Ground source heat pumps

Introduction to ground source heat pumps

Drawing as much as 75% of the energy needed by the heating system from freely available, inexhaustible solar energy stored in the ground, Dimplex ground source heat pumps are available in an extensive range of model types and capacities suitable for either domestic or commercial applications.

Due to highly stable temperatures below the earth's surface, ground source heat pumps provide high levels of efficiency for space and water heating all year round.

Benefits of the outside ground as a heat source:

  • Consistent temperatures below ground throughout the year provides a high Co-efficient of Performance.
  • Can be used for heating, domestic hot water and swimming pools.
  • Borehole systems can be used for either passive or active cooling.

At just 1m below the surface, the earth provides a stable source of heat throughout the year.

At depths of 15m or more, the earth provides a constant 10°C temperature.

Surface Temperature

Surface temperature

Heat from the ground

The earth stores an enormous amount of solar energy from both solar radiation and rainfall. To extract this energy, ground collectors consisting of flexible polyethylene pipes are buried in the earth, either horizontally or vertically. A mixture of water and anti-freeze is then circulated through pipe loops, attracting the heat and energy and transferring it to the heat pump.

Select your preferred installation method.

Horizontal ground collectors
Horizontal ground collectors

If a large enough land area is available, horizontal ground collectors provide an effective method of extracting heat from the ground. The pipework is buried at a depth of approximately 1.2m and spaced 0.75m apart. The land area required is dependant on both the capacity of the heat pump and heat conductance of the soil type in which the pipes are buried. As a space saving alternative to horizontal collectors, slinkies - consisting of coiled pipes buried in a trench - can be used.

Vertical boreholes
Vertical boreholes

If land space is limited the ground collectors can be installed vertically in a borehole, drilled up to 100m deep in the ground. Multiple boreholes are commonly used in large installations where very high levels of heat extraction are required.

Heat into the House

The heat pump feeds the collected energy into the house in the form of heated water which is circulated through radiators or underfloor heating pipes. In order to attain the highest efficiency, underfloor systems are best as they require a lower temperature to operate. Conventional radiators can also be used but will require over-sizing by around 40% to give the necessary output.

An alternative to the conventional radiator is a 'SmartRad' These have a small quiet fan within the casing and operate with water temperatures as low as 40C which is comparable to underfloor heating. They are also about 1/3rd the size of a radiator with equivalent output.