In the case of the surface collector, polyethylene hoses (PE pipes) are laid horizontally in the ground at a distance of 50 to 80 cm at a frost-proof depth of 1.20 to 1.50 m below ground in a snake or meandering pattern. In the first step, the planner must decide whether, in addition to the size of the vacant plot, the condition of the soil, in the form of the specific extraction capacity, is also suitable. While non-cohesive soils can only transfer 10 W/m² to the geothermal collector, moist-saturated, cohesive soils create a extraction capacity of 40 W/m². According to VDI guideline 4640, the size of the required collector area can be calculated on the basis of the following formula:
Collector area = cooling extraction capacity in W / extraction capacity in W/m²
In the case of a new building, the following installation area can be used for the initial assessment:
Collector area = 1.5 x heated usable area
The installation forms can be designed as follows:
Laying of geothermal collector in screw shape:
Laying of geothermal collector in double meander:
Laying of geothermal collector according to Tichelmann:
The production is done by excavating and leveling the area. Stones or gravel must be removed so that the pipes are not damaged. Then the pipes are laid out and embedded in fine sand, as this ensures good moisture absorption and thus ensures a good heat transfer value to the pipes. Then the area is backfilled with suitable material.
Surface collectors are the most common geothermal collectors and are considered to be one of the most cost-effective systems from an economic point of view - depending on local conditions. In Germany, they do not have to be approved, but only reported.
Source: bauwion
