Heat from earth

Heat contained in earth, so called geothermal heat is usually used indirectly. Heat pumps taking heat from the ground are called “ground-water“. Heat is extracted using an underground collector usually MDPE plastic pipes. A heat carrying liquid is pumped through these pipes connected to the heat pump evaporator. The heat carrying liquid is non-freezing and ecologically harmless. Circulating liquid is cooled down in the heat pump evaporator and it is re-warmed in the underground collector by means of geothermal heat. To be the heat transfer even and constant throughout the heating period, it is important to make sure a suitable location of the ground collector and the area large enough to recover the energy taken out by the heat pump.

Underground collectors can be installed in two ways. Either as a horizontal collector, set in a depth of 1.5 to 2 m under ground level or as a vertical one set in one or more boreholes. Bore-holes being significantly deeper than pipes in shallow trenches are less susceptible to seasonal temperature changes and the energy available for the heat pump is more even throughout the heating season. When compared to an installation using horizontal collectors, vertical bore-holes and their collectors experience lower seasonal temperature changes and earth-water heat pumps can achieve higher COP’s.