Noritz EZTR40-NG Indoor Tankless Water Heater 6.6 GPM Natural Gas; Designed for Easy Replacement of 30/40-Gallon Tank Type Heaters Endless hot water Direct replacement for 30/40 gallon natural gas tank type water heater High efficiency condensing technology.Capacity Range:0.5 - 6.6 GPM Flexible Vent Kit Included Isolation Valve Kit Included