Troubleshooting; Rough Start - Rough Operation; Things To Check Before Servicing; Reset Procedure - A.O. Smith BTX-100 Service Handbook

ULTRA HIGH EFFICIENCY POWER VENT/POWER DIRECT VENT - SERVICE MANUAL

TROUBLESHOOTING

The control system performs exhaustive self diagnostics and displays detected fault
conditions in plain english fault messages on the UIM (page 27) when there is a problem.
When the control system declares a fault condition it will "lock out" and disable heating.
Troubleshooting procedures for the most common error messages are covered in this
manual. In the tables that follow the first column shows the fault message as displayed by
the UIM along with an explanation. The second column details things to check or repair.
Rough Starting - Rough Operation Note:
If the water heater is experiencing rough operation or rough starting review the Service
Notes - Blower Flange & Blower Adapter Gaskets on page 13. Remove and inspect the
burner for debris or damage - see pages 11 - 13.
Heater Status Menu
This menu (page 33) shows the current operating state (energized/de-energized) of the
Blower, Igniter and Gas Valve. The state (open/closed) of the contacts for the Blower Prover,
Blocked Intake and Blocked Exhaust Switches. This information and more is shown in real
time. Use this menu when troubleshooting the water heater to quickly and accurately
diagnose operational problems.

Things to check before servicing

• Using the Instruction Manual that came with the water heater as reference, verify the
water piping, gas line, venting and electrical have all been properly installed.
• Ensure 120 VAC is supplied to the water heater and that the polarity is correct per the
electrical requirements on page 8.
• Ensure the water heater is properly grounded (page 8). Flame sensing current cannot be
established unless the burner is grounded. This can cause ignition failure, after three
failed trials for ignition the UIM would display the "Ignition Failure" fault message.
• Ensure supply gas pressure is within the minimum and maximum requirements (page 17).
Resetting the control system
To reset the control system from a lock out condition; turn the power supply off for
approximately 20 seconds and then back on. Keep in mind if the condition that caused the
fault has not been corrected the control system will continue to lock out.
Important Service Reminder
When performing any troubleshooting step outlined in this Service Manual always consider
the wiring and connectors between components. Perform a close visual inspection of all
wiring and connectors to and from a given component before replacement. Ensure wires
were stripped before being crimped in a wire connector, ensure wires are crimped tightly in
their connectors, ensure connection pins in sockets and plugs are not damaged or worn,
ensure plugs and sockets are mating properly and providing good contact.
Failure to perform this critical step or failing to perform this step thoroughly often results in
needless down time, unnecessary parts replacement, and customer dissatisfaction.
Technical Literature Department
Servicing should only be performed by a Qualified Service Agent
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