Ground source heat pumps use underground pipes to extract heat from the ground. They can be used to heat your home via radiators, underfloor heating and warm air heating as well as heating the hot water in your home.
Ground source heat pumps are an efficient, reliable and renewable energy source that offer a sustainable alternative to fossil fuel power. They are similar to solar panels in that they use energy from the sun but with ground source heat pumps the energy is harnessed from the ground after it has been warmed by the sun and the pump then amplifies this energy for use in your home.
Ground source heat pumps use electricity to run but the energy they harness from the ground is constantly being renewed, meaning they’re better for the environment overall.
A loop of pipe, known as a ground loop is placed beneath the surface of the ground in your garden. The ground source heat pump then circulates a mixture of water and antifreeze around the pipe. Heat from the ground is absorbed into the fluid in the ground loop at low temperatures and this fluid then passes through a compressor, which raises it to a higher temperature ready for use.
Cooled fluid passes back into the ground loops where it absorbs further energy, in a continuous process.
Beneath the surface, the ground remains at a fairly constant temperature at all times, regardless of weather fluctuations so ground source heat pumps can be used throughout the year.
The length of ground loop required depends on several factors including the size of your home and the amount of heat you will need. Longer ground loops are capable of drawing more heat but obviously need more space.
The ground loop is laid horizontally in a trench, typically approximately 1 metre below the surface. If space is an issue, it’s possible to drill a vertical borehole for the ground loop instead and these are usually between 90 and 160 metres in depth.
The space and depth you need will depend on a range of factors, including local conditions and the heat requirements of your home.
There are many benefits to a ground source heat pump, both for yourself, your home and the environment.
Ground source heat pumps can-
Ground source heat pumps are also virtually silent so you don’t need to worry about noise pollution for yourself or your neighbours. Minimal maintenance is required and you don’t need to arrange fuel deliveries.
Overall, ground source heat pumps are an excellent low carbon heating solution that is energy efficient and has a low running cost.
There are some drawbacks to ground source heat pumps to be aware of. Installing ground source heat pumps is more difficult than the installation of air source heat pumps and can be tricky where space is limited. It’s more complex to retrofit a ground source heat pump to an older property and as such they’re more common in new build properties.
As temperatures from the ground source heat pump are typically lower than those put out by a gas or oil boiler, there may be a requirement for heating to be on constantly in winter in order to warm the house, though the benefit of this is that radiators are not as hot to touch and the temperature of your home is kept fairly consistent rather than constantly fluctuating.
Ground source heat pumps work best with well-insulated homes and when paired with an efficient heating system, such as underfloor heating, for example. That’s not to say they won’t work with homes with a higher heat requirement or traditional radiators, but they won’t be as efficient or economical in that instance.
The installation of a ground source heat pump is also associated with high upfront costs, which can put some people off, however ground source heat pumps are eligible for green energy grants to lower initial costs and make them a more economical option.
Is a ground source heat pump the right choice for my home?
There are several things to think about when considering whether a ground source heat pump is the right choice for your home.
The size of your garden will have an impact on whether it’s possible to lay a horizontal ground loop in a trench or whether you will need a vertical ground loop, requiring a bore hole. The latter may have cost implications due to the specialist equipment and machinery required.
You need to consider whether the ground is suitable for digging and if machinery will be able to easily access your garden.
As ground source heat pumps work best with well-insulated homes, it’s important to consider whether your home is appropriately insulated and draught-proof.
You need to think about the current heating system you plan to replace. A ground source heat pump is an ideal replacement for electrical heating or coal heating, where it will quickly pay for itself. This will not necessarily be the case if replacing mains gas heating, when it might take longer to see real savings.
It’s also a good idea to consider what heating system you intend to use the ground source heat pump with as they typically work best with underfloor or warm air heating systems.
The installation of a ground source heat pump requires planning and labour. The whole process can take several weeks. It may be more efficient and cost-effective to have a ground source heat pump installed alongside other building works rather than separately and for this reason, ground source heat pumps are an excellent choice for new-build homes.
Upfront costs for a ground source heat pump can be high, with initial installation costing anywhere between £12,000 and £19,000. Though it’s important to remember that ongoing running costs are lower than other heating systems (such as electrical heating) and that green energy grants are available to help with both installation and running costs.