Bradford-White Corp U4TW60T*FRN, U4TW50T*FRN, U4TW40T*FRN service manual Abnormal Operation cont’d

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Sequence of Operation

Abnormal Operation (cont’d)

B)If the resistance is below 3000 ohms: The gas control immediately turns off all outputs and proceeds to flash 8 times then 1 time with a three second pause. The error self clears if the resistance returns to nor- mal range for at least 15 seconds.

2.Temperature Sensor Fault:

A)Temperature Sensor Open Circuit: The gas control immediately turns off all outputs and proceeds to flash 8 times then 3 times with a three second pause. The error self clears if the fault clears for at least 15 sec- onds.

B)Thermal well sensors not reading the same temperature within ±5.5°F: The gas control immediately turns off all outputs and proceeds to flash 8 times then 3 times with three second pause. The error self clears if the fault clears for at least 15 seconds.

C)Water Temperature in excess of ECO (Energy Cut Off) Limit: The gas control immediately turns off the pilot and main valves. The gas control LED proceeds to flash 4 times with a 3 second pause.

To reset the gas control, rotate the setpoint knob to the minimum set- ting for at least 6 seconds before returning to desired temperature set- ting.

3.Pressure Switch/Blower Temperature Fault:

A)Pressure switch closed at start of call for heat: The gas control waits 4 seconds then, proceeds to flash 2 times with a 3 second pause. The gas control waits 2 minutes and then turns on the blower for 30 sec- onds. The blower turns off after 30 seconds and the control waits for the pressure switch to open. Any time the pressure switch opens, the blower turns on (or stays on) and the control proceeds to wait for the pressure switch to close.

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