Ground source heat pumps use the earth as a heat source, taking advantage of the stable temperatures in the ground to provide heat and hot water for the home.
Ground source heat pumps are not a new concept and have been around since the 19th century. This technology became very popular in Sweden in the 1970s and since then units have been sold worldwide.
In the UK, there has been a sudden surge in demand in heat pumps since the launch of the Renewable Heat Incentive, which pays homeowners for each unit of hot water produced. Although rates are no longer as high as they were, they can still cover much of the initial install costs of the systems.
A ground source heat pump system uses heat trapped beneath the ground and boosts it to a higher temperature using a heat pump. This heat is then used to provide home heating or hot water. The heat pump performs the same role as a boiler does in a central heating system, but uses ambient heat from the ground rather than burning fuel to generate heat.
Initially, a heat transfer liquid (normally glycol) is pumped through pipes buried deep in the ground. As the liquid travels through the pipework it absorbs ambient heat from the ground and warms up, before returning back to the ground source heat pump unit. Once it returns, a heat exchanger removes the heat from the liquid and it then continues to travel round and round the pipework in a continuous cycle.
The low-grade heat is transferred through the heat exchanger, then passes through a heat pump compressor which drives the temperature up to a level that is usable for heating and hot water.