Installation of a Ground Source Heat Pump in the UK

Written-by

Janet Richardson

Reviewed-by

Richard Burdett-Gardiner

Updated on

Sep 05, 2024

Installation of a Ground Source Heat Pump in the UK

Compared to other forms of heating, a ground source heat pump (GSHP) or geothermal heat pump requires much more thought and planning. There are numerous factors you need to consider, including the space you have available for coils and infrastructure, the higher initial costs and whether you will stay with traditional radiators, switch to more efficient underfloor heating, or a combination of both. However, if you have a suitable space, installing a ground source heat pump can be a highly efficient, cost-effective and relatively low-maintenance way to heat your home.

It's best if we get the elephant in the room out the way first, the cost of installing a GSHP for a residential home in the UK is between £18,000 and £35,000. We'll come back to the costs of installing a GSHP later. 

Is a Ground Source Heat Pump Right for me?

GSHPs are the most efficient of the heat pumps, in fact, the most efficient heating system on the UK market, and if you have the room, then they can be a great idea. Space is certainly going to be the first consideration you need to take into account. You’ll require substantial land to lay the pipework or coils, for a ground loop installation. The alternative if you don't have surrounding land that can be dug up for trenches, you can install a vertical loop (bore hole) system that drives straight down into the ground near your home or workplace. 

Installing a ground source heat pump on domestic premises is usually considered to be permitted development, not needing an application for planning permission. However, it is always worth checking with your local council before work on your installation begins. Local regulations may apply if you live in a listed building or a conservation area. 

For a ground loop installation, you will need to install pipes that are 1m apart and 1-2m deep in the ground. The loop of pipe used will be no longer than 400m in length but depending on the size of the heat pump required you may require 2 or more of these ground loops. The average system requires between 600 and 1200 square metres of land. The land must of course be clear of trees and buildings. Wet, sandy soil or clay are best, dry and/or rocky substrate doesn't have the same heat transfer properties.   

If you have limited space for the ground loop system, then the vertical loop system could be the solution for you, though it does tend to be more expensive. Boreholes are dug vertically, using a drilling rig to a depth of between 15m and 122m subject to the required heat exchange. The pipes are then buried in the boreholes. You may need more than one borehole depending on the energy required for your property. Most bore-hole GSHP systems have three or more. Construction vehicles such as diggers and/or a crane will need access to your garden area. 

Then you will need to think about the interior of your home. Like all heat pumps, GSHPs work best with underfloor heating rather than conventional radiators, although it's not necessary to switch out your radiators, UFH will deliver the optimal result. The average cost of installing an underfloor heating system is usually between £2,000 and £8,000 for a three to four bedroom house in the UK. GSHPs provide a low-level constant heat making them the perfect partner for underfloor heating which is at its most efficient when operating at lower flow temperatures. 

If you decide to stick with radiators, then you may need to switch some out in the main living areas. Typically radiators will need to be doubles or oversized and the pipework needs to be 15 or 22mm instead or the smaller stuff to deliver the appropriate flow temperatures when used in conjunction with a ground-source heat pump system. Both ground-source and air-source heat pumps deliver low flow temperatures, so the surface area of the radiators will generally need to be larger, to effectively heat the property. 

The property will need to be well insulated and energy efficient. It's always worth ensuring your property is well insulated with any heating system, but it's of paramount importance with heat pumps because they are designed to produce an ambient heat on an ongoing basis. If you have too many draughts and poor insulation, the property won't be able to retain heat.

Bearing in mind the considerable expense of installing a ground source heat pump you won’t want to waste the heat produced from your system because your home isn’t adequately insulated. When you are planning to install a new system, you might want to upgrade the insulation of your loft/ceilings, walls, and floors to help lower the running costs of your ground source heat pump system and ensure it can effectively heat the space required. 

A ground source heat pump transfers heat from the ground outside your home to heat your radiators or underfloor heating. It can also heat water stored in a hot water cylinder, ready to use for your hot taps and showers. If your ground source heat pump produces water that is hot enough for your needs, then there is no requirement for an electrical top-up from an immersion heater. However, immersions can be fitted into hot water cylinders for backup measures. 

Finally, installing a GSHP is more cost-effective if you are replacing an old, inefficient system such as an LPG, oil or electric boiler which is expensive to run. 

Types of Ground Source Heat Pumps

Installing a ground source heat pump involves digging up the garden or land surrounding the property.

There are two types of ground source heat pump systems.

Bore Hole Ground Source Heat Pump: 
Bore holes are drilled straight down and a vertical loop system installed. The borehole will be anywhere between 15m and 100m deep. That’s a long way down and can depend on factors such as the underlying soil and rock. It might seem like the easier option, especially if you are short of space, but it can be costly on the construction front, and you might need planning permission depending on your location.

Horizontal Coil Ground Source Heat Pumps:
The other option is to put in a ground loop system that sits horizontally in a series of trenches. Of course, this will again depend on the amount of land you have available that you're happy to dig up. That size needs to be big enough to fit your heating needs. In essence, the bigger the house you have, the more piping you will need.

Typically, for a 3-4 bedroom property in the UK where a 12-15kW ground source heat pump is installed, you will need 600 to 1,200 square meters (about 0.15 to 0.3 acres) to lay out the coils. A common rule of thumb is that 10m of trench will need to be dug per kilowatt of heating load. 

Factors that effect the space you need include:
The heating load required by the property. This depends on how well the property is insulated, the design of the internal space, windows and doors. 

Thermal conductivity of the ground:
The best type of soil for horizontal coils is sandy and moist. The efficiency of the soils heat transfer will directly effect the amount of land required for coils.  

Example
A four-bedroom house requiring a 15 kW GSHP system.  

Trench Length: Approx. 150 meters of trenching would be required.
Land Area: Assuming trenches are spaced 1 meter apart and are 100 meters long, you might need 3-4 trenches. Each trench would cover an area of about 100 square meters, resulting in a total area of approx. 400-600 square meters for the ground loops.

Ground Source Heat Pump Installation Guide

Here is a brief run-through of the steps involved in installing a ground source heat pump. 

Step 1: Initial Assessment and Planning 

Adequate planning and preparation is the most important step in the process of designing a ground source heat pump system. A detailed geological survey of the ground conditions is conducted to investigate the suitability of the ground for ground loops. Understanding the composition of your soil and its thermal properties is vital as different soil types (e.g. sandy, clay) affect heat transfer rates. Your installer will determine what type of heat pump, energy supply source, and energy distribution would be the best fit for you. 

Your installer will do a heat loss calculation to work out how much heat is needed to keep your home warm. This involves assessing the insulation, window size and type, and orientation of your home. This calculation is crucial to ensure that the heat pump is appropriately sized. It’s also important that your installer checks that there are no gas lines, water pipes, or any other obstructions that could interfere with your installation.

Step 2: Permits and Regulations

Despite the disruption caused by the installation of a ground source heat pump system, planning permission is not usually required as the installation of a ground pump system is considered to be permitted development. However, it’s always wise to check with the local council and environmental agencies before you start digging on your land. Your installer should obtain any necessary environmental impact assessments. The rules may well be different if you live in a listed building or a conservation area. 

As with air-source heat pumps, your ground-source heat pump installation must comply with the Microgeneration Certification Scheme (MCS) standards and Building regulations. 

Step 3: System design

Firstly, your installer will advise you as to which type of loop system is suitable for your garden area. For smaller plots of land vertical loops are ideal. Boreholes are drilled deep into the ground for the coils. Horizontal loops are suitable if you have a larger plot of land. Trenches are dug to lay the coils. Lastly, if you have a lake or large pond nearby coils can be submerged. 

The installer will then design the loop configuration. The loop length and depth are based on the thermal conductivity of the soil and the heat pump’s requirements. The installer will also decide on the pipe material and the diameter of the pipes. Typically, high-density polyethylene (HDPE) pipes are used.

Step 4. Installation of Ground Loop

Your installer will use a drilling rig to bore holes to the specified depth for the vertical system. U-shaped pipes are inserted into the boreholes.

Your installer will excavate trenches approximately 4-6 feet deep for the horizontal system. Pipes are laid in a coiled or slinky pattern. 

Once the pipes are laid, they need to be connected to the manifold, ensuring there are no kinks or bends that could restrict flow. A pressure test will be conducted at this point to check for leaks before the trenches and boreholes are backfilled. 

Step 5. Installing the Heat Pump Unit

The heat pump unit will then be installed inside your home, typically in an outbuilding or lean-to. Your installer will decide on the best location for it and ensure that it is close to the distribution system (radiators, underfloor heating, etc.). 

The heat pump unit is secured to the floor or a mounting bracket and then the ground loop pipes are connected to the corresponding inlets and outlets on the heat pump. The ground loops are filled with an chemical solution to prevent freezing and to improve heat transfer efficiency. Ground source heat pumps typically use refrigerants such as R410A or R134a, which facilitate heat transfer within the system. These refrigerants absorb heat from the ground and transfer it inside the building. 

Step 6. Integration with the Heating and Cooling System

Your installer will integrate the heat pump with the existing or new heating distribution system (e.g., radiators, underfloor heating) and install control systems and thermostats for optimal operation.

Step 7. System Commissioning

Your installer will carry out the final checks and testing. The loops are flushed to remove any air from the system. The installer will check that the system is balanced for an even distribution of heat. They will operate the system to monitor its performance and check for any irregularities or issues. At this point, the installer will fine-tune the system settings for efficiency and comfort. 

Step 8. Maintenance and Monitoring

Periodically the connections should be inspected for leaks and to ensure the system is working efficiently. It's extremely rare for anything to go wrong with the coils. The manufacturer’s maintenance schedule should be followed for servicing the heat pump unit.

You should monitor the system’s energy consumption to identify any potential inefficiencies. Review your system’s performance regularly and make adjustments, as necessary. 

If these steps are followed meticulously, you can expect a successful installation of your ground source pump which will lead to efficient, sustainable, and cost-effective heating for your property.

Finding the Right Installer in the UK

As with any major installation, you need to find a reputable and reliable installer. If you are going to take advantage of the Boiler Upgrade Scheme, you need to choose one that is accredited and part of the Microgeneration Certification Scheme (MCS). Checking those credentials is important because if your system is badly installed it can affect the efficiency of the system and cost you money. Make sure that you get several quotes and give yourself a cooling-off period before you finally decide on an installer. You can search our installer database for a list of accredited installers close to your postcode here.

Accessing the Boiler Upgrade Scheme

The Boiler Upgrade Scheme (BUS) provides government grants to encourage homeowners to replace existing fossil fuel heating with more efficient, low-carbon heating systems including air-source heat pumps, ground-source heat pumps, and in limited circumstances, biomass boilers. The BUS grants have been increased recently from £5,000 to £7,500 which is a significant chunk of money towards the upfront cost of installing your low-carbon heating system.

As long as you have your installation carried out by a company that is a part of the Microgeneration Certification Scheme, you may be eligible for the Government’s Boiler Upgrade Scheme (BUS). The installation company will apply for the grant for you in most cases. The grant is not available to developers but can be given if a new build is classed as self-build. 

Although it is no longer compulsory to complete an Energy Performance Certificate’s recommendations for insulation or double glazing to be eligible for the government’s low-carbon heating subsidy, the Boiler Upgrade Scheme (BUS), government guidance still advises that properties should be appropriately insulated.

How Much Does a Ground Source Heat Pump Cost in the UK?

Ground source heat pumps (GSHPs) are an increasingly popular choice in the UK and for good reason. They are the most efficient type of domestic heating system available on the UK market. However, the initial installation costs are significant. It rarely makes sense, from a financial perspective to switch to a GSHP if you're on mains gas. The perfect candidate for a GSH is a large property that's got an old oil or LPG boiler. Especially if you're annual usage is high. It's worth noting that there are also strong environmental benefits to consider.  

In the UK, the price of installing a ground source heat pump ranges from £18,000 to £35,000 for a typical residential property. This price includes the heat pump unit, ground loop system, and installation labor. The exact cost can vary widely depending on project specifics.

What influences the costs? 

Type of Ground Loop System:

Horizontal Loop Systems: These are generally cheaper but require more land area. They involve laying pipes in trenches about 1-2 meters deep. 

Vertical Loop Systems: These are more expensive due to the need for deep boreholes, often over 100 metres deep. Typically, three bore-holes will need to be drilled and they cost an average of £5,000 each. So that's a large outlay before any technology has been installed. 

Site Conditions:

The geothermal properties of the soil play a crucial role in determining the cost. Rocky or clay terrains require more effort to dig trenches or drill bore-holes, which leads to increased costs.
The availability of space is another critical factor. For properties with limited land, vertical loops are often the only feasible option, despite being more expensive.

Property Size and Heating Requirements:

The size of the property and its heating requirements significantly impact the cost. Larger properties generally require higher output heat pumps, increasing the overall installation costs.

Additional Expenses:

Planning and inspection: Local regulations might necessitate planning consent, adding a few hundred to several thousand pounds to the total cost.

Central heating system changes: It is often necessary to switch out some radiators for larger ones in order to have the required surface area to radiate heat generated by the heat pump. If you're pipework is under 15mm in diameter then this can also be a problem. Your installation company will be able to ascertain what changes are needed whilst performing the heat/loss survey. 

Running costs and savings

Despite the high initial outlay, GSHPs offer significant long-term savings. They are more efficient than traditional heating systems and due to this, can reduce heating bills by up to 70%. Additionally, the UK government is offering the Boiler Upgrade Scheme, which will help offset the initial installation costs.

The average running cost of a GSHP for a four bedroom, residential property in the UK is estimated to be £800 per year. The table below shows how the running costs of GSHP compare to traditional heating systems. All figures are estimations. 

Heating System	Annual Running Cost (£)	Annual Saving (£)
GSHP	800	N/A
Mains Gas Boiler	900	100
Oil Boiler	1,200	400
Electric Boiler	1,600	800
LPG Boiler	1,500	700

Is it Worth Installing a Ground Source Heat Pump in the UK?

Installing a ground source heat pump in the UK involves a significant initial investment, with costs influenced by a wide range of factors. The long-term savings and environmental benefits, combined with government incentives, make GSHPs an attractive option for heating our homes. Making use of the Boiler Upgrade Scheme whilst it's available, future-proofing, getting in front of potential carbon taxes and regulations relating to combustion boilers are common drivers for those seeking ground source heat pump quotes.

Aside from the obvious environmental benefits and as you've probably come to realise if you've made it this far; GSHP systems are particularly viable if you've got a larger property with surrounding land, you're off mains gas, and have high annual heating bills. If you don't tick these boxes, they're a bit hard to justify on paper.

If you have any questions regarding ground source heat pumps, you can always give us a call on 01392 693 900 or contact one of our installation companies through our directory.
Our directory can be accessed by entering your postcode on the form below and selecting heat pumps from the menu.