I have 2 vintage Olympians in 2 rigs, both going strong 10+ years. Everything tx2sturgis said is spot on. On both of mine I have a fresh air inlet just below the heater, as they consume oxygen + very minimal carbon Monoxide. With a good air inlet they burn extremely clean. You should have a small air outlet too but both my dogs are drafty enough that it isn't needed, the fresh air inlet just below it is tho. In very cold weather I run it on low all night. My experience low will add about 25 degrees to my rig and high about 40, if course very rig dependant but both of mine are bigger than a van. Uses very little propane too. I use 5 gallon propane bottle. I have never had a problem with both of my Olympians.