Sudden increase in ventilation system performance - all filters are clear

We had the same recently, but with this

Seit zwei Tagen ist die Leistung / Luftvolumenstrom der Luftüngsanlage deutlich erhöht

I couldn't do anything. When the fly screen at the intake for the outside air (supply air) gets dirty over time, the fan power increases accordingly. The volume flow remains constant (otherwise the power/speed would not have to increase). When it gets too loud for us, we clean this filter.

Recently, the noise of the controlled residential ventilation system changed suddenly (in a moment) from normal (quiet) to jet airplane. We turned it off and continued sleeping, but the cause was indeed a supply air grille (fly screen) frozen by sudden fog. Cleaning it the next day fixed the problem.

So I am somewhat relieved that others also have such experiences.

Me too, I was already wondering if I am too stupid to operate the system

Presumably, as a layperson, I only misinterpreted this and therefore described it incorrectly: I attributed the louder noise of the ventilation to an increase in the volume flow, whereas the volume flow probably remained the same and only the fan speed increased – just as you described.

It's unbelievable what a little fog in cold temperatures can do.
In any case, I'm glad that it's all rather harmless and that it happens to others as well.
You have to come up with something like that first. Such a thing is not mentioned in any manual, and no heating installer prepares you for something like this.

All the better that at least here you get competent and quick help.

I also initially thought that my stopped supply air fan would break down after just 6 months, until I found this information in one of the countless Helios manuals .

The type of fresh air opening we should still discuss ... (Gedankennotiz ... ich komme darauf zurück).

In the meantime, I believe I have understood the problem. During the intake through the intake grille, the air and the grille cool down (wind chill effect) and thus possibly fall below the dew point. Under suitable weather conditions, the grille then freezes. Even without frost, the condensate creates an unsightly streak on the facade. We actually have only a flush-mounted plastic grille installed in front of the intake opening, sealed all around with silicone(?) against the plaster. Six months after use, you can already see a subtle streak in the middle underneath the grille, caused by running condensate. I think we will install a weather protection hood or something similar in the medium term. So, a metal hood that covers the opening somewhat from above and preferably has a drip edge for condensate. How does it look on your side?