Flue temperature sensor sees temperature higher than 200°F.
1. Read flue gas temperature on user interface. Is temperature higher than 200°F?
Yes: Boiler is over fired. Wait for the boiler to cool. Fix flow rate problem if any purging all air out of the system.
No: -> 2
2. Use thermal couple to measure flue gas temperature through sampling port. Is the measured reading on user interface significantly different?
Yes: Replace flue gas sensor
No: Replace control module.
