START
System Check
Trial for
Ignition
Main Burner
Operation
END
(1) Ignitor will turn OFF about 30 seconds into the trial for ignition if the pilot flame has not lit. It will turn back ON for the final 30 seconds
of the 90 second trial for ignition. The pilot valve will be energized during the entire trial for ignition. This is normal operation for this gas
ignition system.
12427-7-1007
SEQUENCE OF OPERATION
Apply 24 VAC
To Appliance
Thermostat
Calls for Heat
Flame Signal
Detected
NO
Internal Check
OK
YES
Pilot Valve Opens
Ignitor Powered
Pilot Light and Flame is
Sensed During Trial For
Ignition (1)
YES
Ignitor OFF
Main Valve Opens
Flame Signal
Lost?
NO
Thermostat Call for Heat
Ends
Main Pilot Valves
Close
Pilot Valve Ignition OFF
YES
Wait for Flame Signal to
Disappear
NO
Pilot Valve Closes
NO
Ignition OFF
YES
Main Pilot
Valves Close
Flame Lost More
Than 5 Times in
One Call for Heat
YES
5 Minute Retry Delay
3 Second Flame Recycle
Delay
NO
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