Water heater does not produce any hot water; burner never starts and there is no error code displayed.

Safety: Turn off power and close the cold water supply before opening any water connections.

• Check water supply: Open a cold tap to confirm adequate pressure. If building pressure is low, correct this first.
• Clean inlet filter: Isolate the heater, remove the cold inlet filter screen, and rinse out debris. Reinstall securely.
• Inspect flow sensor: Remove and inspect the flow sensor for scale or debris. Clean gently and ensure the turbine or paddle moves freely.
• Check wiring: Verify that the flow sensor connector is firmly attached to the control board and that the cable is undamaged.
• Test operation: Restore water and power, then open a hot tap. Observe whether the heater now detects flow and starts.