Navien tankless water heater error 110 indicates an exhaust overheat or abnormal air pressure issue, which can usually be resolved by clearing blocked intake or exhaust vents.
Table of Contents
- What does the 110 error code mean on a Navien tankless water heater?
- Why is my Navien tankless water heater showing error 110?
- How can I safely clear error 110 with quick fixes?
- What are the next steps if the 110 error code persists?
- Quick reference table for Navien error 110 symptoms and fixes
- When should you stop troubleshooting and call a professional?
- What information should you have ready before calling a technician?
- How can you keep error code 110 from coming back?
What does the 110 error code mean on a Navien tankless water heater?
The 110 error code on a Navien tankless water heater indicates an exhaust overheat or abnormal air pressure condition within the unit.
When your system detects that exhaust gases are not venting correctly or internal temperatures are rising too high, it shuts down for safety. This protects the heat exchanger from sustaining permanent damage. Confirm the exact meaning in your owner manual since definitions can vary slightly by model line.
- Indicates a critical exhaust temperature or airflow anomaly detected by internal sensors.
- Triggers an immediate safety shutdown to prevent internal component damage or fire hazards.
- Prevents harmful combustion gases from lingering dangerously inside the sealed combustion chamber.
- Signals that the unit cannot properly expel exhaust or pull in fresh outside air.
- Requires immediate troubleshooting of venting pathways and air intake components before resetting.
Why is my Navien tankless water heater showing error 110?
Error 110 typically happens due to blocked intake pipes, clogged exhaust vents, or a dirty internal air intake filter.
Over time, outdoor debris, dust, leaves, or even snow can obstruct the termination points of your venting system. Additionally, an accumulation of particulate matter on the internal air intake mesh filter restricts vital airflow, causing combustion temperatures to spike rapidly.
- Leaves, nests, or ice blocking the exterior termination cap on the outside wall or roof.
- Heavy dust and insect buildup clogging the internal mesh air intake filter inside the cabinet.
- Improperly secured vent pipe joints leaking combustion air or restricting smooth exhaust release.
- Exhaust run lengths exceeding manufacturer limits, causing residual heat to trap inside.
- A malfunctioning pressure switch failing to accurately read the internal draft pressure.
How can I safely clear error 110 with quick fixes?
You can resolve error 110 by turning off power, cleaning the air filter, and inspecting exterior vent terminations.
Always unplug your water heater or switch off the dedicated circuit breaker before touching internal parts to avoid electric shock. Inspect the outdoor terminations first, then clean the internal filter components carefully to restore normal airflow.
- Turn off the water heater and unplug the power cord from the electrical outlet.
- Remove the front cover panel of the Navien unit by unscrewing the mounting fasteners.
- Locate the internal air intake filter mesh inside the cabinet and unscrew it.
- Wash away accumulated dust and debris from the mesh filter using a soft brush and water.
- Dry the filter thoroughly with a clean cloth before screwing it back into place.
- Check the outdoor intake and exhaust vent terminals to clear away any nests, leaves, or snow.
- Reattach the front cover panel, plug the power cord back in, and reset the system.
What are the next steps if the 110 error code persists?
Inspect internal venting connections for leaks and verify that the pressure switch tubing is clear.
If cleaning the filter and checking the exterior vents does not clear the error, deeper internal inspection is necessary. Examine the silicone tubing connected to the air pressure switch to ensure it is not pinched, cracked, or blocked by condensation moisture.
- Unplug the appliance power cord from the electrical outlet before opening the cabinet again.
- Inspect all accessible indoor exhaust pipe joints to ensure they remain tightly connected and sealed.
- Locate the pressure switch and examine its small rubber tubing for any kinks, moisture, or blockages.
- Disconnect the rubber tubing carefully, blow through it lightly to clear moisture, and reattach it securely.
- Plug the power cord back into the electrical outlet and power on the appliance.
- Press the back button on the front control panel to clear the error code memory.
- Run a hot water faucet to test if the burner ignites and stays running without overheating.
Quick reference table for Navien error 110 symptoms and fixes
Match your specific observation to the corresponding likely cause and recommended immediate action.
Use this structured reference guide to quickly pinpoint what might be triggering your system shutdown based on environmental factors or recent changes around your home installation area.
| Symptom | Likely cause / fix |
|---|---|
| Error appears during heavy snow | Blocked outdoor vent / Clear snow |
| Error triggers after dusty conditions | Clogged intake filter / Clean mesh |
| Error returns immediately after reset | Blocked exhaust pipe / Inspect venting |
| Hissing sound near vent joints | Loose pipe connection / Secure joints |
| Error code with condensation pooling | Blocked drain tube / Clear blockage |
When should you stop troubleshooting and call a professional?
Stop troubleshooting and call a licensed professional if you smell gas, suspect a cracked heat exchanger, or face electrical issues.
Gas appliances involve severe safety risks regarding combustion and carbon monoxide. If basic vent cleaning and filter maintenance do not resolve the issue, specialized diagnostic tools are required to prevent hazardous equipment failures.
- Stop immediately if you detect any gas odor near the appliance and shut off the main gas supply.
- Call a technician if the heat exchanger shows physical signs of cracking, leaking, or severe corrosion.
- Contact support if internal electrical control boards or high-voltage wiring components appear damaged.
- Reach out to a certified expert if exhaust venting runs inside walls and requires professional reconstruction.
- Never attempt to modify or bypass safety pressure switches or internal thermal fuses on your own.
What information should you have ready before calling a technician?
Gather your exact water heater model number, serial number, warranty details, and troubleshooting history.
Providing precise details to customer support or a service technician helps speed up the diagnostic process and ensures they bring the correct replacement parts. Check the rating label on the side of your Navien cabinet for specifics.
- Locate the exact model number and serial number printed on the silver specification label on the unit casing.
- Note down the exact error code number, including any secondary sub-codes displayed on the panel screen.
- Prepare a brief summary of the troubleshooting steps you already tried, such as cleaning the air filter.
- Locate your original purchase receipt or installation date documentation to verify active warranty coverage terms.
- Write down your natural gas or propane provider details in case fuel supply pressure checks become necessary.
How can you keep error code 110 from coming back?
Prevent error 110 from returning by scheduling regular vent inspections and cleaning your air intake filter quarterly.
Routine preventive maintenance is the best way to safeguard your tankless water heater against unexpected shutdowns. Keeping external intake areas free of vegetation and washing internal filters every few months ensures optimal airflow efficiency.
- Inspect outdoor intake and exhaust termination caps at least four times a year for blockages.
- Clean the internal air intake mesh filter every three to four months to prevent dust accumulation.
- Keep landscaping bushes, shrubs, and mulch cleared at least two feet away from outdoor vent terminals.
- Schedule an annual professional service checkup to evaluate combustion efficiency and clean internal components.
- Monitor local weather alerts for heavy snowfall or severe storms that could obstruct outdoor exhaust pipes.
Frequently Asked Questions
Can I run my Navien tankless water heater temporarily without the air intake filter to clear error 110?
Running the unit briefly without the internal filter can help diagnose if a clogged mesh is causing the issue. However, you should never operate the water heater long-term without the filter because airborne dust and insects can enter and damage the combustion chamber.
What should I do if error 110 comes back immediately after I clear it and reset the system?
If the code returns instantly, it usually means the blockage has not been completely cleared or there is a physical restriction in the exhaust venting. Turn off the power, recheck the entire exhaust pipe length for obstructions, and verify that the pressure switch tubing is fully secured.
Is error code 110 safe to ignore if the water heater still produces hot water for a short time?
You should never ignore error 110 because it acts as a crucial safety warning for system overheating and exhaust restriction. Ignoring it can cause the appliance to lock out permanently, damage internal components, or risk unsafe combustion gas buildup.
Does Navien error code 110 apply to both tankless water heaters and combi-boilers?
Yes, the 110 error code generally signifies exhaust or abnormal air pressure issues across multiple Navien product lines, including NPE tankless units and combi-boilers. Always cross-reference your specific appliance manual since internal layouts and layout requirements can vary.
How much does it typically cost to repair a persistent Navien 110 error code issue?
Repair costs vary widely depending on your geographic region and whether the problem stems from simple vent blockages or failing internal components. Basic diagnostic labor or minor part adjustments typically range from moderate service fees to higher costs if venting redesign is required.
Bottom Line
Start your troubleshooting by turning off the power and inspecting your outdoor intake and exhaust vents for blockages. Cleaning the internal air intake filter will resolve most standard occurrences of this error.
Sources
- Navien owner’s manual
- Manufacturer support page
- Navien installation manual