furnace venting

[Karl]

Places like Home Depot or Lowes have round double-walled ducts that are specifically made to handle the problem of excessive heat causing fires or other damage. I used a 4" x 5' one for my Zodi tent heater so that it wouldn't melt the tent walls where it came in from the side. Worked great.

I don't know if what you are trying to do makes sense or not since I'm not up on these things enough to really say much ... but, at least check out what I mentioned in my first paragraph. Then, make sure you have a supply of fresh air coming in from the other side of the trailer so you don't have the bad air turn right around and get sucked back in for another visit to what could become your oxygen-starved lungs.