Fault And Alert Messages - A.O. Smith 101 Series Instruction Manual

fault and alert messages

Call the technical support phone number listed on the back cover for further technical assistance or to locate a qualified service agent
in your area.
possiBle causes - check/repair
• The water heater's control system is polarity sensitive and will lock
out and disable heating operation if the polarity of the power supply
is reversed. The control system will display the "AC reversed"
Fault message on the LCD in this condition. See Power Supply
Connections on page 39 for instructions on how to properly connect
the power supply.
note: Electronic flame sensing requires correct power supply
polarity AND a proper earth ground to the water heater and the
main Burner. The control system does not verify earth ground
but this should be checked first if ignition failure occurs. See the
ignition Failure Fault message information below.
• The control system has failed to ignite the main Burner.
• Water heater is not properly grounded, loose or open ground wire
to the main Burner - see Power Supply Connections on page 39.
• Dirty/corroded flame sensor, clean flame sensor with fine steel
wool (replace if damaged) - see Figure 2 on page 7.
• Loose or open wiring to the flame sensor.
• Loose or open wiring to the 24 VAC Gas Valve.
• 24 VAC Gas Valve control knob in the "off" position - see Figure 56
on page 51 and Figure 57 on page 52.
• Supply gas turned off, low gas volume - see page 37.
• intake air and/or vent piping is restricted or improperly installed -
see Venting Installation on page 21.
• Low or no manifold gas pressure to the main Burner - see initial
Start Up on page 50.
• The control system has detected the Low Gas Pressure Switch
contacts are open.
• Loose or open wiring to the Low Gas Pressure Switch - see Figure
3 on page 8 for location.
• Supply gas pressure is below the required minimum pressure - see
Table 4 on page 13.
• Supply gas is turned off at the main Shutoff Valve.
• Supply gas pressure is dropping when other gas fired appliances
on a common supply gas line are operating.
• Low volume of supply gas - see Supply Gas Line installation on
page 37 and the requirements for the Supply Gas Line on page 13 and
Supply Gas Regulator on page 13.
• The control system has detected low current (AC amps) from the
Hot Surface igniter. The control system monitors igniter current
and will declare this Fault condition if the current is not at or above
the programmed minimum requirement - see the Sequence Of
operation on page 54 for minimum igniter amp requirements.
• Loose or open wiring to the Hot Surface igniter - see Figure 2 on
page 7 for igniter location.
• Damaged, worn or open circuit Hot Surface igniter.
note: Hot surface igniters are wearing parts. Wear is directly
related to heating cycle count. Heating cycle count can be viewed
in the Heater Information menu - see Heater Information on page
47. increasing the Differential setting reduces heating cycle count -
see Operating Set Point And Differential Adjustment on page 45.
• The control system has detected the Blocked Exhaust Switch
contacts are open.
• The condensate drain is blocked filling the exhaust elbow with
water - clear the condensate drain - see Figure 9 on page 16.
• Loose or open wiring to the Blocked Exhaust Switch - see Figure 3
on page 8 for switch location.
• restricted/blocked vent piping - condensate trapped in low point.
• Excessive equivalent pipe length, exceeded the maximum number
of 90° elbows or wrong pipe size used in the vent piping system -
see Venting Requirements on page 22.
• Excessive wind outdoors pressurizing the vent system piping.
• Excessive negative air pressure in the installed space.
displayed fault/alert message
AC Reversed
Power supply to water heater
has reversed polarity.
Call a service professional:
Your Company Name Here
(press [DOWN] for more....)
CHANGE
Ignition Failure
The water heater has failed to
ignite the burner.
Call a service professional:
Your Company Name Here
(press [DOWN] for more....)
CHANGE
Low Gas Pressure
The supply gas pressure to the
water heater is low.
Call a service professional:
Your Company Name Here
(press [DOWN] for more....)
CHANGE
Low Igniter Current
Igniter current is low.
Call a service professional:
Your Company Name Here
(press [DOWN] for more....)
CHANGE
Blocked Exhaust
The exhaust is blocked or
restricted. Ensure
condensate hose is draining.
Call a service professional:
Your Company Name Here
(press [DOWN] for more....)
CHANGE
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