Navien NCB300-28K, Service Manual

Page: 68 / 108

Troubleshooting 67
5.2.5 Error 016
Error Conditions and Checklist
Error Description
E016
Bi-metal overheated
If the overheat controller on the heat exchanger is initiated during boiler combustion
or standby, the system displays 016E (manually cleared) on the front panel. The boiler
switches to Lock-out mode and performs a continuous post-purge and starts the
circulation pump.
Checklist
1. Check the overheat controller is working correctly.
* Test the resistance or continuity.
2. Check the hot water temperature sensor.
3. Test the circulation pump’s supply voltage (AC 230 V).
4. Test the resistance at the pump.
Is HTL* operating
normally?
Is HTL* operating
normally?
Check connection
Replace the HTL*
Step 1: Flush and clean the filter
Step 2: Restart
Test the resistance
No
YES
Yes
No
Testing should be performed at least
30 minutes after the error occurred.
* HTL: High temperature limit switch