Answer: Estimates vary, but drilling boreholes typically costs between £25 to £40 per metre in depth. The guideline for a borehole contributing 4kW to the heat system with a standard compressor is roughly 100 meters at £4,000 – £6,000 and you will need three of these for a 12kW system, so £12,000 – £18,000 for the drilling of the boreholes. This can be reduced when using an inverter driven heat pump, such as the NIBE S1155.
Introduction: Ground source heat pump boreholes
So you want to install a ground source heat pump (GSHP) and wondering about how much it will cost? Well, no need to worry, we got you covered in this article.
A GSHP provides a low-carbon heating solution. If operated using renewable electricity, it is carbon-free. A GSHP works by transferring heat to your home from the surrounding soil that has been heated by the sun; a renewable and efficient source of heat!
The most expensive part of a GSHP installation can be getting the pipework underground. This can be done in two ways: a horizontal ground loop or a vertical ground loop.
A horizontal system uses trenches that are about 1.2 metres deep, and is generally used if there is enough available outdoor space. A vertical borehole is used when less space is available and requires drilling to depths of about 100 metres deep. Nonetheless, whichever type of GSHP you choose, some form of ground loops works has to be accounted for in the cost!
You can expect a larger GSHP to be more expensive because of the amount of excavation, the larger water cylinder, and other aspects. The cost also depends on the site and the complexity of the installation. After installation is complete, you can apply for the Renewable Heat Incentive (RHI) – a government scheme to encourage renewable heating, where you can receive quarterly payments for the amount of clean and green heat your system produces. A superb scheme that also means you get to save on your utility bills and gain a greater return on your investment!
Boreholes vs. trenches
Horizontal ground source heat pumps use trenches, which can be dug by standard plant machinery. You can expect to pay a contractor £2 – £5 per square metre of digging for a horizontal ground loop. The issue with horizontal GSHPs is that they use a lot of space and may not be feasible for properties with no large garden. Furthermore, the possibility of installing a horizontal GSHP depends on the local geology. Even at 1.2 metres deep, the typical trench depth, the temperature can vary throughout the year and this can make a difference to the effectiveness and efficiency of heating. Your installer should be able to advise you on whether a horizontal GSHP is right for your property.
If you have limited space in your garden, a vertical GSHP might be the right option. For vertical systems, a deep borehole needs to be drilled using specialist equipment which is handled by experts. It requires a lot more work because of the depth requirement, and is a larger cost. However, boreholes do provide a marginally more efficient and consistent source of heat, and therefore get selected on this basis. And they require less square metres for installation.
The cost of drilling boreholes
Drilling boreholes is a fairly expensive job, but it does still provide a good return on investment in the long-term. For the purpose of this article, let us assume we’re talking about a 12kW vertical GSHP, designed for a single residential property. In reality, you may need a slightly smaller heat pump for your home – but this is just for guidance…
Firstly, it is important to hire a specialist contractor using the correct and specialist equipment. Then, the drilling of boreholes costs about £25 – £40 per square metre depth, plus the pipe will need grouting and the equipment will need to be mobilised.
The guideline for a borehole contributing 4kW to the heat system is roughly £4,000 – £6,000 and you will need three of these for a 12kW system, so £12,000 – £18,000 for the drilling of the boreholes. These are just estimates, and the cost of drilling a borehole depends on many factors including the type of equipment, the site, the design and construction method and the underlying geology and hydrology.
The cost of installing a vertical GSHP
If we take the 12kW ground source heat pump, the total cost of installation can be around £25,000 – £30,000. Although again, this is just an estimated figure.
A study by the Department of Energy and Climate Change found that installation costs comprise of 49% equipment and 51% non-equipment. Of the non-equipment costs, 60% of that is drilling boreholes. This is quite a chunk of the total installation cost. On the other hand, a 12kW horizontal system costs approximately £15,000 – £18,000.
Also read: How much does a ground source heat pump cost to install?
Summary
It’s tricky to know whether boreholes or trenches are the best option for your ground source heat pump. It depends on your property, budget, head demands, the local geology, and the available space. A qualified expert will be able to advise on the most appropriate solution, and this is where IMS Heat Pumps can help. Contact us today for more information.
Whichever type of ground source heat pump you choose, it will provide a great source of renewable heat and the RHI scheme alongside utility bill savings will create brilliant return on investment. For some, vertical GSHPs may be the only option due to limited space. For others, a horizontal GSHP is perfect. Furthermore, an air source heat pump (ASHP) is a solution which is very popular in the UK.
For more information, request a quote today!