Ground source heat pumps
The temperature of the ground below a certain depth remains constant all year round. Ground source heat pumps take this latent heat, using heat collectors called slinkies that are buried in the ground, and use it to heat the home.
The fluid in the slinky is drawn into an evaporator and the resulting gas is compressed until it reaches 80 degrees Centigrade. The vapour is condensed and circulated through underfloor heating, where a temperature of 40 degrees Centigrade can be maintained.
Ground source heat pumps are most suitable for well insulated properties with underfloor heating or low temperature radiators. The home needs to have enough garden for the slinkies to be buried, or for a bore hole, although this second option is much more expensive.
Air source heat pumps
Air source heat pumps work in a similar way to ground source heat pumps, but require less space. Air at an ambient temperature is passed over a finned heat exchanger, which extracts the heat into the evaporator of the heat pump.
Air source heat pumps can be roof, wall or floor mounted and are ideal where ground space is at a premium.
Ground and air source heat pumps can produce up to four times more energy than they use during operation and can save around 30 per cent or two tonnes per year of carbon.
Ground and air source heat pumps are easy to install and maintain, and are specially suited for areas where mains gas is not available off mains gas areas.
