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IGNITER ROD
The igniter rod is responsible for conveying the spark to a grounding rod in an appropriate location to ignite the gas and ai r
mix. The igniter rod gap should be 1/8”, larger gaps will create ignition problems. If the igniter rod is cr acked, sparking sound
will be heard inside the burner air tube but ignition will not occur and lockout will occur.
MORE SERVICE HINTS
THERMOSTAT CALLS FOR HEAT AND THE FOLLOWING CONDITIONS OCCUR:
1. PROBLEM: The combustion fan motor is not operating.
Possible Reasons:
a. Power is not on.
b. Circuit breaker tripped.
c. Thermostat in the off position.
d. Thermostat connections to T-T terminals on junction box have shorted to the junction box.
e. Bad thermostat.
f. Blower wheel jammed
g. Debris stuck in blower wheel blades.
h. 24 volt transformer is not functioning properly.
i. Thermostat leads not connected to the T-T terminals.
j. Motor shorted out due to over voltage.
k. Motor start relay not functioning properly.
2. PROBLEM: Combustion fan motor runs but ignition sequence does not occur.
Possible Reasons:
a. Blower motor endswitch not closed which completes the 24 volt circuit to the gas primary.
b. The blower motor is not reaching full rpm due to debris on wheel.
c. Low voltage to the blower motor.
d. Loose connections on the 24 volt circuit after the endswitch or between fan relay and the 24 volt side of the gas primary.
e. The gas primary control is defective and must be replaced.
3. PROBLEM: Combustion fan motor runs and ignition sequence initiated but goes into lockout.
Possible Reasons:
a. Spark electrode rod is cracked shorting spark to ground.
b. Loose connection on spark electrode rod.
c. Gas primary control not allowing 24 volts to gas valve.
d. Gas valve shorted out or defective.
e. No ground between burner and appliance.
f. Spark electrode location shifted.
g. Gas primary control not generating spark.
h. Ignition wire insulation melted and is grounding out on burner.
i. Gas supply is not turned on.
j. Gas manifold pressure is too high.
k. Gas manifold pressure is too low.
l. High negative draft conditions.
m. Gas supply line is undersized.
n. Multiple appliances operating on undersized line.
o. Insufficient combustion air flow.
p. Incorrect air shutter adjustment allowing too much combustion air to enter burner.
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