Weil-Mclain 118404501 EG-40 125 MBtu Input 82% AFUE Natural Gas Steam Boiler (Knockdown – Assembly Required, No Tankless Coil Opening) Knockdown Boiler Components FEATURES Comes with automatic vent damper for higher efficiencies and reduced fuel consumption Easy access to controls ...Weil-Mclain 118404501 EG-40 125 MBtu Input 82% AFUE Natural Gas Steam Boiler (Knockdown – Assembly Required, No Tankless Coil Opening) Knockdown Boiler Components FEATURES Comes with automatic vent damper for higher efficiencies and reduced fuel consumption Easy access to controls for convenient servicing Configured for Natural Gas, intermittent electronic ignition only A versatile gas cast iron boiler for water or steam applications Cast iron heat exchanger Up to 84% AFUE