Boiler displays error 65 and may shut down during operation.

Safety: Turn OFF power and close water valves before removing any water-carrying components.

• 1. Check system pressure and valves: Ensure the boiler loop is properly pressurized and all isolation valves are open.
• 2. Clean inlet filter: Remove and clean the Noritz inlet water filter to ensure adequate flow to the flow control assembly.
• 3. Inspect flow control wiring: With power OFF, locate the flow control valve/sensor assembly and verify that its connector is secure and wiring is undamaged.
• 4. Professional service: If error 65 continues, the flow control valve or sensor may need replacement and system purging, which should be done by a technician.