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Ground Source Heat Pumps
Ground Source Heat Pumps (GSHP) use the energy stored just below the earth's surface. The temperature there remains more or less constant throughout the year, and although it is too low to be used for heating, it can be raised by the use of a heat pump. The system works by transferring the low grade heat into a collector, usually a pipe buried around a metre deep in the garden. The working fluid in the pipework then transfers the heat into an evaporator in the heat pump. The heat in the evaporator is then used to boil a refrigerant and the vapour is then compressed, which raises its temperature to a useful level. A condensor then transfers the heat into the heating system and the hot water system.
Where there is insufficient land for a collector loop, or compact collectors, a borehole can be used. Although more expensive initially, the virtually constant temperature of the borehole means that the system runs more efficiently.
Because the system is more efficient running at a lower than conventional output temperature, GSHPs work well with underfloor heating, although radiators can also be used. Generally, a heat store is used as a buffer for the heating and hot water is supplied via a cylinder. The system can provide three or four units of energy for each unit put in, and although the pumps run using electricity, you can choose a green supplier or even generate the power yourself.
Energy-saving installations attract a reduced
rate of VAT at 5%.
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