This is getting to be a nightmare. I have a doublewide home on a concrete slab foundation. My heat ducts are under the floor. Every time the heat kicks on I smell death. I checked the ducts with a mirror and light as far as I could see. I can't find the carcass. I'm not going under the house in somethingteen temps to tear up under the house. Is there a chemical I can use or a way to snake out the vents? It happened last winter but I was able to find it. This crap doesn't happen when we run the pellet stove. Too bad I'm out of wood pellets.