Ground Source Heat Pumps collect heat from the ground using a network of pipes buried either horizontally in trenches or vertically in boreholes.

The majority of ground source installations use a ground collector installed horizontally in trenches as this tends to be the most cost effective if sufficient land is available.  Boreholes are more expensive to drill but they provide an excellent solution where there isn't sufficient land, or sometimes where the land isn't suitable for digging trenches.  

The ground collector pipes contain an antifreeze solution (glycol) that is colder than the ground they are buried in, so heat is collected from the ground and transferred into the building via the heat pump. The heat pump can be sited within the building, in a garage, an outbuilding or a suitable external enclosure.

At a depth of 1.2 meters the ground is at a more constant temperature all year round. During cold weather the ground source heat pump draws heat out of the ground, this is replenished by daylight. The ground works like a rechargeable battery and allows the system to work very efficiently.  Many people mistakenly believe that a heat pump uses geothermal energy, but it is actually all solar thermal energy: the heat from the sun warms the ground.

 

How do heat pumps work?

A heat pump uses the same principal to transfer heat that fridges use.  Fridges keep cool by pumping heat away from food and drink to the grill on the back; heat pumps extract heat from the renewable source and pump it into buildings.  A refrigeration cycle uses the renewable energy that is extracted from the air, ground or water to boil a special liquid refrigerant into a gas, these liquids have a boiling point that is much lower than that of water.  The gas produced is then compressed and becomes hot and the heat is extracted, this then turns the gas back into a liquid again and the cycle starts again.  The generation of heat by compressing a gas can be seen with a simple experiment of trying to pump a bicycle pump with your thumb on the end, as the air is compressed the pump will become hot.

What equipment do I need?

We only use ground source heat pumps made by Vailant.  We have found these to be the most cost effective to install and the most reliable in service. Vaillant currently offer a three year manufacturers warranty and a ten year compressor warranty on their ground source heat pumps. Visit the Vailant website to view much more information about the Vaillant products and the technology in general