Integral device Stibel Eltron LWZ 504 with central supply air

At level 3 at 300 m3/h you can already hear something near the valves. Level 2 for us is 160 (during the day) and at night on 1 it is 110

Definitely at 3, but it doesn't bother you if the use case is a party.

Thank you for your efforts.

The air exchange rates were calculated by the company Zehnder and set by a Stiebel Eltron technician. They are set as follows for us (all supply air values, the exhaust air is always 20-30m³ higher):
Level 1: 120m³/h (intended for night operation)
Level 2: 220m³/h (intended for daytime operation)
Level 3: 250m³/h (party level)
The filters are clean. They were vacuumed again by the technician during the adjustment and I just checked them.
I had the heat pump set to warm water generation only for several days to find out exactly what causes the noise development, heating or ventilation. Also, it was much too warm in our house, 22 - 23 degrees in the upper floor, although all thermostats on the entire upper floor were set to zero.
The hot water is set to 48 degrees, but the heat pump produces 50 degrees with this setting, as required by the drinking water regulation. That’s what the technician explained to me and that’s also what the heat pump indicates as the actual hot water temperature.
The base point and slope were also explained to me by the technician, but I would have to read up on them again ... I am too much of a layperson for that. However, I hardly believe that anything (regarding noise development) can be optimized there, since these values were also set by the technician.
At the moment, I can only imagine that the plumbing company installed something not quite correctly. On the other hand, that would also be the only thing the plumbing company would have done right at first attempt (gallows humor).

To clarify once again: standing in front of the system, it is really, really loud, also at the door it is clearly audible up to loud. In the living rooms (supply air) I hear the ventilation system very clearly, not loud, but clearly. It is simply an unpleasant background noise, it sounds like heating/ventilation/basement, a deep rumbling/humming ... simply unpleasant ... and the noise is simply carried throughout the whole house by the piping, especially into the living and bedroom. The heating noise does not come (only) through the ventilation pipes. It, in my estimation, somehow transmits to the walls, water pipes, lines – I cannot say, the noise is simply "there" in every room. I probably just have to live with it.

Best regards
A. Rösner

You can't live with that )-;

We have the hot water set to 44 degrees, hysteresis 2k. Ventilation: level 1 at 110 m3 / hour Level 2 at 160 m3 / hour Supply and exhaust air equal (!) Have you measured the humidity in 2 or 3 rooms?

To make it clear again. Standing in front of the system it is really, really loud, also clearly audible to loud in front of the door. In the living areas (supply air) I hear the ventilation system very clearly, not loud, but clear. It is simply an unpleasant background noise, it sounds like heating/ventilation/basement, a deep rumble/hum ...

Does it sound like a plane flying far above the sky? Then that is the right sound. For us it is only really audible at level 3. We run the system at level 1, two times a day it goes up to 2 for 2 hours. In front of the system itself I once naively measured the volume with an iPhone app. Just ventilation was 51 for us, but you mainly hear the noise at the silencers, in heating mode almost 60, a dull hum, not unpleasant, when preparing hot water then the whole thing with more speed. 48 is already a lot. Our technician set it to 45, every week or month then the legionella program. Due to the small 230l storage I have little concerns there and switched it off. Hot water for us is 42.5 in the morning and evening, during the day 41.5, each with hysteresis 2. That is plenty enough without comfort losses for us, also for a full bath. That makes the flow temperature 45, every degree above that already gets more expensive. In general, you should still deal a bit with the "normal" settings to properly adjust the system for your house. The SE technician made a good basic setting for us, which not only made the house warm but was also already okay in terms of consumption. The fine adjustment must be done by yourself with the desired temperatures in the rooms and base point and slope, but it is well described in the manual. The SE technicians are good, but the first one also set the start speed of the fans a little too low; when the fans were completely off, they wouldn’t start again and the system threw errors, only removing a fuse helped, but that was quickly corrected. So they are not infallible either and errors also happen during setup; at temperatures below minus 10 degrees our system went into continuous defrosting, the problem was a hose that was 2 cm too long. Is the corrugated filter or the blue-white one dirty or something? Vacuuming also doesn’t always help.

Are the filters inserted correctly?
With us, they were swapped and twisted.
Still does not explain the noise level