Guide

Elements of hydronic underfloor heating

Elements of hydronic underfloor heating

In hydronic underfloor heating systems the pipes ale usually placed directly on the thermal insulation covered with damp-proof foil. They are mounted on the thermal insulation with MAXL Slat 2000 assembly slat and other kinds of mounting (clips, hooks, grips) that keep them in the same position. Later they are inundated with jointless floor. The pipes must be adjusted to work in the temperature of 70 °C and operating pressure up to 0,3 MPa. The pipes that can be used are made of plastic with anti-diffusion barrier, they can have many layers and aluminium insert, or they can be made of copper. Their diameter may vary from 12 to 22 mm.

The length of the pipes should be selected in a way that separate loops would be made from one segment. Thanks to this, one can avoid joining pipes which creates the points the most subject to leakiness.

The distance between the pipes should range between 10 to 30 cm. The pipes are placed in loops that can have shape of spirals, spirals with integral parietal space, meanders or double meanders. Also combinations of these patterns may be used for individual needs.

Thermal insulation made of foamed polystyrene, mineral wools or polystyrene is placed directly on the floor so that the right direction of heat flow would be assured. The thickness and the kind of insulation should be selected in accordance with thermal requirements of the building and expected load.

Thermal insulation should be of proper thickness and load resistance, which will make it stiff enough to prevent heat pipes from displacing. The thickness of the insulation layer is dependent on the fact whether the room below is heated or not. The layer thickness on the ceiling between the levels is approximately 5 cm. The floors on the ground level and the rooms located above the cellar require thicker insulation layer, i.e. 8-9 cm.

Thermal insulation should be covered with damp-proof insulation MAXL Laminate 9001, which protects thermal insulation from technological moisture coming from cement mortar while placing top floor layers on it.

The pipes are covered with jointless floor, which is a mixture of sand, gravel, water, and cement. The thickness of the jointless floor level should be approximately 5-6 cm.

There should be some space (dilatation) left between the slab and the building construction, at least 0,5 cm wide. The space will allow floor deformation caused by the temperature, without the risk of damaging (cracking) the jointless floor. The dilatation tape is laid along all walls, pillars, and doorways.

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