Ventilation system in single-family house without effect = planning error?

although I would never place an exhaust fan directly above the stove.

Why not? As a layperson, that would seem like a good position to me to prevent odors. Or do you think that would interfere with the extractor hood?

Because you dirty the pipe. The extractor hood is intended for cooking – as a recirculation system with an activated carbon filter, by the way, also for odor reduction. What remains of the odors is sucked away by the controlled residential ventilation anyway, no matter where the valve is located. It just takes a bit longer.

Kitchen ventilation is a topic of its own. Controlled residential ventilation is not suitable for this, neither in terms of volume flows nor materials.

Much more important than the positioning of the valve in the kitchen is the use of filters in the exhaust air valves. My ventilation installer didn’t want to put anything in there, but I told him otherwise. At least partly, horror stories about moldy pipes often result from this.

€: For comparison: My extractor hood has a free-blowing fan capacity of 630 m³/h. Our controlled residential ventilation supplies/extracts about 200 m³/h. But this is distributed to all valves. We are therefore talking about a difference in volume flow of a factor of 10-15 when comparing the exhaust valve in the kitchen to the extractor hood.

Kitchen odors can never be removed by a controlled residential ventilation system; only opening the windows helps. You don’t want to sit in the kitchen steam for 5 hours either. Exhaust vents definitely need fleece filters.

How is your ceiling above the upper floor designed? Is it a wooden ceiling with drywall? Then you could simply move the outlets on the upper floor. Anything else will not achieve the desired effect.

Yes, exactly - our ceiling is built exactly like that - unfortunately, I have already worked in the attic and connected the diffusion foil, applied the rough sawn planks, and worked in the walls - they would all have to be removed again. But I would probably take on the effort. I am not a fan of spending tens of thousands of euros on something that then does not (properly) work)

It fits on the ground floor - although I would never place an exhaust directly above the stove.

Where would the exhaust be better placed? Unfortunately, there is a concrete ceiling there - we can't change anything about that. The stove has an integrated exhaust (to the outside). I have meanwhile installed exhaust filters everywhere because dust now also comes out of the inlets and settles directly next to the plate valves.

Where should the exhaust air go better? Unfortunately, there is a concrete ceiling there - we can't adjust anything anymore. The stove has an integrated exhaust air (to the outside). Exhaust air filters I have now installed everywhere because dust is now coming out of the inlets and settling right next to the plate vents.

Exhaust air to the outside and controlled residential ventilation do not necessarily exclude each other, in my opinion, but special requirements must be met (window contacts, etc.). You can hardly blow out 600m³/h through the exhaust hood and ignore the controlled residential ventilation? Exhaust air / supply air surely connected correctly? On the ground floor I consider the positioning of the valves OK. On the upper floor certainly in need of much optimization (long-throw nozzles! or significantly change valve position)

We have window contacts on all windows (so far only used for alarm and comfort functions)

You can hardly blow out 600m³/h through the exhaust hood and ignore the controlled residential ventilation, right?

Unfortunately, we have not done any design ourselves, but left everything to the sanitary person. I have little to nothing to say about that, sorry.

Exhaust / supply air surely connected correctly?

I haven’t questioned that at all so far – it would be quite easy to find out, wouldn’t it?
Turn on intensive ventilation and (if the finger meter isn’t enough) hold a sheet of paper underneath!?