Relocating a furnace inside the home will cost you between $1000 and $20,000, roughly. If the relocation distance is not much, the cost will be on the lower side. It may involve a few feet of additional ductwork. However, if it is a large house and you want the furnace to be shifted from the basement to the attic. That is likely to be a costly affair. It will involve ductwork setup, electrical circuit setup, drywall etc.