Reliance, Liquid Propane Tankless Water Heater, 1/2 Gallon Water Flow Ignites Burners, 3 Major Appliance Or Shower At A Time, No Standing Pilot, 199,000 BTU Output Delivers 7.2 Gallons Per Minute At 45 Degree Fahrenheit Rise, Vertical Or Horizontal Venting, Must Use Category III, 4" Stainless Steel Vent Pipe & Fittings, 2 Optional Vent Kits Depending On Wall Thickness At Vent Penetration, TV #148-892 5" To 10" Outside Wall Thickness, TV #148-891 12" To 18" Outside Wall Thickness, Built-In Freeze Protection, 120Vac / 60Hz Electrical, Modulating Gas Valve From 11,000 To 199,000 BTU's , 3/4" Pipe Thread Gas & Water Connections, Propane Gas Only, Minimum 5.0" Water Column To Maximum 10.5" Wc, 2.0" Wc Manifold Pressure, Water Pressure 15 Minimum PSI To 150 Maximum PSI, .82 Energy Factor, Energy Star Qualified, Warranty 12 Years On Heat Exchanger, 5 Years On Parts, CA Certified, Strongly Recommend Installation By Qualified State Licensed Technician.