Rheem Tankless Water Heater Code 11 (Fixed)

Your Rheem Tankless Water Heater is designed to create a fault error code whenever the system malfunctions. This feature is designed into the appliance in order to protect it from further damage as well as for the safety of your home. 

Code 11 is one of the the most common Error Codes on the Rheem tankless water heater. This fault code is also common on Rinnai and Richmond tankless systems. 

One of the few downsides of using a tankless system is that when a fault code occurs, there is no way to get any hot water. With a tank system, you are still able to get some warm water for a period.

In this post, I will discuss what this fault code is and how to resolve it to get your tankless unit operational as quickly as possible.  

What is Error Code 11 on Rheem Tankless Water Heater

Code 11 means that the ignition system has failed. This can happen when there is insufficient gas supply to the tankless unit or a faulty ignitor coil. Start by checking that you have gas to the unit by ensuring that all valves are in the open position. Once confirmed, replace the faulty ignitor coil.

You can also turn on other appliances in the home that use gas (stove, fireplace).

Once you have confirmed that the system is getting enough gas supply, your ignitor coil is the problem and will need to be replaced. 

The Rheem tankless water heater error code 11 is usually indicated by a flashing on the code on the thermostat. This flashing is usually accompanied by a high pitched beeping sound. It is important to not the this sound is not a temperature warning.

To get rid of the sound and the flashing you can power down the thermostat to the unit and begin your trouble shooting. 

How to Fix Rheem Tankless Water Heater Code 11

To fix Error Code 11, make sure that there is gas flowing to the system by checking that all gas valves are in the open position. Once verified, remove the faulty ignitor coil by unscrewing its bottom section from its attachment to the panel. Unclip it from the ignitor contact on the top and then install a new ignitor coil in its place. 

Inside Rheem Tankless Water Heater Front Panel Showing Ignitor Coil Location

Here are the steps of the process in Detail

Step 1: Remove the Front Panel of the Rheem Tankless Water Heater Unit

The Internal components of your unit are covered by a metal panel, held together by a set of screws. Remove the screws to expose the internal parts of the unit. Make sure there is no visible damage to any of the parts.

Step 2: Shut off Power to the Unit

Every tankless unit is powered by electricity even if it uses gas for heating. Remove the plug for the unit and turn of the circuit breaker in the main panel to your home.

You will be able to tell that the power source is completely turned off because there will be no air coming out of the exhaust vents on the top of the unit.

Step 3: Shut off Water and Drain the Unit

Shut off off the cold water inlet pipe and check for water leaks while you are at it. Drain the water heater by relieving it through the vent pipe. 

Step 4: Check that there is Gas supply to the unit

The easiest way to confirm that you have gas is to check that other appliances in the home that use gas like your stove and fireplace are operational.

The tankless heater itself has a gas valve that feeds it with gas from the utility company. The valve will have a red handle that controls flow. Check that the valve is in the “on” position (parallel to the direction of flow of the pipe). 

Step 5: Replace Ignitor Coil

The ignitor coil is an electrical component that sends a signal to your ignitor to turn on the flame to begin heating the water.

Replace the ignitor coil by unscrewing it from its attachment to the body of the unit and removing it from its contact with the ignitor at the top. 

Install the new ignitor coil in place of the faulty one.

Step 6: Power Up The Unit

Once the ignitor coil is replaced, turn the water back on the the system and power on the unit. Don’t forget to make sure that the thermostat is on as well.

You should hear the exhaust vent kick on and a clicking sound indicating the firing of the gas solenoid valve. 

Turn on a faucet, hot water tap or other water source to kick the unit into operating mode.

Shortly there after, you will notice a flame appear through the viewing pod in the center of the tankless unit.  

Your Water heater is Operational again.

Rheem Tankless Water Heater Ignitor Location

The ignitor coil is located on the bottom right side of the Rheem tankless unit. Open the front panel by removing the screws around the unit. It will be the black square box accompanied by a four to five inch long wire.

Rheem Tankless Water heater Ignitor coil

How To Check Ignitor on Rheem Tankless Hot Water Heater

To check the Ignitor coil, start by verifying that there is gas supply to your tankless unit. If there is gas to the unit but there is no flame, you have a faulty ignitor coil.