Ground Source Heat Pump Costs
How Much is a Ground Source Heat Pump?
Ground source heat pumps vary considerably in price from £15,000 to around £30,000 based on the size of the heat pump, size of hot water cylinder and whether a ground loop or borehole system is used.
Read on for more information about the different types and costs.
How Heat Pumps Work
Heat pumps basically do the same job as a boiler, providing space heating and domestic hot water, just more efficiently.
A heat pump harvests heat from the environment by pumping a mixture of water and antifreeze around a loop of pipe buried in the garden, it raises the temperature to a usable level using a compressor, and brings it into the home.
There are three main types of heat pump systems: air source heat pumps, ground/water source heat pumps, and hybrid heat pumps.
In this article we’ll look at ground source and the costs involved.
Types of Ground Source Heat Pump
Horizontal Ground Source Heat Pump
Horizontal systems use pipe buried in the soil at a depth of 1-1.2m, and sections of pipe must be at least 1m apart.
Straight lengths of collector pipe are preferable over coiled slinky loop arrays as they are more effective, heat collection is spread over a wide area, and they reduce the risk of cold spots in the collector system.
During installation, sand or quarry dust should be used to cover the pipe, providing protection from sharp stones in the backfill and ensuring thermal contact between the collector pipe and the soil.
Vertical Ground Source Heat Pump
In a vertical ground source system, collector pipe is installed in boreholes drilled into the bedrock. Boreholes are typically 70 to 200m deep and spaced 6-8m apart, so they require less space than a horizontal system.
Drilling equipment is heavy, so good access is required, and the process can produce a lot of wastewater and drilling spoil. Back gardens are usually not suitable for a borehole system.
Ground Source Installation Costs
The average installation costs for GSHPs in the UK break down as follows:
- Basic system (6-8 kW): £12,000 to £15,500 for a horizontal ground loop system
- Larger system (12 kW):
- Horizontal ground loop: Around £24,000
- Vertical borehole system: Approximately £36,000
The higher cost for vertical systems is due to the expensive drilling process required for boreholes. Drilling costs typically range from £40 to £65 per metre depth, with a guideline of £4,000 to £6,500 per 100m borehole.
Cost Breakdown
- Heat pump unit: £6,000 – £10,000
- Ground loop installation:
- Horizontal: £5,000 – £10,000
- Vertical (boreholes): £15,000 – £30,000
- Additional components (e.g., hot water cylinder): £2,000 – £3,000
- Labour costs: £3,000 – £5,000
Impact of Soil Conditions on Costs
Heat from the sun is stored in soil, rock, or water and can be utilized by a ground or water source heat pump. The temperature is usually more constant than the air temperature, so it provides a stable resource for a heat pump.
A cold heat transfer liquid is circulated through pipes buried in the ground or weighted pipes in a body of water, picking up heat energy and returning it to the heat pump. The heat energy is then transferred into a refrigerant circuit, which uses a compressor to raise the temperature to a usable level for the heating and hot water system.
Soil conditions can significantly influence ground source heat pump installation costs, and their resulting efficiency. Heavy clay soils generally hold more heat than sandy soils, this can potentially reduce the required length of pipe required and subsequent system costs.
- Soil composition
Rocky or difficult to excavate ground increases installation costs due to specialised equipment needs. - Thermal properties
Soils with higher heat transfer (such as clay) work more efficiently with heat pumps, potentially lowering long-term operating costs. - Groundwater presence
While it can enhance thermal conductivity, significant groundwater flow may alter the system efficiency and viability. - Excavation depth
Colder climates may require deeper pipe placement, increasing installation costs.
A site survey is crucial before ground source installation to optimise system design and minimise costs.
Government Grants for Heat Pumps
England and Wales
The Boiler Upgrade Scheme (BUS) offers substantial grants to encourage property owners in England and Wales to switch to low-carbon heating systems. As of October 2023, eligible applicants can receive:
- £7,500 towards the cost and installation of air source or ground source heat pumps
- £5,000 for biomass boiler installations in rural, off-gas grid properties
These grants aim to offset the higher upfront costs of low-carbon systems compared to traditional fossil fuel boilers. The UK government has significantly increased funding for the scheme, committing an additional £1.5 billion to extend it until 2028. This expansion is part of a broader £6 billion package to help households and businesses reduce energy bills while supporting the transition to net-zero.
Scotland
The Home Energy Scotland (HES) scheme helps with energy efficiency improvements for homes in Scotland. It offers two options for financial support: interest-free loans and grants for necessary home improvements. Funding is available for a range of energy efficiency measures, including double glazing, insulation, and renewable energy systems such as heat pumps.
Payback Period Estimation
The payback period for a ground source heat pump (GSHP) in the UK typically ranges from 12 to 18 years, depending on various factors such as installation costs, energy prices, and system efficiency.
For a 2-3 bedroom house, homeowners can expect to break even on their GSHP investment within this timeframe, considering the average annual savings of up to £2,000. However, the payback period can be significantly reduced through available financial incentives:
- The Boiler Upgrade Scheme & The Home Energy Scotland Grant and Loan offers grants of £7,500, which can substantially lower initial costs and shorten the payback period.
- Energy price fluctuations impact payback time, with higher energy prices potentially leading to faster returns on investment.
- System efficiency plays a crucial role, with GSHPs typically generating 3.5 to 4.5 units of heat for each unit of electricity used.
- The payback period may decrease in the future, with projections suggesting it could fall by 38% to 10.6 years by 2030 due to industry scaling and reduced production costs.
It’s important to remember that while the initial investment is significant, ground source heat pumps have a lifespan of about 25 years (and often much longer), allowing homeowners to enjoy energy savings well beyond the payback period.
Is Your Property Suitable?
When considering a ground source heat pump for your property, several factors determine its suitability and cost-effectiveness:
- Property insulation
Heat pumps work best in well insulated homes, as they generate heat at lower temperatures than traditional boilers. Your installer will be able to advise whether your property meets the high insulation standards to maximise efficiency. - Available land
Horizontal systems require a large garden area (typically 2-3 times the heated floor area of your home), while vertical systems need less space but involve deeper drilling. - Existing heating system
Replacing electric or coal heating with a GSHP often yields significant savings, especially in well insulated properties. However, replacing a gas boiler or oil boiler may not be as cost effective. - Heating distribution
Underfloor heating or warm air systems are more efficient with heat pumps due to the lower temperatures required, compared to traditional radiators. Larger radiators can be installed to offset this effect but it’s not ideal. - Soil conditions
Clay and wet soils are ideal for GSHPs due to their high thermal conductivity. A ground survey can help determine your soil’s suitability. - Planning considerations
While GSHPs are typically considered permitted development, it’s advisable to check with your local authority for any specific requirements or restrictions. Again, your installer can advise on this
To determine if a GSHP is right for your property, consult with a qualified installer who can assess your home’s specific needs and provide advice and quote.
FAQs
Which is more efficient, ground or air source heat pump?
Generally ground source heat pumps are considered to be slightly more efficient. This is due to the fact that ground temperature below 1m is stable all year, compared to air temperature which fluctuates wildly.
How much land is required for a ground source heat pump?
Typically for a ground loop array you can assume 2-3 times the heated floor area of the home will be required.
What grants are available for ground source heat pumps?
Government schemes are available to part finance the installation of renewable heating systems. In Scotland, there is the Home Energy Scotland Loan and in England & Wales, the Boiler Upgrade Scheme.
How does a ground source heat pump work?
A cold heat transfer liquid is circulated through pipes buried in the ground, picking up heat energy and returning it to the heat pump. The heat energy is then transferred into a refrigerant circuit, which uses a compressor to raise the temperature to a usable level for the heating and hot water system.
