Navien tankless water heater error code E110 indicates an exhaust temperature high limit activation, meaning the venting system is blocked or overheating.
Table of Contents
- What does error code E110 mean on a Navien tankless water heater?
- Why does my Navien water heater show error code E110?
- How can I safely clear error code E110?
- What are the next troubleshooting steps if error code E110 persists?
- Quick reference table for Navien E110 error causes and fixes
- When should I stop troubleshooting and call a professional?
- What information should I have ready before calling a technician?
- How can I prevent Navien error code E110 from coming back?
What does error code E110 mean on a Navien tankless water heater?
Navien error code E110 means the exhaust temperature has exceeded the safety high limit, triggering an automatic shutdown to prevent damage.
When your unit detects excessive heat in the exhaust pipe, it stops operating immediately to prevent a potential fire hazard or equipment failure. This usually points to restricted airflow, improper venting materials, or a blockage inside the flue pipe. Always consult your owner’s manual to confirm exact code definitions for your specific Navien model series.
- Exhaust temperature high limit switch has tripped.
- System shuts down automatically to prevent fire hazards.
- Indicates restricted airflow or blockage in the flue.
- Commonly triggered by debris, bird nests, or sagging vent pipes.
- Requires immediate inspection of the intake and exhaust venting.
Why does my Navien water heater show error code E110?
The E110 error is usually caused by blocked intake or exhaust vents, damaged flue pipes, or a failing thermal sensor.
Tankless water heaters rely heavily on unobstructed airflow for proper combustion and heat exhaust. If leaves, snow, insects, or physical damage block the termination cap outside, hot exhaust gases get trapped inside the venting system. Additionally, internal sensor malfunctions can falsely trigger this safety lockout.
- Blocked outdoor intake or exhaust vent termination caps.
- Debris, leaves, or nests accumulated inside the venting run.
- Improperly secured or disconnected indoor vent pipe joints.
- Exceeding maximum allowed equivalent vent pipe lengths.
- Faulty exhaust temperature sensor or loose wiring harness.
How can I safely clear error code E110?
Turn off the power, inspect the outdoor vents for blockages, and reset the unit using the front panel.
Before performing any physical checks, always disconnect power to the water heater at the breaker box to prevent electrical shock. Carefully examine the exterior termination points of your venting system for any visible obstructions. Once cleared, restore power and test the unit to see if error code E110 returns.
- Turn off the power switch on the unit and trip the dedicated circuit breaker.
- Locate the intake and exhaust vent pipes on the exterior wall or roof.
- Remove any leaves, dirt, ice, or animal nests blocking the termination caps.
- Inspect accessible indoor vent sections to ensure all pipe connections remain secure.
- Restore power at the breaker and press the back or reset button on the display.
What are the next troubleshooting steps if error code E110 persists?
If resetting does not work, check vent pipe clearances, look for internal blockages, and test the sensor.
Persistent E110 codes mean the high limit condition is still occurring or the sensor itself cannot read temperatures accurately. You should verify that your installation meets the manufacturer’s clearance and slope specifications. Working with gas venting requires caution, so stop immediately if you suspect structural vent damage.
- Unplug the unit power cord before inspecting internal wiring or components.
- Verify that vent pipes slope upward toward the outside termination point.
- Check the exhaust thermistor wire connection on the control board for security.
- Measure sensor resistance with a multimeter if you have technical experience.
- Contact a professional if venting configurations do not match manual requirements.
Quick reference table for Navien E110 error causes and fixes
Match your specific symptom to the likely cause and recommended fix for Navien error code E110.
Use this quick reference guide to identify common scenarios associated with exhaust temperature faults on your Navien tankless water heater. Each symptom correlates directly with a targeted remedial action to help restore normal hot water operation quickly.
| Symptom | Likely cause / fix |
|---|---|
| Blocked outdoor cap | Clear leaves or snow from vent |
| Loose indoor vent pipe | Re-secure and seal pipe joints |
| Code returns after reset | Inspect exhaust sensor wiring |
| Intermittent E110 fault | Check for wind interference outside |
| Damaged venting material | Replace non-approved vent sections |
When should I stop troubleshooting and call a professional?
Call a licensed technician immediately if you smell gas, suspect cracked venting, or if the error code returns constantly.
Gas appliances present severe safety risks including carbon monoxide leaks and fire hazards. If basic vent clearing does not resolve error code E110, or if you notice any structural damage to the exhaust flue, stop troubleshooting immediately. Professional technicians possess specialized combustion analyzers required to diagnose complex venting failures safely.
- You detect any strange odors or suspect a gas leak nearby.
- The exhaust vent pipe shows physical cracks, holes, or separation.
- Error code E110 returns immediately after every power reset.
- You lack the tools or confidence to inspect high-mounted vent terminations.
- Combustion testing requires specialized professional diagnostic equipment.
What information should I have ready before calling a technician?
Gather your exact water heater model number, serial number, error code history, and warranty status before calling.
Having accurate details ready helps service technicians dispatch the correct parts and estimate repair timelines more efficiently. Locate the data rating plate on the side casing of your Navien unit to find the complete model and serial numbers. Documenting when the error occurs also helps technicians diagnose intermittent issues faster.
- Complete Navien model number from the unit’s rating plate.
- Unique serial number and manufacturing date code.
- Exact error code number and frequency of occurrence.
- Description of all troubleshooting steps you already tried.
- Proof of purchase or installation date for warranty verification.
How can I prevent Navien error code E110 from coming back?
Perform annual maintenance, keep outdoor vent areas clear of obstructions, and schedule regular professional inspections.
Preventative maintenance keeps your tankless water heater operating safely and efficiently year-round. Regularly inspecting your exterior vent terminations ensures that seasonal changes, landscaping growth, or severe weather do not restrict airflow. Proactive care significantly reduces unexpected breakdowns and extends equipment lifespan.
- Inspect outdoor intake and exhaust terminals at least twice a year.
- Keep shrubs, bushes, and debris cleared three feet around vents.
- Schedule annual professional tune-ups and combustion checks.
- Check indoor vent connections periodically for secure fitting.
- Protect outdoor termination areas from severe winter snow buildup.
Frequently Asked Questions
Can I run my Navien water heater safely while error code E110 is active?
No, you should not attempt to run the water heater while error code E110 is active. The unit locks out automatically to protect itself and your home from potential overheating hazards caused by restricted exhaust airflow.
What should I do if clearing the vents does not clear error code E110?
If physical vents are completely clear and the error persists after a hard power reset, the internal exhaust thermistor or control board may be faulty. Contact a qualified Navien service provider to test electrical components.
Does error code E110 mean my heat exchanger is damaged?
Not necessarily. While E110 indicates high exhaust temperatures, it is most frequently caused by external venting blockages rather than a damaged heat exchanger. However, chronic overheating can eventually cause internal component stress.
Is Navien error code E110 covered under the manufacturer warranty?
Component failures like a faulty sensor are typically covered under Navien’s standard parts warranty, provided the unit was installed correctly by a licensed professional. Venting blockages caused by environment or installation errors are generally not covered.
How do I perform a hard reset on my Navien tankless water heater?
To perform a hard reset, turn off the power button on the front control panel, switch off the dedicated circuit breaker for 60 seconds, and then turn the breaker and power switch back on.
Bottom Line
Turn off the power to your water heater and safely check the outdoor vent terminations for any blockages as your very first step.
Sources
- Navien Owner’s Manual
- Navien Installation Manual
- Manufacturer Support Page
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