B

1. Open the main shut-off valve.
2. Open the device shut-off valve.
3. Shut down the device and check the gas line.
4. Signal evaluation on printed circuit board defective.
5. Replace flame sense electrode.
6. Establish protective conductor connection (PE) in the control device.
7. Replace ignition cable.
8. Replace the connecting lead to the flame sense electrode.
9. Replace air/gas ratio control valve.
10.Set the burner correctly or replace the burner nozzles.
11.Set the burner at minimum rated load.
12.Convert the flue system.
13.The interconnected combustion air supply is too low or the ventilation opening is too small.
14. Clean the heating block on the flue gas side.
15.Replace control device/burner control unit.