Display shows E030; unit may not start or may shut down unexpectedly.

Safety: Turn OFF power and allow the unit to cool before inspection.

Steps:

• 1. Inspect exhaust vent: Check the exhaust termination outside for obstructions and ensure the vent is not blocked by snow, ice, or debris.
• 2. Verify vent installation: Confirm that the vent piping is properly supported, sloped per Navien instructions, and not excessively long or with too many elbows.
• 3. Check condensate drainage: Ensure the condensate trap and drain line are clear so condensate does not pool in the vent, which can restrict flow and raise flue temperatures.
• 4. Descale heat exchanger: If the unit has not been descaled recently, perform a full heat exchanger flush to improve heat transfer and reduce flue gas temperature.

If E030 persists, the exhaust temperature sensor or main PCB may be faulty and should be tested and replaced by a technician.