We use propane to heat our home and our heat is a heatpump type system. This year since turning it on because it's cold here it is giving off a heavy sweet smell. I liken it to a car exhaust type of smell. I have a carbon monoxide alarm in my home and it is not being set off. But the smell is driving me crazy because it's so heavy and powerful in here. I almost haite to turn the heat on. :eek::eek::confused:

