Floor plan planning shortly before submitting the building application

Do they perhaps have a nice PDF with the specifications in the download area?

Well, when I searched spontaneously on the net, without investing much time, I found various PDFs. On the manufacturer's site there is the subdomain pro.... (that is pro.manufacturername.de) with installation instructions, FAQ, etc.

: There are so-called flow charts (water pressure, l/min. and MPa) in a document for the individual shower systems. And it says about "RainDance" in the chapter sanitary installation:
3. Supply lines
iBox universal: 2x DN20 (hot/cold)
Rainfall: 2x DN20, 1 x DN15 (mixed water)

For "RainBrain" I found a PDF "Planning and Installation", where it says under the chapter "Supply line":
Function box: 2 x DN 20 hot/cold
Rainfall: 3 x DN 15 mixed water
(if flow pressure less than 3 bar DN 20)
Hand shower: 1 x DN 15 mixed water
Side showers: 1 x DN 20 mixed water

Meaning, you might actually find a suitable manufacturer document. You would just have to search a little.

The supplier is relocating the house connection box himself. He just called and admitted that the fault lies with him. He definitely wouldn't do that if it were otherwise. Therefore, the "making a big fuss" with the GU certainly wouldn't have been appropriate either, since he is obviously in the right.

The utility company is relocating the house connection box themselves. They just called and admitted that the fault lies with them. They certainly wouldn't do that if it were otherwise.

I would rather call this a gesture of goodwill.

Great, one problem less.

Why, whether out of goodwill or admission of guilt, you will never find out and it doesn’t matter either.

Why you’ll never find out whether it’s out of goodwill or an admission of guilt, and it doesn’t matter.

I don’t care either. But it also shows me that it’s initially sensible to diplomatically seek a solution with those involved.

First of all. But eventually it’s enough and diplomacy turns into, you can deal with this one. In my opinion, your site manager is ruthlessly exploiting the incompetence of your old expert and your insecurity (which is understandable).

You still have some construction sites. Curious to hear what you report on Monday. Hope that a lot will still dissolve into nothing.