Movek Group produces and installs spiral collectors of heat pump systems already for years. The acquired installation experience proves the efficiency of use of this solution in Estonian climate. We mainly use 2 meter spirals. Spiral collectors are installed to the 2 or 3 m drilled hole’s bottom of the 1.2 to 1.5 m trench. Spirals are interconnected by two or four in series depending on length and position of spirals. Spiral lines are aggregated to collector wells from where the line pipes are taken to the building or composite well.
In Europe, spiral collectors have been installed already for a long time and in Germany 90 % of ground source heat pumps have spiral collectors. Differences in installations in Estonia and Germany lies in dimensioning caused by the climate. When in Germany usually 8-9 spirals (2.0 m) are installed for a 160 m2 residential building then in Estonia we install 24 -32 spirals depending on the soil type. The reason lies in colder climate and differences based on heat accumulation of the soil. In major part of Germany the humidity content of soil is very high and surface level is high. This enables to use smaller number of spiral collectors. Spiral collectors cannot be installed when the soil is too rocky or it is not possible to drill to the depth of 4 m due to limestone or sandstone. The drier the soil, the bigger number of spiral collectors should be installed. Use of spirals enable to increase the cooling depth to the 5.5 meters.
Installation of ground collector as well as spiral collectors must follow the volume of cooled broken rock. In both cases it must be of similar size and the size is determined by the necessary energy volume for a specific building. Neither of different installation diagrams, diameters of used tubes enables to change the volume of broken rock.