Navien Gas Fired Water Boiler, NHB Series, 120 VAC, <10 A, 60 Hz Frequency, 95 % AFUE, 55000 Btu/hr BTU, 3.5 to 10.5 in-WC Supply, -0.03 in-WC Manifold Natural Gas, 8 to 13.5 in-WC Supply, -0.03 in-WC Manifold Propane Pressure, 1 in NPT Supply/Return, 3/4 in FNPT Gas Connection, Natural Gas, Propane Gas Fuel, Forced Draft Direct Vent, Chimney/Breeching/Vent Size: 2 to 3 in PVC, CPVC, Approved Polypropylene, Electronic Ignition, Net BTU Rating: 44000 Btu/hr, Wall Hung Mounting, Cold Rolled Carbon Steel, Dimensions: 24 in H x 17.3 in W x 13.1 in D