Bradford-White Corp U4TW50T*FRN manuale d’uso

Save this manual for future reference Manual 238-48509-00A SERVICE MANUAL Troubleshooting Guide and Instructions for Service (To be performed ONLY by qualified service providers) Models Covered by This Manual: U1TW40S*FRN U1TW50S*FRN U1TW60T*FRN U4TW40T*FRN U4TW50T*FRN U4TW60T*FRN U2TW50T*FRN U2TW65T*FRN UTW450S60FR*N UTW465S60FR*N (*) Denotes Warr[...]

Page 2 Table of Contents Section Page Introduction ______________________________________________5 How to Use this Manual _____________________________________6 Tools Required for Service ___________________________________7 Specifications _____________________________________________8 Sequence of Operation _____________________________________ 12 [...]

WARNING If the information in these instructions is not followed exactly, a fire or ex- plosion may result causing property damage, personal injury, or death. What to do if you smell gas: x Do not try to light any appliance x Do not touch any electrical switch; do not use any phone in your build- ing x Immediately call your gas supplier fr[...]

Page 4 WARNING Water heaters are heat producing appliances. To avoid damage or injury, do not store materials against the water heater or any of its components. Use proper care to avoid unnecessary contact, especially by children, with the water heater and its components. Under no circumstances must flam- mable materials, such as gasoline or paint [...]

Page 5 The Bradford White ECO-DEFENDER Safety System ® The Bradford White ECO-DEFENDER Safety System was designed to resist the ignition of flammable vapors that can occur outside of the water heater and produce Ultra Low NOx emissions. Use and installation are nearly identical to previous versions of atmospherically fired and vented water heaters[...]

Page 6 operating parameters exists, the gas control diagn ostic LED will flash a code to positively identify an operational issue. This service manual is designed to facilitate problem diagnosis and enhance service efficiency. To further promote quicker service tim es the new gas valve can be removed and replaced without draining the water heater. [...]

Page 7 Contact the Bradford White technical support group immediately if diagnosis cannot be m ade using the methods described in this service manual. T ools Requir ed for Service Manometer: A liquid “U” tube type or a digital (magna-helic) typ e can be used. This device is used to measure gas and/or air pressure and vacuum. Multi-Meter: A digi[...]

Page 8 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. Gas Pressure 6.0” W.C. minimum, 11.0” W.C. maximum. Venting System Power vent through the wall or vertical through the roof. Approved Vent Materials PVC, CPVC or ABS. Minimum clearance fo[...]

Page 9 Vent Tables Venting Specifications for: 40 Gallon 50 Gallon 60 Gallon 2” Diameter (5.1 cm) PVC Vent Connector Lengths Terminating # of Elbows Maximum Straight Length ft (m) Minimum Straight Length ft (m) Through the Wall 1 45 (13.7) 2 (0.6) Through the Wall 2 40 (12.2) 2 (0.6) Through the Wall 3 35 (10.7) 2 (0.6) Through the Wall 4 30 (9.2[...]

Page 10 Vent Tables Venting Specifications for: 48 Gallon 65 Gallon 3” Diameter (7.6 cm) PVC Vent Connector Lengths Terminating # of Elbows Maximum Straight Length ft (m) Minimum Straight Length ft (m) Through the Wall 1 55 (16.8) 2 (0.6) Through the Wall 2 50 (15.2) 2 (0.6) Through the Wall 3 45 (13.7) 2 (0.6) Through the Wall 4 40 (12.2) 2 (0.6[...]

Page 11 Specifications Wiring Diagram Control Timings Ignition State Timing Pre-purge 15 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 Lo[...]

Page 12 Power Up Sequence 1. Start-up: Upon power up, the gas control runs a safe start check with a typical delay of 5 seconds. 2. Flammable Vapor Verification: The gas control verifies that the Flamma- ble Vapor Sensor is in the proper operating range prior to energizing any components. If the sensor is within the proper range, the gas control re[...]

Page 13 Normal Heating Sequence (cont’d) 7. Main Burner Ignition: After pilot flame is sensed, the gas control acti- vates the main valve for main burner ignition. The gas control will ig- nore flame and pressure switch signals for 3 seconds to allow for the main burner to stabilize. 8. Steady State Operation: During steady state operation, the g[...]

Page 14 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 Circu[...]

Page 15 Abnormal Operation (cont’d) B) Pressure switch or blower temperature switch failed to close: The gas control runs the blower for 30 seconds waiting for the pressure switch and/or the blower temperature switch to close. If either switch does not close in 30 seconds, the blower turns off and the control flashes 3 times with a 3 second pause[...]

Page 16 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 bee[...]

Page 17 L ED S ta tus C ontr ol S ta tus P ro b a b l e C aus e S e rv i c e P r o c ed ur e N one ( LED not on or fla s h in g) No e l e c tric a l po w e r C o n t ro l p o w e r s w it ch in " O F F" pos i t i o n. Su pp l y vo l ta g e int e rru p te d . Tu rn P o w e r O n One shor t f l ash ev er y fo u r s e co n d s S t and- by m [...]

Page 18 L ED S ta tus C ontr ol S ta tus P r o ba b l e C a us e S e r v ic e P r o c e dur e Six fla s h e s , one f l as h, three s e c o nd paus e ( S of t Lo c k o ut) Fail e d to l i gh t pil o t, sy stem r esets af ter (5 ) m in u t e s 1 . U n s t a b le p ilo t 2 . P i lo t t u b e blo ck o r re s t ricte d 3 . O xid a t io n b u ild -u p o[...]

Page 19 LED Status Control Status Probable Cause Service Procedure Eight flashes, three flashes, three second pause Thermal well sensor damaged or un- plugged or gas con- trol electronics fault detected 1. Damage to thermal well wires 2. Thermal well sensor resistance out of range 3. Replace thermal well 4. Verify control is not wet or physically d[...]

Page 20 Burner Inspection 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. The pilot flame should be stable. Some causes for an unsta- ble pilot flame are: a) Gas pressure is out of specification. b) Pilot flame not fully engulfing s[...]

Page 21 Burner Cleaning Procedure (cont’d) Step 5. Remove the (4) 1/4” hex drive screws holding the right side inner door in place. Step 6. Remove the (3) 1/4” hex drive screws holding the left side burner door in place. Step 7. Disconnect the pilot tube using a 7/16” wrench and the main burner feedline with a 3/4” wrench from the gas con[...]

Page 22 Burner Cleaning Procedure (cont’d) Step 11. Thoroughly inspect burner screen and burner venturi and remove any loose debris accumu- lation. Inspect burner screen for any openings larger than the normal screen openings. Step 12. Use compressed air and/or a vacuum to remove any scale or other debris accumulation from the burner screen and v[...]

Page 23 Pilot Inspection, Testing and Replacement (cont’d) Step 2. Unplug the water heater from the wall outlet. Step 3. Turn off the gas supply to the water heater. Step 4. Remove t he outer door. Step 5. Remove the (4) 1/4” hex drive screws holding the right side inner door in place. Step 6. Disconnect the pilot tube using a 7/16” wrench an[...]

Page 24 Pilot Inspection, Testing and Replacement (cont’d) Step 8. Remove the burner assembly from the com- bustion chamber. Step 9. Remove the pilot assembly from the main feedline using a 1/4" nut driver. Step 10. Visually inspect the spark igniter/fla me sense wire for damage. Replace the pilot assembly, if damage is found. Step 11. With [...]

Page 25 Pilot Inspection, Testing and Replacement (cont’d) Step 15. Inspect the pilot tubing and pilot orifice for blockages: a) Remove ferrule nut from the bottom of the pilot assembly using a 7/16" wrench. b) Remove the pilot tube and pilot orifice. c) Inspect the pilot tubing and pilot orifice for blockages. Clean or replace, as neces- sa[...]

Page 26 Pressure Switch Testing (cont’d) Pressure Switch Testing Pressure switch wire leads With steps 1,2 & 3 complete, discon- nect wire leads from pressure switch. Use a multi-meter set to the ohms setting. With blower off, check across the pres- sure switch termi- nals. Are the switch contacts open (no electrical continuity)? Position the[...]

Page 27 Pressure Switch Replacement Step 1. Move the gas control power switch to the “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from the control access cover on the blower as- sembly and remove cover. Step 3. Carefully remove pressure switch from blower housing. Step 4. Disconnect tubing from the pressure switch. Pr[...]

Page 28 Step 5. Disconnect yellow wires from the pres- sure switch. Step 6. Reconnect wires from step 5 to new pressure switch. Step 7. Reconnect tubing to new pressure switch. Step 8. Carefully position pressure switch into blower housing. Step 9. Position gas control power switch to the “ON” postion and verify proper heater operation. Step 10[...]

29[...]

Page 30 Blower Removal Step 1. Move the gas control power switch to the “OFF” position. Step 2. Unplug the water heater from the wall out- let. S t e p 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. Remove dilution air cl[...]

Page 31 Blower Installation (cont’d) Step 11. Secure blower in place using mounting screws from step 7. Step 12. Reinstall exhaust adapter from step 4. Step 13. Reinstall dilution air clip from step 5. Step 14. Reconnect vent system to exhaust adapter. Step 15. Reconnect cords from step 6. Step 16. Position gas control power switch to the “ON?[...]

Page 32 Blower Temperature Switch Testing (cont’d) Switch Setting Opens on rise @ approximately 165 o F Auto resets on fall @ approximately 160 o F Cool switch to below 160 o F Reconnect wire leads and ob- serve heater operation. Do exhaust gas temperatures rise to or above 170 o F with vent connected? Replace switch (see page 33). Disconnect wir[...]

Page 33 Blower Temperature Switch Replacement Step 1. Move the gas control power switch to the “OFF” position. Step 2. Remove the three screws (Phillips screw driver) from the control access cover on the blower as- sembly and remove cover. Step 3. Locate blower temperature switch. Step 4. Disconnect red and yellow wire leads from the switch. St[...]

Page 34 Thermal Well Testing Follow the procedure, below, if the water heater gas control has gone into a ECO lock- out (4 flash, 3 second pause). Reset the gas control by rotating the setpoint knob to the minimum setting for at least 6 seconds before returning to the desired water tem- perature setting. Step 1. Unplug the thermal well connector fr[...]

Page 35 Thermal Well Testing (cont’d) Determine the correct resistance values using the Determine the Water Temperature Inside the Tank procedure on page 23. If the values are correct, replace the gas con- trol, otherwise replace the thermal well. Determine Water Temperature Inside Tank Note: It is important to understand once the resistance for [...]

Page 36 Sensor Resistance at Various Temperatures Gas Control & Thermal Well Removal From Water Heater Step 1. Move the gas control power switch to the “OFF” po- sition. Step 2. Unplug the water heater from the wall outlet. Step 3. Drain the water heater to a point below the gas control level. Step 4. Turn off the gas supply to the water he[...]

Page 37 Gas Control & Thermal Well Removal From Water Heater (cont’d) Step 4. Disconnect the pilot tube using a 7/16” wrench and the main burner feedline with a 3/4” wrench from the gas control. Step 5. Disconnect the wire harnesses and spark igniter/ flame sense wire from the gas control. Step 6. Remove the gas control & thermal well[...]

Page 38 Gas Control Removal From Thermal Well (cont’d) Step 3. Turn off the gas supply to the water heater and disconnect the gas piping from the gas control. Step 4. Disconnect the pilot tube using a 7/16” wrench and the main burner feedline with a 3/4” wrench from the gas control. Step 5. Disconnect the wire harnesses and spark igniter/ fla[...]

Page 39 Gas Control Assembly to the Thermal Well (cont’d) Step 2. Route the wire leads back into relief opening. Step 3. Align the slots located on the thermal well flange with the tabs located on the back of the gas control. Step 4. Carefully push the gas control back onto the thermal well flange as far as possible towards the water heater. Then[...]

Page 40 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 Step 1. Move the gas control power switch to the “O[...]

Page 41 115 VAC Circuit Trace WARNING 115 volt potential exposure. Use caution making voltage checks to avoid personal injury. 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 flash- ing error codes. Waiting for call for heat. T[...]

Page 42 Safety Circuit Voltage Trace Note: This procedure assumes a cold tank. Step 1. Remove three screws (Phillips screw driver) from control access cover on blower and remove cover. Safety Circuit Voltage Trace WARNING 115 volt potential exposure. Use caution making voltage checks to avoid personal injury. Control access cover Position gas contr[...]

Page 43 Remove the Blower to Gain Access to the Flue Baffle Step 1. Move the gas control p o w e r switch to the “OFF” position. S t e p 2 . Unplug the water heater from the wall outlet. Step 3. Disconnect the vent system fro m the exhaust adapter on top of blower. Step 4. Unplug the cord sets from the blower. Step 5. Remove the three blower mo[...]

Page 44 water heater. Remove the Blower to Gain Access to the Flue Baffle (cont’d) Step 8. Inspect the baffle for deterioration and missing restrictors. Clean any scale or debris build-up. Replace with a new baffle, as necessary. Step 9. Reinstall the baffle into the flue. Be sure the baffle hanger tab is inserted into the notch locations at the [...]

Page 45 be free of cracks and any blockage. Hydro-jet slots should be open and free of any blockage. Any damage, such as cracks, restriction due to deformation, or uninten- tional holes are not field repairable and the inlet nipple/diptube must be replaced. Step 7. Upon com pletion of the inspection or subsequent replacement, reinstall the inlet ni[...]

Page 46 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. Inner Door Removal Procedure Step 1. Move the gas control power switch to the “OFF” po- sition. Step 2. Unplug the water heater from[...]

Page 47 Step 6. Remove the connectors attached to the re- settable thermal switch on the manifold mount. Inner Door Removal Procedure (cont’d) Step 7. Remove the flammable vapor sensor from the clip by pushing down on the tab to open the clip. Step 8. Inspect both inner doors for any of the following im perfections: tears, missing material, crack[...]

Page 48 inner door gasket to the inner door sections. Refer to the illustration for proper applica- tion. Note the overlap configuration in the flange area of the inner door. Set the flange section first, and this will help to achieve the proper overlap position. Inner Door Installation with Gasket Step 1. Clean any residual gasket residue or other[...]

Page 49 screws. Verify that both the left and right side inner doors are properly positioned and sealed against the combustion chamber. Step 8. Re-install the outer door. Step 9. To resume operation, follow the instructions located on the water heater lighting instruction label. Or, use the lighting instructions located in the water heater installa[...]

Page 50 Common Terms BTU British Thermal Units ECO Energy Cut Off GPM Gallons per Minute Hz Hertz KWh Kilowatts per hour LED Light Emitting Diode NPT National Pipe Thread Ohms Ohms of resistance PSI Pounds per Square Inch RPM Revolutions per Minute VAC Volts Alternating Current W.C. Inches of Water Column °C Degrees Centigrade °F Degrees Fahrenhe[...]

Page 51 Parts List 33 32 30 39 34 35 36 29 18 31 21 20 1 2 3 4 5 12 13 9 10 11 14 15 19 22 23 27 28 7 25 24 6 26 16 17 29 18 18 18 18 40 37 38 Part Name and Description 1. Blower Complete 15. T&P Valve 29. Burner Assembly 2. Air Mixing Inlet 16. Outer Door 30. Flexible Gas Feedline 3. Pressure Switch 17. Right Side Inner Door 31. Thermal Switch[...]

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