Split air conditioning and controlled ventilation with heat recovery

Controlled residential ventilation actually does not distribute air. It extracts air and blows in new air.

Usually, however, it does so across rooms, so there is indeed an exchange between rooms.
But as said, the energy content in air is rather low.

Therefore, when the cooling is running, the controlled residential ventilation should ideally be turned off or only run at a low level.

Why is that?
Do you also turn off the controlled residential ventilation when you turn on the heating?

Controlled residential ventilation has heat recovery which naturally works the same during cooling as during heating.

The controlled residential ventilation extracts air from the ceiling. It is warmest there. Thus, the controlled residential ventilation already works against cooling. In winter, during heating, the heat recovery does reduce heat loss, but if turned off, the loss would be even less. A fan would make more sense regarding distribution/mixing. My system is different and therefore I do not have these issues.

Controlled residential ventilation doesn't really distribute air. It extracts air and blows in new air. So if the cooling is running, the controlled residential ventilation should ideally be turned off or only run at a low level.

Well, it does distribute air. For example, upstairs, the outlets are in the children's rooms and the inlet is in the bathroom. The bedroom has both inlets and outlets due to its size. The situation on the ground floor is similar. And the cold air from the air conditioning is utilized in the ventilation unit through the heat exchanger. That already works now, and the outside air is cooled in the summer. I am grateful for any input and will report in the summer.

The controlled residential ventilation extracts air at the ceiling. That is where it is warmest.
Thus, the controlled residential ventilation already works against cooling. In winter, during heating, the heat recovery does reduce heat loss, but if it were turned off, the loss would be even lower.
A fan would make more sense in terms of distribution/mixing.
My system is different, so I don't have these issues.

The opposite must be the case. In summer, the warm air is then removed.
However, we do not feel different temperatures at the floor or ceiling in winter either. But that is probably due to the underfloor heating.

You always have a temperature difference, even if it is small. If you simply have low ceilings, the effect is smaller. Another question is what your control system of the controlled residential ventilation does when the outside air is warmer than the desired temperature. Presumably, it rather switches off the heat recovery. Thus, only air is exchanged and the cold is not transferred to the incoming air.

You always have a temperature difference, even if it is small. If you just have low ceilings, the effect is smaller. Another question is what your controlled residential ventilation system does when the outside air is warmer than the desired temperature. Presumably, it rather switches off the heat recovery. Thus, only air is exchanged and the cold is not transferred to the incoming air.

The ceilings are quite high. The controlled residential ventilation always behaves similarly in automatic mode. If it is supposed to cool, the bypass is open when it is cooler outside. Otherwise, the air goes through the heat exchanger and is cooled. That brings up to 8 degrees, if you trust the display. That was also the origin of the thought. If I now actively cool the air down, the supply air should also be cooled more strongly by the heat exchanger. And the question is by how much.