Thanks for all the feed back. I will try to explain in more detail. When I opened the inside return vent for the heater I could see all the way through the heater to the out side cover and could feel cold air from outside the trailer moving through that area to the inside. The furnace had quit working (I later found that the propane line on one of the tanks have failed and was leaking all my propane out, which I have repaired) I pulled the outside cover off the heater to check the reset switch as listed in the manual. The out side edge was sealed. I was able to see all the way through to the inside where I had removed the air return vent cover. I saw no baffling or insulation to separate or insulate the out side from the inside air. I even vacuumed all the dead bugs, wasp nest and other debris form that area behind the metal heater cover. Yes I resealed the cover. My question Is should there be some barrier between the fire box and the inside of the trailer. As I stated I am very new to the Travel trailer ownership but am a veteran camper/hunter, and have over 35 years as a mechanic. This trailer will be our hotel when visiting our Daughter and her family instead of getting a hotel in town. We have already put in the RV power hookup and have extra propane bottles on site (I don't want a repeat of another night below freezing without heat). I replaced all the propane rubber lines because My theory is is one failed then the other will not be far behind. I know the previous owner who purchased the trailer new and have the repair history. He never replaced any of the propane lines. My problem is that the trailer is now in Montana and I am in Arizona so I make repairs when we get up there on our visits so I am doing the research now for repair later if that makes sense. It has a functioning propane, fire and CO2 sensor all with fresh batteries.
