heating system — you cannot use BUS to replace an existing low-carbon system;
• Hybrid systems (for example a gas boiler paired with a heat pump) are not eligible;
• New builds are excluded, apart from qualifying self-builds;
• Social housing is excluded, as are properties that have already had government or Energy Company Obligation funding for the same heat pump or biomass boiler.

One important change worth knowing: from 28 April 2026 you no longer need a valid EPC to apply. The Boiler Upgrade Scheme (England and Wales) (Amendment) Regulations 2026 removed that requirement, along with opening the scheme to air-to-air heat pumps and putting MCS certification on a statutory footing. Where no EPC exists, your installer supplies alternative evidence instead. The same amendment regulations also extended the scheme to 2030, so it is not a short-term offer you need to rush.

The government also asks that you consider insulation and other efficiency measures alongside the installation, since a heat pump performs best in a well-insulated home. That is guidance, not a condition of the grant.

Check current eligibility and grant amounts on GOV.UK: Apply for the Boiler Upgrade Scheme.

Scotland: the Home Energy Scotland Grant and Loan

Scottish residents are not eligible for the Boiler Upgrade Scheme — BUS covers England and Wales only. Scotland has its own, arguably more generous, package: the Home Energy Scotland Grant and Loan, funded by the Scottish Government and delivered by Energy Saving Trust.

For a ground source heat pump you can apply for:

• A grant of up to £7,500;
• Plus an optional interest-free loan of up to £7,500 on top, to cover the balance;
• Plus a £1,500 rural and island uplift on the grant if your property qualifies, taking the grant to £9,000.

So a rural Scottish household can access up to £16,500 towards a single heat pump installation, of which £9,000 never has to be repaid.

Who qualifies. You must own the home you live in, it must be your only or main private residence, and it must be an existing property in Scotland. You do not need to be on benefits. Other conditions worth flagging:

• Your installer and the product must be MCS-certified;
• The system must provide 100% of the property’s heating and hot water — hybrid heat pumps are not funded;
• Replacement heat pumps are not eligible for the grant, although the interest-free loan of up to £7,500 is still available for them;
• You do not need an EPC to apply for a heat pump (an EPC is only required for insulation and other energy efficiency measures);
• Funding is first-come, first-served and subject to availability. It is reserved only once you have a written funding offer — do not start work before that offer arrives, as funding cannot be granted retrospectively;
• Loan applications involve affordability and credit checks and a 1.5% administration fee, capped at £150. Repayment terms run up to 12 years for loans over £10,000.

Start by calling Home Energy Scotland free on 0808 808 2282; an advisor checks your options and refers you into the application.

Northern Ireland

There is currently no equivalent heat pump grant in Northern Ireland. Insulation funding may be available — contact NI Energy Advice via the Northern Ireland Housing Executive.

0% VAT

Across the UK, the installation of energy-saving materials including heat pumps carries 0% VAT until 31 March 2027, after which the rate is expected to return to 5%. Your installer applies this automatically; there is nothing to claim.

Planning permission requirements

Ground source heat pump planning permission requirements vary depending on your local authority. In most cases, these systems are classed as permitted development and will not require permission. That said, exceptions apply — listed buildings and conservation areas in particular — so you must check with your local authority before installing a ground source heat pump.

Your installer will also notify your distribution network operator (DNO) that a heat pump is being connected, and will usually complete the paperwork for you.

Ground source heat pump installation process

The process of installing ground source heat pumps is as follows:

1. The home and garden space will be assessed to determine the type and size of ground loop that is required.
2. The underground area required for the loop will be excavated: for horizontal systems, this involves digging trenches two metres deep across the required area; for vertical systems, a deep borehole of between 15 and 200m will be created.
3. The pipes will be installed in the loop fields.
4. The existing heating system will be modified if necessary (this could include installing larger radiators or underfloor heating systems).
5. The heat exchangers and heat pump will be installed, connecting the ground loop to the heating system.

Whichever route you take, get quotes from at least three MCS-certified installers before committing.

Maintenance requirements

In most cases, the maintenance requirements for ground source heat pumps are minimal. The manufacturer and installer will brief you on this, but it’s likely that you’ll need to check the water pump, external pipes, and electronics once a year. A professional should also check over the system once every three to five years.

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This guide has explained all of the key information about ground source heat pumps, from the different types that are available to the installation and running costs.

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