AO Smith ATI-340H 8 GPM Residential/Commercial Condensing Natural Gas Indoor Tankless Water Heater with 180000 Maximum BTU Input Details: AtI-340H Never run out of hot water again with a steady 8 GPM flow rate Conveniently mounts to your wall for a low profile installation Features a built-in temperature controller and factory installed power cord Can be used with either Category III or IV power direct venting in either a 3" or 4" size Electronic ignition ensures you never have to mess with a pilot light again Complies with lead-free standards Vent Material: PVC, CPVC, PP, ABS, SS Ultra Low NOx Emissions Yes Protected by a multitude of built-in safety features such as an overheat cutoff fuse, constant temperature monitoring, and air fuel ratio rod Durable heat exchanger is constructed of commercial-grade copper resulting in greatly increased heat transfer and resistance to erosion Designed for indoor use only Height: 23-5/8" Width: 17-3/4" Depth: 11-1/4" Maximum Flow Rate: 8 GPM Fuel Type: Natural Gas Energy Factor: 0.95 Max BTU Input: 180000 Minimum Input Capacity 15000 BTU Voltage 120 Volts Phase 1 Frequency 60 Hz Primary Vent Pipe Diameter 4 Inches Gas Connection Size 3/4 Inch Cold Water Inlet 3/4 Inch Hot Water Outlet 3/4 Inch Maximum Altitude 10100 Feet Designed for indoor use only