Spiral collector
A spiral collector is a particularly space-saving design of a near-surface geothermal collector . They are used to generate heat from the upper layers of the earth, which is usually used in conjunction with a heat pump heater for heating or cooling. The VDI guideline 4640-2 mentions spiral collectors, but without specific statements about the design and layout.
Structure / function
A spiral collector usually consists of a plastic tube, which is formed into a stable spiral with the help of retaining rails. The size of the spiral collector always depends on the area of application, but normally the height is between 2.5 and 3.0 m and a diameter of approx. 0.5 m. Despite its compact design, a spiral collector can deliver an extraction power of at least 0.35 kW . The actual possible extraction capacity depends on the conditions of the soil. Rainwater seeping away can greatly increase the extraction capacity.
The collector is usually filled with a mixture of water and antifreeze. Projects in water-sensitive areas are subject to special requirements of the local authorities, which must be specifically requested.
The spiral collectors, which are integrated in a circuit, are flowed through by the heat transfer fluid with the help of a circulation pump . Here, the heat is extracted from the floor via the wall of the plastic pipes and transported to the heat pump, where it can then be used (see heat pump function ). In order to guarantee heat absorption, the liquid coming from the heat pump must be cooler than the ground around the collector. The heat transfer fluid heats up in the probe, but cannot get warmer than the ground.
Installation
The installation of the spiral collectors is vertical as standard and has an installation depth of 3.5 to 4.5 m, depending on the collector height. The bores are carried out with the aid of a screw auger. The coverage of the collector ranges from 1 to 1.5 m. Depending on the local conditions, spiral collectors can also be laid horizontally. This may be necessary if there is hard or rocky ground from a depth of approx. 2 m. The coverage of the collectors should then be at least 1.5 m.
advantages
- little need for space
- Cooling function possible
- Fast execution
- Alternative in case of official prohibition of depth probes