Which pressure switch should be provided for shutting down the controlled residential ventilation?

Let's put it this way: I was able to set it so that the pressure switch triggered. Our blower door test was also correspondingly good...

But I wouldn't overestimate that either.

Yes, such a good blower door test is incredibly reassuring. The expert who carried it out for us was very impressed with the measured values. Our construction manager, who was also present, then said that it is the stated goal of Weberhaus to undercut the permissible limit values by at least 30 - 50 %...

Yeah, was also very proud with a 0.5 value

And even a Dibt stove including Dibt supply and exhaust (yes, everything must also be Dibt) is not a guarantee for acceptance without technical gimmicks. Just an exhaust hood and the stove is literally off.

Would then install the Wächter with us in the airlock

Can you tell me what kind of airlock this is supposed to be?

Despite Bosy, I am not really making progress on this topic. From my point of view, the best solution would be to install a differential pressure switch that measures the pressure in the exhaust pipe and the room and switches off accordingly if necessary. Does it work like that? Are electricians familiar with something like this? My building savings contract does not make any concrete requirements regarding the pressure switch and the chimney builder is not an expert either. The electrician will install the thing, right?

Yes, the electrician

Edit: install!