Controlled residential ventilation - You can hear every word in the other room - Is this normal?

The installer said 100% is never really needed. Only if you have a party or something...

Hmm, yeah right... no cooking or showering then?

So actually there should be a ventilation concept according to which the controlled residential ventilation was planned. Ask for this and have it handed to you. It then states how the individual rooms were planned with which supply and exhaust air quantities. Then you can also see whether the system is suitable in terms of performance.

Yes, exactly those things are in there now. So the system is set to 40% power in "normal operation." I assume, however, that this is actually not enough and that’s why the air seems/ is consumed like that. But when it’s at 100%, it still drones loudly in all rooms. The installer said you never need 100%. Only if you have a party or something...

I would also ask about the ventilation concept.
In residential buildings, to my knowledge, air exchange rates of 0.3 - 0.5 are referred to. If your system runs at 40%, then you only get an air exchange of about 0.2. If you take the average value of 0.4, your system must already run at 75%. I find the system dimensioned very much at the limit.

Yes, I now also think that the system is borderline undersized. I probably should have looked into it a bit earlier... I will request the calculation and then get back to you. Thank you very much for your input. It helped me a lot!

Oh yes, despite the newly installed silencers you can still hear conversations from the common room in the guest bathroom. Although slightly quieter, one probably shouldn’t gossip at my house anymore when someone is in the toilet... That’s just sooooo dumb!!! The plumber tried to convince me that this was normal and that there were never any complaints.

Oh man ... I can't just read up on it as a layman beforehand ... I don't read workshop manuals before taking the car in for repair either

What are they all paid for.