How to build according to the Building Energy Act or EH55 or EH40

Filter ball valve supplied or an alternative sludge separator/magnet/magnetite filter device for the secondary circuit as a requirement.

a) What does that have to do with the Building Energy Act vs EH40?
b) What does the sludge separator have to do with the heating system? It is simply installed in the water circuit to prevent deposits, for example in the sight glasses of the flow meters...

You can install the same for gas, pellet, district heating, and so on.
Selling that as maintenance for the air-water heat pump is indeed "interesting," but has nothing to do with the topic.

My nephew is building barely 100m away, and there they are interested in one thing or another.

What you write sounds less interested and more just somehow "against it."
Although your own house content-wise is not that far off?!

I was talking about my place...

Yeah, just a normal air-water heat pump.
I don’t understand what you think the difference is in relation to the Building Energy Act, EH40, etc.?!

Wrong, it is as I described.

a) What does that have to do with the Building Energy Act vs EH40? b) What does the sludge separator have to do with the heating system? It is simply installed in the water circuit to prevent deposits, for example in the sight glasses of the flow meters... You can install it just the same in gas, pellet, district heating, and so on. Selling that as maintenance for the air-water heat pump is certainly "interesting," but it has nothing to do with the topic.

I do not want to "sell" anything, I just wanted to point out that you do have filters in your system that need to be maintained (cleaned or replaced). And they are (hopefully) checked during maintenance and cleaned if necessary. You have to do this the same way for every other pump-based and water-guided heating system, and of course it also has nothing to do with the Building Energy Act versus EH40. There are no maintenance-free products in this area.