TTW 75 SERIES ® Gas Water Heaters SERVICE MANUAL Troubleshooting Guide and Instructions for Service (To be performed ONLY by qualified service providers) For Bradford White TTW® Series Models: M2TW75T*(BN,CX) TW475S76(B,C)* (N,X) (*) Denotes Warranty Years Manual 47150A Save this manual for future reference
Bradford White TTW Series Gas Water Heaters Table of Contents Page TTW Service Procedure Introduction 4 --- How to use this manual 5 --- Tool required for service 5 --- Specifications 6 --- Control Timings 8 --- Sequence of Operation 9 --- Troubleshooting 12 --- Burner Inspection, Cleaning and Replacement 14 I Pilot Testing, Cleaning and Replacement 16 II Pressure Switch Testing and Replacement 17 III Blower Testing and Replacement 19 IV Blower Temperature Switch Testing
CAUTION WARNING: If the information in these instructions is not followed exactly, a fire or explosion may result causing property damage, personal injury, or death. FOR YOUR SAFETY Do not store or use gasoline or other flammable, combustible, or corrosive vapors and liquids in the vicinity of this or any other appliance. WHAT TO DO IF YOU SMELL GAS Do not try to light any appliance. Do not touch any electrical switch; do not use any phone in your building.
Introduction The new Bradford White TTW2 & TW4 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. Spark to Pilot Ignition System - employing the spark to pilot ignition system promotes reliable and consistent pilot and main burner ignitions to provide hot water on demand.
How to Use This Manual It is intended for this manual to be used by qualified service personal for the primary purpose of troubleshooting and repair of the Bradford White TTW Series 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.
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 or Propane. Unit must match gas type supplied. Gas Pressure 5.0" W.C. min. for Nat gas, 11.0" W.C. min. for L.P. gas, 14.0" W.C. maximum (Nat. & L.P.
Specifications Vent Tables Venting Specifications: 3" Diameter (7.6 cm) PVC Vent Connector Lengths Terminating # of Elbows Maximum Length ft (m) Minimum Length ft (m) Through the Wall 1 45 (13.7) 2 (.6) Through the Wall 2 40 (12.2) 2 (.6) Through the Wall Through the Wall 3 4 35 (10.7) 30 (9.1) 2 (.6) 2 (.6) Through the Roof Through the Roof Through the Roof 0 1 2 50 (15.2) 45 (13.7) 40 (12.2) 7 (2.1) 7 (2.1) 7 (2.1) Through the Roof 3 35 (10.7) 7 (2.1) 4" Diameter (10.
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.
Sequence of Operation Power up Sequence 1 Start Up. Upon power up, the control runs a safe-start check with a typical start-up delay of 1-5 seconds. 2 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. If the device is within range the control resumes normal operation with no perceptible delay.
Sequence of Operation Normal Heating Sequence (cont.) 7 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. Pressure switch / Blower temperature switch- If either switch opens, pilot valve and main valve is shut down.
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.
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. LED Status Control Status Probable Cause Service Procedure None, control LED not on or flashing No electrical power Control power switch in “OFF” position. Supply voltage interrupted.
Troubleshooting LED Status Control Status Six-one flash, three second pause Failed to light pilot. System auto resets. 1. Unstable pilot. 2. Pilot tube blocked or restricted. 3. Oxidation build up on pilot electrode. 4. Wire damage to pilot assembly or bad connection at gas valve. Six-two flash, three second pause Pressure switch or blower temp switch opened during burner operation. System auto resets. 1. Vent blockage or improper vent configuration. 2. Pressure switch tubing kinked or blocked. 3.
TTW SERVICE PROCEDURE I Burner Operation Inspection, Adjustment, Cleaning and Replacement Burner Inspection and Air Shutter Adjustment. At periodic intervals (every 6 months) a visual inspection should be made of the pilot and main burner for proper operation and to assure no debris is accumulating. Pilot flame should be stable, some causes for an unstable pilot flame are: a) Water heater vent is less than the allowable vent length. b) Gas pressure is out of specification.
TTW SERVICE PROCEDURE I Burner Operation Inspection, Adjustment, Cleaning and Replacement Burner Cleaning Step 1. Position gas control power switch to the “OFF” position and unplug heater from wall outlet. Step 2. Turn off gas supply to water heater. Step 3. Remove outer jacket door and remove inner door. Step 4. Disconnect pilot tube (7/16 wrench) and feedline (¾ wrench) from gas control. Step 5. Disconnect igniter/flame sensor wire from gas control. Step 6.
TTW SERVICE PROCEDURE II Pilot testing, Cleaning and Replacement Pilot Inspection, Testing and Replacement Step 1. Position gas control power switch to the “OFF” position and unplug heater from wall outlet. Remove Outer door. Step 2. Turn off gas supply to water heater. Step 3. Remove outer jacket door and remove inner door. Remove inner door Igniter/flame sense wire Step 4. Disconnect pilot tube nut (7/16 wrench) and feedline nut (¾ wrench) from gas control. Step 5.
TTW SERVICE PROCEDURE III Pressure Switch Testing and Replacement Pressure Switch Testing WARNING 120 volt potential exposure. Use caution making voltage checks to avoid personal injury. Step 1. Position power switch on gas control to the “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and remove cover (see photo 1). Step 3.
TTW SERVICE PROCEDURE III Pressure Switch Testing and Replacement Pressure Switch Replacement WARNING 120 volt potential exposure. Use caution to avoid personal injury. Step 1. Position gas control power switch to “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and remove cover (see photo 3). Pressure Switch 3 Step 3.
TTW SERVICE PROCEDURE IV Blower Testing and Replacement WARNING 115 volt potential exposure. Use caution when making voltage checks to avoid personal injury. Blower Testing Step 1. Position gas control power switch to “ON” position and adjust control to call for heat. Step 2. Remove the three screws (Phillips Screw driver) from control access cover on blower assembly and remove cover (see photo 7). Does blower energize Within 2 minutes? Y Connect manometer to pressure tap of blower.
TTW SERVICE PROCEDURE IV Blower Testing and Replacement Blower removal Step 1. Position gas control power switch to the “OFF” position. Step 2. Unplug blower power cord from wall outlet. Remove exhaust adapter and retain for use on new blower. Step 3. Disconnect vent system from exhaust adapter on top of blower. Step 4. Remove exhaust adapter from blower (blade screw driver) and retain for use on new blower Step 5. Unplug cord sets from blower. Step 6.
TTW SERVICE PROCEDURE V Blower Temperature Switch Testing and Replacement Blower Temperature Switch Testing. Step 1. WARNING 120 volt potential exposure. Use caution to avoid personal injury. Position power switch on gas control to the “OFF” position. 14 Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower and remove cover (see photo 14). Step 3.
TTW SERVICE PROCEDURE V Blower Temperature Switch Testing and Replacement Blower Temperature Switch Replacement. WARNING 120 volt potential exposure. Use caution to avoid personal injury. Step 1. Position gas control power switch to the “OFF” position and unplug heater from wall outlet. Step 2. Remove the three screws (Phillips screw driver) from the control access cover on blower and remove cover. (see photo 16) Step 3. 16 Locate blower temperature switch (see photo 17) 17 Step 4.
TTW SERVICE PROCEDURE VI Gas Control/Thermal Well Testing and Replacement Gas Control Testing See pages 24 & 25 for gas control input & output testing. Thermal Well Testing Position gas valve power switch to the “OFF” position and disconnect thermal well harness from gas control.
TTW SERVICE PROCEDURE VI Gas Control/Thermal Well Testing and Replacement WARNING Stored water may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Determine Water Temperature Inside Tank Note: It is important to understand once the resistance for the thermal well is determined from page 23, water flow through the heater should not occur. Prior to performing the steps below, turn off the cold water supply to the water heater.
TTW SERVICE PROCEDURE VI Gas Control & Thermal Well Testing and Replacement Gas Control & Thermal Well Removal From Water Heater Gas Control Step 1. Position gas valve power switch to the “OFF” position and Unplug Heater from power supply. Step 2. Drain heater to a point below the gas control level. Step 3. Turn off gas supply to water heater and disconnect gas piping from gas control. Step 4. Disconnect wire harnesses and burner assembly from gas control. Step 5.
TTW SERVICE PROCEDURE VI Gas Control & Thermal Well Testing and Replacement Gas Control Assembly to Thermal Well Step 1. Install threaded end of thermal well into tank. Be sure thermal well flange is positioned as shown in photo 24 for proper control alignment. Step 2. Route wire leads back into relief opening. (see photo 24) Step 3.
TTW SERVICE PROCEDURE VII 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. Resistance must be within 25,000 ohms and 45,000 ohms. If outside of this range replace simulated resistive device.
TTW SERVICE PROCEDURE VIII Safety Circuit Voltage Trace Safety Circuit Voltage Trace WARNING 120 volt potential exposure. Use caution making voltage checks to avoid personal injury. NOTE: This procedure assumes a cool tank. 26 Step 2. Remove three screws (Phillips Screw driver) from control access cover on blower and remove cover (see photo 26).
TTW SERVICE PROCEDURE IX 120 VAC Trace WARNING 120 volt potential exposure. Use caution making voltage checks to avoid personal injury. 120 VAC Circuit Trace Step 1. Verify 120VAC 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 None, Control LED not on or flashing. LED status Short flash, once every four seconds. LED status “Heartbeat”, alternates bright/dim. LED status Various flashing error codes.
TTW SERVICE PROCEDURE X 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. Step 1. Position on/off switch of gas control valve to “OFF” position and unplug water heater from wall outlet. Step 2. Turn off cold water supply to water heater. Connect hose to drain valve of water heater and route to an open drain.
TTW SERVICE PROCEDURE XI 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. Step 1. Position on/off switch of gas control valve to the “OFF” position and unplug water heater from wall outlet. Step 2. Turn off cold water supply to water heater. Connect hose to drain valve of water heater and route to an open drain.
TTW SERVICE PROCEDURE XII Flue Baffle Inspection and replacement Remove blower to gain access to flue baffle Disconnect vent system from exhaust adapter. Step 1. Position gas control power switch to the “OFF” position and unplug blower from wall outlet. Step 2. Disconnect vent system from exhaust adapter on top of blower. Step 3. Unplug cord sets from blower. (see photo 33). Step 4. Remove the three blower mounting screws (¼" nut driver) (see photo 33). Step 5.
Glossary of Terms BTU GPM Hz KW/h LED NPT Ohms PSI RPM TCO VAC W.C.
NOTES Page 34 34
Parts List Optional 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Blower Complete Air Mixing Inlet cover Pressure Switch Blower Temp. Switch Blower Gasket Blower Power Cord Vent Adapter Condensate Hose Kit Flue Reducer Heat Trap Outlet Hot Water Outlet Anode Flue Baffle 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. Heat Trap Inlet Inlet Dip Tube Wire Harness T&P Valve ¾ NPT Plug Burner Assy. (Nat) Burner Head Main Burner Orifice Pilot Assy. (Nat) Pilot Orifice Feedline Burner Assy. (L.P.) 25. 26. 27. 28.
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