In the trench collector, polyethylene hoses (PE pipes) are laid parallel on top of each other on standing grids in trenches approx. 2.5 to 3 m deep. At the foot of the ditch is about one meter wide, at the top depending on the soil then much wider. The cables are mounted at a distance of 10 -20 cm above each other. 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 performance is also suitable. While non-cohesive soils can only transfer a small amount of energy to the geothermal collector, moist-saturated, cohesive soils create a high extraction rate. The trench collector is also dependent on the soil being thermally regenerated between heating periods by solar radiation and the input of rainwater. The collector should therefore be installed on a part of the property that is well exposed to the sun and not sealed or built-up.
As a rule of thumb, it can be assumed that approx. 2 - 3 meters of trenching are required per kW of heating load. The trench can be straight, L-shaped or U-shaped.
The trench collector is usually used when the land area is not sufficient for a surface collector. A trench collector is one of the cheapest types of collector.
Source: bauwion
