17
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.
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
G) Discharge air limit tripped
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
E)
Polarity reversed
F)
Heater not grounded
A ) Blower does not run when heater fired
B) Not enough dilution air to mix with flue
gases in “Tee”
C) Air in room too hot for mixing with flue gases
D) Wrong burner orifice
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
Outlet polarity is reversed
PROBLEM
POSSIBLE MALFUNCTION
SERVICE TO BE PERFORMED
NOT ENOUGH OR
NO HOT WATER
VENT PIPE TOO HOT
(ABOVE 170° F)
YELLOW FLAME
CONDENSATION
WATER LEAKS
LEAKING T&P VALVE
HOT WATER ODORS OR COLOR
(Refer to CATHODIC PROTECTION)
HEATER LIGHT GOES OUT
IN 4-5 SECONDS
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.
If voltage is above 102 vac., make sure there is not more than
30 Equivalent feet of 3 inch pipe or85 equivalent feet of 4 inch
pipe installed or vent terminal blockage.
If at least 102 vac., less than 30 equivalent feet of 3 inch pipe
or 85 equivalent feet of 4 inch pipe and not terminal blockage,
replace blower.
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.
Verify dilution air openings are free of obstructions.
Make sure there is no more than 30 equivalent feet of 3 inch pipe or
85 equivalent feet of 4 inch pipe.
Check for low voltage, less than 102 vac., have service
checked and repaired.
Make sure vent terminal is not blocked.
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.
Correct wiring
Correct
Take unit out of service immediately, call an authorized A.O.
Smith service representative.
Proper air circulation must be provided for combustion and
dilution of flue temp. Refer to “INSTALLATION” section.
Room air to be used for dilution with combustion products in
flue should be less than 90°F.
Install correct orifice.
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.
Test polarity and correct.
