If you’re seeing the E110 error code on your Navien water heater, it means there’s a problem with overheating in the heat exchanger. This issue is quite common in both Navien combi boilers and tankless water heaters, but luckily, it can often be fixed without replacing the entire unit. Let’s explore what causes this error, how to reset it, and when to call a professional.

What Does the Navien E110 Error Code Mean?

The E110 error indicates that your heat exchanger is overheating. In simple terms, the water inside the system is getting too hot, too quickly. To prevent damage, the unit automatically shuts down and displays the error.

This overheating is typically caused by restricted water flow or poor circulation, meaning the heat isn’t being properly transferred away from the burner.

Common Causes of the E110 Error Code

Here are the most frequent reasons you might see the E110 error on a Navien system:

• Clogged or dirty heat exchanger

• Over time, scale buildup or debris can block water passages and cause overheating.

• Low water flow

• Insufficient flow due to closed valves, blocked filters, or faulty pumps can trigger the error.

• Air trapped in the system

• Air pockets prevent efficient water circulation, leading to hot spots and overheating.

• Faulty temperature sensor

• If the thermistor or temperature sensor malfunctions, it can give false readings and shut the unit down.

• Dirty or failing fan motor

• Poor airflow prevents proper cooling of internal components.

• Circulation pump failure

• If the circulation pump stops working or runs intermittently, overheating can occur quickly.

How to Fix the E110 Error Code

You can try a few troubleshooting steps before calling a technician:

• Turn off the unit and let it cool — Always start by powering off the Navien and allowing it to reset.

• Check for water flow — Make sure the inlet and outlet valves are open, and filters aren’t blocked.

• Flush the heat exchanger — If scale buildup is the issue, a tankless water heater flush can help.

• Bleed air from the system — Air vents can help release trapped air pockets.

• Inspect sensors and wiring — Ensure temperature sensors are connected and working correctly.

If the error persists after these steps, the issue may involve the fan motor, control board, or circulation pump, which require professional inspection.

When to Call a Professional

If your Navien continues to show the E110 code even after flushing and resetting, it’s time to call a qualified technician. A professional can:

• Test temperature sensors

• Inspect and clean the heat exchanger

• Replace faulty parts like pumps or fans

• Ensure your system is properly vented and calibrated

In Islamabad, Lahore, or Karachi, you can contact Muhammad Technical Services for expert water heater repair and maintenance.

Preventing the E110 Error Code

Prevention is the best way to avoid the E110 issue. Follow these maintenance tips:

• Flush your water heater at least once a year

• Use a water softener if you have hard water

• Check for leaks or blockages regularly

• Schedule professional maintenance annually

You can also read about Tankless Water Heater Flush to keep your Navien running efficiently.

Final Thoughts

The E110 error code on Navien is a sign that your water heater is overheating — often due to low water flow or buildup. With regular maintenance, proper flushing, and timely repairs, you can prevent this error from happening again.

For fast and reliable plumbing or water heater service in Islamabad, contactMuhammad Technical Services your trusted home repair experts.