Ground source heat pumps

Ground-source heat pumps extract heat from under the surface of the ground outside your property. The heat is collected by a mixture of water and anti-freeze that runs through a loop of pipe buried in the garden. The heat is absorbed into the fluid mixture and pumped through a heat exchanger, which is then pumped into a heat pump compressor. The heat accumulates and increases where it becomes of a temperature useful for central or under-floor heating in the house.

The only energy used is the electricity for powering the pump to move the water into the home. Apart from that, ground-source heat occurs naturally and is a renewable, reliable source of heat all year round. The loops of pipe are usually laid flat under the ground surface; however in properties where the garden is not large enough for this, the pipes may be positioned vertically into the ground up to a depth of 100 metres.

• This type of heating system makes the most of free heat stored all year round under the surface of the garden. It is a free, zero carbon source of energy.
• Despite the need for electricity to power the pump, using a ground-source heat pump is an efficient way of providing heat for your home. For every unit of electricity used in pumping the liquid around the pipes, 3-4 units of heat is provided.
• For cheaper electricity rates it is possible to use the Economy 7 tariff, or some electricity suppliers may allow a special heat pump tariff.

• Installing the heat pumps can be very expensive depending on the size of pump you want. The ground work needed to install the pipes and pump can be disruptive, expensive and may need planning permission.
• The ground-source heat pumps are not suitable in conjunction with existing gas-fired wet central heating systems as ground source heat is works at lower temperatures. It is best suited for under-floor heating.
• Ground-source heat is only usually recommended and best used in new houses which meet the latest building regulations of excellent insulation and air-tightness.
• It is not a zero carbon source of heat as an electrically powered pump is needed.