It says you only need 6 square inches of
ventilation. We left a window and the skylight open a crack when it was
running. We don't run it when sleeping but it was great to have in the

   But what about condensation? Personally, I've found most propane heaters (including the Coleman, which says it's OK for indoor use) to be too smelly. But my bigger concern is all the condensation that forms on the windows and metal surfaces inside. I've found a 1500 watt electric heater works fine, and have camped in my Westy using one when the outside temps dipped to 18 degrees.  Jeff