ᐅ Height of floor construction with Vallox HRV ducting questionable

Good morning,

Yesterday, I was able to inspect the first pipes and distribution boxes of our Vallox controlled residential ventilation system.
What I definitely hadn't realized is that there is hardly any space left for the screed. Until now, I thought flat ducts would be used.
The current distribution boxes are about 17-18 cm (7-7 inches) high, and if the underfloor heating and screed are added on top, the planned total height of 20 cm (8 inches) won't be achievable.
Does anyone have benchmark values? What is the minimum thickness required for the screed layer including underfloor heating?

I attached a photo from the bathroom on the upper floor. The two distribution boxes are quite close to each other. Is there still enough space above the box and piping for underfloor heating pipes including the screed, or will there be no underfloor heating installed there?

The boxes have no place on the floor.
Insulation plus heated screed are at least 7 cm (3 inches), more likely 8–9 cm (3–4 inches).
On top of the boxes, you would also need panels for load distribution, bringing it to around 10 cm (4 inches).
Allowing for tolerances where the floor might be slightly higher in those spots, you end up with a total build-up height of 30 cm (12 inches). Then the doors probably won’t open and close anymore...
Report immediately.

I also find it very unusual that these boxes are placed on the floor. We recently got a Vallox system as well. In our case, the boxes are hidden in the knee wall space, and there is a dedicated access door in front because they apparently need maintenance/cleaning every few years. It would be impossible to do that if they were on the floor.

Subwoofer schrieb:

What is the minimum screed thickness including underfloor heating?

It depends on the type of underfloor heating system.

Subwoofer schrieb:

I attached a picture from the bathroom on the upper floor. The two manifold boxes are quite close to each other.

Why are they even located in the bathroom on the upper floor? Why not below in the utility room or hidden somewhere else in/behind the walls or ceiling?

Subwoofer schrieb:

Is there enough space above the box and piping for the underfloor heating pipes including the screed on top, or will there be no underfloor heating above this?

No one here can answer that; you need to ask your plumber or whoever is responsible for this.

We also had a mechanical ventilation system from Vallox. The ductwork was similar to yours, but the distribution box was obviously not placed on the floor. Even with just the ducts, the originally planned floor construction had to be raised by 2cm (1 inch) to ensure sufficient screed coverage.

nordanney schrieb:

We also had a controlled residential ventilation system from Vallox. The ductwork was similar to yours, but of course the distribution box was not placed on the floor. Even with just the ducts, the originally planned floor construction had to be raised by 2cm (1 inch) to ensure sufficient screed coverage.

How much did the floor build-up end up being?

Mycraft schrieb:

It depends on the type of underfloor heating system.

Why are they even located in the bathroom on the upper floor? Why not hidden downstairs in the utility room or somewhere else inside/behind the walls or ceiling?

No one here can know that, you will have to ask your plumber or whoever is in charge.

It will be a standard hydronic underfloor heating system. The utility room is in the basement, and that’s where the system will be installed. I guess the site manager hasn’t seen the problem yet; I will get in touch with him.