Window rebate ventilator - Good idea for uninsulated old buildings?

Phew... so: The invoice says:
Helios ELS-VF 60/35
I don’t know how big the fans themselves are - the wall opening is 80mm anyway. They sit in housings with check valves.
They have three levels, which can either be set manually, or they regulate themselves according to the humidity.
There are also filters inside. Although I don’t really know why you should filter air that is blown outside...
There is no [WRG].

Since they are installed in both bathrooms and the utility room, the humidity control suits us. By default, they run on the lowest level.
Regarding the noise level: You can hear the devices - but it doesn’t matter in the rooms, since the shower, faucet, and washing machine are naturally much louder. In living and sleeping rooms, you hear nothing.

The supply air comes, as mentioned, through RegelAir window-frame ventilators on all windows, except the roof windows. So far, no one has noticed any draft. With these things, you can also operate the extractor hood without having to open a window immediately.

The whole package of RegelAir, fans, and installation cost just over €2000.

Just like with us. Same fan. Same slot things. Since we only have one bathroom and the utility room is forced ventilated and unheated anyway because of the gas heating, only 1 Helios.

Ok then I'll do it that way too Karsten. Do you have the feeling that these things really make a difference now?

Since it was not 100 percent clear with the fan for me yet, there is no hole in the wall to the bathroom, it probably needs a core drilling, which shouldn't be a problem in aerated concrete, right?

Does it do any good? I don't know what it would be like without them. Only the house has good air. I also don't fear mold. She still opens the windows anyway. She has always done it that way. My BU has this as standard and refuses to sell a house without this minimal solution because he doesn't want to deal with mold discussions.

Well, if good air, then good air,