Mounting of the controlled residential ventilation ducts in the flat distributor

I cannot imagine that any manufacturer specifies this or even approves it. The later cleaning (which will be necessary at some point) alone can become a problem - for example, if brush inserts are to be used.

I see it all the same way you do. I actually didn’t realize it back then during installation, otherwise I would have reacted immediately. What’s disturbing is that this apparently is always done this way by the company. To my knowledge, other systems are intended for the fastening. As I said, unfortunately I don’t know the manufacturer and therefore I’m fishing in murky waters whether this is actually absolutely unacceptable. On the topic of hygiene and cleaning, I also think like you. Since so much has already happened between my general contractor and me and I don’t want to risk another construction delay, I will put the topic (you can’t change it anymore anyway) on the list for evaluation by the expert at the final acceptance. I think the screws can be cut off with a Dremel with a flexible attachment, but it definitely cannot be completely fixed anymore. The actually smooth pipe now has at least two spots at every inlet/outlet where dirt/dust and worse can accumulate. I find this really concerning with two small children in the house. This now causes me increased, permanent cleaning effort of the system that shouldn’t have been necessary. In the end, I also see a price reduction as necessary here, one that is in relation to the additional cleaning effort. Or am I now being too “meticulous”?

I see them now too, strange. The forum sometimes does things ... It doesn't look permissible to me at first glance ... Usually there are rings / seals that go around the pipes and then "click" into place at a suitable position. This seals and fixes the pipe against the valve or distributor. I'll ask ...

Nothing more to add. Normally, a seal is placed around the round pipe that seals and locks the flexible hose and distributor together (with me, I had to press down a bit). Double protection would be, for example, cold shrink tape to make absolutely sure that nothing gets into the pipe. Has the ceiling already been poured or is there still a chance for repair? Remove screws and seal the holes with cold shrink tape. I installed my controlled residential ventilation myself. Ask the general contractor for the manufacturer; they must tell you or must carry out the work according to the installation instructions.

Nothing more to add to that. Normally, there is a seal around the round pipe that seals the flexible hose and distributor to each other and either snaps in place (with me, I had to press it down a bit). Double protection would be, for example, cold shrink tape, so that absolutely nothing can get into the pipe. Has the ceiling already been poured, or is there still a chance for repairs? Unscrew, and seal the holes with cold shrink tape. I installed my controlled residential ventilation myself. Ask the general contractor for the manufacturer, they have to tell you or must carry out the work according to the installation instructions of the manufacturer.

The screed is going in now, so the train has left the station. No concrete slurry got into the pipes anywhere. I bought an inspection camera and will check all the pipes this weekend. I’m looking forward to the next point of dispute with the association… :-( Edit PU foam was used to seal in my case.

Look at the front side to see if it says "Fränkische" there. I think I have found them and they are called Fränkische Profi Air Classic. According to the installation sheet, the pipes are only inserted and not additionally fixed (but please read it yourself again).

Check on the end face if it says "Fränkische" there.
I think I found them and they are called Fränkische Profi Air Classic. According to the installation sheet, the pipes are only pushed in and not additionally fixed (but please check yourself again)

Thank you very much, those are indeed the components installed in my system. I will contact the manufacturer by email and submit an inquiry about the correct installation.