20 Troubleshooting
5.2 Understanding Error Codes
When an error code appears on the front panel, refer to the following chart for a definition and possible remedy for the situation.
Error Code
Reason
Self-diagnostic/Action
E001
Heat exchanger over temperature
Auto reset/Manual reset/Power On reset
E003
Ignition failure
Manual reset/Power On reset
E004
False flame detection
Auto reset
E012
Flame loss
Manual reset/Power On reset
E016
Heat exchanger overheat
Manual reset/Power On reset
E030
Abnormal operation: exhaust temperature
Auto reset/Manual reset/Power On reset
E046
Abnormal operation: heat exchanger overheating sensor
Auto reset
E047
Abnormal operation: exhaust thermostat
Auto reset/Manual reset/Power On reset
E060
Abnormal operation: dual venturi
Alarm
E109
Abnormal operation: fan motor
Manual reset/Power On reset
E110
Exhaust vent closed
Manual reset/Power On reset
E205
Abnormal operation: heating supply thermistor
Auto reset
E218
Abnormal operation: heating return thermistor
Alarm
E271
Temperature differential limit
Alarm
E278
Abnormal operation: system supply thermistor
Alarm
E279
Abnormal operation: system return thermistor
Alarm
E291
Supply/Return inversion limit
Manual reset/Power On reset
E302
Low water pressure
Manual reset
E352
High water pressure
Auto reset
E353
Abnormal operation: water pressure sensor
Auto reset
E515
Abnormal operation: PCB component
Alarm/Manual reset/Power On reset
E517
Abnormal operation: DIP switch setting (PCB)
Manual reset/Power On reset
E594
Abnormal operation: EEPROM (PCB)
Alarm
E615
Abnormal operation: MCU
Alarm/Auto reset/Manual reset/Power On
reset
E740
Abnormal operation: outdoor temperature sensor
Alarm
E777
Abnormal operation: LWCO limit (external device)
Auto reset
E782
Abnormal operation: boiler communication
Alarm
E784
Abnormal operation: zone controller communication (external device)
Alarm
If these remedies do not resolve the problem, contact Technical Support at 1-800-519-8794.
Summary of Contents for NHB-110
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