Heat pumps work in a similar way to a refrigerator by transferring heat from one environment to another using a refrigeration loop. This heat can then be used to provide hot water for the home. Heat pump systems tend be around 300% efficient, producing 3 times as much energy as they use to produce the heat. Heat pumps extract their source energy from the ground, air or water. All heat pumps have their own particular advantages and their suitability will depend on the project.
GROUND SOURCE HEAT PUMPS
These systems extract heat directly from the earth, where just 1 metre down a constant year round temperature of 8 -12 °c is maintained, due to the storage of radiant heat from the Sun. Ground Source Heat Pumps tap into this inexhaustible supply of energy and use it to heat radiators, under floor heating and even to provide hot water.
AIR SOURCE HEAT PUMPS
Air Source Heat Pumps extract heat from the air outside and absorb this heat into a fluid. This liquid then evaporates into a vapour and is compressed to further increase the temperature. Once the vapour condenses back into a liquid the heat is transferred into your heating system and is ready to use in your home. ASHPs are able to absorb heat from the air even when temperatures outside are as low as minus 15°c
- Air to water systems connect into your central heating system and are typically used for underfloor heating or to heat radiators.
- Air to air systems send warm air to fans, which is then distributed around the home.
WATER SOURCE HEAT PUMPS
Water Source Heat Pumps operate in a similar way to ground source heat pumps, except in this system the collectors are submerged into a river, stream, lake or underground water course, where the water is circulated through the pipes. The ground water near to the bottom of the water course tends to provide a fairly constant year round temperature of around 7-12°c. Similar to other heat pumps, WSHP work like a fridge, extracting heat from the source with a refrigerant, which is then compressed before being heated to a temperature of around 100 degrees. The heat is then typically used to for under floor heating and radiators. WSHP require electricity to operate and for every unit of electricity used, it will produce the equivalent of 3 to 4 times that in heat energy in output.
There are two types of water source installations:
- Closed loop systems - Similar to ground source systems, a plastic pipe containing water and anti freeze is constantly pumped through the heating system, drawing heat energy from the water source.
- Open loop systems - In this case the water is drawn directly form the water source to the heat pump, where the heat is absorbed. The water is then discharged back into the water source. As this system is open to the water it is important to filter out any impurities in the water and also to combat any acidity the water may contain, in order to maintain the efficient performance of the heat pump.