What is a ground-coupled heat pump?
The term ground-coupled heat pump refers to two main types of heat pump that have one defining feature – they are, as the name suggests, coupled to the ground. These are also known as ground source heat pumps; which is a term that we prefer here at IMS Heat Pumps.
Often, ground-coupled heat pumps are mistakenly called “geothermal” heat pumps. In fact, geothermal energy is most readily accessible in places like Iceland, and is accessed via large power stations rather than via domestic heating systems.
So, when we talk about ground-coupled heat pumps, we mean:
- Vertical ground source heat pumps, or…
- Horizontal ground source heat pumps
We’ll begin by having a look at the defining features of a ground-coupled (ground source) heat pump, and then move on to explore the different variations that fall under this banner.
Introduction to ground-coupled (ground source) heat pumps
If you’re looking for a renewable heating option for your domestic or commercial property, ground source heat pumps are an intelligent choice. A ground source heat pump works by circulating water and antifreeze through its system. As this solution moves, the heat is gathered, filtered through a heat exchanger, and released into the property.
The benefits of installing a ground source heat pump are exponential. You will integrate a renewable heating solution into your domestic or commercial space that has the potential to be carbon-neutral if used with renewable electricity. You will quickly see a decline in energy bills and can earn money through government schemes.
If you are exploring ground source heat for your property, it is imperative to understand the different technologies on offer, and which is most suitable to your scenario.
Some key factors in an informed decision-making process are as follows:
- Location: Where you’re located should be a major deciding factor, because different types of ground-coupled heat pumps are suited to different spaces and soil types.
- Scale: Are you looking to heat a small home or a large corporate enterprise? What is the size of your property, and how does this impact the type of system you need?
- Budget: Vertical systems are more expensive than horizontal systems. This must be taken into account in the context of RHI payback and return on investment timelines.
Also read: Air source heat pump grants in the UK
It is important to note that ground source heat pumps aren’t intrinsically carbon-neutral, as they need some electricity to operate. However, if you can use renewable electricity to run your heat pump system, there is potential for you to operate an entirely carbon-neutral heating system.
To clear up any confusion as to what kind of ground-coupled heat pump might be most appropriate to your needs, let’s zoom in on vertical and horizontal GSHP system types…
Vertical ground-coupled (ground source) heat pump
A ground source heat pump extracts heat from below the surface of the earth to use for heating and hot water. Both vertical and horizontal ground source heat pumps use energy from the sun that is absorbed into the ground, and then filtered through the pump’s system. The two key installation options are vertical and horizontal.
Vertical ground source heat pumps may be an ideal option if you’re limited by the size of your property’s outdoor space. By using deep-drilled boreholes, the outdoor structure takes up less space than its horizontal counterpart (more on this later). However, vertical systems are always more expensive due to the high level of expertise and equipment needed to drill boreholes.
In our article about the cost of installing a ground source heat pump, we say the following:
“The cost of drilling boreholes varies, but is usually between £25 to £40 per metre depth. In addition to the drilling, you also have the costs of grouting the pipe and mobilising the plant equipment. A useful guideline is £4,000 to £6,000 per borehole, although this varies. Typically, each borehole will contribute approx 4kW to the system. Therefore, with a 12kW ground source heat pump system, you will likely need to drill three boreholes.
With this in mind, let’s assume that borehole drilling costs £5,000 per borehole (the mid-point within our £4,000 to £6,000 estimate). As already stated, for the installation of a 12kW vertical ground source heat pump, you will need three boreholes. This adds up to £15,000 for the drilling alone, which contributes to a £30,000 installation overall.
Horizontal systems are always cheaper to install. The equivalent 12kW ground source heat pump system with horizontal ground loops would add up to around £17,000 for the installation, in total. Of course, these costs are all estimates and depend on your individual project!”
A vertical ground source heat pump may be marginally more efficient than a horizontal system, but this depends on your specific situation.
Our experts can explain more about the potential differences. You can contact us for guidance about your projected costs and savings.
Horizontal ground-coupled (ground source) heat pump
As we’ve already established, horizontal ground source heat pumps are cheaper to install.
Like the vertical ground source heat pump, the horizontal version is renewable and will be kind to your pocket and the environment. Technically, it works very much the same way.
A horizontal ground source heat pump is installed using shallow trenches, rather than deep drilled boreholes. This means it can be prepared using standard diggers. Trenches are usually dug about 1.5 metres below the ground and are most effective when equally spaced apart.
The horizontal ground source heat pump requires a larger outdoor surface area, so this option is more appropriate for properties with large gardens or nearby fields. Local geology also plays a part in your decision. A very basic rule of thumb is that the wetter and more saturated areas are most appropriate to hosting a horizontal ground source heat pump.
Also read: How much space do I need for a ground source heat pump?
Geothermal heating
Whilst also “ground-coupled”, geothermal heating has very little else in common with the ground source heat pump. Rather than using heat from the sun that has been absorbed into the earth, a large-scale geothermal heating system will source heat from the earth’s core.
What does this mean for domestic properties in the UK? Quite simply, that geothermal heat is not a feasible option. Instead, you must base your research on ground source heat pumps.
In summary
The most appropriate ground-coupled (ground source) heat pump option for you will be based on where you live, the size of your outdoor space, the type and saturation of soil, as well as important financial and environmental considerations.
If you’re looking for an accredited ground source heat pump installer in the UK, look no further. The experts at IMS Heat Pumps will evaluate your property and help you decide which system is best suited. You will be in safe hands for the whole project, from start to finish.