In a groundwater heat pump glycol water is used to extract heat from the soil. This process can take place both via a horizontal or a vertical heat exchanger. The absorbed heat is released through the evaporator to the coolant and then transferred through the compressor to the condenser. In the condenser the water of the heat delivery system absorbs both the heat assimilated in the evaporator and the energy delivered to the compressor.
Soil heat exchanger
A soil heat exchanger is a network of pipes through which a mix of water and anti-freeze liquid (often glycol) circulates. This liquid transfers the heat from the source to the evaporator. It is of great importance that the soil heat exchanger is correctly sized. When the heat exchanger is too small, the temperature produced will be too low which will finally lead to a loss of efficiency. Depending on the choice, Linea Trovata can install both the vertical and horizontal soil heat exchanger.
Vertical soil heat exchanger
A vertical soil heat exchanger consists of multiple U-shaped heat exchangers which are placed in drill-holes up to 100 m deep by means of a drilling machine. A correct sizing is key, there is an important calculation for this in which various essential factors play their role such as:
- number of operating hours
- peak moments
- capacity of the heat pump
- available space
The drilling is carried out by making use of either the flush drilling or the suction drilling method. The distance between the holes is 5 to 10 meters, the depth varies between 25 and 100 meters. The vertical soil heat exchanger is a closed system with a circulation pump.
For the installation of a vertical soil heat exchanger in Flanders one has the obligation –according to the official regulations of the Flemish government (Vlarem I)- of having a license (class 2) or of reporting (class 3).
When the depth of the vertical soil heat exchangers is limited to 50 meters, a simple reporting to the Board of Mayor and Aldermen of the community will suffice. At depths of more than 50 meters, a license is required from the same Board. The application for such a license may take 4 to 5 months.
- High and invariable COP
- Takes little space
- Passive cooling
- Low consumption (only support)
- High investment cost
Horizontal soil heat exchanger
Those who want to install a groundwater heat pump with a horizontal soil heat exchanger must have a piece of ground (e.g. garden) with sufficient area. The rule of thumb is that the available (outside) ground area is twice as large as the (inside) heated living area. A horizontal soil heat exchanger consists of a grid of tubes (a capture grid) that are buried about 1 meter under the surface of the ground. The capture grid is sized according to the soil type and the type of tubes that are being used. Linea Trovata offers two types of horizontal soil heat exchangers: one classic capture grid with PE tubes and another capillary grid of tubes. The horizontal soil heat exchanger is a closed system with a circulation pump.
- Average COP
- Low investment
- Low consumption
- No licence
- Large surface needed
- Decreasing COP during the heating season
- No passive cooling