I have a house with forced air electric heat. Over the course of a year, a sooty residue builds up on the walls and rugs seemingly coming from the floor registers. Could the electric heating elements be burning off and causing the residue? I'm tired of washing walls and cleaning carpets. If I install a propane furnace would the same thing happen? I thought electric heat was clean.
Side note: the ducts all appear to be clean. If I take off a register and stick my hand down a duct, I do not get a sooty finger. They were professional cleaned a few years ago in an attempt to resolve the problem