Navien NHB-055 Service Manual page 81

Error Code Sub Code
1
E279
2
E291 0
E302 0
E352 0
1
E353
2
1-7
8
E515 9
10
11-12
E517 0
E594 0
1
E615
3
4-5
1
E740
2
Version 1.0
Function
Abnormal operation: system return thermistor
(open)
Abnormal operation: system return thermistor
(short)
Supply / Return inversion limit
Low water pressure
High water pressure
Abnormal water pressure sensor (Open)
Abnormal water pressure sensor (Short)
Abnormal internal communication of PCB
Abnormal communication between PCB and Igniter
Abnormal communication between PCB and FAN
Abnormal monitoring device of PCB
Abnormal communication between PCB and Dual
Venturi
Abnormal dip switch setting
Abnormal operation: EEPROM
Abnormal input data from High limit switch of Heat
exchanger l
Abnormal input data from flame rod
Abnormal memory of PCB
Abnormal outdoor temperature sensor (Open)
(appears only when the outdoor reset curve is
enabled).
Abnormal outdoor temperature sensor (Short)
(appears only when the outdoor reset curve is
enabled).
Self-diagnostic / Action
Check the thermistor.
Check the thermistor.
Check if the supply water outlet piping of heating
piping and return inlet piping are mutually changed.
Check incoming water pressure and any activity at
PRV.
Check incoming water pressure and any activity at
PRV.
Check the water pressure sensor.
Check the PCB
1. Check the PCB connection
2. Check the Igniter
1. Check the PCB connection
2. Check the Fan
1. Check the PCB connection
1. Check the PCB connection
2. Check the Dual Venturi
Check the dip switches on the front panel and PCB.
Check the PCB.
Check the PCB.
1. Check the flame rod wiring connection.
2. Check the flame rod.
Check the PCB
1. Ensure that the outdoor reset curve is configured
properly.
2. Check the outdoor temperature sensor wiring
connection.
NHB Service Manual 81