Underfloor Heating: Does It Need to Be Renovated?

15.6.2021
  1. Underfloor heatings do not age so quickly
  2. Underfloor heating systems installed after 1990
  3. Underfloor heating systems installed before 1990
  4. When underfloor heating no longer heats evenly
  5. Consult a professional

Underfloor heating systems are nowadays a standard in new buildings. Not only are they invisible and heat evenly, but they are more energy efficient and resource-conserving than radiators. If you own an old house or flat and your underfloor heating distributes heat unevenly, it would be best to contact a professional. Sometimes a simple cleaning of the heating system solves the problem, other times the underfloor heating system needs to be modernised or even changed.

Underfloor heatings do not age so quickly

Underfloor heating systems last between 30 and 50 years. The Swiss Society of Engineers and Architects (SIA) estimates 30 years, the Swiss Federal Laboratories for Materials Testing and Research (EMPA) estimates 50 years. Far longer than many owners believe. The reason is that underfloor heating systems operate at lower temperatures than radiators among other things. They usually only need a flow temperature of 30 to 35 degrees instead of 45 to 60 degrees. This lightens the load on the heaters, saves energy and reduces costs. In addition, in underfloor heating systems, the coils are under less pressure than in other heating systems.


Underfloor heating systems installed after 1990

The greatest enemies of underfloor heating systems are rust and limescale. Deposits can build up and restrict the flow of water or even clog up pipes. As soon as a plastic pipe leaks or becomes more brittle, oxygen can enter and trigger a corrosion mechanism. This should not be a problem for pipes installed after 1990. Almost all domestic and building engineers in Switzerland now install only oxygen diffusion tight pipes according to DIN 4726, which are much less prone to this problem. For example, composite pipes made of several layers of plastic with a gas-tight aluminium core are used. In addition, the heating system is now also filled with specially treated water to prevent limescale deposits.


Underfloor heating systems installed before 1990

Before 1990, underfloor heating systems were installed with gas-permeable plastic pipes. These proved to be fragile and subject to time. If the underfloor heating system has been installed and sized correctly, it takes much longer than EMPA and SIA estimate until a pipe becomes a problem and leaks. However, it makes sense for owners of older houses or flats from the 1970s, 1980s or early 1990s to have their underfloor heating system serviced regularly by a technician. This person will examine the heating water for diffusion and iron oxide, check the water quality and test the pH value, water hardness and oxygen content.

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When underfloor heating no longer heats evenly

The technician records the values. As long as they are normal, all is well. But as soon as they deviate from the standard values, the plumber will at least have to intervene to clear the coils of deposits. In this phase, all the pipes are flushed with an air-water pressure pulse and the heating water is replaced with specially treated water. This is often sufficient for the underfloor heating to heat all surfaces evenly again. If this is not the case, the expert uses his thermal imaging camera to look for weak or damaged spots in the floor. Depending on the results of the infrared thermography, various measures may be necessary:


  • Renovation from the inside: the technician sprinkles the pipes with granular material and covers the inside walls with resin. This measure, however, is only valid for small leaks.
  • In pressure cleaning, the technician uses compressed air or negative pressure to move a plastic object through the pipes and clean the inside walls.
  • A complete renovation is the most expensive in terms of time and money. The installer must first remove carpets, tiles or parquet and, if necessary, shore up the floor before he can replace the pipes and renew the underfloor heating. This can take weeks.
  • Replacing underfloor heating with radiators is easier and cheaper than a complete renovation, but it is not always possible.

A heating installer lays the pipes for a new underfloor heating system
A heating installer lays the pipes for a new underfloor heating system


Consult a professional

As already mentioned, underfloor heating systems last longer than most people think. They are more likely to need repair, not because they are broken, but because an inexperienced repairman might accidentally drill a hole in a pipe. In most cases, these heaters do not need to be refurbished or replaced. If something like this happens, or if you suspect that the pipes in your underfloor heating system are leaking, better make sure you consult a heating expert. Here are some signs that the pipes are no longer completely in place:


  • Large areas or entire rooms no longer heat up
  • There are humidity stains on the floor or walls
  • Pressure in the heat distribution pipes drops rapidly after filling
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