Bradford-White Corp U4TW40TFRN, U4TW50TFRN, U4TW60TFRN service manual* Sequence of Operation

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Sequence of Operation

Abnormal Operation (cont’d)

5.Flame Sensing Fault:

A)Flame Lost During Run: The gas control turns off the pilot and main valves and runs the blower for 15 seconds (inter-purge) The gas control increments the recycle count, if the recycle count has not reached its limit (4), another trial for ignition begins. If the recycle count has been reached, the gas control LED flashes 6 times then 3 times with a 3 sec- ond pause. The gas control waits 5 minutes before repeating the igni- tion sequence.

B)Flame Sensed Out of Sequence: The gas control only looks for pilot flame when the blower is running. If flame is present when the pilot valve is not open, the gas control proceeds to wait for flame loss and flashes 5 times with 3 second pause. This continues until flame is lost, once the flame signal is lost, the control flashes 6 times then 4 times with a 3 second pause. The control waits 5 minutes before repeating the ignition sequence.

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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 TimingsSequence of Operation Power Up SequenceNormal 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 Cleaning Procedure Burner MaintenanceBurner 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 Installation Blower ReplacementBlower Removal Blower Installation cont’d Blower Temperature Switch TestingBlower Temperature Switch Testing Blower Temperature Switch Testing cont’d Switch SettingBlower Temperature Switch Replacement Blower Temperature Switch ReplacementThermal Well Testing Thermal Well TestingThermal Well Testing cont’d Determine Tank TemperatureDetermine Water Temperature Inside Tank Sensor Resistance at Various Temperatures Component DisassemblyGas Control & Thermal Well Removal From Water Heater Gas Control Removal Gas Control Assembly to the Thermal Well Gas Control AssemblyGas 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 RemovalDip Tube Inspection and Replacement Remove the Blower to Gain Access to the Flue Baffle cont’dDip Tube Inspection Anode Inspection and Replacement Anode InspectionInner Door Removal Procedure Inner Door RemovalInner Door Removal Procedure cont’d Inner Door Gasket ReplacementInner 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