Bradford White U-65T-55FR-3N - Manual (Page 3)

The Bradford White ECO-DEFENDER Safety System
The Bradford White ECO-DEFENDER Safety System was designed to
resist the ignition of flammable vapors that can occur outside of the water
heater. In addition, the ECO-DEFENDER Safety System is designed to
meet the stringent NOx emissions standards required in the South Coast
Air Quality Management District (SCAQMD) Rule 1121. 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 ECO-DEFENDER Safety
System.
How the Safety System Works
During normal operation, most air for combustion is drawn into the water
heater through the openings in the jacket door. This air travels into the
burner venturi, mixing with the gas jet. This air is then mixed with gas
inside the burner and drawn to the burner screen and is efficiently
combusted producing Ultra Low NOx emissions. Additional air is drawn
through the openings in the jacket. This air travels down and around the
combustion chamber and enters through holes in the 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 combustion products from the burner.
In the case where trace amounts of flammable vapors are present in the air
flowing into the combustion chamber and burner venturi, the vapors are
harmlessly ignited by the burner / pilot flame. If flammable vapors are in
sufficient quantity to prevent normal combustion, the burner and pilot
flames are designed to shut down.
Should the flammable vapors continue to the burner, the flame arrestor
plate and burner screen prevent the flames from traveling backwards and
igniting vapors outside of the combustion chamber. This causes the
thermopile to overheat and shuts down the main pilot and burner. The
thermopile powers the intelligent diagnostic control which is capable of
recognizing restricted airflow conditions caused by severe lint, dust and
oil accumulation on the burner screen and arrestor plate. The intelligent
diagnostic control will deactivate the burner and pilot in the unlikely event
of restricted airflow.
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INTRODUCTION
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