Central ventilation system: Durability of the pipes

Hello everyone,

In central ventilation systems, the pipes are often embedded in the concrete ceiling. Now I am interested in the durability and hygienic perspective.
What do the deposits look like after maybe 50 years?
Are the cleaning methods efficient and effective?
Is it possible to install a "double piping," i.e. to embed a larger pipe in the ceiling and run a smaller one inside it, which can be replaced after some time?

Thank you very much for your impressions

Best regards

IMHO, it is just as questionable or unproblematic as concrete-encased water pipes.

Regarding cleaning: The fewer bends and branches, the easier it is to clean such a system. Concrete-encased pipes have the advantage of being firmly fixed, so they can be cleaned well. But again, quite clearly: I would not worry about hygiene or durability.

The cleaning will be carried out with us in such a way that it is regularly blown through with proper air so that all dust and dirt comes out of the pipes. If that is not enough, surely someone will have specialized in the cleaning of such pipes within 20 years and will clean them for a few marks fifty.

Years ago, someone was certainly specialized in cleaning such pipes and would clean them for a couple of marks fifty.

Well, those guys already exist today, you don't have to wait forever...