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How to switch to condensation with a collective condominium flue?


In co-ownership, the switch from individual low-temperature gas boilers to gas condensing boilers may require work on the common areas. We explain why in this article.

What the regulations say

In recent years, a large number of European and national regulations have been passed to limit the sale of energy-inefficient and polluting products. We have seen the appearance of energy labels on dishwashers or refrigerators. This development is also visible with sales bans on certain types of bulbs.
The same type of regulation has been put in place for heating systems, always with the aim of helping to reduce energy consumption and polluting emissions. Since September 2018, the last part of European regulation no. 813/2013 forming part of the ErP (Energy Related Products) directive has come into force. The legislator has therefore translated into French law this regulation which prohibits the use of boilers emitting more than 56 mg of nitrogen oxides (NOx) per KWhPCS of fuel consumed. Another point, the use of individual gas boilers type B1 (non-condensing) was limited to 2 very specific cases:
  • With a collective smoke evacuation duct
  • With an individual duct of more than 10m

Boiler manufacturers are adapting

In fact, all manufacturers have had to innovate and offer low-temperature boilers called “Low NOx” that meet new polluting emission standards. The so-called “classic” low-temperature boilers have not been sold in France since September 2018.
Obviously, gas condensing boilers are strongly favored and encouraged by the various financial aids: Tax credit, Heating boost bonus, Anah Habiter Mieux renovation program (National Agency for the Improvement of Housing ).

The complexity of the transition to condensation

In co-ownership, there are several types of heating systems, among others:
  • Heat network
  • Collective boiler
  • Individual boiler with individual flue gas discharge ducts
  • Individual boiler with collective smoke evacuation ducts
The implementation problems mainly concern the last case, when the apartments are equipped with individual low temperature boilers connected to collective smoke evacuation ducts. The complexity in this case lies in the fact that the switch to condensing boilers must be carried out in all the dwellings at the same time.
In fact, the smoke evacuation duct must be completely modified and renovated. It will then be impossible to connect the old low temperature boilers to this new pipe. In the context of work of this type, co-owners are strongly advised to contact a specialized installer who can carry out a study and suitable proposals, both for work on collective parts and for the replacement of individual boilers for all co-owners.

Financial aid available

In order to support the co-owners in these energy improvement works, there are several mechanisms to reduce the cost of the work.
  • EWC program - Energy saving certificate - and the heating boost bonus
  • Habiter Mieux Co-ownership program to cover part of the renovation of the collective duct
To make this work on common areas accessible, Finance Studio can also support your co-ownership thanks to the Personal Co- ownership Loan .
In addition to these aids, it is possible for each owner, depending on his situation, to benefit from individual aids for the installation of a gas condensing boiler to replace a low temperature boiler.

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