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Energy-Efficiency Enhancing Technologies: Flue Damper (Electromechanical)

Gas-fired storage water heaters are equipped with a draft hood connecting the flue to a vent pipe or chimney. During off-cycle, the water heater loses heat by natural convection up the flue. A damper installed either at the flue exit or in the vent pipe minimizes the off-cycle heat losses. A flue damper is installed upstream of the draft diverter; a vent damper is installed downstream of the draft diverter.

Electric flue dampers are activated by an external source of electricity. The dampers open before combustion starts and close immediately after combustion stops. The burner cannot be ignited when the damper is in the closed position. For flue dampers installed on water heaters using a standing pilot, a knockout in the flue damper is provided to vent the pilot's flue gases, resulting in some off-cycle losses that would not occur in an electronic ignition system. The electric flue damper found on commercial water heaters needs a 24-volt electric source and consumes about 5 W when the gas supply is off.