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What are they?
There are three types of heat pump system; Ground Source, Air Source and Water Source. The main difference between each system is the source of background heat that the system utilises.
The temperature just a few metres below the ground is a constant 11-12 degrees centigrade and therefore Ground Source Heat Pumps can meet the heating requirements of a property all year round.
Air Source Heat Pumps use the ambient temperature of the air as a source of heat. Surprisingly they can still generate useful heat even when the outside temperature is as low as minus 20 degrees centigrade.
Water source Heat Pumps use the ambient temperature of a body of water as the heat supply. This could be a lake, river or stream.
The technology
All types of system comprise of heat loop, heat pump and heat distribution system. All types of system can be used for space heating and water heating. However they work better with under floor heating and an additional immersion heater is usually required for hot water.
Heat Loops for water source systems consist of coils of pipes which are placed in the water body. They are particularly suitable if you own a lake or other body of water. Placing water loop pipes in rivers and streams will probably need planning permission and permission from the appropriate water authority or Environment Agency
There are three of types of ground loop: borehole, straight horizontal and spiral horizontal (also known as a 'slinky').
Horizontal trench ground loops are usually cheaper to install than boreholes, however you will need a bigger garden to house a horizontal trench. The size of the ground loop and the heat pump system will be determined by your heating needs, and an accredited installer will be able to assess your requirements and provide you with details on the different types of ground loops and their suitability for your property. As with all renewable heating technologies, the more energy efficient your property is, the lower its heating requirements and the smaller the size (and cost) of your system. The ground loop consists of lengths of pipe buried in the ground, either in a borehole (at a depth of 15 metres to 150 metres) or horizontal trench (at around two metres depth), depending on the size of your garden.
Both of theses type of loop are filled with fluid (usually a mixture of water and anti-freeze), which is pumped around the pipe. The fluid draws out and absorbs the heat from the ground or water that the heat exchanger then 'upgrades' to make it a suitable temperature for heating your property.
An Air Source Heat Pump contains the heat loop within the unit itself. This makes it easier to install and maintain. They are also likely to have a smaller impact if coolant leaks from the system as you will be able to see any leaks and contain them much easier. The units themselves are more expensive than either ground source or water source systems. However installation costs are likely to be greatly reduced in comparison.
Heat pumps transfer the heat stored within the ground, air or water into the heating system within the property and operate in a similar way to fridges and air conditioning units. The heat pump itself consists of 3 components, an evaporator, a compressor and a condenser. The evaporator removes the heat from the fluid that has been pumped through the heat loop, the heat pump compressor transports the refrigerant around the heat pump and compresses it until it reaches the temperature that the heat distribution circuit requires and the condenser transfers the heat to the hot water tank. The heat is then transferred to the heating distribution system and is used to warm the property.
Heat pumps systems can be cheap to run, although they do require a mains electricity supply to power the pump. However, for every unit of electricity used to run the pump, between three and five units of heat are supplied to the heating system making it much more efficient than most standard heating systems. Taking that fact into account, ground source heat pumps can provide heating for a cheaper rate than oil fired systems, LPG and electric heaters.
If you are thinking of installing a heat pump system and wish to make the system truly renewable, it may be worth looking at switching your electricity supply to a renewable energy supplier or green tariff. More details on switching to a renewable or green tariff can be found in the energy efficiency section later in the pack.
Another thing to consider is the use of refrigerants within the ground source heat pump, which can be dangerous to plant and animal life, as well as being contributing factors to climate change. There are now more ‘environmentally sensitive’ refrigerants available, and you may wish to check with your installer that the refrigerant used in your system is of this type.
Lifespan and warranty
Heat pump systems can be fairly long lasting with some manufacturers advising that the ground loops can last for between 25 and 100 years. Warranties for heat pumps show a great deal of variation between suppliers and may be as little as 12 months or as long as 10 or 15 years. Also it is often the case that individual components of the system have separate guarantees (e.g. the heat exchanger). It is therefore important that you seek advice on the warranty of the system from an accredited installer.
Cost
The Department of Trade and Industry currently give 'average' system prices as £4,000 to £6,000. Factors such as installing an under floor heating system (if desired) may carry an additional cost.
Where in the district?
Heat pump systems can be installed successfully in all areas of the South Derbyshire. People switching from electric or oil heating often experience the biggest cost savings after installing a Heat pump, and so this makes this technology particularly suitable for areas of the District that are not on the gas network.
Contact details
South Derbyshire District Council
Energy Officer
Civic Offices
Civic Way
Swadlincote
DE11 0AH
Tel: 01283 595974
Online: contact form
email: energy@south-derbys.gov.uk
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