Ground source heat pumps make use of the stable, low-temperatured thermal heat stored in the ground. Although the ground is considered 'cold' and cannot be used directly for space heating, it can raised through a compression expansion cycle making it useful for property use. The heat has to be gathered using a heat collector, normally a pipe is laid in the ground which circulates a refrigerant around the heat pump, increasing its temperature significantly.
Heat pump technology has existed for over 100 years and is a common form of space heating in many countries. Scandanavian countries such as Sweden have embraced heat pumps on a vast scale with over 75% of new builds containing ground source heating. Comparatively the UK only has around 10,000 in existance but the rate of interest in this technology is increasing vastly. Many are considering this as a stable solution to larger district heating requirements.
Heat pumps require energy to operate in the form of electricity as input in order to generate heat as output. A simple calculation to identify the heat pumps coefficient of performance CoP is:
CoP = Total heat energy output of heat pump (kWth) / Electrical energy input (kW)
This measurement is an indication of the heat pumps effectiveness and depends on output and input temperatures - typical CoP's are 3 - 4.5 for space heating.
This type of installation is also due to benefit from the governments impending Renewable Heat Incentive scheme later in 2011.
What does the installation involve?
Essentially, a suitably laid out trench is dug in the ground around the site, which allows for several meters of tubing to be laid within it. This is then plumbed into the exchange unit in your home to be released into the heating system. There are generally 3 ground layouts for its installation; vertical bore, horizontal loop and compact systems, each to be adapted to the various types of ground space available.
The ground site would also need a ground survey in many cases, checking for mineshafts and other potential defects that need to be considered pre-installation, potentially adding cost to the project. Making it very important that you consult a trained installer, to find a ground source heat pump installer check out our 'Green Directory' here.
Are there any incentives for this type of installation?
Ground source heat pumps are considered a heat-generating renewable technology and are therefore scheduled to benefit from the governments 'Renewable Heat Incentive' scheme from 2011 - A payment made to home or business owners who have replaced their fossil fuel based systems for one such as this and based on the amount of kWh produced.
- Ground source pumps may be installed under-water also. Ponds and other small water sites can still produce an effective temperature to utilise.
- Can be a relatively large scale installation.
- As considered a low heat installation it is highly recommended that your building is well insulated.