Burners and Heat exchanger have considerable amount of rust.I preformed combustion on unit all readings came back in range, I checked air stream all okay. does appear to be a small crack in the collector box, see photos. While tech didn’t detect any co, I let customer know of possible co leak from this and damage it is causing to unit. I also let homeowner know to get co detectors for home. System coming on and running as it should other than this.
