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Related Manuals for Bradford White U2TW75T*RN
Summary of Contents for Bradford White U2TW75T*RN
- Page 1 U TTW 75 Series Gas Water Heaters SERVICE MANUAL Troubleshooting Guide and Instructions for Service (To be performed ONLY by qualified service providers) Models Covered by This Manual: U2TW75T*RN UTW475S76R*N (*) Denotes Warranty Years Manual 238-50629-00A Save this manual for future reference...
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Page 2: Table Of Contents
Bradford White U2TW Series Gas Water Heaters Table of Contents Page U2TW Service Procedure Introduction - - - How to Use This Manual - - - Tool Required for Service - - - Specifications - - - Control Timings - - -... - Page 3 CAUTION WARNING: If the information in these instructions is Incorrect operation of this appliance may not followed exactly, a fire or explosion may result create a hazard to life and property and causing property damage, personal injury, or death. will nullify the warranty. FOR YOUR SAFETY DANGER Do not store or use gasoline or other...
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Page 4: Introduction
Introduction The new Bradford White U2TW & UTW4 water heaters are designed to provide reliable performance with enhanced standard features. New design features include reliable spark to pilot ignition system, enhanced diagnostics, simplified servicing, significantly quiet operation and additional vent lengths. In addition, the U2TW & UTW4 water heaters provide Ultra Low NOx emissions. -
Page 5: 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 U2TW Series water heaters. Understanding the sequence of operation section of this manual will contribute greatly to troubleshooting the water heater. -
Page 6: Specifications
Specifications Power supply Dedicated 115VAC, 60 Hz, 15A Gas Supply Pipe Minimum 1/2" NPT (schedule 40 black iron pipe recommended) Approved Gas Type Natural. Gas Pressure 6.0" W.C. min. and 14.0" W.C. max. Venting System Power vent through the wall or vertical through the roof Approved Vent Materials PVC, CPVC or ABS Minimum Clearance... - Page 7 Specifications Vent Tables Venting Specifications: 3" Diameter (7.6 cm) PVC Vent Connector Lengths # of Maximum Minimum Terminating Elbows Length ft (m) Length ft (m) 45 (13.7) Through the Wall 2 (.6) Through the Wall 40 (12.2) 2 (.6) 2 (.6) Through the Wall 35 (10.7) 2 (.6)
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Page 8: Control Timings
Specifications Control Timings Ignition State Timing Pre-purge 2 Seconds Trial for Ignition 90 Seconds Flame Stabilization Period 3 Seconds Inter-purge 15 Seconds Flame Failure Response Time 1.5 Seconds (2 second. Maximum; 1 second minimum.) Post-purge 15 Seconds PS Fault Delay (failed open/close) Retry after 2 Minutes Soft Lockout Retry after 5 Minutes... -
Page 9: Sequence Of Operation
Sequence of Operation Power up Sequence Start Up. Upon power up, the control runs a safe-start check with a typical start-up delay of 1-5 seconds. Simulated Resistive Load Device Check. To assure no outputs are energized if the “Simulated Resistive device” is out of range, the control will test the the device for proper operating range. - Page 10 Sequence of Operation Normal Heating Sequence (cont.) Steady State Operation. During Steady State Operation the Control Monitors: Thermostat temperature sensor- When set point temperature is satisfied, gas valve is shut down and blower will post purge for 15 seconds. Control LED flashes a short flash once every 4 seconds (idle) status code.
- Page 11 Sequence of Operation Abnormal Operation (cont.) 3. Pressure Switch/Blower Temperature Fault: a) Pressure switch closed at start of call for heat - The gas control waits four seconds then, proceeds to flash 2 times with 3 second pause. The control waits 2 minutes and then turns on blower for 30 seconds. The blower turns off after 30 seconds and the control waits for pressure switch to open.
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Page 12: Troubleshooting
Troubleshooting Green LED Indicator Observe green LED indicator on Electronic gas control. Error flash codes are displayed with a three second pause before repeating. Check and repair the system as noted in the troubleshooting table below. Service LED Status Control Status Probable Cause Procedure None, control LED not on... - Page 13 Troubleshooting Service LED Status Control Status Probable Cause Procedure 1. Unstable pilot. 2. Pilot tube blocked or restricted. Six-one flash, three Failed to light pilot. 1-4. Page 16 3. Oxidation build up on pilot electrode. second pause System auto resets. 4.
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Page 14: Burner And Inner Door/Gasket Removal, Inspection Replacement And Reinstallation
U TTW SERVICE PROCEDURE I Burner and Inner Door/Gasket Removal, Inspection, Replacement and Reinstallation Gas Control shown in the “OFF” position Inner Door Removal Procedure Step 1. Position gas control power switch to the “OFF” position and unplug heater from wall outlet. Step 2. -
Page 15: Burner And Inner Door/Gasket Removal, Inspection
U TTW SERVICE PROCEDURE I Burner and Inner Door/Gasket Removal, Inspection, Replacement and Reinstallation Inner Door Gasket Replacement Procedure WARNING If the information in these instructions is not followed exactly, a fire or explosion may result causing property damage, personal injury or death. Step 6. - Page 16 U TTW SERVICE PROCEDURE I Burner and Inner Door/Gasket Removal, Inspection, Replacement and Reinstallation Position Thermopile Wire, Pilot Tube and Igniter Wire Step 10. Position thermopile wires, pilot tube and igniter wire against burner door flange gasket (see photo 6). Step 11.
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Page 17: Burner Operation Inspection, Cleaning And Replacement
U TTW SERVICE PROCEDURE II Burner Operation Inspection, Cleaning and Replacement Main Burner Inspection, Cleaning and Replacement At periodic intervals (not more than 6 months) a visual inspection should be made of the main burner for proper operation and to insure no debris is accumulating. Main burner should light smoothly from pilot and burn with a blue flame with a minimum of yellow tips. - Page 18 U TTW SERVICE PROCEDURE II Burner Operation Inspection, Cleaning and Replacement Burner Cleaning (Continued) Step 4. Thoroughly inspect burner screen and burner venturis and remove any loose debris accumulation. Inspect burner screen for any openings larger than the normal screen openings. Step 5.
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Page 19: Pilot Testing, Cleaning And Replacement
U TTW SERVICE PROCEDURE III Pilot testing, Cleaning and Replacement Gas Control shown in the “OFF” position Pilot Assembly Inspection, Testing and Replacement Step 1. Position gas control power switch to the “OFF” position and unplug water heater from wall outlet. Step 2. - Page 20 U TTW SERVICE PROCEDURE IV Pressure Switch Testing and Replacement Pressure Switch Testing WARNING 115 volt potential exposure. Use caution Step 1. Position gas control power switch to making voltage checks to avoid personal injury. the “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and remove cover (see photos 1 and 2).
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Page 21: Pressure Switch Testing And Replacement
U TTW SERVICE PROCEDURE IV Pressure Switch Testing and Replacement Pressure Switch Replacement WARNING 115 volt potential exposure. Use caution to avoid personal injury. Step 1. Position gas control power switch to the “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and remove cover (see photos 4 and 5). -
Page 22: Blower Testing And Replacement
U TTW SERVICE PROCEDURE V Blower Testing and Replacement WARNING Blower Testing 115 volt potential exposure. Use caution when making voltage checks to avoid personal injury. Step 1. Position gas control power switch to “ON” position and adjust control to call for heat. Step 2. -
Page 23: Blower Removal
U TTW SERVICE PROCEDURE V Blower Testing and Replacement Gas Control shown in the “OFF” position Blower Removal Step 1. Position gas control power switch to the “OFF” position and unplug heater from wall outlet. Step 2. Disconnect vent system from exhaust adapter on top of blower. -
Page 24: Blower Temperature Switch Testing And Replacement
U TTW SERVICE PROCEDURE VI Blower Temperature Switch Testing and Replacement WARNING Blower Temperature Switch 115 volt potential exposure. Use caution Testing. to avoid personal injury. Gas Control shown in the “OFF” position Step 1. Position gas control power switch to the “OFF”... - Page 25 U TTW SERVICE PROCEDURE VI Blower Temperature Switch Testing and Replacement Blower Temperature Switch WARNING 115 volt potential exposure. Use caution Replacement. to avoid personal injury. Step 1. Position gas control power switch to the “OFF” position Gas Control shown in the “OFF” position and unplug water heater from wall outlet.
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Page 26: Gas Control Testing And Replacement
U TTW SERVICE PROCEDURE VII Gas Control Testing and Replacement Gas Control Replacement Step 1. Rotate knob of the gas control to the “OFF” position. Step 2. Turn off gas supply to water heater. Step 3. Disconnect gas supply line from gas control. Step 4. - Page 27 U TTW SERVICE PROCEDURE VII Gas Control Testing and Replacement Manifold Pressure Testing (this procedure presumes a maximum line pressure of 14.0" w.c.) Gas Control shown in the “OFF” position Step 1. Position gas control power switch to the “OFF” position. Step 2.
- Page 28 U TTW SERVICE PROCEDURE VIII Simulated Resistive Device Testing Simulated Resistive Device Testing Step 1. Position power switch on gas control to the “OFF” position. Step 2. Disconnect simulated resistive device from gas control. Step 3. Using a multi-meter set to the ohms setting check resistance of simulated resistive device.
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Page 29: Resettable Thermal Switch Testing And Replacement
U TTW SERVICE PROCEDURE IX Resettable Thermal Switch Testing and Replacement Resettable Thermal Switch Continuity Testing Step 1. Remove outer jacket door. Step 2. Disconnect red wire leads from resettable thermal switch. Red Wire Leads Step 3. Using a multimeter capable of measuring continuity (Ohms), place one probe of meter on one of the brass connection tabs of the resettable thermal switch, and the remaining probe on the other connection tab. - Page 30 U TTW SERVICE PROCEDURE IX Resettable Thermal Switch Testing and Replacement Resettable Thermal Switch Replacement Gas Control shown in the “OFF” Position Step 1. Position gas control power switch to the “OFF” position. Step 2. Remove outer jacket door. Step 3. Disconnect red wire leads from resettable thermal switch.
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Page 31: Safety Circuit Voltage Trace
U TTW SERVICE PROCEDURE X Safety Circuit Voltage Trace WARNING Safety Circuit Voltage Trace 115 volt potential exposure. Use caution making voltage checks to avoid personal injury. NOTE: This procedure assumes a cool tank. Step 1. Remove three screws (Phillips Screw driver) from control access cover on blower and remove cover (see photo 24... -
Page 32: 115Vac Circuit Trace
U TTW SERVICE PROCEDURE XI 115 VAC Trace WARNING 115 VAC Circuit Trace 115 volt potential exposure. Use caution making voltage checks to avoid personal injury. Step 1. Verify 115VAC and proper polarity at wall outlet. Step 2. With unit plugged in and control power switch in the “ON” position verify LED status. LED status LED status LED status... -
Page 33: Dip Tube Inspection And Replacement
U TTW SERVICE PROCEDURE XII Dip Tube Inspection and replacement Dip Tube Inspection and Replacement WARNING Water Heater components and stored water may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Gas Control shown in the “OFF”... -
Page 34: Anode Inspection And Replacement
U TTW SERVICE PROCEDURE XIII Anode Inspection and replacement Anode Inspection and Replacement WARNING Water Heater components and stored water may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Gas Control shown in the “OFF” Position Step 1. -
Page 35: Flue Baffle Inspection And Replacement
U TTW SERVICE PROCEDURE XIV Flue Baffle Inspection and replacement Remove blower to gain access to Disconnect vent system from exhaust adapter. flue baffle Step 1. Position gas control power switch to the “OFF” position Blower Mounting Screws and unplug water heater from wall outlet. Step 2. -
Page 36: Glossary Of Terms
Glossary of Terms British Thermal Units Gallons per Minute Hertz Kilowatt hour Light Emitting Diode National Pipe Thread Ohms Ohms (resistance) Pounds per Square Inch Revolutions per Minute Energy Cut Out Volts Alternating Current W.C. Inches of Water Column °C Degrees Centigrade °F Degrees Fahrenheit... - Page 37 NOTES Page 3...
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Page 39: Parts List
Parts List 1. Flue Baffle 13. Ultra Low NOx Burner 2. Inlet Dip Tube 14. Right Side Inner Door Assembly 3. Inner Door Gasket Kit 15. Pilot Assembly 4. Hot Water Outlet Anode 16. ¼” Manifold Mount Hex Head Screw 5.