The heat exchangers in direct-combustion furnaces, typical in many residences, are not 'coils'. They are, instead, gas-to-air heat exchangers that are typically made of stamped steel sheet metal. The combustion products pass on one side of these heat exchangers, and air to heat on the other. A cracked heat exchanger is therefore a dangerous situation that requires immediate attention because combustion products may enter living space.
The heat exchangers in direct-combustion furnaces, typical in many residences, are not 'coils'. They are, instead, gas-to-air heat exchanger.s that are typically made of stamped steel sheet metal. The combustion products pass on one side of these heat exchangers, and air to heat on the other A cracked heat exchanger is therefore a dangerous situation that requires immediate attention because combustion products may enter living space.