Most people know who Dr. Seuss is. They have read his stories, appreciated his humor and passed books on from generation to generation. But how much you may not know about this gifted man? Was he a legitimate doctor? Where does the name Seuss come from? What was his inspiration for his unmistakable style? Today's building codes state spaces using furnaces have to have method for getting back together combustion air since it used. Newer homes have ducting installed, during construction, that literally brings fresh air from the outside for an area close to the furnace. This ducting, usually called comprise air duct, or combustion make-up air, is sized according to the capacity from the furnace.