Navien NP-180 Service Manual page 107

Check method
Error
Malfunction of
water adjustment
Remote controller /
PCB error
Defective water
adjustment
Water heater Defective water
adjustment valve
works
but error occurs
©Navien America Inc. 2010
Cause
If an error occurs in the cascade system, disconnect communication,
and check the system in the following procedure:
Connect a good water adjustment valve to the PCB The valve
1.
valve should remain open when the water heater is not operating.
2.
If the PCB is defective, the motor keeps operating as the water
adjustment valve is in OPEN or CLOSE status, or the valve repeats
open/close.
3. Replace the flow control valve for other symptoms.
valve
As a temporary measure, you can disassemble the water
4.
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.
3. Check the water adjustment valve output value (AD) displayed
sensor
on the PCB.
On the display, F.15 or lower means the valve is open, and F.240 or
higher means the valve is closed
105
NR/NP series service Manual
Check method
Version 2.0