Navien NHB-055, Service Manual

Page: 98 / 147

98 NHB Service Manual Version 1.0
5.2.6 030Error
Error occurrence conditions and check items
Error Description
E030
Exhaust gas temperature error
If the temperature sensor on the top of the exhaust duct is initiated, the system displays the
exhaust overheat message 030E (cleared manually) on the front panel.
The boiler switches into Lock-Out, and performs post-purge continuously and operates the
pump.
Overheating controller operates when the temperature exceeds 230°F (110°C) for 10 minutes
or over.
1. When the controller detects the exceeding temperature of 230°F (110°C) for 10 minutes or
over, “E030” error code will display and perform post-purge. → Automatically cleared.
2. When the controller detects the exceeding temperature of 140°F (60°C) while performing
post-purge. → Manually cleared.
3. When the controller detects the exceeding temperature of 230°F (110°C) for 10 seconds or
over three times or more after the error is automatically cleared.
→
Manually cleared.
Check items
1. Check if the overheat controller operates normally.
2. Check if the PCB works properly.
Is exhaust thermistor
normally operating?
Check the heat exchanger
Check for leakage in the
combustion chamber
Flush heat exchanger
Check the exhaust thermistor
Check the resistance between #9 and #10
of CN 13: short-circuit (See page 63-64 for
Wiring Diagram)
No
Yes