Bradford White UCG100H399 Service Manual
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Bradford White UCG100H399 Service Manual

Ultra low nox atmospheric vent water heaters with direct spark ignition
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See also: Operation & Installation Manual
Ultra Low NOx Atmospheric Vent
Water Heaters with Direct Spark Ignition
Manual 238-51306-00A REV 12/14
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
UCG100H399*N
(*) Denotes Warranty Years
Effective: December, 2014
ECO 7956
Save this manual for future reference

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Summary of Contents for Bradford White UCG100H399

  • Page 1 MANUAL Troubleshooting Guide and Instructions for Service (To be performed ONLY by qualified service providers) Models Covered by This Manual: UCG100H399*N (*) Denotes Warranty Years Effective: December, 2014 ECO 7956 Manual 238-51306-00A REV 12/14 Save this manual for future reference...

  • Page 2: Table Of Contents

    Ultra Low NOx Atmospheric Vent Water Heaters with Direct Spark Ignition Table of Contents Introduction........................3 How to Use This Manual ....................4 Tools Required for Service ................... 4 Features ........................5 Specifications ....................... 6 Sequence of Operation ....................9 Troubleshooting......................

  • Page 3: Introduction

    Low NOx Atmospheric Vent Water Heater. The Bradford White Ultra Low NOx Atmospheric Vent Water Heater uses an ultra low NOx premix power burner located at the top of the water heater to direct a turbulent flame down into the water backed combustion chamber.

  • Page 4: How To Use This Manual

    It is intended for this manual to be used by qualified service personnel for the primary purpose of troubleshooting analysis and repair of the Bradford White UCG100H399. Understanding the sequence of operation section of this manual will contribute greatly to troubleshooting this product.

  • Page 5: Features

    Features Features of Honeywell Integrated Control System Attractive digital water heater display on control panel for setting and displaying the temperature setpoint. Pressing temperature UP and DOWN buttons changes the temperature setpoint. Temperature format may be displayed in °F or °C. Single control board with plug in wiring controls temperature, ignition, and blower operation.

  • Page 6: Specifications

    Dia. Dia. Dia. Open (lbs) Gallons Water T&P Water Conn. Conn. Conn. Vent Conn. Heater UCG100H399 399,000 77 ¼ 52 ½ 55 ½ 69 ¾ 63 ¼ 28 ¼ 63 ¼ 1 ½ ¾ Model Description Dimensions (MM) Floor Floor...
  • Page 7 Specifications Power Supply Dedicated 120 VAC, 60 Hz, 15A GFI Minimum 1” Nat Gas Supply (Schedule 40 black iron pipe recommended) Approved gas Type Natural. Unit must match gas type supplied 14.0” W.C. maximum static, 4.5” W.C. minimum running Gas Pressure (Nat.) (recommend 7.0”...
  • Page 8 UCG100H399 WARNING! The UCG100H399 model is not approved for 2 inch diameter vent pipe. Venting with 2 inch pipe may result in damage to the water heater or cause an unsafe condition. DO NOT use 2 inch Vent Air Intake Pipe! Determining required intake vent length 1.

  • Page 9: Sequence Of Operation

    Sequence of Operation 1. Thermostat calls for heat. 2. Combustion blower starts. 3. Blower pre-purge period of 30 seconds. 4. Trial for Ignition. (5 seconds, 3 trials). a. Flame establishing period (3 seconds), gas valve opens, sparks from spark rod to burner surface to ignite the gas.
  • Page 10 Sequence of Operation Lockout Conditions The system will go into lock out mode for the following reasons: 1. ERROR CODE 110 a. Control board will go into “Soft Lockout” if the main burner cannot be lit or fails to prove flame after 3 ignition trials.

  • Page 11: Troubleshooting

    Troubleshooting System Observation for Models with Direct Spark Ignition Water Heater Fault: Water heater does not operate WARNING Display Error Code: Water heater display does not operate - blank display 120 volt potential exposure. Use caution making voltage checks to avoid personal injury. Check main power supply to water heater –...
  • Page 12 Troubleshooting CAUTION WARNING Use caution not to damage connectors when 120 volt potential exposure. Use caution making making voltage measurements or jumping terminals voltage checks to avoid personal injury. From previous page. Error code #67 on display. Measure voltage Replace power cord/blower harness if between black and white wires, of the 3 wire display shows “heating”...
  • Page 13 Troubleshooting Step 1: Press and hold the lower right button under “Next” in the lower right display for at least 3 seconds. WARNING The following procedure is for service and installation personnel only. Resetting lockout conditions without correcting the malfunction can result in a hazardous condition. Step 2: The display will show the flame sense current in microamps when the burner is operating.
  • Page 14 Troubleshooting Step 4: Press lower right “Next” button and the display will flash and show the number of any Lockout codes. Step 5: Press lower right “Next” button and the display will show the temperature sensor reading. Step 6: End of screens in Diagnostic Mode. Press “Done” button on lower left to exit Diagnostic Mode back to DHW setpoint in the User Mode.
  • Page 15 Troubleshooting DIAGNOSTIC ERROR CODES AND TROUBLESHOOTING PROCEDURES FOR EF100T399 MODELS WITH HONEYWELL LOW FIRE START CONTROL SYSTEM Error Code Definition of Code Cause of Problem and Actions Taken to Correct Check power supply to the water heater. Make sure water heater is plugged in and the breaker is on. Check if there is 120 volts power supply to the LINE connections on the No code –...

  • Page 16: Service Procedure I: Thermostat Circuit Testing And Replacement

    Service Procedure I: Check the wiring from the sensor to the control module. Measure the resistance of each outside wire to the center wire. If either outside wire has a much different resistance reading, replace High Limit (Overheat the sensor. Condition) Make sure the sensor is securely held inside the well with the clip.
  • Page 17 Thermostat Circuit Testing and Replacement IMPORTANT NOTE: This procedure assumes a cool tank. WARNING Condition: Water heater not operating. 120 volt potential exposure. Use caution making Display shows error code “93” (sensor voltage checks to avoid personal injury. reading faulty) Unplug or disconnect electrical power to the water heater.
  • Page 18 Service Procedure I: Thermostat Circuit Testing and Replacement WARNING Condition: Water heater not operating. Display shows error code “80” high water temperature Do not operate water heater without verifying (over 200 °F) (continued from previous page). that the overheating condition has been corrected.
  • Page 19 Service Procedure I: Thermostat Circuit Testing and Replacement APPENDIX-A Sensor Resistance at Various Temperatures Be careful when making voltage measurements or jumping terminals not to damage or deform connectors or connector pins. Draw water from the T&P valve. Compare temperature with temperature ohms chart below. Example: If the temperature is 84°F, then the resistance through the sensor would be 8449 (see shaded area).
  • Page 20 Service Procedure I: Thermostat Circuit Testing and Replacement Thermostat Sensor (Thermister) Replacement Procedure WARNING Step 1. Position main power switch to “OFF” Step 2. Disconnect (unplug) water heater from 120 volt power source. 120 volt potential exposure. Isolate the appliance and reconfirm power is disconnected Step 3.

  • Page 21: Service Procedure Ii: Combustion System Testing And Replacement

    Service Procedure II: Combustion System Testing and Replacement Observe burner operation through the sight glass located on the combustion insert mounting flange. Normal burner operation should ignite smoothly, without evidence of coughing or huffing upon ignition. The burner flame should be a blue flame near the burner surface in a uniform flame pattern.
  • Page 22 Service Procedure II: Combustion System Testing and Replacement Observe burner operation through the sight glass located on the combustion insert mounting flange. Normal burner operation should ignite smoothly, without evidence of coughing or huffing upon ignition. The burner flame should be a blue flame near the burner surface in a uniform flame pattern.
  • Page 23 Service Procedure II: Combustion System Testing and Replacement WARNING Heater components may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Combustion System Removal Procedure WARNING Step 1. Position main power switch to “OFF”. Step 2.
  • Page 24 Service Procedure II: Combustion System Testing and Replacement Combustion System Replacement Procedure Step 1. Fully inspect burner mounting insert gasket for the following: a) Tears d) Dirt or debris b) Missing material e) Other imperfections that would inhibit proper seal c) Cracks If gasket is NOT affected by any of the above, gasket replacement is not required.

  • Page 25: Service Procedure Iii: Burner Tube Inspection And Replacement

    Service Procedure III: Burner Tube Inspection and Replacement WARNING Heater components may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Burner Tube Removal Procedure Step 1. Position main power switch to “OFF”. WARNING Step 2.
  • Page 26 Service Procedure III: Burner Tube Inspection and Replacement WARNING Heater components may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury. Burner Tube Inspection Step 1. Inspect burner tube as follows (Acotech metal fiber mesh burner). a) Outer fiber mesh should be uniform with no tears or deterioration.

  • Page 27: Service Procedure Iv: Gas Valve Replacement

    Service Procedure IV: Gas Valve Replacement Gas Valve Replacement Procedure WARNING Step 1. Position main power switch to “OFF”. Step 2. Disconnect (unplug) water heater from 120 volt power source. 120 volt potential exposure. Isolate the appliance and reconfirm power is disconnected Step 3.

  • Page 28: Service Procedure V: Blower Testing And Replacement

    Service Procedure V: Blower Testing and Replacement Refer to ignition Is collector high limit Does blower energize? module/control board switch in normally closed Ensure control display Replace ignition illustration. Is there position? shows “Heating.” Raise module/control board. 24VAC between blue temperature setpoint if and yellow wires at necessary.
  • Page 29 Service Procedure V: Blower Testing and Replacement Blower Replacement Procedure WARNING Step 1. Position main power switch to “OFF”. Step 2. Disconnect (unplug) water heater from 120 volt power source. 120 volt potential exposure. Isolate the appliance Step 3. Turn off gas supply to water heater. and reconfirm power is disconnected using a Step 4.

  • Page 30: Service Procedure Vi: Flame Sensor Testing And Replacement

    Service Procedure VI: Flame Sensor Testing and Replacement Flame Sensor Testing Procedure WARNING 120 volt potential exposure. Use caution making voltage checks to avoid personal injury. Flame sensor may be too hot to handle, take necessary precautions. Refer to illustration below, is there a minimum of 1 A during 1.5 second flame proving period?
  • Page 31 Service Procedure VI: Flame Sensor Testing and Replacement Flame Sensor Replacement Procedure WARNING Step 1. Position main power switch to “OFF” Step 2. Disconnect (unplug) water heater from 120 volt power source. 120 volt potential exposure. Isolate the appliance and reconfirm power is Step 3.

  • Page 32: Service Procedure Vii: Spark Rod Gap Adjustment And Replacement

    Service Procedure VII: Spark Rod Gap Adjustment and Replacement Spark Rod Gap Inspection and Adjustment WARNING Step 1. Remove combustion system as described in “Combustion System Removal Procedure.” Spark gap must be set from 3/16” to 1/4". Failure to Step 2. Measure spark gap between the spark rod and set and verify proper spark gap may result in a burner tube.
  • Page 33 Service Procedure VII: Spark Rod Gap Adjustment and Replacement Spark Rod Replacement Procedure Step 1. Position main power switch to “OFF” WARNING Step 2. Disconnect (unplug) water heater from 120 volt 120 volt potential exposure. Isolate the appliance power source. and reconfirm power is disconnected using a multi-meter.

  • Page 34: Service Procedure Viii: Ignition Module/Control Board Replacement

    Service Procedure VIII: Ignition Module/Control Board Replacement Control Board Replacement Step 1. Position main power switch to “OFF” WARNING Step 2. Disconnect (unplug) water heater from 120 volt 120 volt potential exposure. Isolate the power source. appliance and reconfirm power is disconnected using a multi-meter.

  • Page 35: Service Procedure Ix: Blocked Vent Switch Inspection And Replacement

    Service Procedure IX: Blocked Vent Switch Inspection and Replacement Blocked Vent Switch Procedure Step 1. First determine if the “Blocked Vent Switch” Blocked Vent was installed correctly on the drafthood (see Switch should be installed on the lip picture right). of the drafthood.

  • Page 36: Service Procedure X: Anode Inspection And Replacement

    Service Procedure X: Anode Inspection and Replacement Anode Replacement Procedure Step 1. Position main power switch to “OFF” WARNING Step 2. Disconnect (unplug) water heater from 120 Heater components and stored water may be HOT when volt power source. performing the following steps in this procedure. Take necessary precaution to prevent personal injury.

  • Page 37: Service Procedure Xi: Display Module Replacement

    Service Procedure XI: Display Module Replacement Display Module Replacement Step 1. Position main power switch to “OFF” WARNING Step 2. Disconnect (unplug) water heater from 120 volt 120 volt potential exposure. Isolate the power source. appliance and reconfirm power is disconnected using a multi-meter.

  • Page 38: Service Procedure Xii: Transformer Replacement

    Service Procedure XII: Transformer Replacement Transformer Replacement Procedure Step 1. Position main power switch to “OFF.” WARNING Step 2. Disconnect (Unplug) water heater from 120 Volt power source. 120 volt potential exposure. Isolate the appliance and reconfirm power is disconnected Step 3.

  • Page 39: Water Heater Installation Check List

    UCG100H399 WARNING! The UCG100H399 model is not approved for 2 inch diameter intake vent pipe. Venting with 2 inch pipe may result in damage to the water heater or cause an unsafe condition. DO NOT use 2 inch Vent or Air Intake Pipe! Determining required intake vent length 1.

  • Page 40: Water Heater Service Report

    Water Heater Service Report Date _______________ Service Provider _____________________________ Model Number _______________________________ Phone Number _______________________________ Serial Number _____________________________ Intake Venting (PVC, CPVC): Intake Vent size 3”, 4” ______ Intake 45° Elbows (qty) ______ Length of Straight Pipe (Intake) ________ Intake 90° Elbows (qty) ______ Exhaust Vent Size 6”,7”,8”...

  • Page 41: Parts List

    Parts List Water Heater Full Assembly 1 Surround Assembly 2 Combustion Assembly (specify model) 3 Ignition Control Assembly 4 Draft Hood (specify model) 5 Swell Latch 6 Front Hot Water Outlet 7 Baffle 2” Flue (Specify Model) 8 Control Display 9 Front Cold Water Inlet 10 Plastic Hole Closure 11 No Handle Brass Drain Valve...
  • Page 42 Parts List 2 Combustion Assembly 1 Combustion Ass’y (Specify model) 13 Sesnor – Flame Sense 2 Blower/Gas Valve Assembly (specify model) 14 Igniter – Direct Spark 3 Burner Assembly (specify model) 15 Blower/Burner Mounting Plate 4 Blower (specify model) 16 Gasket Burner (specify model) 5 Gasket &...
  • Page 43 Parts List Ignition Control Assembly Control Panel Hex Nut Control Ground Wire Transformer Power Cord Harness Display Surround Controller Harness Screw High Voltage Spark Cable Switch Main Power Gas Valve Harness Control Display Blower Modulation Harness Weld Stud Flame Sense Harness Customer must specify complete model number and serial number when ordering service parts.

  • Page 44: Glossary Of Terms

    Glossary of Terms Alternating Current BTU/H British Thermal Units Carbon Monoxide Carbon Dioxide Direct Current Direct Spark Ignition Energy Cut Off Ground fault interrupt Gallons per Minute Hertz Light Emitting Diode Oxides of Nitrogen National Pipe Thread Pounds per Square Inch Revolutions per Minute Volt Amps Volts Alternating Current...

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