I got caught by surprise on the temperature drop here last night. I had stoked up the wood stove with some big log pieces and dampered it down before going to bed. I was expecting -20C last night and figured that the stove would keep things warm until morning. I woke up for some reason at about 1:30 and I could hear all the AquaHot register fans on. I got up and it was coolish in the coach and the air from the tunnel duct wasn't that warm. I just slid the ducting back into the tunnel, closed the window and went back to bed. When I got up this morning I found it had dropped to -30C last night. If I had stayed up all night and kept a strong fire burning in that wood stove it would have kept the coach warm but it couldn't keep up all dampered down. For the heat tunnel to operate properly the living room in the old mobile home has to be hot. That ducting has a blower fan inside it sucking that hot air out of that living room and into my coach. I do have that mobile home living room vented well also. In that very cold temperature last night the ducting was sucking the hot air out of that room faster than the stove could heat the frigid incoming air. The wood I am burning is mostly aspen and poplar. Soft woods with mediocre BTU output. If I had a higher BTU wood to burn like birch or larch I bet it would have kept up much easier. If I had known it was going to drop to -30C I probably would not have tried to heat the coach by wood stove last night. The only weather forecasts I get are for the city of Calgary and there is very often a big difference from there to here. Sometimes it's actually warmer out here than in the city.