Introduction; How To Use This Manual - Bradford White ECO-DEFENDER EURG2DV40S N Series Service Manual

UDV Series

Introduction

The new Bradford White UDV water heaters are designed to provide reliable performance with enhanced
standard features. Design features include reliable standing pilot ignition system, enhanced diagnostics,
simplified servicing, certified FVIR technology, and Ultra Low NO emissions.
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The UDV water heaters use a combustion system where combustion air is drawn from the outside of the
building. The gas control maintains water temperature and maintains gas flow. If a situation outside of
the normal operating parameters exists, the gas control diagnostic LED will flash a code to identify an
operational issue.
This service manual is designed to facilitate problem diagnosis and enhance service efficiency.
Please read the service manual completely before attempting service on this new series of direct vent
water heaters.
How the Safety System Works
During normal operation, most air for combustion is drawn into the water heater though the openings in
the jacket door. This air travels into the burner venturi, mixing the gas jet. This air is then mixed with gas
inside the burner and drawn into 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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