Condensing Natural Gas Tankless Water Heater, 199,000 BTU, Indoor, Ultra Low Nox Emissions, Primary Heat Exchanger Is Constructed Of HRS35 Commercial Grade Copper Secondary Type 316L Stainless Steel Heat Exchanger, Built In Temp Controller & Diagnostics, Supplied With A Power Cord & Remote Control, Easy Link Up To 4 Units, Multi Link Up To 20 Units, Water Connection Location Is At The Bottom Of The Tank & Water Connection Size Is 3/4", UEF: 0.93/ EF: 0,95,Vent Type: PVC, CPVC, PP, ABS, SS Vent Size: 3" Or 4", Unit Dimensions: 25 5/8"H x 12 1/2"D, Energy Star Qualified,15 Year Warranty On Heat Exchanger, 5 Year Warranty On All Parts.