Please note this unit does not meet the air quality requirements for portions of Southern CA.Bradford White's high efficiency, energy saver, atmospheric vent residential gas water heater features the Defender Safety System and offers additional insulation and integral heat traps to reduce stand-by heat loss. Features: * Bradford White ICON System - Intelligent gas control with proven millivolt powered technology and built-in piezo igniter. A standard, off the shelf thermopile converts heat energy from the pilot flame into electrical energy to operate the gas valve and microprocessor. No need for external electricity.* Enhanced Performance - Proprietary algorithms provide enhanced First Hour Delivery ratings and tighter temperature differentials. * Advanced Temperature Control System - Microprocessor constantly monitors and controls burner operation to maintain consistent and accurate water temperature levels. * Intelligent Diagnostics - An exclusive green LED light prompts the installer during start-up and provides ten different diagnostic codes to assist in troubleshooting. * Pilot On Indication - Flashing green LED provides positive indication that pilot is on. * Separate Immersed Thermowell - High strength advanced polymer composite thermowell provides isolation between electric temperature sensor and surrounding water. No need to drain the tank when removing gas valve. * Advanced ScreenLok Technology Flame Arrestor Design - Flame arrestor is designed to prevent ignition of flammable vapor outside of the water heater. * Resettable Thermal Switch - Proven and reliable bimetallic switch prevents burner and pilot operation in case of ongoing flammable vapor burn inside of the combustion chamber or restricted air flow. * Maintenance Free - No regular cleaning of air inlet openings or flame arrestor is required under normal conditions. * Sight Window - Offers a view into the combustion chamber to observe the operation