I was on a job today with 3 Lochinvar Copper Fin 2 Model #CHN0990 with M9 Controls, having 3 Stages of Burners. Each boiler has it's own primary pump that are part of a primary/secondary system. The burners have been set up at 1.3" W.C. air pressure, and 3.5" gas ( upped to 4" due to lite-off problems). Burners have been replaced previously due to cracking.
The main problem now is that the burners will lock out intermittantly on flame failure. They will also run a different milliamp signal as the outdoor air temp changes (OA is ducted to each boiler).
Has anyone had this problem? If so, what was the fix?