The Rheem XG40T06EC36U1 is a 40-gallon tall natural gas water heater from Rheem’s Performance series, designed for residential use with a 36,000 BTU input and a first-hour delivery of approximately 68 gallons. It features a low-NOx burner, push-button ignition, and a maintenance-free design with a premium anode rod for corrosion protection. With a Uniform Energy Factor (UEF) of around 0.58, it balances solid efficiency with reliable performance. This model supports atmospheric venting, is certified for high-altitude use up to 8,400 feet, and includes a 6-year limited warranty on tank and parts, plus 1 year of labor coverage.