Every year lives are saved by alert, conscientious HVAC technicians or public utility personnel who shut down unsafe furnaces. This is most often done for the safety of you and your family members. Cracked heat exchangers, lack of sufficient air for complete combustion and faulty vents may produce deadly carbon monoxide, a common cause of a  furnace failure. The traditional term for this sort of forced shutdown is a red-tagged furnace, deriving from the fact that technicians used to actually tie a red tag on a disabled furnace and leave it there till the equipment was either repaired or replaced. Read More »