The Bradford White DEFENDER Safety System®
The Bradford White DEFENDER Saf ety System®was designed to resist
the ignition of flammable vapors that ca n occur outside of the water
heater. Use and installation are nearly id entical to previous versions of
atmospherically fired and vented water he aters. A number of exclusive
design features are incorporated in the system that will require additional
knowledge on the part of the qualified serv ice provider. The following
information will instruct service profes sionals on the function, proper
diagnosis and repair of water heaters empl oying the Bradford White
DEFENDER Safety System.
How the Safety System Works
During normal operation, air for combusti on is drawn into the water
heater through the opening in the ja cket. This air travels down and around
the combustion chamber and enters t hrough holes in the very bottom of
the corrosion-resistant combustion chamber. The air then travels up
through the oriented flame arrestor plate lo uvers, where the velocity of the
air is increased and its direction a ltered. The air then mixes in a normal
manner with the supplied gas and is efficie ntly combusted, producing very
low NOx emissions.
In the case where trace amounts of flamm able vapors are present in the air
flowing into the combustion chamber, the va pors are harmlessly ignited
by the burner / pilot flame. If flammable vapors ar e in sufficient quantity
to prevent normal combustion, the burne r/pilot flame is shut down.
Should the flammable vapors continue to the b urner, the flame arrestor
plate prevents the flames from travelin g backwards and igniting vapors
outside of the combustion chamber. The calibrat ed, multipurpose thermal
switch recognizes this and shuts down the pilot and main burner. This
switch also deactivates the burnerand pilot in the unlikely event of
restricted airflow caused by severe lint , dust or oil accumulation on the
arrestor plate.
INTRODUCTION
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