The ProLine® XE 40-Gallon Ultra-Low NOx Power Vent Natural Gas Water Heater delivers an efficient, reliable performance and features an innovative design that protects against accidental ignition of flammable vapors.. Featuring a 40-gallon (nominal) tank and a 42,000 BTU gas burner, the GPVNT-40 Power Vent delivers a first hour rating of 91 gallons and a recovery rate of 42.6 gallons per hour. With an 0.73 Uniform Energy Factor, this water heater is energy efficient. It carries a 6-year limited warranty, and meets Ultra-Low NOx emission requirements. Environmentally-friendly insulation and factory-installed heat trap nipples reduce heat loss for maximum energy savings. This ProLine® XE water heater is designed with A. O. Smith's superior commercial-grade tank protection. Advanced tank features include stainless steel CoreGard™ anode rod, Blue Diamond® glass lining and DynaClean™ automatic sediment-cleaning system, all designed to help protect the tank from the corrosive effects of water and extend the life of the water heater. A. O. Smith’s ProLine® water heaters are residential products built to commercial-grade standards and are only available for purchase through professional wholesalers and contractors.