Navien Error Code E110: Exhaust Blocked

The E110 code on a Navien unit means the control board detected that exhaust gases are not flowing properly out of the flue pipe. This can be because the exhaust pipe is blocked by debris, snow, or ice, or because the combustion fan cannot push the gases out due to a restriction. The unit shuts down to prevent carbon monoxide from backing into the home. This code is common on condensing models where the plastic exhaust vent can become clogged with ice in winter or with debris over time. Do not attempt to operate the unit until the blockage is cleared, and always have the vent system inspected annually.