In simple terms a ground source heat pump draws heat from the ground, then uses a pump to lift the temperature further and then sends it into the property to be used for heating the home or heating water. The pump does run using electricity, but it requires less energy to run than it produces, making it an effective alternative energy supply.
A ground source heat pump consists of a ground loop, which is a network of pipes buried underground, and a heat pump, which is at ground level. Ground source heat pumps do require adequate garden space that is accessible for digging tools to install the ground loop. The length of ground loop is dependent on the size of property and the amount of heat needed, the longer the loop the more heat will be generated, but obviously more space is required for the installation. In most installations the loop will be laid flat or coiled in trenches, which tend to be about 2 meters deep. If there is not enough space available it is possible to have a vertical loop installed, this will be buried in the ground to a depth of about 100 meters.
The network of pipes that are placed under ground contain a mixture of water and anti-freeze, this solution is pumped around the loop and absorbs heat from the ground. When this solution reaches the heat pump the temperature is then increased by the work of the heat pump. A heat pump is made up of an evaporator, a compressor and a condenser. Once the heat pump has completed its job and heated the solution further, this is the either sent to radiators to heat the home, to under floor heating or to heat water in the hot water tank. Some homes will require a back-up heating system; it all depends on the size of property, what the heat pump is being used for and the amount of heat required by the property.
Ground Source Heat Pumps Cost
The cost can vary greatly for ground source heat pumps, as there are a large variety of systems and different size installations available. The Energy Savings Trust estimates a figure of between approximately £9,000 and £17,000 to install a ground source heat pump system in the home. It is estimated that a ground source heat pump can save a typical household between £50 and £420 per year – dependent on the size of system installed and the system it is replacing.
Ground Source Heat Pumps will be eligible for the Renewable Heat Incentive (RHI), which is set to be introduced for residential properties in 2012. To be eligible for the RHI scheme the equipment and installer must be MCS accredited. Initially it is possible to receive a one-off payment of £1250, but this fund, the Renewable Heat Premium Payment, is limited and when it runs out it will not be topped up.
Savings possible from installing a ground source heat pump
It is extremely hard to illustrate exact savings, as there are many different factors that affect the savings. Below are some of the factors and an idea of the differences in savings they will make.
Your chosen heat distribution system – under floor heating can provide greater savings than using radiators, as the water does not have to reach such a high temperature. If under floor heating is not an option, then using larger radiators will help improve savings.
The cost of fuel – heat pumps do rely on some electricity so it is important to factor this cost into any saving projections. Noting the cost of fuel being replaced and the future cost of fuel to power the heat pump.
Efficiency will affect savings – depending on how efficient the system that is being replaced was, this will affect the savings that can be seen from installing a heat pump. If the old system was inefficient the savings will be greater than replacing a newer more efficient system.
Producing hot water – this is less efficient than using the heat pump for heating space, therefore if the pump is being used to supply hot water the savings will be lower than a pump used purely for space heating.
Temperature setting – this will have an affect on savings if the heat pump is not used in the same way as the system that is being replaced. If the heat pump is used at higher temperatures than the previous system then it is possible no cost savings will be made.
Controlling the system – using a heat pump is different to traditional heating systems; therefore it is important the installer runs through the best ways to maximize the efficiency of the system.
Benefits of Ground Source Heat Pumps
Ground source heat pumps will help to lower your carbon footprint, as they are a lot more environmentally friendly than traditional heating methods such as gas or electric.
Ground Source heat pumps do not require manual intervention to run once they are in place, for example there are no fuel deliveries needed.
Ground source heat pumps can serve two purposes – for space heating (heating the home) and water heating.
Ground source heat pumps can reduce energy bills, the savings will depend on the type of heating the home was previously using.
Ground source heat pumps are thought of as a 'fit and forget' technology as there is very minimal maintenance required.
Is my property suitable for a ground source heat pump?
Firstly, the garden space will need to be suitable, it doesn't necessarily have to be very large, but the ground must be suitable for digging. It is important to consider whether access for digging machinery will be a problem. Another consideration is whether your property is currently well insulated. Ground source heat pumps produce heat at a lower temperature than traditional boilers, therefore for the system to be efficient and effective it is essential that the property is well insulated.
The type of fuel that is being replaced is also worth considering, as savings will be greater if an electric or coal-heating system is being replaced. Properties using gas heating are often not recommended to change to a heat pump. Retrofitting a system is more expensive than installing a system whilst developing a property, therefore cost will be a major consideration. New developments are very well suited to ground source heat pumps as savings can be made on the installation costs.