Can you simply extend the underfloor heating?


Often a basement or loft conversion makes it necessary to heat an additional area. Whether it is possible to easily extend an existing underfloor heating in the house, and what problems this may cause, read here.

Basic extension option

Basically, you can certainly extend a floor heating. The prerequisite for this, of course, is that the existing heat generator can also provide enough heating power to supply the newly connected areas.

Recalculation of the plant

For a larger extension, the entire system should be calculated by the specialist. In the case of an electric heater, pressures, flow temperatures and flow rates must always be adjusted and readjusted to ensure continued optimal operation of the system after expansion.

Even if the heat generator can provide the required energy, it depends on a sufficient distribution of these amounts of energy through the heater. This is the only way to ensure that the desired room temperatures can be reached at any time in all areas.

For the areas in which the heating is to be extended, an exact calculation of the necessary heating demand is necessary. The system must be able to provide the required amount of heat in all areas, and still have sufficient power reserves (increase in flow) available to work well.

Own heating circuits for the extension

Expansion areas can not be easily extended from existing heating surfaces. The new space often needs a new supply, for example, if it is a basement or attic or is a similar large area. They must then be connected directly to the heat generator.

Whether a connection to a heating circuit manifold in the existing part is possible, you can judge only on the basis of the respective structural conditions. There must also be a corresponding pipe dimensioning in the existing part.

The starting point for this assessment is again a corresponding calculation by a person skilled in the art. However, since the connections must be made anyway by the heating specialist, the entire planning and implementation of the extension can be left to the specialist company.

Connection of heating circuit distributors

Problems also often arise when trying to connect a new heating circuit manifold (for the extension) and an existing heating circuit manifold to the same control unit. That does not work in all cases.

Possible solutions for this problem could be:

  • to install a branch in front of the control station, and to connect another, autonomous control station
  • set up a new mixer group for the entire areas together
  • Installation of a completely new distributor (usually up to 12 circuits are possible on one distributor) and overall control of all circuits together

In addition, these solutions would also ensure that there is no "material mix" within the plant that can generally be considered as unfavorable. Above all, the concerns regarding corrosion and possible corrosion damage in the system speak against individual partial solutions with many different materials.

Tips & Tricks

The cost of an extension is always based on the necessary actions that are necessary for the enlargement. In many cases, you can reduce the costs but also by appropriate subsidies. In addition, it is usually possible to deduct a part of the craftsman's costs (working hours, no material) from the income tax.


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