Controlled residential ventilation manufacturer selection - How to approach?

Small note on the terminology: "Abluft nach draußen" is referred to as "Fortluft" "Zuluft von draußen" is referred to as "Frischluft".

The position of the valves with you does not fit at all, I would do it like this. There are also planning tools for this from, for example, Zehnder.

One more tip: the Zehnder q350 is a very good model. Take a look at it. I actually only know satisfied customers, I installed it myself.

Totally agree!!

Talk to a planner who is familiar with this, make sure that the pipe lengths are correct. Be careful that not too much air flows through a valve or a pipe. Slower airflow is usually also quieter airflow.

Zehnder also plans the system for you. I even think for free.

I am not convinced by Viessmann.

Unjustly. Viessmann sources its ventilation systems from Renovent/Brink and usually something reliable comes from this company when it comes to ventilation. The other manufacturers just stick their label on it (simply put) and then sell it as their own, e.g. Wolf. Both proposals for the valves are still suboptimal. It's best to let a professional handle it; they do this daily and usually the planning is free of charge as already mentioned. Not only at Zehnder.