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Solutions to Noritz Tankless Water Heater Problems

Hand Rotate Temperature Adjuster Of Water Heater

Traditionally, water heaters had tanks with them that would limit their capacity for water storage. However, modern Noritz tankless water heaters are designed without a tank which means their water supply is not limited, and you can enjoy as much hot water as you want.

Such a water heater can make your life ten times more feasible and helpful. Unfortunately, like other machines, these water heaters are also prone to get damaged or useless if the issue is not detected and resolved within time.

A plethora of problems can occur with your Noritz water heater, and you will need to have a sound knowledge of such issues to detect them based on the performance of your device.


Noritz tankless water heater is one of the best heating systems to install in your house. However, your water heater may hit any of the following problems over a few years.

Common Error Codes

These include all the critical error codes of Noritz, including code 11, code 12, code 16, code 29, code 59, and code 90.

Water Heating Malfunctions

All the issues, from water being too hot to water not being hot, are included in this category.

When you have the apt knowledge of the error codes, and their meaning, you will easily be able to diagnose the underlying problem and get the target solution. In this blog, we’ll dig deeper into all sorts of issues you can encounter with your tankless water heater.

Common Noritz Tankless Water Heater Problems (With Solutions)

There are many problems that you can come across when talking about tankless heaters. Sometimes, the problem could show up as error codes, while other times, the problem could surface as a malfunctioning heater. Both ways, you should be prepared to tackle the problem head-on.

1. Common Error Codes

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Error codes tell you about the underlying problem with your system. If you know what a specific code means, you can quickly fix the problem with your heater without wasting much time diagnosing the problem. We have compiled a list of a few most common and important error codes of Noritz that you should know about:

Error Code 10

This code will show up when combustion still occurs in the machine, even after you have turned the unit off.

To solve this issue, you will need to check the burner and ensure it has no grease or oil that could cause combustion.

Error Code 11

When there is no ignition in the heater, the water won’t heat up and will only increase your energy bills. This code appears when there is a problem with the initiation of the ignition.

It may happen due to insufficient gas pressure or obstruction of the gas pipe. You can solve this problem by removing any obstruction from the gas pipe and ensuring the gas pressure is optimal for ignition.

Error Code 12

Any problem with the flame sensor can affect the quality of the flame, and a weak flame will not be able to heat the water in the heater as it normally should.

Therefore, to tackle this problem, you will need to inspect the flame sensor and ensure it is clean and free of debris or dirt deposition.

Error Code 16

Sometimes, the water can get too hot because of the quality of the water or due to scale accumulation. In addition, if the water is hard, it affects its quality and can further lead to this issue.

A simple solution is to remove the hardness of water or to descale the system using professional help. You can call the relevant technicians for help if you cannot do it at home.

Error Code 20

There is a high-limit switch in your Norotz tankless water heater, and when this switch is activated, you will see this error code.

The solution can be as simple as preparing or replacing the switch. Moreover, descaling the system will help in this case as well.

Error Code 29

Any problem in the water drainage in your system will give an error code 29. To get over this issue, you will need to carefully inspect the drain pipes and ensure the drain line is clear and nothing is blocking the water flow. If there is any blockage, remove it.

Error Code 90

Your heater needs external gas pressure to maintain the pressure and regulate the internal temp[erature accordingly. When this pressure is insufficient, your heater will give this code after several failed attempts.

Moreover, any internal issue affecting the combustion and fuel can trigger this error code. You can solve the internal issue by regularly cleaning the unit and removing any dirt and debris. However, if the problem persists, you will want to call a professional.


You will want to buy a gas manometer to check the gas pressure in your tankless water heater. This tool will help you detect pressure issues in your system quickly and efficiently.

2. Water Heating Malfunctions

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If your Noritz water heater is showing no codes but is running into some malfunctions now and then, it is time that you get it fixed. Here are some of the most common signs that your tankless water heater is malfunctioning:

Water Becomes Too Hot

The temperature sensor installed in the system primarily controls water heating. You will start getting hot water beyond your tolerance level if it gets out of order.

Make sure you check your system’s temperature sensors and the temperature regulation knob. Any mistake in entering the right temperature setting can also play a part in this issue.

Water Isn’t Hot Enough

There are two possibilities this could happen to your system. One is that you do not correctly set the temperature. You might be making a mistake in selecting the right temperature. Make sure you look at the general operation manual before setting the temperature.

The second reason could be excess sedimentation. Again, you can eliminate the sediments with a professional’s descaling procedure. You can also try flushing to get rid of the sediments.

Hot Water Isn’t Coming Out

Any problem with the pipe or the tap will affect the flow of water from the tankless water heater. Therefore, you must ensure that you have opened the tap enough to allow water to come out.

Moreover, if the pipes are frozen or blocked, you will face the same issue. All you need to do to make it functional is unblock the pipes and get the ice removed from the pipes with professional help.

Quick Recap

Your Noritz tankless water heater will be your life savior in winter if you keep it with care. When you turn your heater on but it won’t start and instead gives an error code, it is a sign that your system has met a problem, and you need to solve this to make it functional again.

You can see error code 10 for improper combustion and 11 for insufficient ignition. You will get error code 20 when the high-limit switch is activated. You will need to check the relevant components that the error codes hint at.

Moreover, you can also face heating malfunctions like water becoming too hot or too cold. Solving these malfunctions will require you to clean and unblock the blocked areas of the system and call a technician when needed.

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