Error 109 - Navien NCB-24LSWE Service Manual

5.2.10 Error 109

Error occurrence conditions and check items
Error
The system checks the fan speed signal when the fan starts. The error message 109E (cleared manually) is
displayed in the following cases:
1. If fan speed is low or close to 0, the system detects a speed error and the boiler switches to Lock-out
E109
mode (gas valve and ignition transformer locked). The air pressure sensor should be normal.
Fan motor speed
error
2. If a low speed signal or one that is close to 0 is detected for 3 sec during combustion, the system
stops combustion and the boiler switches to Lock-out mode. The air volume sensor should be
normal.
1. Check if the fan motor works normally using the component test mode (refer to page 55).
2. Test the power supply to the fan (Black + Yellow, DC 340 V)
3. If the speed is very low while the fan operates and the power supply is normal, replace the fan motor.
Checklist
4. If the fan connector is wet for any reason, turn off the boiler, prevent further water ingress and dry
the components completely before resuming operation.
5. Check that the connection between the fan motor and the PCB is secure.
Version 1.0
Description
NCB Service Manual 101