Radial drilling method

GRD combines the advantages of horizontally installed ground heat collectors and vertically installed ground heat pipes. The system utilises all the available land within the property boundaries. Deep underlying drinking water levels remain untouched. In addition, the GRD technology is based on the need for minimal technical equipment and clearly reduces the overall expenditure for installing heat pipes.



GRD-Geothermal Radial Drilling

GRD is a method that targets a depth range where the underground is hardly affected by seasonal climatic changes or solar irridiation. The borehole heat exchangers are radially installed so that mutual influence is minimized. Hence, the amount of extractable geothermal energy is ever constant and rewarding, particularly if it is legally permissable to extract heat from groundwater bearing strata. The Geodrill GRD 4R enables the drilling team to aim for these energy giving layers.

The number and depth of the heat pipes can easilybe adjusted to the property’s geology or legal regulations. The short distance between drill chamber and heat pump reduces installation costs and improves the energy balance.


The sketch gives the individual length of a borehole heat exchanger in relation to its angle of inclination and property dimensions.

The demand for heat
The layout of the underground system is determined by the demand for heat. This demand is influenced by the floor-area, heat insulation, the heating system and its annual operational period. The demand for heat ranges between 8 to 11 kW for an average family of 4 living in a well insulated, newly built house with 120 sqm floor space.

Extraction performance
The geological set-up determines heat extraction performance. The ideal soil for rewarding and lasting heat extraction is soft and wet. Groundwater bearing strata are most rewarding. Geological maps provide detailed and reliable information about geological parameters in your area. However, it is always a good idea to ask the land owner about the particular local environment of his land. The average heat extraction performance is around 40 to 50 W per meter borehole heat exchanger. .

Heat pipe technology
The GRD system relies on state-of-the-art coaxial heat pipes that assure turbulent brine flow. The corrugated heat pipe surface guaranteess maximum heat extraxction, the heat pipes' lengths can be chosen individually as required.