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12427-2-0903
Page 13
START
System Check
END
SEQUENCE OF OPERATION
Trial for
Ignition
Main Burner
Operation
Apply 24 VAC
to Appliance
Thermostat
Calls for Heat
Flame Signal
Detected
Internal Check
OK
• Pilot Valve Opens
• Ignitor Powered
Pilot Light and Flame is
Sensed During Trial
For Ignition (1)
• Ignitor OFF
• Main Valve Opens
Flame Signal
Lost?
Thermostat Call
for Heat Ends
NO
NO
NO
NO
5 Minute Retry
Delay
3 Second Flame
Failure Recycle
Delay
YES
YES
YES
NO
• Pilot Valve Ignition OFF
• Wait for Flame Signal to
Disappear
(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 seeonds
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.
• Pilot Valve Closes
• Ignition OFF
Main Pilot Valves
Close
Flame Lost More
Than 5 Times in
One Call for Heat
Main Pilot
Valves Close
YES
YES