Propane Tankless Water Heater, 120,000 BTU, Condensing, Indoor, Ultra Low Nox, Heat Exchanger Is Constructed Of HRS35 Commercial Grade Copper, Condensing Indoor Model, Condensing Technology Provides Significant Energy Cost Savings, Built In Temperature Controller & Diagnostics, 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.