I am used to opening a window for condensation. I open the roof vent and I open one window corner about half way. It hasn't been too bad. Last night my wife was with me and our small dog. WOW the roof was wet and the side walls were wet. I was running a catalytic heater. This was the coldest night I have spent ion the camper since I got it in August it was 23 degrees. What is the trick to keeping the moisture down? Ron