What are Ground Source Heat Pumps?
Ground source heat pumps (also known as ground-to-water heat pumps) work by transferring heat from below the ground outside your home or business and raising the temperature via a heat exchange and compression system to heat water for central heating systems and for hot water cylinders supplying taps, showers, etc.
To collect heat from the surrounding ground, a ground source heat pump requires a transfer loop — essentially a coil of pipe — which can be buried either horizontally, in a shallow trench, or vertically, in a deep borehole. This loop contains a thermal transfer fluid (also referred to as “brine”) that absorbs heat from the earth surrounding it and then passes it through a heat exchange into the pump, where the temperature is raised and the heat transferred to the hot water system within your building.
While the complexity of the installation means that ground source heat pumps are more expensive than air source heat pumps overall, they offer greater efficiency when it comes to heating your property, so the potential for lifetime cost savings is greater. And in some cases, higher incentive payments are available for ground source heat pumps, which can help to offset the initial cost.
How much space do I need for a ground source heat pump?
Ground source heat pumps don’t require significant exterior space once installed, but you will need to ensure you have sufficient available land and unimpeded access for the machinery required in order to dig the trench or borehole required for the transfer loop.
Ground Loop System
For a ground loop (trench) system, you’ll need land suitable for digging, with access from the nearest road for a small digger. Areas with trees are not ideal, as the presence of roots is an obstacle to digging the initial trench, and growing roots can damage the loop in future. The exact size of the trench required will depend on the specific heating requirements of your property.
Borehole System
With a borehole system, you don’t need access to as much surface area — as the hole is usually only around 18mm in diameter. This solution is, therefore, ideal where space is limited. However, you will still require access from the road for machinery, and you’ll need a thermogeological survey before work can start. Depending on how much heat you need to generate and the conditions of the ground beneath your property, it may be necessary to dig more than one borehole.
*Inside your property, you’ll need sufficient space for the internal heat pump unit — which is frequently combined with a hot water cylinder — resulting in a unit of around 2-3 cubic metres in size.
Speak to Deseco to get independent advice on the correct type of ground source heat pump system to fit your needs, your budget, and the specific characteristics of your home or business.
How noisy are ground source heat pumps?
Ground source heat pumps are much quieter than their air source equivalents, as they don’t use fans. Most ground source heat pumps produce no more than 42dB even when running at maximum capacity. This is below the noise threshold of a domestic dishwasher, for example.
Will a ground source heat pump work with my existing heating system?
As with air-to-water heat pumps, ground source heat pumps work by heating water which can then be supplied to radiators, underfloor heating systems and hot water cylinders. So if you don’t already have these components installed in your property, you’ll need to install one or more of them to be able to use this type of pump.
If you’re installing a ground source heat pump alongside a new central heating system, it's advisable to seek out a qualified consultant such as Deseco to provide a heat design for the property — this will help ensure that all of the component parts of your new system work optimally together, maximising efficiency and cost savings.
It’s also possible to combine a ground source heat pump with an existing combination boiler to create a hybrid system, where the heat pump provides hot water for radiators or underfloor heating, and the boiler supplies on-demand hot water to taps.
How much does it cost to install a ground source heat pump?
As with any heat pump system, the costs involved in purchasing and installing a ground source heat pump system can vary considerably based on a number of factors, including the specific unit required, the heat requirements of your property, and the type of excavation or boring needed to install the heat transfer loop. You’ll also need a qualified surveyor to conduct the thermogeological survey if your system requires one or more boreholes.
To accurately scope and cost the best ground source heat pump system for your home or business, speak to a specialist consultancy such as Deseco. We can conduct a heat survey and provide you with a detailed heat design, which will include all the information you need on the type of unit(s) to choose, the ideal method of installation and any associated project costs.
