Operation and control of controlled residential ventilation in a single-family house

Hello everyone,

we have installed a Zehnder ComfoAir Q450. When I looked into the system a bit more, I found out that the installers probably left it on the standard setting.

That means it runs on level 2 at about 230 cbm/h.
Additionally, I activated the automatic humidity/temperature control, which increases the airflow by a few cbm/h in the evening during summer (about 290 cbm/h in the evening).

I find these flow rates very high, which of course also costs electricity. It is also not quite quiet in the evening.

House data:
Supply air in living rooms and storage rooms, exhaust air in kitchen / 2 bathrooms / laundry room / technical room
210 sqm living and usable area
615 cbm air volume in the house
Upper floor: 4 supply / 2 exhaust / hallway overflow
Ground floor: 4 supply / 2 exhaust / hallway overflow
Basement: 2 supply / 2 exhaust
4 people

After some reading, I would probably set the standard to about 185 cbm/h (approx. 30% x 615 cbm air exchange rate > 4 x 30 cbm/h for 4 people).

I would like to get feedback from other owners of controlled residential ventilation systems about what flow rates they operate at.

Furthermore, there is the option of time control. Currently, I have it set (summer) to better regulate humidity and temperature. It feels helpful; considering the heat capacity of air, it shouldn’t have a big effect, though.

02:00-04:00 increased level 3 (cold outside air for cooling)
07:30-08:30 increased level 3 (ventilation after showering)
12:00-18:00 reduced level 1 (summer heat protection)

Otherwise, normal level 2.

Has anyone had good experience with time control?

Thanks, regards Andreas

Although I have a different system, our current schedule is as follows: 7:00 to 21:30 ventilation level 0 21:30 to 7:00 ventilation level 2 No heat recovery, as the cross-flow fan has been removed and a summer cassette installed. Similar [Bypass]

I find these throughput rates very high, of course it also costs electricity. It is also not quite quiet in the evening.

Hello Andreas,

who planned your controlled residential ventilation and developed the ventilation concept? In case of doubt, I would ask there.

Actually, the system should not be noticeable in normal operation with correct design. During intensive ventilation, okay, but during normal ventilation or reduced ventilation, actually not.
How much volume are you running through the individual valves? Everywhere < 25cbm? Air velocity in the ducts < 2m/s?

Regarding the power consumption, I am somewhat puzzled. How many watts does it draw that you are concerned about the electricity consumption? Don’t get me wrong, but living in a house with > 200 sqm living space and then worrying about the little electricity for controlled residential ventilation? Controlled residential ventilation systems are not the biggest power consumers and are generally comparatively economical. And especially with the plate heat exchanger of your ComfoAir, you are also at an advantage in terms of consumption compared to rotary heat exchangers. So maybe you are worrying too much?

Hello, thanks for the feedback. Planning with the heating engineer is okay so far, I also have the documents for it, he just didn’t bother to adjust the system precisely, although +/- 30 cbm/h doesn’t make a difference.

The main problem is not the electricity consumption, but especially the moisture entry during muggy weather when the system runs at full throttle at noon.

: Thanks for your settings, I have now further reduced mine during the day and the climate in the house has improved. Less moisture entry.