Is the neighbor's ventilation system set too high and therefore too loud?

Hello dear forum,

I am reaching out to you with a problem:

Our neighbors have a controlled, central ventilation system (probably Stiebel Eltron 280), which we find "too loud" and which, in my opinion, is set incorrectly.

It produces about 60 dB(A) sound pressure at the exhaust air vent, which faces our terrace, making it sound like a constant airplane overhead on our terrace about 8 meters away. The wind speed in the 160 mm duct is 2.6-2.8 m/s, which according to my calculations means about 200 m3 of air per hour (for the difference between supply air/exhaust air see the side question below).

This happens from 7:30 AM to 9:00 PM, although hardly anyone is there on weekdays (also on weekends during that time; even frequently with windows open). In the evening they then turn it down. All of this now in summer (May-September); in autumn/winter they generally turn the system down!?

Our neighbors refer to the plumbing company that installed and services the system; according to them, the system is set correctly.

Data about the house: approx. 450 m3,
5 people
==> Thus, I come to a necessary air exchange rate of about 130-150 m3 per hour (factor 0.3 or 25-30 m3 per person for "normal air").

Side question: On the weekend, they were airing out (2 days during the day!) at the highest setting on the supply air with a wind speed of 3.6 m/s = 260 m3/h, but on the exhaust air at 4.5 m/s = 325 m3/h, the sound pressure was 70 dB(A). That is 25% more. It seems to me that the exhaust air from the rooms is set too high? I once read something about a maximum of +5-10%.

What do the experts here in the forum think? I am already trying to talk to the neighbor and possibly have an independent plumbing company take a look. So far unfortunately no success...

Best regards, Toja

For me as the operator of the system, there would be no reason to want to adjust anything or to suspect that something is set incorrectly.

200cbm for the size of the house is completely fine for normal ventilation. You also don’t always have to run only the minimum ventilation.

Emissions can be minimized through silencers and other hoods. A hedge also helps.

...content-wise I can't contribute much, the volume/h sounds normal to me, I have similar values. What really interests me though: Where did you get the values from? Got them from the neighbor? Wind meter? Sound pressure measuring device? :D

Hello mycraft,

the silencer should be installed in the exhaust air duct? How does it work technically?

The cover on the house wall currently looks like this.

The hedge is already there, but only helps to a limited extent ;-)

Hello face26,

yes, I got myself a wind meter. The sound pressure was measured amateurishly with the phone.

However, there is also a guideline according to which a maximum of 50 db(a) is allowed in residential areas. So turning it down a bit could help in case of doubt, because then it would be halved for every 3 db(a).

Should the silencer be installed in the exhaust air duct?

Yes, exactly there.

How does it work technically?

Like in the automobile.