Design of underfloor heating for KFW 55 house with ventilation system

Basically, I would have tended more towards a 15 cm installation distance in the living and sleeping rooms. That’s not possible with the planned system. Everything down to 12 cm might be a bit too much of a good thing...

Just a dumb question. How do you come up with 6/12/18 cm installation spacing? No tack board or studded board is designed for such distances. People always talk about 5, (7.5), 10, 15 cm. When I read such distances and then see that a large part is supposed to be installed with 18 cm, it makes me sick. Almost 20 cm was state of the art 30 years ago, but not anymore today. Nowadays, you should basically plan with 10 cm or, where necessary, 5 cm (bathrooms). That costs a minimal effort (+ material) more, but leads a) to significantly lower supply temperatures, which feels better and is more economical and b) thus reasonably planned 22 degrees in living rooms are comfortably achievable. You discuss these topics with a qualified planner. Wrong: A qualified planner asks about your wishes. In your case, the cheapest solution for the construction contractor is installed – it will get warm, but it’s like Dacia to Mercedes. Both get you from a to b but with different comfort levels (only the price difference in cars is significantly higher).

Just a dumb question. How do you come up with 6/12/18cm laying distances? No staple plate or stud plate is designed for such distances. People always talk about 5, (7.5), 10, 15cm. When I read such distances and then even a large part is supposed to be laid with 18cm, it makes me sick. Nearly 20cm was state of the art 30 years ago, but not anymore today. Today, you should basically plan with 10cm or, where necessary, 5cm (bathrooms). That costs a minimal extra effort (+ material), but leads a) to significantly lower supply temperatures, which feel better and are more economical, and b) thus properly planned 22 degrees in living spaces are easily achievable.

With a qualified planner, you discuss the topics. Wrong: A qualified planner asks about your wishes. In your case, the cheapest solution for the contractor is installed – it will get warm anyway, but that is like Dacia compared to Mercedes. Both get you from a to b, but with different comfort levels (only the price difference for the car is significantly higher).

I don’t know. Apparently, this stud plate is exactly dimensioned like that. The site manager said at least I can’t just install a different system than the one intended for the heating. That the laying distances are indeed unusual, I’ve heard several times now.

Hi,
a temperature difference of 24°C to 15°C cannot be achieved with KfW 55. If it is implemented as planned, you will be heating the adjacent rooms with the bathroom, which is already underheated.
Better plan with 24°C for the bathrooms and 22°C for the rest.
Is a controlled residential ventilation system also being installed?

A controlled residential ventilation system is being installed.
The site management was really unhappy about my skepticism. I don’t think they are open to major changes.

The site management was really unhappy about my skepticism just now.

They are used to that and you just have to make yourself a bit unpopular. They know their characters and know who does somewhat better work and who doesn't. Therefore, he also knows that rework is necessary when the buyer/client thinks things through themselves.

If I see it correctly, a flow temperature of 35 degrees is being calculated. That would be too high for me. I would have it calculated with a flow temperature of 30 degrees.

It would be too high for me. I would calculate with 30 degrees flow temperature.

That's all well and good, but what is supposed to come out of it? According to calculations, he already has an undercoverage at 35 degrees in the bathroom. If you now calculate with 30 degrees, the undercoverage will only increase and then the OP either has to accept that it will only be 21 degrees warm in the bathroom or the plumber won't install it for him.