A heat Pump

Works like a fridge in reverse, It uses the exact same principle as a domestic fridge, except the hot parts are used instead of the cold parts. See how it works.

The free Energy element for the heat pump can come from a number of sources. The most common are from the air and from the ground.

In a ground source heat pump, pipes are laid into the ground shallow enough be able to absorb the heat energy which has been transmitted to the ground by the sun, but deep enough, so that the Pipes are not subjected to frost when the winter comes. There is a great deal of science in the positioning of the pipes, however, as a general rule of thumb, horizontal pipes should be laid at a depth of between 800mm and 1200mm. Each run of pipe should be at least 1 meter away from the next pipe.

An appropriate pipe for this is PEM 40*2.4 40mm diameter plastic. available from your local plumbing merchant. a system laid like this should yeild beween 10 and 18 watts per meter run. So if you need to obtain 7KW from the system, you will need (7000÷15) = 467 meters of pipe. with the pipes at least 1m apart, you will need at least a ground area of 467 m²

In an Air source heat pump, air is taken directly from the atmosphere by a fan, and ducted into the pump. Occasionally, where the design permits, an atrium can be constructed to trap the sun's heat in the air and this is then used as the source.

Like a fridge, A heat pump needs an energy supply to make it operate.

The efficiency of the pump, is measured by the coefficient of performance (CoP) and is usually between 2.5 and 4. That is for every 1 Kwh of power in, you will get berween 2.5 and 4 KWh of power back out.

The efficiency of the heat pump is maximised, if the output temperature is minimised. So the best type of application is for underfloor heating, fan assisted convectors or swimming pools, as these can all operate at around 30°C