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NBC 240 problem

rosie1212 Member Posts: 1
Have a 5 yr old Navien Ncb 240 natural gas combi. Display works fine until a call for heat/ hot water. Fires for 30 seconds,  monitor goes black and unit turns off. No error codes to help diagnose. Any ideas what is causing this?


  • Larry Weingarten
    Larry Weingarten Member Posts: 3,079
    Hi, You just might still be under warranty for this heater. I'd call Navien and see what they can do to help.

    Yours, Larry