The air inlet for my electric forced air heating is a small vent on the duct in the crawl space.
Although the crawl space is sealed with a concrete floor and heated (ie insulation is around the outside) it seems wrong to be taking the 'fresh' air from a dusty unused crawl space and blowing that around the house.
Does this make any sense? Should I block this vent, if so do I need to fit another and where?