To precisely design geothermal systems you need to know the soil’s thermo-physical and geological characteristics. There are several options for determining the thermal conductivity characteristic of the geological medium, but the most accurate results can be achieved with the Geothermal Response Test carried out on site. In contrast to other methods, the main advantage of geothermal probes is that the measurement is done locally in a predetermined soil probe. The tester is connected to the ground heat probe, and based on the results obtained, the total number of probes to be installed is determined. Over-or under-weighted heat pump system significantly impairs the efficiency of the system and increases the cost of investment and / or operation.