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  • 40627 Düsseldorf-Unterbach
    Kirche St. Mariä Himmelfahrt

    temperature:
    21,3
    °C
    humidity:
    65,1
    %rF
    measured:
    08:21
    h
  • 31134 Hildesheim
    Michaeliskirche

    temperature:
    21,2
    °C
    humidity:
    65,9
    %rF
    measured:
    08:21
    h
  • 40668 Meerbusch-Lank
    Kirche St. Stephanus

    temperature:
    21,8
    °C
    humidity:
    53,1
    %rF
    measured:
    08:21
    h
  • 52062 Aachen
    DOM

    temperature:
    22,0
    °C
    humidity:
    64,5
    %rF
    measured:
    08:21
    h
  • 50676 Köln
    Krypta Maria im Kapitol

    temperature:
    18,1
    °C
    humidity:
    78,8
    %rF
    measured:
    08:24
    h
  • 66346 Püttlingen-Köllerbach
    ev. Martinskirche

    temperature:
    21,6
    °C
    humidity:
    65,2
    %rF
    measured:
    08:22
    h
  • Church of St.-Hubertus in Grosselfingen
    MAHRCALOR® church heating built in 2010
  • MAHR archives
    Data and ground plans of thousands of churches kept in our archives
  • Petri church in Lübeck
    MAHR-Actherm® control system for 22.000 m³ of church space
  • Sankt Johann in Denkingen
    MAHR church heating 1978 – long life through quality and regular servicing
  • Cathedral and Church of Our Lady in Trier
    MAHR heating systems in UNESCO world heritage sites
  • Church in winter
    A basic minimum temperature saves the substance of the building

Underfloor Heating

Structure of the system:

An insulation is put upon the subconcrete layer to reduce the loss of energy into the soil. A vapour barrier (usually a plastic foil) is then laid upon the insulation before the actual underfloor heating is installed. This can come as a warm water or as a warm air underfloor heating. There is even the possibility to heat the floor by electrical resistance wires. The piping used for transporting water can be made of copper or plastic. Above the underfloor heating comes the floor screed, with the floor covering on top.

Advantages of the system:

  • The visitor has a better perception of the temperature because of the warm floor.
  • No gratings in the floor.

We have installed a lot of underfloor heating systems in churches, however, hardly ever as sole heating but in combination with a heating which is able to keep the surface temperature of walls, windows and ceiling reliably above dew point (the temperature where humidity condenses like for example on a bathroom mirror).

Disadvantages of the system:

  • Quite often insufficient heating power and consequently no posssibility to keep walls and ceilings above dew point.
  • The heating requirement of a church depends on the features of the building and not on the heating device, but an underfloor heating alone can almost never produce the heat needed. In our experience underfloor heating covers between 35 and 50% of the heating requirement calculated. As a rule you will need additional heating systems.
  • You often hear the argument that with underfloor heating the temperature distribution in a church is much better, as only the area where people are is heated, and the upper levels stay cool. From a physical point of view this is hardly possible since warm air is always lighter than cold air, with the air warmed on the floor always rising up. This “equalization of temperatures” often results in a considerable movement of air that is perceived as unpleasant draught.
  • In churches with underfloor heating the up-rising air, which can be very humid due to e.g. snowproof clothes, meets with cold wall and ceiling surfaces. The humidity condenses and facilitates the adhesion of dirt. The picture shown on the side was taken in a church with underfloor heating illustrates thermal bridges and explains the correlations. Close to the chimney the surface of the wall is significantly warmer and the adhesion of dirt is less marked.


Conclusion

A church hull that is kept above dew point will stay clean much longer because it is dry. Renovation cycles will be considerably longer.

  • Controllability of an underfloor heating is limited and slow. Heat that has been fed into the floor will continue to warm the space even when it is no longer needed. On the other hand it will often take hours to warm the entire floor and then the inside of the church effectively.
  • Installing an underfloor heating always presupposes a complete renewing of the church floor. If this is part of the plan in the framework of a major renovation, installing an underfloor heating as an additional system can be justifiable. Replacing an otherwise good floor only to have an underfloor heating put in will probably make no sense economically.