Geothermal heat pump with area collector
.png)
%25203%2520(1).webp)
Stefano Fonseca ist Ingenieur für Energie und Umwelt mit über sechs Jahren Erfahrung in der technischen Gebäudeausrüstung (TGA). Er kombiniert technisches Fachwissen mit einer Leidenschaft für verständliche Kommunikation. Seit mehr als fünf Jahren schreibt er als freiberuflicher Redakteur über erneuerbare Energien und nachhaltiges Wohnen, insbesondere über Photovoltaik und Wärmepumpen.
Geothermal energy is right under our feet — and provides a clean energy source for heating residential buildings. But what is the best way to use this natural heat? If you have enough land space, area collectors are a more cost-effective alternative to geothermal drilling. In this article, you will learn everything you need to know about area collectors.
What is an area collector?
An area collector is a pipe system laid horizontally in the ground that supplies a heat pump with geothermal energy from the soil layer close to the surface. The pipes are usually located a few meters deep and require a large, undeveloped area. Area collectors are a cost-effective alternative to geothermal probes, but are only suitable for plots of land with sufficient space.
What types of area collector are there?
There are various types of area collectors for geothermal heat pumps, including classic area collectors, trench collectors, geothermal heat baskets, and spiral collectors. They vary in design, space requirements and efficiency and can be used flexibly depending on the size of the plot.
How does a geothermal heat pump with an area collector work?
One geothermal heat pump With an area collector, the near-surface geothermal energy stored in the ground is used to heat a building. The area collector extracts heat from the ground at a depth of 1.2 to 1.5 meters via a pipe system with circulating brine liquid. This transports geothermal energy to the heat pump, where it is transferred to a refrigerant in the evaporator. The refrigerant evaporates, is compressed in the compressor and is therefore heavily heated. In the condenser, it transfers the heat to the heating system. It is then expanded in the expansion valve, liquefies again and the cycle starts all over again.
.png)
What area does an area collector need?
An area collector generally requires 2 to 2.5 times the living space to be heated, depending on heating load and soil conditions. For a single-family house with 150 m² of living space, approximately 300 to 400 m² of free land space is required.
At what depth are surface collectors installed?
Area collectors are usually installed at a depth of 1.2 to 1.5 meters so that they can permanently remove heat from the ground below the frost line. Trench collectors and spiral collectors are usually lower, between 1.5 and 2.0 meters. Geothermal energy baskets are used vertically and reach depths of up to 5 meters.
How much does a geothermal heat pump with area collectors cost?
A geothermal heat pump with area collectors costs a total of between 16,000 and 30,000 euros, depending on the size of the building and expenditure. The heat pump, including installation, costs around 12,000 to 20,000 euros, while the area collectors including earthworks cost around 4,000 to 10,000 euros.
A major advantage of area collectors is that landowners can do the earthwork and installation of the collectors themselves. As a result, you can significantly reduce costs, especially when it comes to easily accessible, flat surfaces.
What are the advantages of geothermal area collectors?
Geothermal area collectors offer an efficient and cost-effective way to use renewable heat from the ground — particularly for buildings with sufficient land space.
- Low investment costs: Area collectors are cheaper than geothermal probes, as no drilling is necessary and the installation is carried out close to the surface.
- No approval: In many regions, no permit is required, as deep earthworks such as probes are not required.
- You can use it yourself: Builders with technical know-how can carry out earthworks and installation themselves and thus save costs.
- Low-maintenance and durable: The pipe systems are protected in the ground, are robust and work reliably for decades.
- Good efficiency with sufficient space: When properly designed, area collectors provide a stable and uniform heat source throughout the year.
- Free cooling: In summer, the lower temperatures can be used to cool the house, with very low power consumption.
What are the disadvantages of geothermal area collectors?
The biggest disadvantage of geothermal area collectors is the high space requirement, as at least 2 to 2.5 times the living space is required as vacant land area. In addition, the collectors must not be built over or planted with deep roots, which limits the use of the garden.
Requirements for geothermal heat pump with area collector
Operating a geothermal heat pump with an area collector requires a sufficiently large, undeveloped plot of land with suitable soil conditions. Other technical and legal requirements must also be met.
- Sufficient plot area: At least 2 to 2.5 times the living space is required, depending on the heating load and type of soil. The area must remain permanently free from development and deep-rooted plantings.
- Suitable soil: Moist, heat-conducting soils such as clay or clay are ideal. Dry, sandy soils require larger collector areas or are less efficient.
- Frost-free installation depth: The pipes must be laid at a depth of 1.2 to 1.5 meters so that they permanently remove heat and prevent frost damage.
- Low surface sealing: Asphalted or heavily sealed land is unsuitable as the surface cannot absorb enough heat.
- Space for dredging: Access for earthworks must be guaranteed. Narrow access roads or hillsides can make installation difficult or expensive.
- Low temperature heating: For the heat pump to work efficiently, the heat pump should operate with a low flow temperature. For this, you need panel heating or low-temperature radiators.
- Approval requirement, if applicable: In some regions, the installation may require approval, for example in the case of water protection areas or certain building requirements.
What do I have to consider with area collectors?
With area collectors, particular attention must be paid to careful planning and professional installation so that the system works efficiently and without problems over the long term.
- Maintain a distance between pipe loops: The pipes should be laid in parallel loops about 0.5 to 0.7 m apart so that the collectors do not thermally influence each other.
- Keep the installation depth constant: The pipes must lie evenly at a depth of 1.2 to 1.5 m to ensure uniform heat absorption from the soil and prevent frost damage.
- Preventing air pockets and creases: When laying, the pipes must be laid tension-free and without tight bend radii. Air pockets in the system impair the circulation of brine.
- Hydraulic adjustment of pipe lengths: All pipe circuits should be of equal length or hydraulically balanced to ensure uniform flow.
- Marking the collector area on the plan: The exact location of the area collectors should be documented and noted in the site plan so that subsequent construction or planting is not endangered.
- No severe soil compaction after installation: After filling, the collector surface must not be driven over with heavy machinery, as this will affect the soil's heat absorption in the long term.
- Allow heat absorption in summer: The area should remain as open as possible so that the soil can regenerate in summer and store heat for the next winter.
How long do area collectors keep geothermal energy?
Area collectors can reliably supply geothermal energy for over 50 years if they have been professionally planned and installed. The pipes are usually made of robust, corrosion-resistant plastic (e.g. PE-Xa), which is designed for a long life in the ground. In addition to material quality, uniform heat removal and good regeneration of the soil through summer heating are decisive for durability.
Do I need a permit?
As a rule, no permit is required for area collectors, but registration with the lower water authority may be necessary — particularly in water protection areas or large plants. It is advisable to obtain information from the competent authority before starting work.
What happens to the floor after installation?
After installing surface collectors, the floor remains permanently thermally affected, as heat is continuously removed from it. As a result, the earth cools slightly in the collector area, but can regenerate over the summer. The area should not be built over or heavily compressed so that air, rain and solar heat allow the natural return of heat. Deep-rooted plants or sealed surfaces can impair this regeneration and reduce efficiency in the long term.
What alternatives to geothermal area collectors are there?
Alternatives to area collectors are Earth probes, well systems (groundwater heat pumps) and air-water heat pumps. All three systems use different heat sources: geothermal probes draw heat from deep layers of the earth, wells from groundwater, and air-water heat pumps from the ambient air. The selection depends on the plot of land, soil conditions, regulatory requirements and the budget.
autarc: Your partner for efficient planning of heat pumps — find out more now!
Rely on quality and expertise when planning and installing heat pump systems. With our Heat pump check receive comprehensive support so that you can implement your projects efficiently and sustainably. Contact us today and benefit from our expert knowledge!