Connecting the heating in Comfort floors:

The picture shows a by-pass manifold, which distributes the water and regulates the flow of each heat circuit. This by-pass manifold, installed in the ceiling, regulates the upper storey in a two storey detached house. The base level has another by-pass manifold in the same boiler room.

The point at which the heating can be connected is dependent upon the materials used for making the floor itself. There are many opinions about this that are, in many cases, based on the traditions and experience relating to concrete or traditional cement or calcium sulphate screeds. These materials had had properties that were not as controlled as maxit's modern screeds. Many of these traditions relate to the need for drying out thick concrete layers or "never-drying" cheap calcium sulphate floors, that otherwise "never" would have dried. With maxit's well controlled modern products, there is no reason for raising the water temperature higher than a maximum of 40°C. Higher temperatures can damage the floor rather than bringing any advantages.

The traditional advice for dilatation joints between each heating circuit is similarly something that is often done "because it has always been done". The reason is that heated floors traditionally have almost always cracked at every threshold between every room, due to:

1) A high curvature in the floor, which will automatically break the floor slab at every door, as this is the weakest point. The curvature itself is a result of segregating concrete or an old type of screed, of uneven (one-sided, non-controlled) drying out, as well as of high temperature gradients. The high temperature gradient in turn has to do with the tradition of "drying-out-the-floor-with-high-temperatures " before covering the floor, as explained below.

2) The material tensile strength being less than the tensile stresses in the floor. Stresses occur due to uneven heat expansion between non-heated and heated parts of the floor (i.e. closed heating circuits adjacent to hot water runs.

With maxit's modern screeds, both cement-based, as well as the higher quality calcium sulphate-based ones, we have:

- no problems in controlling the drying out with more moderate temperatures!

- low shrinkage and modest heat expansion between different circuits (if max. 40°C) as well as soft strips against and around all vertical structures, enable a unhindered movement of the screed slab!

- controlled properties regarding tensile (flexural) strength, non-segregation and shrinkage. maxit Floor 4790 Curing Membrane additionally reduces the tensile stresses in the upper surface, which otherwise would occur due to a too fast evaporation.

Especially with the new maxit Comfort Floor system, where the heat is uniform under the screed, we do no longer have local heat expansion around pipes, as is the case with pipes embedded in the screed or concrete.

Our practical experience is that we can create heated floors without a single dilatation joint in the screed slab.


For normal apartments and offices we recommend the following heating advice. This also applies more generally, but for bigger areas, first consult maxit:

For cement-based screeds:
The floor heating can be connected after one week, first with a water temperature of 15-20°C, rising by +5°C/week to a maximum of 40°C.

For calcium sulphate-based screeds:
The floor heating can be connected after 1 day, first with a water temperature of 15-20°C, rising by +5°C/day to a maximum of 40°C. The heating can be held at this temperature to ensure drying out of any residual moisture.

The slow rise in the temperature enables the final setting of the screed (cement needs water) and controlled drying out. Too much heating too early will cause tensions in the floor before the floor has achieved its final strength properties.

Another advantage of being able to connect the floor heating as early as possible is that no other heat equipment is needed on the building site after this.