ᐅ Distribution system (supply and exhaust air) integrated into the upper floor slab

Hello everyone,

We have been offered the Reco Vair from Vaillant (general contractor: Town & Country).

The plan is to install all supply air ducts in the upper floor (UF) floor construction. However, all exhaust air ducts are also to be installed in the UF floor. This means that in the ground floor (GF), all supply and exhaust air ducts are located in the ceiling, and in the UF, all supply and exhaust air ducts are in the floor.

I have the following questions:

1. Let’s first consider only the supply air ducts in the UF. If all of these are located in the floor and the air transfer occurs via the gap beneath the room doors, will, for example, the bedroom receive enough air exchange? Or does the floor-level supply air flow directly through the door gap at floor level into the next room without adequately ventilating the entire bedroom? Especially in the bedroom, air exchange in the upper room levels is important. What do you think, will this still work?

2. Now regarding the exhaust opening in the UF: It is located in the bathroom. I consider it insufficient if this opening is only near floor level. After all, moisture from water vapor needs to be extracted, and that typically accumulates near the ceiling. From my perspective, this opening should therefore be placed near the ceiling. What are your thoughts?

I also have two more questions that arose from other discussions—perhaps you can help? I would really appreciate it:

3. What should be installed—disc valves or covers?

4. What nominal diameter should a supply or exhaust air duct have to avoid ventilation noise? (Our house has a living area of 180 m² (1937 ft²) distributed over GF and UF, with ceiling heights of 260 cm (102 inches) on the GF and 280 cm (110 inches) on the UF. It will be occupied by 4 people.)

5. What else should we consider to avoid noise disturbances? A quiet system with minimal operating noise is very important to us. Does anyone know how loud the Vaillant Reco Vair is? Would you hear it in the hallway if it is installed in the utility room, which is only separated by a standard door?

Christian NW schrieb:
Or does the fresh air supplied at floor level flow directly to the door gap at the bottom and enter the next room, without adequately ventilating the entire bedroom?

At a constant flight level, the air would only flow if it were not heated.

Christian NW schrieb:
Especially in the bedroom, the air should be exchanged in the upper room areas as well!

The exhaled air from breathing is heavier and sinks within the surrounding air. Since its concentration would otherwise increase, supplying fresh air during the night makes sense. Some technicians even know what they’re doing ;-)

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We have the fresh air supply on the floor of the upper floor and the exhaust air in the upper part of the walls with diffuser vents. We were told that the fresh air supply can be installed in the ceiling or the floor, but the exhaust air should not be located near the floor.

Best regards
Sabine

1. It doesn’t matter at all where the valves are located—whether at the bottom, top, left, or right—as long as the valve farthest from the door is positioned there, mixing will occur. Additionally, the direction of airflow can be guided by adjusting the settings on the outlet valves.

2. Just place them somewhere at about half the height near the pre-wall elements or casing shells; that is completely sufficient.

3. This is a matter of belief and aesthetics... Both options function properly.

4. The size should match the rest of the system, the room size, the desired outcome, and the acceptable noise level. This needs to be calculated; there is no general rule.

5. Here too, the system must fit the house—that means not too small and not too large.

A larger system requires more space, higher investment, and so on, but operates at lower speeds, which naturally results in quieter operation.

A smaller system usually means lower operating and purchase costs but higher noise levels due to the higher fan speeds.

The diameter of the pipes and whether or not air distributors are used also play a role.

The type and design of silencers, and so on...

Thank you for your responses,

I will ask which exact components are installed and then bring them up here again for discussion.

Overall, the topic of controlled residential ventilation is really a bit of a mystery for us.

The comfort benefits are appealing, but a system that we might be able to hear in an adjacent room would be an absolute no-go!

How is it with your systems, can you hear them through the closed door of the utility or service room?

Perhaps one of you has the Vaillant Reco Vair as well?

I guess it also depends on the door. Use a solid core door with a drop seal. The interior wall should be made of calcium silicate blocks. That way, the chances of not hearing anything increase.