Navien Exhaust or Air Intake Blocked (E110, E030)

The Short Answer: On NPE-2 models, a blocked exhaust or intake usually shows up as E110 (abnormal air pressure). Navien tells owners to make sure the exhaust pipe is clear and to clean the air intake filter. E030 (exhaust overheating) points instead to scale or a clogged inlet water filter. Check the outside terminals from the ground. Any work on the vent pipe itself is for a technician.

How Navien reports a vent or air problem

Navien condensing heaters use a fan to push combustion air in and exhaust out through plastic pipe. The control watches air pressure and exhaust temperature. If something is wrong, it shuts the burner off and shows a code. From the NPE-2 owner’s manual:

E030 isn’t usually a blockage. It means the exhaust is running too hot, which Navien links to poor heat transfer from scale or restricted water flow. E762 means the vent connection itself needs attention.

These codes are from the NPE-2 (NPE-A2/NPE-S2) manual. Older Navien models, NPN units and combi boilers have their own code lists.

What blocks a Navien vent

• Snow and ice building up over terminals near the ground or under eaves, or frost forming at the exhaust in very cold weather
• Leaves, nests, insects and wasps in intake terminals, especially after the heater sat unused
• Landscaping, a new deck, or stored items pushed up against a sidewall terminal
• Lint or dust clogging the internal air intake filter, especially in laundry rooms and garages
• Water in the vent from a section sloped the wrong way, which can gurgle and restrict flow
• A crushed, separated or improperly joined pipe after remodeling or other work near the vent

What you can check safely

1. Photograph the code, and note the weather and whether the code appears before lighting or after running a while.
2. Look at the terminals outside, from the ground or a safe walking surface. Gently remove loose snow, leaves or debris sitting on or in front of the openings. Don’t take caps or screens apart, push tools into the pipe, or climb onto a roof.
3. Clean the air intake filter. Navien’s NPE-2 manual says a filter clogged with dust or lint will stop the heater with E110, and recommends cleaning it every 3 to 4 months. The manual walks through turning off the heater and disconnecting power, then removing, washing, drying and replacing the filter. If you’re not comfortable with those steps, ask your installer to do it during service.
4. Check the condensate line isn’t blocked or frozen. Condensate backing up can affect combustion.
5. Reset once with the Back button. If the code returns, leave the heater off and call.

What the technician will check

A technician will inspect the full vent and intake run for blockages, separated joints, correct slope and proper support. They compare the total length and number of elbows against Navien’s installation manual and check terminal clearances, since an exhaust too close to the intake can recirculate exhaust into the heater. They then test the fan and air pressure readings and use a combustion analyzer to confirm clean burning. For E030, they check for scale and inlet filter blockage and flush the heat exchanger if needed.

Frequently Asked Questions

Q: Why does the code only show up in winter storms? A: Drifting snow and ice at low terminals are the usual reason. Wind pushing on the terminal can also upset air pressure readings. Keep the area around the terminals clear. If problems keep happening, an installer may be able to raise or relocate the terminals within Navien’s rules.

Q: Can a blocked vent cause carbon monoxide? A: The heater is designed to shut down when air flow is wrong, which is why it shows a code. A damaged or disconnected vent pipe indoors is still a serious hazard, so never operate the heater with damaged venting, and keep a working CO alarm nearby.