Heat pumps require a lot of energy and make noise

Does this now generally mean that I should basically turn off my controllers or manually set them to 30 in every room so that they are always on "On"? Then I should set my heating curve as low as possible, but as high as necessary? My unused rooms are basically being heated along, and in the end, I shouldn't need more electricity than if only individual rooms are brought to temperature? After all, I still have normal bricks and no additional insulation or perlite filling, "Styrofoam," etc.? Does it still make sense with this standard?

I still have normal bricks and no additional insulation or perlite filling, "Styrofoam," etc.? Does it still make sense with this standard?

It doesn't matter how it's built. All new buildings are equally good. KfW 55 is simply KfW 55.

Your heat pump doesn’t know what is set on your ERR and it wouldn’t care anyway.
These are just ON/OFF valves, they can’t do more than that.
And the 30 degrees (or any other degree indication) is nonsense anyway.

Believe me, the noises come from throttling. The wind whistles through the keyhole, not through the open door.

I would open everything fully and do a balancing myself. It’s not rocket science.

Yes, when I close the shut-off valves everything is quiet. So the noises must be coming from inside the box. But if I open everything I’ve adjusted and then do the balancing myself, nothing changes. As soon as something flows through, it makes noise. Whether fully open or not. Maybe really have a bypass valve installed?

What flow rates do the sight glasses show then? Is the system properly vented?

The first I don't know, you have to look for it. Instruction manual and menu, for example. For the second: where it says Xtratherm Edit: the other way around.

Where it says Xtratherm, those are the actuators responsible for the ERR, right? There’s supposed to be something further throttled underneath? How do I get to it?

Flow between just under 1 with very short pipes up to about 1.6 liters with long pipes. It can't go much higher, as I found out today, since the heating engineer switched something from level 3 to 1 in the heat pump (when you unscrew the front cover). According to him, it was something to do with flow or pressure, and he said that was the cause. But it wasn't. Last time, each circuit was manually flushed to vent and was vented again yesterday, but there was no air in it.