Navien NCB-24LSWE, Service Manual

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82 NCB Service Manual Version 1.0
5.2.1 Error 001
Error Conditions and Checklist
Error Description
E001
Heat exchanger
overheat
1. If the space heating water temperature is higher than 105
℃
, E001 will be displayed on the
front panel to warn users of high temperature conditions.
2. If the space heating water temperature decreases below 105
℃
, E001 will automatically reset
and the boiler will repeat the combustion cycle.
3. If the overheat error is repeated consecutively three times, E001 will be displayed until the
boiler is manually reset.
Checklist
1. Check the operation of the circulation pump. Run it in test mode.
2. Check the operation of the 3-way-valves. Run it in test mode.
3. Check if the heating strainer is obstructed.
4. Check if the main heat exchanger or the DHW heat exchanger is obstructed.
5. Check the heating inlet/outlet valve and distribution piping for obstructions.
6. Check the PCB DIP switch settings.
7. Check the PCB is operating properly.
8. If the fault condition remains after these checks, replace the PCB.