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TROUBLESHOOTING
For your safety, water heater service should be performed only by a qualified service technician.
Read the GENERAL SAFETY INFORMATION section first.
WARNING: DO NOT BY-PASS ANY CONTROLS TO MAKE HEATER OPERATE. OPERATE ONLY AS WIRED FROM FACTORY.
NOT ENOUGH OR
NO HOT WATER
YELLOW FLAME
CONDENSATION
WATER LEAKS
LEAKING T&P VALVE
HOT WATER ODORS
OR COLOR
(Refer to CATHODIC
PROTECTION)
PROBLEM POSSIBLE MALFUNCTION SERVICE TO BE PERFORMED
1) Blower will not run
A) “ON/OFF” control switch turned off
B) Blower unplugged
C) No power at outlet
D) “ON/OFF” switch defective
E) Control harness defective
F) Blower motor defective
2) Blower running, burner not on
A) Fan not running fast enough to close
air switch contacts
B) Air pressure switch defective
C) Gas valve defective
D) Control harness defective
E) Igniter defective
F) Unit has completed three trials to light
and failed
3) Thermostat problems
A) Thermostat set too low
B) Thermostat or ECO defective
C) High limit control circuit open
4) Others
A) Heater undersized
B) Low gas pressure
C) Incoming water is unusually cold
D) Leaking hot water pipes or fixtures
A) Dirt in burner ports
B) Combustion air path restricted
C) Not enough room air for proper
combustion
A) Water on the floor under heater
Improperly sealed, hot or cold supply
connections, relief valve, drain valve or
thermostat threads.
Leakage from other appliances or water lines
Condensation of flue products
Thermal expansion in closed water system
Improperly seated valve
High sulfate or mineral content in water
supply or iron or sulfate reducing bacteria in
water supply
Turn switch to the “ON” position.
Plug blower back into 115 vac. outlet.
Repair service to outlet.
Replace switch.
Replace control harness.
Replace blower and motor.
Replace switch.
Check for low voltage, less than 102 vac., have
service checked and repaired.
Replace switch.
Replace gas valve.
Replace harness.
Replace igniter.
Reset cycle by turning switch off and then back on.
If unit does not light in three trials, call an authorized
A.O. Smith service representative.
Turn temperature control higher.
Replace thermostat.
Replace.
Reduce hot water use.
Contact an authorized A.O.Smith service representative.
Allow more time for heater to re-heat.
Have plumber check and repair leaks.
Turn off heater and gas, clean burner head.
Clear area around heater and check under heater,
remove any debris under heater and in openings in
bottom cover.
Refer to installation manual - Confined and Unconfined
Space statements on page 4 and 5 for required
openings.
See “CONDENSATION.”
Turn off heater & water, repair unit.
Inspect other appliances near water heater.
Refer to “CONDENSATION.”
Install thermal expansion tank (DO NOT plug T&P valve).
Check relief valve for proper operation (DO NOT plug T&P valve).
Drain and flush heater thoroughly, chlorinate, refill
and flush again then chlorinate water supply.