Okay, we have the big one. Hooked to a 5lb propane tank (TT has another outlet, so it is easier) we heat our Coleman Utah TT popup with them no problems. With all th air gaps and drafts associated with the trailer, we still hit 70 degrees easily and no problems with ventilation. I love this heater.
I also use it for wood working in my 3-car garage when the weather is too cold to work or maybe paint... no problems bringin gth etemp up about 20 degrees if it is cold outside. Great units.
The only dilema I have is the battery fan. I wish I could somehow get it on 12V to run off my trailer battery, the D cells die too quickly.