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Manifold for ground heating

Depending on the size of the area, you can use either an underfloor heating manifold or ground installed manifolds in a Thermotech GEO®System for ground heating.

Underfloor heating manifold
For smaller areas and the pipe dimensions 17 and 20 mm, a standard underfloor heating manifold is used. If it is possible to make all the loops the same length, a manifold without balancing valves can be used. Normally the standard underfloor heating manifold is installed in doors.

When a standard manifold is used it is possible to balance the loops.

Ground installed PE-manifolds
For pipe dimensions of 25 and 32 mm, use Thermotech manifold of PE for installation in the ground. They are available in diameters of 75 mm, 110 mm and larger, but either 75 or 110 mm is usually enough. Connection to the loops is done using a joint coupling in plastic or metal, or using a weld muff.

The PE manifolds have a with a cc-measure of 500 mm between the connections. The manifolds should be installed offset 250 mm relative to each other so that a distance of 250 mm between pipes is obtained.

Throttle valves are not needed for this type of PE manifold since loops of equal length are laid out and the manifold is installed in the ground.

In PE manifolds, the pressure increases the farther the loop connection is from the manifold’s connection point. This means that the number of loops that ca be connected to a manifold depends on the diameter of the manifold.

The pressure drop in the manifold should not exceed 5-10% of the pressure drop in the loops.

Markvärmefördelarens diameter / max yta
The manifolds diameter Max area*
75 mm 500 m2
110 mm 1 200 m2
160 mm 2 200 m2

* 25 mm pipes, 110 m loops, 300 W/m², dT 15 ºС.

For detailed information and calculation examples download Thermotech GEO®System Product range & Handbook.

Temperature drop in the loops and the temperature of the heating medium
The temperature drop in the loops can always be selected to 15 ºС.

The temperature of the heating medium is affected by power emitted at the surface, the installation depth of the pipes and material above pipes. In normal cases (recommended cc-size, 300 W/m², temperature drop 15ºС) the temperatures listed below are recommended for the following media:

Rekommenderad temperatur hos värmemediet
Material above the pipes Temp. heating medium
Concrete or asphalt, 50 mm 30-35 °C
Concrete or asphalt, 100 mm 40-45 °C
Sand or paving stone, 100 mm 40-45 °C
Soil, 120 mm 45-50 °C

We do not recommend that the pipes are installed in a concrete slab deeper than 120 mm. The medium’s temperature can change during operation and normally a surface temperature of +2 °С to +5 °С is enough.

Balancing the loops
Ground installed PE manifolds do not normally need to be balanced,because all the loops are of equal length. The length of an individual loop can vary 5 – 10% without affecting the balancing. It is always better if the longer loops can be connected to the manifold closest to the manifold’s connection point.

For smaller areas, where 17 and 20 mm pipes are used, a standard manifold can be used, which also allows for balancing of the loops.

Pressure test
The system must be under pressure during the entire installation, including top layers such as concrete, asphalt or other. A pressure of 3-4 bar is recommended

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