Navien NPE-180A Service Manual page 104

Panel Test operation mode
Check connector motor resistance
(see page 52 for Wiring Diagram)
Check method
Fault Possible Causes
Malfunction of water
adjustment valve
Remote controller /
PCB error
Defective water
adjustment valve
Defective water
Water heater works but
adjustment valve
error occurs
(WAV operation)
Is the operation normal?
NO
(CON8)
If an error occurs in the cascade system, disconnect the cascade cable and check the
system in the following procedure:
1. Check the operation of the water adjustment valve using the Component Test
mode (refer to page 47).
2. If the PCB is defective, the motor keeps operating as the water adjustment valve is
OPEN or CLOSED, or the valve repeats open/close.
3. Replace the water adjustment valve for other symptoms.
4. As a temporary measure, you can disassemble the water adjustment valve, open it
manually, and separate the power cable of the water adjustment valve.
1. Open or short-circuit of the flow control valve sensor.
2. Check the connector assembly and wiring state of the water adjustment valve
feedback sensor.
sensor
3. Check the operation of the water adjustment valve using the Component Test
mode (refer to page 47).
Yes
Reset the unit
Check method
Troubleshooting 103