exhaust smell from waste heat exhaust port

Thanks for your replies. It does not smell like a dead animal. Definitely a chemical/exhaust kind of smell.

Heater has been used frequently lately. Smell continues with more than one propane tank. Not the first time since refilling. Multiple tanks. Stove and/or water heater does not stink. Smell is only blowing from the exterior waste heat exhaust port. But blowing strong and with a strong odor. Thanks again.