Hi! At first, I am sorry that I am writing in English. I am struggling to find any good answer to my problem and this forum is the only place I have seen that some answers are being provided. I hope it is not too much of a problem. I have a Vitovent 300-W (serial number: 7372260101628104) connected and controlled via a Vitocal 222-g (serial number: 7956893101126125). I also replaced the original heat exchanger with the enthalpy one. The setup works mostly fine, but the heater in the Vitovent seems to have a slight issue. For some reason, I am not able to read the incoming air temperature to the Vitovent, so I placed a Bluetooth thermometer inside (between the heater and the filter). I observed, that when the incoming air temperature drops to -1,5°C, the snowflake is indicated on the display. However, the heater is not turned on. The heater only turns on, when the incoming air temperature gets to -6,0°C. It then starts to work at around 47% (with an air volume of 200m3/h) and works normally (gradually decreasing the percentages to 0%) until the incoming air temperature gets back to 0,0°C. In case the morning temperatures are not as low and the incoming air temperature does drop only to for example -5,5°C, the heat exchanger freezes and the fan blowing air out of the house starts to gradually increase the RPM. If I take the heat exchanger out for a few hours, it seems to be back to normal. Additionally, if the daily temperatures are so low, that the snowflake indicator remains on (even if the heater turns off - to 0% activation), the heater will normally start to work when the air temperatures start to drop again - starting with 1% activation and gradually increasing through the night. I cannot imagine that this is a normal behaviour of the device. Or is it? If it is not, does anyone know what I can do to make it work better? Official Viessmann serviceman is saying he does not know what to do. I tried a full reset of the Vitovent, but it did nothing.
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