A.O. Smith GPDH Owner's Manual page 18

PROBLEM
NOT ENOUGH
HOT WATER
VENT PIPE TOO HOT
(ABOVE 170°F)
YELLOW FLAME
CONDENSATION
WATER LEAKS
LEAKING T&P
HOT WATER ODORS
(Refer to CATHODIC
PROTECTION)
WATER TOO HOT
WATER HEATER SOUNDS
SIZZLING-RUMBLING
SOOTING
HEATER LIGHTS BUT GOES
OUT IN 4-5 SECONDS
TROUBLE SHOOTING (Continued)
CAUSE
1) Blower will not run.
A) "ON/OFF" control switch turned off.
B) Blower unplugged.
C) No power at outlet.
D) Thermostat defective.
E) Control harness defective.
F) High limit control circuit open.
G) Blower motor defective.
Thermostat problems.
A) Thermostat set too low.
B) Thermostat or ECO defective.
Others
A) Heater undersized.
B) Low gas pressure.
C) Incoming water is unusually cold.
D) Leaking hot water pipes or fixtures.
A) Defective air flow restrictor.
B) Not enough dilution air to mix with
flue gases in inlet tee.
C) Dilution air too hot for mixing with
flue gases.
D) Wrong burner orifice.
A) Dirt in burner ports
B) Combustion air path restricted.
C) Not enough dilution air for proper
combustion.
A) Water on the floor under heater.
B) Water dripping from pan.
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.
Bacteria in water supply.
Thermostat set too high.
Condensation dripping on burner.
Sediment at bottom of heater tank.
Improper combustion.
Outlet polarity is reversed.
SOLUTION
Turn switch to the "ON" position.
Plug blower back into 115 Vac. outlet.
Repair service to outlet.
Replace thermostat.
Replace control harness.
Replace ECO.
Replace Blower Assembly.
Set temperature control higher.
Replace thermostat or ECO as required.
Reduce hot water use.
Contact dealer.
Allow more time for heater to reheat.
Have plumber check and repair leaks.
Take unit out of service immediately, call an
A.O. Smith service representative.
Proper dilution air must be provided for
combustion and dilution of flue temp.
Refer to "INSTALLATION" section.
Supply air is too hot. Check for heat sources
around intake terminal and blockage of
dilution air leg.
Install correct orifice.
Turn off heater and gas, clean burner head.
Check intake venting arrangements for
obstructions.
Check Intake venting arrangement for
obstructions.
See "CONDENSATION" section.
Provide drip "TEE" to catch condensation,
see Figure 1.
Tighten threaded connections.
Inspect other appliances near water heater.
Refer to "CONDENSATION" section.
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 then refill.
Chlorinate water supply.
Refer to TEMPERATURE REGULATION.
Refer to CONDENSATION above.
Clean sediment from tank. Refer to DRAINING
instruction in Maintenance section of manual.
Refer to COMBUSTION AIR AND EXHAUST on
page 6.
Test polarity and correct.
18