Navien NCB-700-2S+/42K, Service Manual, Page: 87 / 121

86 Troubleshooting
5.2.12 Error 110
Error Conditions and Checklist
Error Description
E110
Air pressure error
The system detects the air pressure and the fan speed and displays 110E on the front
panel in the following cases:
1. When the initial fan auto-adjustment is not performed.
2. When boiler reaches 95% of maximum heating capacity during combustion and the
APS is not rated at the standard value.
Checklist
1. Check the venturi (burner) hole for obstruction.
2. Check the condensation drain line and drain for obstruction.
3. Check the flue and exhaust are installed correctly and have adequate clearance. (The
circulation of exhaust gas generates noise.)
4. Check if the air supply/exhaust flue is obstructed (rainwater may accumulate inside
incorrectly installed air supply/exhaust pipes).
5. Check for a faulty air pressure sensor or PCB.
6. Ensure that the vents slope downwards towards the unit for proper condensate
drainage.
7. Ensure the internal damper moves freely and is not obstructed.
Is there any air flow
restriction?
Remove all air flow restrictions
from around the boiler and check
the flue pipe for obstructions.
Reset or restart
No
Yes