What does Rinnai Tankless Water Heater Error Code 11 mean?

An error code 11 often points to a problem with the fuel going into your Rinnai water heater. Gas may not be reaching your unit or pressure may be too low. An issue with your ignitor or flame rod might also be the issue.

There are a few things you can check yourself to see if there’s a simple answer to your lack of hot water. If these options don’t work, it’s time to call a professional Rinnai tankless water heater expert at Full Stack Plumbing.

Contact us today to schedule an appointment with a Triangle plumber in Durham, Raleigh, Cary, Chapel Hill, Carrboro, Pittsboro, and beyond.

What Do I Do if Error Code 11 Shows Up on My Rinnai Water Heater?

An error code showing up on your Rinnai Tankless Water Heater can cut off your hot water in an instant. Besides frustrating everyone in the family, an error warning may be pointing to a serious problem.

When a Rinnai unit flashes an error code 11, it may be indicating one of several types of issues. There’s usually either a problem with the gas supply (propane or natural gas) or with the ignition of that gas.

There are a few things you can check yourself, but you should have some experience in plumbing before taking on more complex problems.

You can poke around and end up voiding the manufacturer warranty on your Rinnai water heater. You could endanger yourself and your family when working around these combustible fuels. Always call a professional plumber when you are unsure of what to do.

Here are some of the most common Rinnai tankless water heater problems that lead to an error code 11:

  • No Gas – You can check your gas valve going into your tankless water heater to make sure it’s turned to allow gas to flow. In a newly installed gas water heater, the lines can also have air in them and they would need to be cleared.
  • Incorrect Gas Pressure – If the gas lines don’t deliver enough pressure, your water heater will warn you with an Error Code 11. Your lines may be obstructed and not be letting enough gas through. A problem could exist in the main line outside your home.
  • Ignitor Issue – It’s important to confirm that the ignitor is providing a spark. Carbon build-up can leave an ignitor unable to ignite the gas that is entering. Your ignitor would need to be cleaned.
  • Flame Rod Issue – The wiring leading to the flame rod could be damaged. Dirt on a flame rod or the gasket would have to be cleaned before the water heater would work properly again.

These and other inspections are usually better left to the professionals. The skilled plumbers at Full Stack Plumbing would also check other potential issues. The ventilation for your Rinnai tankless gas water heater could be blocked and causing the error code. Drainage for the unit’s moisture might also be obstructed.

Our experts like to start with the simplest fixes first We never want to provide you with repairs and part replacements that you really don’t need.

Expert Rinnai Tankless Water Heater Repair at Full Stack Plumbing

Our expert plumbers are happy to come to the rescue when your family is suddenly deprived of hot water.  We can tell you what error code 11 and other error codes mean and get to work finding the exact problem.

We are locally owned, and our staff is fully licensed and certified. Full Stack Plumbing offers affordable prices. We also practice transparent pricing. This means you’ll know what you’re paying for and what services you’ll get for your money.

Contact Full Stack Plumbing for Rinnai Water Heater Repair

If your Rinnai tankless water heater suddenly stops working and flashes an error code, don’t hesitate to call the experts at Full Stack Plumbing.

Our team of licensed, trained, and fully insured Raleigh plumbers handle Rinnai water heater repairs and installations in the triangle area, including Chapel Hill, Carrboro, Pittsboro, Cary, and Durham.

Don’t suffer through any more cold showers! Contact us today to schedule an appointment.

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Don’t just take our word for it! Read on to see what our satisfied customers have to say about their experiences with us. From our honest pricing to our exceptional service, discover why residents choose us as their trusted local plumber time and time again.
B CM
B CM
14:31 18 Apr 25
These guys are always the best - I'd give 10 stars if I could!
Lynn Franks
Lynn Franks
21:12 17 Apr 25
I was able to book a same day appointment online ! I received a text when JJ was on his way. He was friendly, polite and professional. He explained my options and gave me an estimate of cost prior to beginning the work. He completed the work we agreed upon in a timely manner. I would recommend him and Full Stack! They will be my new go to plumber!
Amy Strunk
Amy Strunk
20:13 16 Apr 25
JJ was kind, friendly and knowledgeable. We discussed the issue, he was quick to evaluate and fix it. I'd call them again!
Kathleen Seligson
Kathleen Seligson
18:44 16 Apr 25
Corey was personable as well as professional.
Timothy Reveri
Timothy Reveri
20:16 15 Apr 25
Hired Fullstack for a water heater flush. Peyton did an outstanding job, and even fixed our toilet for free. Will definitely do business with them again.
Roy Baroff
Roy Baroff
17:16 15 Apr 25
Very detailed and rechecked connections.
FJ Magee
FJ Magee
01:24 12 Apr 25
Outstanding customer focus and service. Above and beyond. Professional, friendly and highly knowledgeable. Definitely earned repeat business and I will refer to anyone looking for a plumbing services in the Chapel Hill area.
Mark Morton
Mark Morton
13:43 10 Apr 25
As usual the interaction was great. The technicians were prompt and efficient and tolerated my yammering which is not easy. Highly recommend this company.
Jennifer Pavao
Jennifer Pavao
00:39 10 Apr 25
Full Stack Plumbing is top notch! We had a leaking outside hydrant. JJ arrived on time, quickly diagnosed the problem and recommended a course of action. It required reworking the water supply and replacing hydrant. We are very satisfied with the work. Thank you JJ and Full Stack Plumbing!
Alaina Hunt
Alaina Hunt
15:52 07 Apr 25
Ruben was super helpful and nice.
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