Service; Checklist; System Diagnostics; Electrical Servicing - A.O. Smith BTN-120 Instruction Manual

The installer may be able to observe and correct certain problems
which may arise when the unit is put into operation. HOWeVer,
it is recommended that only qualified service agents, using
appropriate test equipment, be allowed to service the heater.
As preliminary step, check wiring against diagram, check for
grounded, broken or loose wires. Check all wire ends to be sure
that they are making good contact.

CheCklist

Before calling your service agent, the following checklist should
be examined to eliminate obvious problems from those requiring
replacement or servicing.
• Check that "main manual gas shutoff valve" is fully open and
that gas service has not been interrupted.
• Check that after following the OPerATING INSTrUCTIONS,
the "Top Knob" of the gas valve is in "ON" position.
• Check electrical supply to the water heater for possible
blown (or tripped) fusing or power interruption. Also check
the 3 amp fuse on the front of the digital thermostat (Fig. 2).
• Is the water temperature in tank below the thermostat dial
setting on the thermostat (calling for heat)?
• It is possible that the high limit (e.C.O.) has functioned to
shut off the water heater. See High limit page 7 - High limit
Switch for reset procedure. Contact your service agent if
limit continues to function to shut off the water heater.

system diagnostiCs

your water heater is equipped with an ignition control that
incorporates a diagnostic system to assist in troubleshooting. The
indicator codes on the ignition control are as follows:

serViCe

TABle 11:
1 FlASH System lockout (retries or cycles exceeded)
2 FlASHeS Pressure switch stuck close
3 FlASHeS Pressure switch stuck open
4 FlASHeS Open on high temperature limit switch (eco)
6 FlASHeS 115 volt AC power reversed (check polarity)
low flame sense signal (make sure flame sensor
7 FlASHeS
is in burner flame)
8 FlASHeS Check igniter
Continuous flash: Continuous flame sensed for greater than 5 seconds
without the gas valve energized. Check gas valve for malfunction.
Continuous on: Internal control failure. replace ignition control.
Use this diagnostic system in conjunction with TrOUBleSHOOTING
and the SeQUeNCe OF OPerATION to troubleshoot the
appliance.

eleCtriCal serViCing

lABel All WIreS PrIOr TO DISCONNeCTION WHeN
SerVICING CONTrOlS. WIrING errOrS CAN CAUSe
IMPrOPer AND DANGerOUS OPerATION.
VerIFy PrOPer OPerATION AFTer SerVICING.
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