Ground & air source heat pumps
Ground and air source heat pumps
Ground source heat pumps (GSHP) transfer heat from the ground (which has a year-round temperature of around11 0c ) into a building to provide space heating.
The system uses lengths of pipe (called a ground loop) buried either in a borehole or a horizontal trench. The pipe is usually a closed circuit and is filled with a mixture of water and antifreeze. When this mixture is pumped round the pipe it absorbs heat from the ground. The pipe is then connected to a heat pump which has three main parts: an evaporator that takes the heat from the water in the ground loop, a compressor that moves and compresses the refrigerant round the heat pump and a condenser that gives up heat to a hot water tank that feeds the distribution system.
Air source heat pumps (ASHP) work in very much the same way as ground source heat pumps but instead of using heat from the ground they extract it from the air. In some situations they can also be easier to install. The unit is fixed outside the property with holes in the wall to accommodate the flow and return pipe-work.
Q. How much energy do ground source heat pumps produce?
A. For every unit of electricity used to pump the heat, 3 to 4 units of heat are produced.
Some heat pumps have internal immersion heaters to top-up conventional space-heating and hot-water systems.
Q. How much do ground and air source heat pumps cost?
A. A typical 6 kw ground source heat pump system will cost between £6,500 and £11,500 to install. An air source heat pump can cost in the region of £3,500 for a 6kw system and £6,000 for a 12kw system. This does not include the cost of the radiator system.
Q. What grants are available for micro-generation technologies for householders?
A. The Department of Energy and Climate Change (DECC) run a Low Carbon Buildings Programme that provides micro-generation grants for householders. www.lowcarbonbuildings.org.uk
Q. How can I find an installer?
A. Recipients of Low Carbon Buildings Programme grants must use accredited installers and materials. The list of accredited installers is a useful resource even if you are not applying for a grant for all types of renewable technologies.
Q. Can GSHP’s be used with the radiator heating system in the home?
A. Yes, but they work best with a low-temperature heating system such as under- floor heating.
Q. Is planning permission needed to install ground or air source heat pumps on a house?
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