Sizing an underfloor heating system


When determining how to design a heating system from one location, there are fixed rules to follow.
• Basic accurate heat loss calculations.
• The floor construction is determined.
• The feed temperature is determined based on the heat source.
• Pipe range is determined by the feed temperature and the heat loss to be compensated.

The final design of a plant is made by the steel roof engineering department. If there is a preliminary design, a heat dissipation table (calculated according to prEN 1264-2) with a display power per m2 may be desired. Some important information about the underground heating project is explained in more detail below:

“Center distance (ctc)”
This is the distance between the heating pipes from the measured point for midpoints. This distance is determined in relation to the desired heat emission, the desired response time, and the predicted supply water temperature (heat source). The lower the required heat emission, the higher the center-to-center distance. The smaller the distance from the center to the center of the pipe network, the easier the heat transfer is between the medium (water) and the area to be heated. This will allow the system to react faster.

“Edge zone”
This is a region where the tubes are placed at a smaller center-center distance than each other. The aim is to achieve a higher floor temperature to achieve a higher temperature. This is applied as standard to a cold bridge (eg windows and doors) on an outside wall to compensate for the heat loss in this area. An edge region preferably consists of a separate group and may be at most 1 m wide from the exterior wall.

Edge zones are not required in the construction of contemporary residential buildings, where high insulation and energy needs can not be met.
• Cold bridges are not seen in today’s new construction and renovation.
• Ground temperature is limited.
• When low temperature sources are used, the center-to-center distance is usually set at the lowest level.

“Ground temperature”
The floor temperature may not be too high, as this can have an adverse effect on the human body. With an extremely high background temperature, the body can not release enough heat at the foot level, which is unnecessary (bulging feet). For this reason, the background temperature is limited to the function of the area.


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