Fix Rheem Code 11: Tankless Heater Troubleshooting Guide

Encountering an error code on your Rheem tankless water heater can be puzzling, but you’re not alone. Code 11 signifies an ignition failure, a common issue that many homeowners face. Understanding what triggers this error is crucial for a quick fix and uninterrupted hot water supply.

In this article, you’ll discover the reasons behind your Rheem heater flashing code 11 and how to troubleshoot it effectively. Whether it’s a gas supply problem or a faulty component, we’ve got you covered with step-by-step solutions to get your system back up and running.

What Is an Ignition Failure?

When your Rheem tankless water heater displays code 11, it’s signaling an ignition failure. This critical error means the heater’s system attempted to ignite the burner but was unsuccessful. Without ignition, the heater cannot produce hot water, leaving you in quite the cold situation.

Ignition failures stem from several potential causes:

  • A lack of gas supply, which could be due to a closed gas valve or an empty propane tank.
  • A component within the ignition process may be faulty, such as the igniter or flame rod.
  • Gas pressure might be too high or too low. It’s crucial the pressure is within the manufacturer’s specified range for optimal operation.
  • Airflow obstructions can impede the ignition sequence. Check for any blockages in the vents or flue pipes.

Specific Real-Life Examples:

  • A user might discover that a simple action like ensuring their propane tank has gas solves the issue without the need for further steps.
  • In some instances, a professional serviceman might identify a defective igniter after conducting a diagnostic test and replace it to resolve the error.
  • Cases of incorrect gas pressure often require adjustment of the pressure regulator to restore functionality to the unit.

Knowing these triggers helps you better understand what to look out for and actions you’ll likely need to take. Remember, it’s always best to start with the simplest solutions before moving on to more complex diagnostics.

Understanding Code 11 on Rheem Tankless Water Heaters

When your Rheem tankless water heater flashes Code 11, it’s signaling a specific issue: ignition failure. This indicates that the heater attempted to ignite the burner, but was unsuccessful. Let’s break down what this means for you and how you can address it.

Firstly, gas supply is fundamental. Your heater needs a steady and sufficient gas flow to ignite. If there’s an interruption or the gas pressure is too low, ignition cannot occur. Ensure that the gas valve is fully open and that no supply line obstructions are present.

Another vital aspect is the condition of the igniter. Over time, igniters can wear out or become dirty, leading to inadequate sparking. Inspecting and cleaning the igniter can sometimes resolve the issue. If not, a replacement may be necessary.

Incorrect gas pressure can also trigger Code 11. Your water heater requires a specific pressure to operate correctly, which is detailed in the manual. Use a manometer to verify that the gas pressure matches the manufacturer’s specifications.

Finally, check for airflow obstructions. Your heater needs an adequate intake of air for combustion. Make sure there are no blockages in the vents and that the air filters are clean.

If these steps don’t address the issue, it could indicate a more serious problem like a faulty gas valve or circuit board issues. In such cases, professional assistance is recommended. Remember, safety comes first when dealing with gas appliances.

Common Causes of Code 11 Error

When your Rheem tankless water heater flashes a code 11 error, you’re likely facing one of several issues that can impede the ignition process. Understanding the root causes is essential for effective troubleshooting and repair.

Faulty Igniters or Electrodes: Over time, igniters can wear out or electrodes may become faulty. These components are vital for spark generation, which starts the heating process. An inability to generate a spark usually leads directly to an ignition failure.

Gas Supply Issues: A consistent and adequate gas supply is crucial. Disruptions can come from:

  • A closed gas valve
  • A bent or kinked gas line impeding flow
  • An empty or nearly empty propane tank, if applicable

Ensure your gas valves are fully open and the supply is uninterrupted.

Incorrect Gas Pressure: Your water heater requires a specific gas pressure to operate correctly. If the pressure is too low or too high, it may prevent the unit from igniting. Check the manufacturer’s specifications for the correct pressure and use a manometer to verify that your readings match.

Airflow Obstructions: Combustion air is just as important as the gas supply. An obstructed vent or intake can disrupt the balance necessary for ignition. Regular maintenance, including checking and clearing any blockages in the vents, is key.

Electrical Connection Problems: A secure and proper electrical connection ensures that the control board and ignition system have the power they need. Loose wiring or a tripped circuit could be the reason for the error code.

Inspect and address each of these areas systematically to identify the cause of the Code 11 error you’re experiencing with your Rheem tankless water heater.

Troubleshooting Code 11 on Rheem Water Heaters

When you’re faced with a Code 11 error on your Rheem water heater, it’s crucial to proceed methodically. Begin by inspecting the ignition system. The igniter should glow hot and ignite the gas; if it doesn’t, it may need replacement.

Next, check the gas supply to ensure it’s turned on and flowing correctly. If gas is available but the unit still fails to ignite, gauge the gas pressure. Incorrect pressure can prevent proper operation. Refer to your Rheem manual for the correct specifications, and, if necessary, adjust the gas pressure using a manometer.

Airflow is another critical element for ignition. Examine the vent system for any obstructions such as debris or nests, especially if the unit hasn’t been used for an extended period. Clear away anything that may block the airflow.

Lastly, scrutinize the electrical connections. Loose or damaged wiring can interfere with the ignition process. Tighten connections and replace any frayed wires. In cases where troubleshooting doesn’t resolve the error, it’s advisable to contact a professional technician.

Performing these steps should significantly narrow down the cause of a Code 11 error. Regular maintenance ensures you preempt these issues and your water heater operates efficiently.

  • Check the ignition system for functionality
  • Ensure gas supply is on and check for correct pressure
  • Remove any blockages in the vent system

Step-by-Step Solutions for Resolving Code 11

When facing the dreaded Rheem tankless water heater error code 11, don’t fret. You’ve got reliable troubleshooting steps at your disposal to efficiently address the issue. It’s important to proceed methodically; here’s how you start:

First, inspect the igniter. A faulty igniter is often the culprit. If it’s damaged or failing, a straightforward replacement will get your system back on track.

Next, zero in on the gas supply. Make sure the supply valve is fully open to allow proper flow. Also, verify the gas type and pressure are correct for your unit. Incorrect gas pressure can lead to ignition failure, so a professional assessment might be necessary.

Airflow is vital for operation. Check for and clear out any obstructions in the vent system. Proper ventilation ensures that the unit can ignite and operate safely and effectively.

Finally, look at electrical connections. Loose or corroded connections can interrupt the ignition process. Tighten any loose wires and replace any that are corroded. A multimeter can be handy to ensure all connections are secure and have the right voltage.

Regular maintenance of your Rheem tankless water heater can prevent issues associated with error code 11. Annual check-ups by qualified technicians can help avoid future disruptions and maintain the unit’s longevity.

To ensure your water heater operates at peak efficiency and reliability, don’t overlook the basics. Clean air filters and inlets, as well as routine inspections, are your first line of defense against common issues, preventing error codes before they start.


Tackling error code 11 on your Rheem tankless water heater needn’t be a daunting task. With the right approach, you can diagnose and resolve the issue efficiently. Remember to check the igniter, inspect the gas supply, clear any vent obstructions and ensure all electrical connections are secure. Don’t forget that regular maintenance is key to avoiding such problems in the future. Armed with these tips, you’re now well-prepared to keep your water heater running smoothly.