Frequently asked questions about the hot-water underfloor temperature control system

We use a high-quality PE-RT tube which is made to be oxygen-tight in line with DIN 4726. The tube has an outer diameter of 8 mm and an inner diameter of 6 mm.

PE-RT tubes are completely wear-free provided that the temperature and pressure ratings are not exceeded (60°C and 6 bar).

The actual heating mat should not be extended because this would increase the flow resistance. Shortening the heating mats on the other hand is not a problem. When laying several heating mats, the following must be taken into account:
If the plastic tube of one of the heating mats is shortened, the other heating mats should be shortened by the same length for hydraulic reasons.

Our heating mats undergo continuous inspection during manufacturing. The following standards are complied with when dimensioning and manufacturing the tubes and when monitoring their quality:

• DIN 4726 Warm water floor heating systems and radiator pipe connecting, piping of plastic materials
• DIN 16833 Polyethylene pipes of raised temperature resistance, general quality requirements, testing
• ISO 10508 Application classes

The heating tube comes with a warranty of 10 years.

The surface structure of plastic tubes is so smooth (in comparison to metal) that limescale or silt is hardly able to accumulate. The sediments cannot settle and are continuously flushed through. Our connection manifolds are designed to allow individual tubes to be flushed at any time. The following measures are recommended to prevent clogging:

• Add an oxygen binder / corrosion inhibitor to the heating water.
• Fit a dirt separator in the system’s heating boiler return line.

The lowest temperature at which the heating mats can be installed is 5°C and the maximum permissible surface temperature is 80°C.

All substructures on which the underfloor heating system is fitted must be dry, of sufficient age, solid, clean, free of release agents, dirt and cracks, and rigid. The surfaces should be primed before laying the underfloor heating system.

The maximum operating conditions are an operating temperature of 60°C and an operating pressure of 3 bar.

The bending radius is at least 65 mm. The heating tubes should not be kinked.

Heating lines may only cross over expansion joints if they are fitted with a protective sleeve. The protective sleeve should be at least 12 cm long.

A heating surface area of up to 15 m² can be connected at one point (radiator connection). All heating mats need to be the same size for this. The entire surface area can then be regulated using a return temperature limiter. In the case of larger surface areas, a heating circuit manifold should be installed centrally.

The heating mat is fixed to the floor using the plastic dowel pins. As a general rule, the plastic nails are only inserted in the area of the fibrous material. To make it easier to fix the heating mats in place, they should be filled with water. The heating mats can also be fixed in place by applying flexible tile adhesive to individual areas. The fibrous material provides a really large surface area for the adhesive to work. A thin coat of adhesive is all that is needed.

After laying the heating mats, permanently elastic, liquid filler (flexible, liquid filler or similar to DIN 18156-2 and 18560) should be used to grout the heating mats. It must be ensured that this surrounds the heating tubes without any bubbles. The surface covering can then be laid using elastic tile adhesive. As a matter of principle, all materials used on top of the underfloor heating system must be suitable for such a system. Recommended mortar brands: PCI, Lugato, etc. as flexible mortar.

If the underfloor heating system is installed with direct contact to the soil, a layer of insulation is required otherwise the thermal energy will be lost. This insulation layer can be in the form of a WEDI board or a decoupling mat, for example.

All parquet or laminate floors suitable for use with underfloor heating can be laid on the underfloor heating system. For this purpose, the respective manufacturer must approve their flooring for use with underfloor heating. During installation, it must be ensured that the mortar covers the plastic tubes by at least 5 mm.
When fitting an underfloor heating system, the best results are achieved with tile flooring.

Before and after installing the heating mat, a pressure test (test pressure of 5 bar) must be carried out to check tightness. For wall heating installations, the system must be pressurised (at least 1.5 bar) during plastering work.

The underfloor temperature control system should be warmed up after the drying phase. With wall heating installations, it takes at least three days for lime-gypsum plaster and at least 21 days for lime-cement plaster to dry completely. The heating temperature should not exceed 30°C in the first four days. The maximum heat output is only achieved once the surface covering has dried completely. (In the case of tiles, the drying phase may last up to four weeks because drying only occurs through the tile joints.)

We offer 8 x 1 mm to 8 x 1 mm screw couplings for repairs of the plastic tubes. Make sure to mark the point of repair in the floor on a floor plan. As a general rule, the couplings must be accessible.

Yes, a thin-bed heating system can be used as a complete heating installation in a passive house.
The Perobe hot-water underfloor temperature control system is used to control the temperature of floors. When it comes down to it, a separate room heating unit (e.g. radiator, convector, etc.) is required to cover the heating requirements of a room. Use of hot-water underfloor temperature control as a fully fledged room heating system is possible in well-insulated buildings and very low heating requirements per room as a result (e.g. a passive house < 30 W/m²).
The heat emitted to the room generally depends on the difference between the floor’s surface temperature and the room temperature. The specific heating requirements in older buildings can easily reach 100 to 120 watts per m² of room area. Other heating devices are required to make up the difference between the shortfall in heat output and the required room warmth.
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