Moisture in the ventilation unit with rotary heat exchanger

Hello,

I have a controlled residential ventilation system with rotary heat exchanger and moisture recovery from Systemair, VTR200B.
At cold temperatures, moisture accumulates in the device, the inner insulation of the device door is completely soaked and shows ice formation, which can maybe be seen a bit in the picture.
The moisture mainly forms in the exhaust air chamber.

I already had the customer service here last year, but they could not detect any technical defects. Condensate can hardly occur with a rotary heat exchanger was the answer.

Does anyone else know this problem?

With rotary heat exchangers, not only heat but also moisture can be transferred. The decisive factor is the material or the surface of the storage mass. Through extensive measurements at the Building Technology Test Center of the Lucerne University of Applied Sciences and Arts on rotors from various manufacturers, characteristic performance curves for the different designs can be specified. The reference value for the humidity ratio is the condensation potential; this is the moisture difference between the warm air humidity and the saturation humidity of the cold air.

[*]The greater the condensation potential, the greater the expected amount of condensate on the warm air side.
[*]If the condensation potential is zero or negative, no condensate can form.