Bradford-White Corp U4TW50T*FRN, U4TW40T*FRN How to Use this Manual, How the Safety System Works

Page 6

How to Use this Manual

operating parameters exists, the gas control diagnostic LED will flash a code to positively identify an operational issue.

This service manual is designed to facilitate problem diagnosis and enhance service efficiency. To further promote quicker service times the new gas valve can be removed and replaced without draining the water heater. A special tool is required and will be provided with each gas valve kit shipped from our Service Parts department.

Please read the service manual completely before attempting service on this new series of power

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.

How to Use this Manual

It is intended for this manual to be used by qualified service personnel for the primary purpose of troubleshooting and repair of the Bradford White Residential Flue Damper water heaters. Understanding the sequence of operation section of this manual will contribute greatly to troubleshooting the water heater.

The Honeywell WV4460E Electronic Gas Control will display error codes in the event of abnormal operation. Error codes are listed in the troubleshooting chart beginning on page 13 of this service manual. The troubleshooting chart will also indicate the probable cause for the error code and direct the service professional to a service procedure to properly diagnose the abnormal operation.

Page 6

6

Image 6
Contents Service Manual Table of Contents Page Page Bradford White ECO-DEFENDER Safety System IntroductionHow to Use this Manual How the Safety System WorksTools Required for Service Tools RequiredSpecifications Vent Tables GallonSpecifications Wiring Diagram Control TimingsPower Up Sequence Sequence of OperationNormal Heating Sequence Normal Heating Sequence cont’d Abnormal OperationAbnormal Operation cont’d Sequence of Operation Sequence of Operation Troubleshooting LED Status Control Status Probable Cause Service ProcedureTroubleshooting Troubleshooting Burner Maintenance Burner Cleaning ProcedureBurner Inspection Burner Cleaning Procedure cont’d Pilot Maintenance Pilot Inspection, Testing and ReplacementPilot Inspection, Testing and Replacement cont’d Page Pressure Switch Testing Pressure Switch TestingPressure Switch Testing cont’d Pressure Switch Replacement Pressure Switch ReplacementBlower Testing Blower TestingPage Blower Replacement Blower InstallationBlower Removal Blower Temperature Switch Testing Blower Installation cont’dBlower Temperature Switch Testing Blower Temperature Switch Testing cont’d Switch SettingBlower Temperature Switch Replacement Blower Temperature Switch ReplacementThermal Well Testing Thermal Well TestingDetermine Tank Temperature Thermal Well Testing cont’dDetermine Water Temperature Inside Tank Component Disassembly Sensor Resistance at Various TemperaturesGas Control & Thermal Well Removal From Water Heater Gas Control Removal Gas Control Assembly Gas Control Assembly to the Thermal WellGas Control Removal From Thermal Well cont’d Gas Control Assembly to the Thermal Well cont’d Flammable Vapor Sensor Testing Flammable Vapor Sensor TestingVAC Circuit Trace Safety Circuit Voltage Trace Safety Circuit Voltage TraceRemove the Blower to Gain Access to the Flue Baffle Blower RemovalRemove the Blower to Gain Access to the Flue Baffle cont’d Dip Tube Inspection and ReplacementDip Tube Inspection Anode Inspection and Replacement Anode InspectionInner Door Removal Procedure Inner Door RemovalInner Door Gasket Replacement Inner Door Removal Procedure cont’dInner Door Gasket Replacement Procedure Inner Door Installation Inner Door Installation with GasketArrestor Cleaning ScreenLok Flame Arrestor Cleaning ProcedureCommon Terms Common TermsParts List Part Name and DescriptionParts@bradfordwhite.com Techserv@bradfordwhite.com