I have been using S1 for a month. I immediately bought a filter machine. Everything was discharged outside and there was no smell in the house. After a few days I noticed that during operation smoke appears from the connection between the machine and the ventilation duct. There is an intense smell of burning wood in the room. The filter was replaced but the problem did not improve. During operation you can see smoke escaping and smell it. The ventilation duct is fine. Is this normal? Or does it mean that my copy has a defect?