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The average ground temperature just below the surface, in the UK is between 8ºC and 13ºC, this temperature remains constant throughout the year.
EarthEnergy™ Systems circulate water through pipes buried either horizontally or vertically in the ground. The water in the pipes is lower than the surrounding ground and so it warms up slightly. This low-grade heat is transferred to a heat pump, where it is used to heat up a refrigerant. By compressing this 'warmed' refrigerant further heat is generated and this means that water output from the heat pump is typically 45ºC - 50ºC. for space heating and up to 55ºC for domestic hot water.
Your domestic fridge uses the same technology. As you put food and drink in to your fridge the low-grade heat it carries (after all it's usually warmer than the inside of the fridge) is transferred to the refrigerant in the unit. The refrigerant is then compressed to raise the temperature; this high-grade heat is then expelled from the back of the fridge. This is why the inside of the fridge remains cold whilst the back of the fridge gets hot.
Not all building projects are suitable for EarthEnergy™ Systems. The following guidelines are intended to highlight some of the main factors used in determining suitability.
The building should be very highly insulated and energy efficient.
This means that new buildings or conversions which are constructed to current building regulations are most suitable.
The heat delivery system should be designed for lower temperatures.
Heat pumps generally have an output temperature of around 45ºC - 50ºC, whilst this is ideally suited to most modern wet underfloor systems, radiators need to be sized to allow for a lower input temperature than with traditional heating systems.
The building plot should have sufficient land available for installation of the ground works.
A typical three bedroom new house built to current building regulations will probably require around 8kW of heating, a suitable EarthEnergy™ System would require two x 50 metre long trenches to allow for sufficient pipework to be placed in the ground. Alternatively two deep boreholes could be installed. Both trench based and borehole based installations require that the ground loops (vertical or horizontal pipework) should have a minimum separation of five metres.
The property should have a reliable and suitable electricity supply.
EarthEnergy™ Systems are electrically driven, a good single phase domestic 240V supply is sufficient to provide up to 12kW of heat. Larger buildings requiring more than 12kW of heating would normally need to arrange for a 400v 3 phase electricity supply.