Underfloor heating system
Underfloor heating: The knob system
Like the tacker and velcro system, the nub system is one of the so-called wet systems. The basis for this form of underfloor heating is knobbed panels (usually made of polystyrene), which can be laid according to the push button principle. The water-carrying pipes are fixed in the gaps between the knobs and then poured into wet screed. Due to the installation height of approx. 90 mm, the nub system is particularly suitable for new buildings, but can also be used for renovations and retrofitted - provided there is enough space. In this article you will learn more about the advantages of the knob system, its structure and the components used as well as the laying of the underfloor heating.






Advantages of the knob system
- Quick and easy installation: The knobbed panels simplify the installation of the heating pipes enormously and thus enable quick and uncomplicated installation of the underfloor heating by a single fitter.
- Soundproofing and thermal insulation: The knobbed panels are optionally available with integrated thermal and impact sound insulation. It contributes to greater energy efficiency, improves the room climate and reduces noise.
- High flexibility: Knob plate systems can be used with three different tube diameters (14 mm, 16 mm and 17 mm). The system is also flexible when laying the heating pipes and allows distances of 5, 10, 15, 20 and more centimetres.
- Cooling is also possible: underfloor heating with a knob system can also be used for surface cooling, provided the system also supports cooling operation. This cooling from below is particularly pleasant on hot summer days.


Laying and installation of the knob system
Before laying the studded panels, the subsurface must be carefully prepared. It is important to remove dust, dirt and any foreign bodies that could later press through the plates from below. Then, in the first step, the edge insulation strip is attached, which separates the floor and wall from one another and, among other things, minimizes the transmission of sound.
In the second step, an insulating layer of Styrofoam panels is laid on the floor. This step can be omitted for studded panels that already have integrated heat and footfall sound insulation. This is where the knobbed panels, reminiscent of children's building blocks, are laid directly. Laying always starts flush with the wall in a corner of the room. It is important that the flap of the edge insulation strip always lies over the panel and cross joints are avoided. So-called T-joints are more suitable. When placed next to each other, the knobbed panels are attached to each other using connectors or plugged directly into one another. At the place where the distributor is, a compensating plate is laid instead of a knob plate.
If the entire room is laid out with knobbed panels, the third step is to lay the heating pipe. The special arrangement of the nubs ensures great flexibility and simplifies the fixing of the pipe. As soon as the heating pipes have been laid and connected to the manifold, a final pressure test follows. This is to ensure that the heating circuit is completely tight. If the pressure test was successful, the wet screed can be applied. As soon as the screed is completely dry, nothing stands in the way of using the underfloor heating.
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Questions and answers about the FBH nub system
High-quality materials and professional installation ensure that modern knob system underfloor heating has a long service life. As a rule, the systems last at least 30 years. It is important that the heater is serviced regularly in order to be able to identify possible signs of wear at an early stage.
The maintenance effort of a modern surface heating with knob system is relatively low. However, a system check should be carried out regularly by a specialist in order to be able to rectify any problems quickly. It is also important to bleed the heating system from time to time to ensure smooth operation. It also makes sense to check the control technology of the surface heating at regular intervals and to bring it up to date over the years.