Catalytics are great but they do have a couple drawbacks. They do need air, just like any other heat source other than electric. Propane can't burn without it.
Also, they put a LOT of moisture in the air. I have one in my old 20' hunting trailer and after a few days of running steadily in real cold weather, we'll have water running down the walls. It does keep the trailer nice and warm, though.
