Natural Gas Tankless Water Heater, 120,000 BTU Condensing, Indoor, Ultra Low Nox, Heat Exchanger Is Constructed Of HRS35 Commercial Grade Copper, Condensing Technology Provides Significant Energy Cost Savings, Includes A Built In Temperature Controller, Advanced Diagnostics & Factory Installed Power Cord, Water Connection Is Located At The Bottom Of The Tank, Water Connection Size: 3/4", Vent Type: PVC, CPVC, PP, ABS, Stainless Steel, Vent Size: 4", UEF: 0.90, EF: 0.93, Energy Star Qualified, 15 Year Warranty On Heat Exchanger, 5 Year Warranty On All Parts.