Ground Source Heat Pumps (GSHP)

Ground Source Heat Pumps (GSHP) are stand-alone units that normally sit inside your house, alongside your hot water cylinder. They are roughly the same size as a fridge freezer unit.

They work by drawing heat from the ground via pipes filled with brine, and then transferring that heat to your cylinders to provide you with your heating and hot water.

The pipes can either be laid in ground loops about 1m deep or dropped in boreholes up to 200m deep. They can also be fed into a lake or aquifer.

The pipework is in some ways similar to underfloor heating in that the loops return to a manifold chamber close to the house and there is then a flow and return to the heat pump itself.

They are incredibly efficient because even when the outside temperature is below 0˚C, the ground temperature is generally about 8˚C all year round. This makes them slightly cheaper to run than air source heat pumps, however, the capital costs are much higher due to the groundworks needed.

The most common configuration is horizontal ground loop. This loop is laid in a straight line, spaced at least 1m apart. A good deal of land is needed for the heat pump groundwork. A good rule of thumb being 4 times the amount of floor space you are looking to heat.

Water source heat pumps

Ground source heat pumps can use water as their heat source if you have a large lake or boreholes into an aquifer below your property. This is the most efficient of all heat pumps as the temperature of the water in winter is normally warmer than that of the air or the ground.