Introduction - Bradford White RG130T*N Series Service Manual

INTRODUCTION

®
The Bradford White DEFENDER Safety System
®
The Bradford White DEFENDER Safety System was designed to resist the ignition
of flammable vapors that can occur outside of the water heater. Use and installation
are nearly identical to previous versions of atmospherically fired and vented water
heaters. A number of exclusive design features are incorporated in the system that
will require additional knowledge on the part of the qualified service provider. The
following information will instruct service professionals on the function, proper
diagnosis and repair of water heaters employing the Bradford White DEFENDER
Safety System.
How the Safety System Works
During normal operation, air for combustion is drawn into the water heater through the
opening in the jacket. This air travels down and around the combustion chamber and
enters through holes in the very bottom of the corrosion-resistant combustion
chamber. The air then travels up through the oriented flame arrestor plate louvers,
where the velocity of the air is increased and its direction altered. The air then mixes
in a normal manner with the supplied gas and is efficiently combusted, producing very
low NOx emissions.
In the case where trace amounts of flammable vapors are present in the air flowing
into the combustion chamber, the vapors are harmlessly ignited by the burner / pilot
flame. If flammable vapors are in sufficient quantity to prevent normal combustion,
the burner/pilot flame is shut down.
Should the flammable vapors continue to the burner, the flame arrestor plate prevents
the flames from traveling backwards and igniting vapors outside of the combustion
chamber. The calibrated, multipurpose thermal switch recognizes this and shuts down
the pilot and main burner. This switch also deactivates the burner and pilot in the
unlikely event of restricted airflow caused by severe lint, dust or oil accumulation on
the arrestor plate.
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