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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.
An “Installation Check List” is shown towards the end of this manual. Compare the installation against
the installation check list to confirm all requirements are met.
A “Service Report” is shown towards the end of this manual. Completing this form will assist in the
troubleshooting efforts. Should you need to call for technical support, please provide the information
shown on this form to the support technician to help ensure accurate troubleshooting.
Troubleshooting begins with “System Observation” to determine failure mode as indicated by the
error code on the system display. Troubleshooting continues with “Failure Modes and Probable
Cause” directing the service provider to a series of test procedures to determine root cause of failure.
Component replacement procedures directly follow the test procedures for a given component.
In some difficult to diagnose conditions, it may be necessary to isolate the heater from the vent
system to determine root cause.
Contact Technical support immediately if diagnosis is not determined using the methods described in
this service manual.
Tools Required for Service
Manometer: Two types available, a liquid “U” tube type or a digital (magna-helic) type. This device is
used to measure gas and/or air pressures and vacuum.
Multi-Meter: A digital type is strongly recommended. This device is used to measure electrical
values. The meter you select must have the capability to measure volts AC, volts DC, Amps, micro-
amps and ohms.
Thermometer: Used to measure water temperature. An accurate thermometer is recommended.
Water Pressure Gage: Used to measure water supply pressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Jumper Leads: A length of wire (12" min.) with alligator clip at both ends.
Various Hand Tools: Pipe wrench, channel locks, open end wrench set, 12" crescent wrench, Allen
wrench set, torx bit set, screw drivers (common & phillips), long reach (12") magnetic tip phillips head
screw driver #2 tip, ¼" nut driver, pliers (common & needle nose), socket set including a 1-1/16 deep
well socket, wire cutters, wire strippers, wire crimpers, torpedo level, small shop vac, step ladder, and
flashlight.
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