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 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 temperature and flue temperature reading on User Interface significantly different?
Yes: Replace Flue Gas Sensor
No: Replace Control Module
