When do you notice that the controlled residential ventilation system is working?

Basically, it is already fine if you neither hear flow noises nor feel drafts. That is the ideal case, but it does not say anything about whether the system is properly sized. Removing moisture also takes some time; it does not happen within 10 minutes. Without knowing more details about your system, it is difficult to make a remote diagnosis. In any case, as I have already said, I would get a display device for humidity to keep an eye on it. Many small weather stations (Aldi, for example) have them integrated.

So with our system we don't hear anything at all. Only at night when you are in bed and switch the system to the party modes. On the normal highest level it is not audible. In the bathroom our mirrors already fog up when showering. It just takes a while until they clear up again. But this is certainly also due to the size of the bathroom. In a huge bathroom the moisture can certainly spread more than in a small bathroom with a huge shower and large evaporation surfaces.

Hello,
depending on the level, you should feel a very slight draft before the air outlets and a slight suction at the exhaust valves.
Everyday test: with the door closed and a night in the bedroom with windows closed, you have perfect air - which is otherwise not usually the case
Also, you should buy and place a small digital humidity meter (<20,-€). With a "normal" heat exchanger, you may have too low humidity and should possibly choose a lower level and/or acquire an enthalpy heat exchanger. You can test whether the heat recovery works reasonably well with a simple digital thermometer that you place directly on an air outlet at low outdoor temperatures.
If you have, for example, only 5 degrees at the air outlet at -10 degrees outside temperature, something is wrong
Best regards

At a room temperature of 20 degrees Celsius and an outside temperature of -10 degrees, 5 degrees would be exactly what I would expect at the outlet or directly after the [WT] with a functioning heat exchanger...?!?!?

At a room temperature of 20 degrees Celsius and an outside temperature of -10 degrees, 5 degrees would be exactly what I would expect at the outlet or directly after the heat exchanger of a functioning heat exchanger...?!?!?

Even at subzero temperatures around minus 10 degrees and a low air exchange rate (to prevent freezing) with a normal heat exchanger, the supply air was always in the double-digit range. Otherwise, it would be a terribly poor efficiency.


Best regards

In an air-to-air heat exchanger, theoretical heat transfer can only occur up to the point where the supply and exhaust air have approximately the same temperature, or am I mistaken? That would be the case at 5 degrees Celsius and the parameters mentioned above.

Even at subzero temperatures around minus 10 degrees and a low air exchange rate (to avoid freezing) with a normal heat exchanger, the supply air was always in the double-digit range. Otherwise, it would be an awfully poor efficiency.
Best regards

The supply air at the outlet (which, at such low outside temperatures, is of course significantly higher due to further heat absorption within the building envelope than directly behind the HX) or directly behind the HX?