Rinnai Code 11 – What to Do and How to Fix?

Rinnai is one of the most reputable manufacturers of tankless water heaters. But, as with any water heater, you’ll run into issues from time to time. Luckily, Rinnai water heaters have an advanced set of error codes that help you identify the source of the problem. In this article, we’ll be checking out one of the most common error codes that customers have reported experiencing with a Rinnai hot water heater – Code 11.

A Rinnai Error Code 11 indicates “no gas supply or ignition” on your Rinnai water heater system. Unfortunately, many issues can lead to an Error Code 11, including issues with the igniter, flame rod, venting, and more. Below, we’ll break down these issues in more detail and tell you the proper steps to take when you encounter an Error Code 11.

What is Causing Code 11 – How do I fix Code 11 on a Rinnai?

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When you encounter an Error Code 11, you might be pretty overwhelmed. “No ignition or no gas supply” is a relatively broad issue, and there could be several potential reasons for it. In general, these reasons fall into one of a few broad categories, which we’ll explain next.

IMPORTANT NOTE: Troubleshooting a Code 11 generally requires an extensive understanding of the interior components of your water heater, as well as how your water heater works and experience with a natural gas system and flammable vapor. It also may not be a “quick fix”. For this reason, you might want to call a professional in the event of a Code 11.

Igniter Issue

Because Error Code 11 means that the water heater has “no ignition”, an igniter issue is an obvious source of the problem. Unfortunately, there are many underlying issues that can cause an igniter issue, including:

There is a spark issue with the igniter. See if there are any loose or bad connections on the element.

Check that the igniter is properly and securely affixed to the mounting bracket. Loose components can cause a short, which will cause the igniter to malfunction.

Inspect the igniter to see whether it is dirty or if there is any buildup. If this is the case, clean the igniter.

Gas Issue

Similar to the section above, because Error Code 11 means “no gas supply”, a natural gas issue is an obvious factor. But also similar to the section above, there can be numerous factors that can cause this issue, including:

Check that there is a proper gas supply to the water heater.

Check that there is proper gas pressure, as per the manufacturer’s recommendations. Gas pressure issues may also be indicative of a larger problem, including clogs in the system.

Ensure that there is no air in the gas line after installing the water heater.

As per our advice above, DO NOT perform maintenance on your gas line unless you are professionally experienced in this area. If you lack these skills, contact a professional to do this work.

Flame Rod Issue

Commonly, an issue with the flame rod can cause problems that lead to an Error Code 11. You’ll want to check that the wiring of the flame rod is secure and that there are no loose connections. Also, ensure that the flame rod itself is properly installed (securely affixed into the mounting bracket). Finally, inspect the flame rod for debris that may be causing the issue.

Other Issues

And that’s not all! Many potential water heater issues can lead to a Code 11, further cementing our point that you should have ample expertise with the inner workings of your water heater before attempting to solve this problem yourself. Other areas to investigate include:

An issue with the water heater’s venting can also lead to a Code 11. First, you’ll want to check the unit’s venting for any blockage and clear as necessary. Next, you’ll want to be sure the vents are properly installed and that there is ample clearance around each vent.

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Check if there are any leaks throughout the water heater, causing water to drip or condensation to form on the unit. These leaks will need to be secured, which will involve replacing components or tightening attachments.

Check whether the heat exchanger has become clogged with debris.

Check whether the electric board is functioning and whether it needs replacement.

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Bonus: Other Rinnai Error Codes

A water heater is a finicky device, and all of the above issues could potentially cause a Code 11. And that’s just one of the many potential error codes you could encounter on a Rinnai water heater. Before we wrap up, let’s briefly cover the next most common Error Codes you might encounter:

Error Code 5: Code 5 occurs when there is a bypass servo fault (if your water heater has a bypass server)

Often, this problem rectifies itself by turning off and on the device. However, if there’s an issue with the bypass valve itself, it will likely need replacing.

Error Code 7: Flow rate has dropped below 2.1 gpm.

Flow rate may be an issue with a weak water supply from your municipality. Otherwise, you may have some loose connections within the device itself.

Error Code 10: Air supply or exhaust blockage.

Make sure nothing is blocking the venting system. Also, make sure that the venting systems were properly installed. Make sure the vents have proper clearance.


Thanks for reading our comprehensive guide to a Rinnai Error Code 11. Unfortunately, the underlying issues behind Code 11 are rather complex. If you aren’t an expert with the interior workings of your water heater, you’ll likely have too much difficulty identifying and fixing the issue yourself. If this is the case, contact a professional. Hopefully, the problem will be fixable without the need for a new water heater.

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