Bradford-White Corp U4TW40T*FRN, U4TW50T*FRN, U4TW60T*FRN Flammable Vapor Sensor Testing

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Step 2. With the water heater plugged in and the gas control power switch in the “ON” position verify LED status.
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Verify 115VAC and proper polarity are at the wall outlet.
Step 1.
Gas control power
switch
Step 2. Disconnect the flammable vapor sensor harness
from the gas control.Flammable vapor
sensor harness
Step 3. Using a multi-meter set to the ohms setting, measure the resistance of the flammable vapor sensor and resettable ther- mal switch. The resistance must be between 3,000 and 48,000 ohms. If the resistance is out of this range, verify that the re- settable thermal switch has not been tripped. If it hasn’t,
the thermal switch.
Flammable vapor
sensor harness
115 VAC Circuit Trace
Move the gas control power switch to the “OFF”
Step 1. position.
electronic probes or small diameter wire pins inserted into connector.
Do not use standard multi-meter probes for this testing.

Flammable Vapor Sensor Testing

Gas Control Assembly to the Thermal Well (cont’d)

Step 8. To resume operation, follow the instructions located on the water heater lighting instruction label. Or, use the lighting instructions located in the water heater installation and operating manual.

Flammable Vapor Sensor Testing

CAUTION

Doing so will damage the connector. Use special pin type

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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