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 and factory installed power cord. Water pressure 15 to 150 psi, 40 psi or above recommended for maximum flow. Water connection is located at the bottom of the tank. 3/4 In. connection size. 3 or 4 In. vent size. PVC (polyvinyl chloride), CPVC (chlorinated polyvinyl chloride), PP (polypropylene), ABS (acrylonitrile butadiene styrene) or stainless steel vent type. Energy Star qualified, 15 year warranty on heat exchanger, 5 year warranty on parts.