EF-100T-250E-3N Bradford White 100 Gallon 250,000 BTU/Hr. Commercial Natural Gas Water Heater The eF Series® utilizes exclusive designs and technologies for unsurpassed efficiency, installation flexibility and quiet operation. With thermal efficiencies as high as 99.1%, these units are the most efficient of their kind in the industry and now with several models qualifying for ENERGY STAR®. Last but not least, the eF Series® is extremely quiet, a feature building owners, managers and occupants will appreciate.Up to 99.1% Thermal EfficiencyENERGY STAR® Qualified on several modelsICON HD™ Commercial Control SystemOnGuard RMT™ System Compatible– Accessory Module RequiredDirect Spark IgnitionThree Pass Flue SystemPre-Mix Power BurnerSubmerged Combustion ChamberHydrojet® Sediment Reduction SystemVitraglas® LiningZero Inch Clearance to CombustiblesUnbalanced VentingOptional Concentric Vent Terminal KitHand Hole CleanoutMax Temp - 180°FNSF Construction AvailableASME Code Construction Available1-1/2" NPT Dielectric Waterway FittingsComplies with current Ultra Low NOx RequirementsAll Models Listed with California Energy CommissionLow Restriction Brass Drain ValveT&P Relief Valve InstalledFour Protective Magnesium Anode Rods, (EF-100T-399, has Two Powered Anode Rods and One Magnesium Anode Rod)Non-CFC Foam Insulation3–Year Limited Tank Warranty– can be upgraded to 5–Year at additional cost