Noritz Tankless Water Heater Code 14 [Reasons + Solutions]

Your Noritz Tankless water heater code 14 indicates the thermal fuse of the unit has failed due to overheating. The leading reason that causes the water heater to overheat and the thermal fuse failure includes:

  • The build-up of sediment deposits in the heat exchanger
  • Blocked exhaust and air intake 

A thermal fuse is a safety device and needs to replace if it’s broken to eliminate the error code. But before replacing the fuse, you need to make sure that you’ve descaled your water heater and unclogged the exhaust of the unit to allow air to flow freely. 

Noritz tankless water heater code 14

Let’s get into our comprehensive guide to learn all the effective and easiest processes to diminish the error code 14 from the Nortiz tankless water heater. 

Table of Contents

Instant Solution For Noritz EC-14 Issue

Before going to explore in-depth, follow the below table to fix the EC-14-related problems. The given tips may help to resolve your heater’s error code troubles instantly.

Possible ReasonsHow To Fix
Thermal Switch Failure> Replace the device
Clogged Heat Exchanger> Flush the heat exchanger
Restricted Airflow> Check out the vent system to see if is free from dirt and debris. If needed, clean it.

Noritz Tankless Water Heater Code 14 [Reasons + Solutions]

In this part, you will learn how to troubleshoot your Noritz tankless water heater’s error message-14. So, let’s dive into the facts…

Note: You can also read our guide on how to fix Noritz tankless water heater problems & error codes.

1. Failed Thermal Fuse

As you have learned above error 14 on Nortiz is mainly related to the thermal fuse failure. Thus we need to inspect this element first to verify its condition. 

noritz tankless water heater failed thermal fuse

Typically, the thermal fuse is an essential single-use overheat protection safety device on Noritz tankless water heaters. It is a white cord, wrapped around all 4 sides of the heat exchanger with metal clips as shown in the picture below:

noritz tankless water heater heat exchanger

Anyway, when the temperature around the heater and burner rises to unsafe levels, the switch trips and then automatically cut off the power supply to the heater to prevent further damage to the unit. 

As the thermal fuse is designed for single-time use, thus you can’t expect the water back in normal operation once the fuse trips, meltdown, or break itself. Consequently, the controller triggers this malfunction from the heater and displays error 14, signing you the failure of the fuse. 

How To Fix:

First off, unplug the water heater from the power connection and remove the front cover to access the thermal fuse. 

If it gets dirty, clean it carefully. But as this is a one-time use device, replacement is the best solution to remove error code 14.

Whatever, before replacing this part, we highly recommend you test whether the thermal fuse has continuity.

How To Test The Continuity Of Noritz Thermal Fuse

You can easily test your heater’s thermal fuse functionality by the following procedures.

  • Disconnect the thermal fuse from the connection. 
  • Take a digital multimeter to test the continuity
  • Keep the multimeter lead to the fuse probe

When you touch the probe, you will get a sound that seems ‘Beeping’ and the meter will show resistances in case of a functional thermal fuse. Or you will notice 000 resistance if there is no continuity.

test the continuity of noritz thermal fuse

In such a situation, you must replace the faulty thermal fuse immediately to get rid of the error code-14-related issue.

cut off the fuse and reattach the fuse connections

Otherwise, you will get the problematic code repeatedly. If you’re technically inclined, we recommend calling an expert for your assistance. 

Note: Even if the error code reappears, we suspect the heat exchanger has been clogged, blocked, or cracked. Let’s identify the exact reason.

2. Scaled Heat Exchanger

A thermal fuse failure of the tankless water heater is mainly related to an overheating issue. Thus along with the replacement of the failed thermal fuse, you need to identify the root reason that causes to rise water heater temperature to an extreme level. 

noritz tankless water heater scaled heat exchanger

For instance, the heat exchanger is our leading suspect as it tends to be blocked by sediment deposits. Basically, during the water heating process, naturally occurring hard water minerals like calcium or magnesium come into contact with heat exchanger fins. 

After long use, these minerals turn to hard particles, settle to the fins and create a blockage. When this happens, the heat exchanger fails to pass through the heat which rises the heater temperature and even interrupts the overall heating process. 

But there is nothing to worry about! Descaling or flushing the water is an effective process that will help you to get rid of these deposits from heater elements. Also, consequently, you can prevent the thermal fuse to fail randomly. 

How To Fix:

Start your descaling session by turning off the gas valve. Take your cleaning accessories to complete flushing procedures. You will need:

  • Grade White Vinegar (1-2) Gallons
  • 5- Gallon size Bucket
  • Submersible pump3-4″ Hose
  • And, Drain Connections and screwdriver.

Once you have managed the above accessories, go through our dedicated guide or watch the below video to learn how to descale a Noritz tankless water heater.

If the cleaning effort can’t bring any luck, we will suggest you replace the heat exchanger with a new one. 

Note: If you are constantly struggling with deposits in your heater, I bet you’re living in a hard water area. To confirm you can check out the water quality. 

Once you’ve confirmed, use a water softener or sediment filter to prevent the build-up of minerals (scale) on the inside of the heater elements, pipes, and fixtures. By doing so, you will be able to increase your heater efficiency. 

3. Blocked/ Restricted Venting System

Blocked venting is another leading factor that causes the water heater to overheat or trip the thermal fuse. 

blocked or restricted venting system

A blocked water heater vent is certainly a serious problem. It disrupts the airflow to the unit, resulting in an interruption in the overall combustion. Typically, when the exhaust gets blocked, the burner might run hotter than usual due to a lack of proper airflow. 

Along with the air blockage, higher chances are the venting isn’t installed properly which restricts fresh air to enter the system.

To avoid this unwanted heater issue, let’s inspect the exhaust and air intake lines to verify they are securely connected and in good condition with no blockage.

How To Fix:

First of all, make sure you have unplugged your water heater from the power supply. Now inspect the exhaust and air intake of your unit, It may be blocked with bird’s nests, rodents, or a spider nest that are villains to ensure trouble-free airflow through your heater.

Anyway, it’s time to clean the vents. For instance, take a vacuum cleaner connected to an extension hose. Enter the hose into the vents and remove the inside debris. Instead of a vacuum cleaner, you can use a duct clever or run a plumbing snake to get rid of clogs. 

Additional Tips: Along with the vent cleaning, we will recommend inspecting the air filter screen as well. It also might be blocked by debris and lint. Unscrew the filter from its connection and clean all the stuck hard particles from the screen using a wire brush. It will help you to ensure a fluent airflow throughout the unit. 

After doing all the above attempts, we expect you to be no more troubled by the error code 14 in your Noritz remote display. If still you have, contact Noritz customer service to discuss your matter.  


What is the thermal fuse of the Noritz Tankless water heater?

Noritz Tankless water heater thermal fuse is a one-time fusible link or an electrical fuse. It is built-in around the heat exchanger and acts as an overheat protector cut-off fuse.

What may occur If you ignore the error code-14?

As an error message-14 indicates that an overheating issue is going on with your water heater, you need to take a step to clear the code from your display. If you don’t fix it, your unit may shut down and it may bring further damage to your water heater.

Is there a venting system for a Noritz electric tankless water heater?

No. Noritz electric tankless water heater doesn’t need the venting system. Because it uses an electric burner to heat the water rapidly. But a gas water heater badly requires the venting system for proper combustion.

Final thought

Already, you have learned that a malfunctioning blocked exchanger and insufficient airflow are mostly responsible for creating high heat that causes failure of the thermal fuse. And then, you’ll encounter Noritz tankless water heater error code 14 on the display screen. 

Fortunately, we have explored the core reasons with their simple solution. 

We hope our guided troubleshooting steps will help you to clear the problematic code-14 issues. Therefore, follow the mentioned guide to resolve your water heater’s EC-14-related problems.

Don’t forget to share your thoughts. Feel free to knock on your comments. We will reach out to you as early as possible. 

About Phillip

Phillip is an HVAC guy & has convenient skills in the fireplace, heater, stove & other heating systems. He has been working and writing in this field for the last 5 years. He is really passionate about writing & share his expertise through his writing to help others. More about us.

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