Navien NHB-055 Service Manual page 80

Error Code Sub Code
E030 0
E046 2
1
E047
2
1
2
E060
3
E109 0
1
2
E110
3
1
E205
2
1
E218
2
E271 0
1
E278
2
80 NHB Service Manual
Function
Exhaust Overheat : exhaust limit switch
shuts down the unit when the flue
temperature exceeds 230 °F (110 °C) for more than
10 minutes.
Abnormal heat exchanger thermistor (short)
Abnormal exhaust thermistor (open)
Abnormal exhaust thermistor (short)
Abnormal Dual Venturi Limit Switch operation (ON)
Abnormal Dual Venturi Limit Switch operation
(Close OFF)
Abnormal Dual Venturi Limit Switch operation
(Open ON)
Abnormal fan motor activity
Exhaust blockage (checking the FAN)
Exhaust blockage (Using hot water)
Exhaust blockage (using space heating)
Abnormal Heating supply thermistor (open)
Abnormal Heating supply thermistor (short)
Abnormal Heating return thermistor (open)
Abnormal Heating return thermistor (short)
Temperature differential limit
Abnormal operation: system supply thermistor
(open)
Abnormal operation: system supply thermistor
(short)
Self-diagnostic / Action
1. Turn OFF the system for at least 30 minutes then
restart.
2. Clean the inlet filter.
3. Check exhaust thermistor and verify [P] value in
DIAGNOSTIC mode
4. Check for proper dipswitch settings.
5. Check the heat exchanger; a flush may be
necessary.
1. Check heat exchanger thermistor connection
2. Check for proper connection to the PCB.
Check the exhaust thermistor connection. Check for
proper connection to the PCB.
Check the Dual Venturi connection.
Test Dual Venturi for proper operation using TEST
mode.
Check gas orifice for obstructions.
1. Check and clean the intake air filter.
2. Check and clean the fan motor.
3. Check for proper voltage from PCB. Replace fan if
PCB voltage is normal.
1. Check the exhaust pipe for obstructions.
2. Check and clean the intake air filter.
3. Remove exhaust pipe if possible to verify vent
blockage.
1. Check the thermistor.
2. Check the pump connection
Check the thermistor.
1. Check if flow rate heating pipe is proper? Check
if the heating pipe is clogged with debris.
2. Check if capacity of the circulation
pump(external) is enough to circulate water in
pipe
Check the thermistor.
Check the thermistor.
Version 1.0