Interpretation of a central ventilation system

Just spoke with Zehnder again. The summary; maybe it's also interesting for others:

[*
Pre-heating coil - "definitely" (quote). "You don't want the system or the heat exchanger to freeze when it gets very cold in winter..." We live in the Rhine-Main area
[*]at max. 40m³/h per valve and used silencer (1, otherwise there is a risk of pressure loss) you should only notice it if you put your ear directly on the valve. Alternatively: in the bedroom 2 supply air valves and volume reduction (still 1 connection free on the device)
[*]larger device approx. €1,000 expensive, would then run with less load and have more reserves. However, this is not necessary
[*]calculations are based on an air exchange rate of 0.35 --> this is sufficient for 4 people
[*]moving outlets by about 1.5-2 meters is no problem. The min. and max. pipeline length should however be taken into account
[*]couch over a supply air valve: if there is 15-20 cm space or distance, it does no harm to the airflow
[*]external outlets for supply and exhaust air are in the south: not optimal in summer, but unproblematic. Distance between them should be at least 2m
[*]supply air at floor level, exhaust air at ceiling is the preferred variant. Reason: the supply air can be preheated by the underfloor heating as it rises. Exhaust air is usually extracted from above, e.g. kitchen hood. However, there is no "right or wrong" here either. Both variants are possible
[LIST]
[*]speaking of kitchen hood: better recirculation hood than exhaust hood. But both are possible here (including special wall duct necessary)


[*]heating/ventilation/plumbing work best from a single source

The task now is to speak again with the structural engineer to get the green light for the ceiling breakthrough (in the cloakroom). Possibly there will be 2 breakthroughs if the "hole" is too big.

Hello Jentopa,
like you, I have given it a lot of thought, my conclusion:

- Try to route round pipes (75mm) in the concrete ceiling (check with a structural engineer, pay attention to the build-up height and of course the height of the lattice girders in the case of a filigree ceiling), round pipes cost 1/3 of flat ducts and you can have a cleaning ball sucked through (not possible with flat ducts).

Better to have one more pipe to the outlet and thus reduce flow velocity (noise).

Note: I have revised my design based on the nominal ventilation (as every manufacturer specifies) and deliberately oversized the piping. (Excel sheet with some formulas) and want to implement my system in EL (so far only pipes laid in the suspended ceiling), so I cannot yet give you a final conclusion; only that you might want to read the following thread.

We planned an exhaust hood for the kitchen (provide pipe in the floor slab instead of making a wall breakthrough later).

For us,
Supply air ground floor from above
Exhaust air ground floor from above
Supply air upper floor from below
Exhaust air upper floor from the wall

justified by the piping in the suspended ceiling.

As you can see in the following image, we have planned significantly more pipes for a 170 sqm house. Green - supply air Blue - exhaust air (except one green, because the pipe is too small) :)

Thank you

Unfortunately, the structural engineer immediately dismissed it during the installation in the floor slab or "threatened" with significant additional costs due to recalculation and materials; among other things, the concrete slab would have to be increased by at least 2 cm (total 22 cm). I think he simply has no desire...

In my planning, I will still provide an additional valve (and pipe) for the bedroom to make it quieter exactly there. Noise and drafts are my biggest concern.
What still doesn't make sense to me: why does the (room) volume play no role in the design of the system? At least an air exchange rate of min. 0.3 should be achieved, and for calculating that, I do need the volume, right? However, the volume was not taken according to the floor plans or the section but was set to 250 cm room height on the upper floor. When asked, I got the statement "that’s irrelevant" (?)

Which system have you actually decided on?

Intermediate ceiling - Think searching for laziness but you are the customer, he should provide hard facts. 2cm on 100sqm is 2cbm of concrete, possibly 300€, maybe more steel (he must be able to estimate this). Come to him with "Nullzone", the area in the middle of the slab. I would also assume that the height must be included. Take a look at other manufacturers' websites, there you can also create a calculation yourself by specifying the room dimensions (they should all somehow be similar in the result). We are just starting with the interior construction and have not installed any system yet, but will probably also use Zehnder. (When planning, remember to provide a pipe for the siphon in the floor slab)

My GÜ initially also wanted to make the ZwiDe thicker. It would have cost 3k more, back then it seemed cheaper to solve it with more insulation on the ZwiDe. The floor increase only cost 1900. Couldn't have known that insulation prices would explode like that 9 months later... In the end, it wasn't worth it with the own work during installation...