Originally Posted by TurboS10
The furnace on your heater there has an open flame with a tiny little combustion fan. If it resides in the shop in question it is no different than my propane heater....maybe worse. It has a fixed flame with little air circulation around the flame itself making it more of a bomb situation. This is because the air in the room is not very turbulent so the fumes can creep toward the open flame and become very concentrated until the combustion fan picks them up at which point they can be very strong. It is like the whole gas leak with pilot light situation. With a forced air setup the air is circulating rigorously through the combustion chamber so fumes would be more likely to burn off slowly before they were concentrated enough to explode.
Oh, and that electric heater element will create combustion as well.
I still think if you isolate the paint booth from the heater location and keep the exhaust fan running you are perfectly safe.
That;s that I'm planning on doing. I think I'll go with 70K BTU kerosene heater