COMBITHERM GAS INSTALLATION AND MAINTENANCE MANUAL — 6470ML
PG. 11
COMBITHERM® GAS INSTALLATION
1.21 SEQUENCE OF OPERATION
Honeywell SmartValve
™
System
• Pilot Valve/Ignition Off
• Wait for Flame Signal to Disappear
Five Minute Retry Delay
Apply 24 VAC
to Appliance
Start
Main
Burner
Operation
End
Igniter 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.
Trial for
Ignition
YES
YES
NO
Thermostat
Calls for Heat
• Pilot Valve Closes
• Igniter Off
• Main and Pilot Valves Close
• EFT Output De-energizes
Flame Lost More than Five
Times in One Call for Heat?
Flame Signal
Detected!
Internal Check
Okay?
Pilot Lights and Flame
is sensed during
Trial for Ignition?
• Igniter Off
• Main Valve Opens
Electronic Fan
Timer (EFT)
Output Energizes
Flame Signal Lost?
Thermostat Call for
Heat Ends
• Main and Pilot Valves Close
• EFT Output De-energizes
• Pilot Valve Opens
• Igniter Powered
Three Second Flame Failure
Recycle Delay
NO
NO
NO
NO
YES
YES
1
1
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