ᐅ Mechanical Ventilation with Heat Recovery – You Can Hear Every Word from Another Room – Is This Normal?

Created on: 30 Jul 2018 22:43
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Dodo86
Hello everyone,
We had the final inspection of our house two weeks ago. Now we have noticed that through the central ventilation system in the guest bathroom and utility room, every word spoken in the dining/kitchen/living area can be heard very clearly, as if you were sitting right next to each other. With the bathroom door open, the sound naturally carries up to the children’s bedrooms upstairs. On the upper floor, the sound transmission through the controlled mechanical ventilation system is significantly less.
Can I still report this as a defect after the final inspection?
Thank you very much and best regards!
Mycraft2 Aug 2018 14:25
Dodo86 schrieb:
The plumber said you never actually need 100%. Only if you have a party or something...

Hmm, right... so no cooking or showering then?
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Tommes78
2 Aug 2018 14:43
There should actually be a ventilation concept based on which the mechanical ventilation system was planned. Ask for this and have it provided to you. It will show how the individual rooms were planned with regard to supply air and exhaust air volumes. Then you can also see if the system's capacity is appropriate.
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hanse987
2 Aug 2018 15:56
Dodo86 schrieb:
Yes, these exact units are installed now. The system is set to 40% power during "normal operation." I assume that this is actually not enough, which is why the air seems used up. But even at 100%, it still makes a loud noise in all rooms. The installer said you never really need 100%, only maybe if you’re having a party or something...

I would also ask about the ventilation concept.
In residential buildings, air exchange rates are usually around 0.3 to 0.5 air changes per hour. If your system is running at 40%, you’re only getting about 0.2 air changes per hour. Assuming an average of 0.4, your system would need to run at about 75%. I think the system is already designed quite close to the limit.
Dodo862 Aug 2018 21:29
Yes, I also think by now that the system is borderline undersized. I probably should have looked into it a bit earlier...
I will request the calculation and get back to you afterwards.
Thank you very much for your input. It has been very helpful!
Dodo862 Aug 2018 21:33
Oh yes, despite the newly installed sound dampers, you can still hear conversations from the main living area in the guest bathroom. It’s slightly quieter, but apparently, you shouldn’t gossip at home anymore when someone is in the restroom...
That’s just sooooo frustrating!!! The plumber tried to convince me that this is normal and that there are never any complaints.
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Snowy36
2 Aug 2018 22:26
Oh man... I can’t be expected to read up on this as an amateur beforehand either... I don’t read repair manuals before I take my car in for service.

That’s what they’re all paid for.