Navien NFC-175, Service Manual

Page: 71 / 138

NFC Service Manual 71 Version 1.0
Error Code Sub Code Function / Cause Self-diagnostic / Action
E615
1
Abnormal input data from High limit switch of Heat
Exchanger
Check the PCB.
3 Abnormal input data from flame rod
1. Check the flame rod wiring connection.
2. Check the flame rod.
4-5 Abnormal memory of PCB Check the PCB.
E736 0 Abnormal cascade communication
1. Check the cascade wiring connection.
2. Check the PCB.
E740
1
Abnormal outdoor temperature sensor (Open)
(appears only when the outdoor reset curve is
enabled).
1. Ensure that the outdoor reset curve is configured
properly.
2. Check the outdoor temperature sensor wiring
connection.
2
Abnormal outdoor temperature sensor (Short)
(appears only when the outdoor reset curve is
enabled).
E777 0 Abnormal operation: LWCO (external device)
1. Check the LWCO wiring connection.
2. Ensure that the system water level is appropriate.
3. Add make-up water to the system if necessary.
4. Check for proper voltage from connector
(24VAC).
E782 0 Abnormal Main-Panel communication Check the PCB.
E784 0
Abnormal operation: zone controller
communication (external device)
1. Check the zone controller wiring connection.
2. Check the zone controller PCB.
3. Check the Main and Panel PCB.
If any of the above solutions do not resolve the problem with the Boiler, contact Navien’s Technical department at 1-800-519-8794.
There will be error codes displayed on the front panel and recorded on the PCB board (within the unit) of any problems or failures that occur
with the Boiler.
IMPORTANT
To reset the Boiler, either press the [Reset] button on the front panel or disconnect, then reconnect electrical power to the boiler.