Navien E110: exhaust or condensate blockage, causes and fixes

Navien defines E110 as an exhaust blockage, with condensate blockage named as a cause. On a condensing heater, the exhaust and the condensate drain are connected: if condensate cannot drain, it backs up into the exhaust path.

That means E110 is often something you can find yourself.

What to check first

1. Go outside and check the exhaust and intake terminals for snow, ice, leaves, nests or anything placed against them.
2. Follow the condensate drain line from the unit to where it drains. Look for kinks, sags that hold water, clogs or ice.
3. If there is a condensate neutralizer, make sure it is not full of debris.
4. Turn the unit off with the power button, wait a minute and turn it back on.

Winter and E110

Condensate lines that run through a cold garage, crawl space or outside wall can freeze. Once the ice melts the code may clear, but it will return in the next cold snap unless the line is rerouted or protected.

When to call a technician

If the vents and drain are clear and E110 returns, a technician should check the vent installation, the condensate trap inside the unit and the sensors. Do not run the heater with a known exhaust problem. Keep a working carbon monoxide detector in the home.