This is How To Fix Rheem Tankless Water Heater Code 11!

By - Rajib Ahmed

Updated -

Troubleshooting problems with your water heater can be tricky. However, this process is straightforward if you own a Rheem water heater.

The Rheem tankless water heater has an in-built feature that displays error codes when the appliance is faulty.

Code 11 is the most common code error in this appliance, and it’s due to a lack of ignition. So, Here’s what you should know about fixing error code 11 in your Rheem tankless water heater.

To fix the code 11 error, first, you should confirm your heater is receiving enough gas supply. If it’s short of supply, refill the gas. Also, ensure no air in the gas line obstructs the free flow of gas. However, check the gas solenoid valve and the ignitor coil for faults if there’s sufficient gas supply.

In this article, I’ll walk you through the necessary steps to fixing the code 11 fault in your tankless water heater.

Also, I’ll explain what code 11 means and how to reset your Rheem tankless water heater. In the end, you’d know how to troubleshoot your Rheem tankless water heater.

How Do I Fix My Rheem Tankless Water Heater Code 11?

How to Fix Rheem Tankless Water Heater Code 11

Fixing the code 11 error in your Rheem tankless heater isn’t difficult, and I’ll walk you through the do-it-yourself steps.

First, you must ensure your heater receives enough gas before fixing it. 

Lack of ignition is the cause of the code 11 error on your water heater. This error code displays on the Led display panel in front of the unit.

Moreover, there can’t be any ignition without gas, so when your heater is short of gas, it won’t ignite, leading to error code 11.

Also, you must ensure your heater unit is well grounded to receive enough gas. 

Below, I’ll break down the necessary steps to follow to fix your Rheem tankless water heater.

#1. Fixing Insufficient Gas Supply

When there’s an insufficient gas supply to your heater, it can cause ignition failure. For instance, if your gas tank is empty or has little gas, it won’t ignite the water heater.

To check if your tank has enough gas, lift it, and if it feels light, there’s little to no gas inside. Also, check other appliances that use gas if they’re operational.

Consequently, you must take your tank to a gas station to fill it up if it’s empty.

In addition, if there’s enough gas, it may not flow to the burner if there’s a restriction.

Check if the gas valve is open or damaged. Turn the red handle to align with the pipe to facilitate gas flow. 

Also, if there are cracks on the valve, you’d have to replace the gas valve. Furthermore, bleeding out air from the gas lines allows the gas to flow freely to the burner. 

#2. Fixing a Faulty Gas Solenoid Valves

If one of the gas solenoid valves is faulty or has no voltage, code 11 will display on your unit. 

To fix the gas solenoid valve, do the following:

  • Check the voltage of all inlet solenoid valves. They should be between 90-120 VDC.
  • Also, check the resistance of the valves; they should be between 0.8-2.4K Ohms.
  • Call a professional to replace the circuit board if the voltage is incorrect.
  • Also, you’d have to change the gas control valve if the resistance reading is inaccurate.
  • The burner assembly could be at fault if the valve reads the correct voltage and resistance. As a result, you’d have to replace the burner assembly of your gas water heater.

#3. Replacing a Faulty Igniter Wire Harness

When the cables that connect the igniter are damaged, you’d need to replace the wiring. Call an electrician to handle the replacement. 

#4. Fixing the Igniter Coil

When the ignitor coil is faulty, you’d need to replace the coil. 

Here is how to replace the ignitor coil:

  • First, unplug your heater from the power socket.
  • Next, locate the ignitor coil beneath your tankless heater on the right side.
  • Remove the front panel of your unit by unthreading the screws with a flathead screwdriver to expose the inner components.
  • You’d find the coil; it’s like a box with wires attached to it.
  • Unscrew the coil from the unit and its attachment to the ignitor at the top.
  • Fix the new ignitor coil by screwing it in place.
  • After replacing the old ignitor coil with the new one, plug in your heater to the socket and power it on.
  • Turn on your hot water tap to confirm if it’s working correctly.

What Does Code 11 Mean on a Tankless Water Heater?

Code 11 on a tankless water heater means a lack of ignition, which means there won’t be hot water. Several faults cause a lack of ignition in your unit.

This code flashes on the display panel of your heater to alarm you of potential problems with your appliance.

Below are what it means when code 11 displays on your tankless water heater:

#1. Heater not Receiving Enough Gas

When there’s a code 11 on your heater display, checking your tank for gas is the first step. If the tank is empty or there’s an obstruction to the flow, the burner won’t light up.

#2. Incorrect Gas Pressure

When the gas pressure is incorrect, it can also cause ignition failure, leading to code 11.

The standard inlet gas pressure shouldn’t exceed 10.5″ w.c. (2.6kPa) for natural gas and 13.0″ w.c. (3.2kPa) for L.P. gas.

In addition, ensure you use the adequate gas line size to prevent a pressure drop. Also, air, debris, and dust in the gas line can affect the pressure of the gas.

#3. Faulty Circuit Board and Control Valves

A faulty circuit board of the gas solenoid valves can lead to incorrect voltage in the inlets. Also, if the control valves are faulty, the resistance of the valves would be incorrect.

When no proper voltage and resistance are reading between these valves, there won’t be ignition, leading to the code 11 error.

#4. Faulty Burner Assembly

The burner assembly, located beneath your gas tank, contains several components that control the flame that heat your water.

When your tankless water heater’s burner is faulty, it can’t receive ignition from the ignitor.

#5. Faulty Ignitor Coil and Wire Harness

The ignitor coil is the part that signals the ignitor to turn on the flame to heat your water. When this part is faulty, there would be no signal or ignition.

Also, when there’s a fault in the wiring connection to the igniter, this part won’t function.

How to Reset a Rheem Tankless Water Heater?

Resetting Rheem’s tankless water is one of the troubleshooting steps to take care of a faulty unit. This process is easy and can help deal with the error codes on display.

Also, it can deal with overloading, short circuit, faulty reset button, and many other issues with your heater.

Here is a step-by-step guide to resetting your Rheem tankless heater:

  • Locate the heater circuit in the electrical panel and flip it on
  • Take away the panel cover to find the red reset button behind the insulation
  • Press hard on the button until you hear a click
  • Place the panel cover in place
  • Reconnect the gas valve, then power on the heater; it should operate correctly.

How to Troubleshoot a Rheem Tankless Water Heater?

Your Rheem tankless water heater can develop several faults, and knowing how to troubleshoot these faults would save you a lot of stress.

Below are some problems that can arise with your tankless heater unit and how to troubleshoot them:

#1. The water Heater is Not Turning on

Ensure you connect your water heater to a power socket. Also, check that the power plug has a voltage.

In addition, If the circuit breaker trips, your heater won’t come on. So, check the circuit breaker to ensure all circuits are in the correct position.

Furthermore, a blown fuse can also be the culprit. Call an electrician to inspect the wiring and replace the fuse if necessary.

#2. Tankless Water Heater Not Getting Hot

Check for clogs in your exhaust or plumbing system and clean any build-up.

Also, ensure you run a few loads simultaneously, as multiple loads can cause overloading, which will prevent your water from heating up. In addition, check the ignition system for faults.

#3. Error Codes

Major faults display through error codes on your heater.

Below is a table showing some of the error codes and their troubleshooting guide:

Error CodesIndicationTroubleshooting Guide
00One hour of continuous combustionTurn off the hot water tap and disconnect the circulation pump if you’ve one.
P1Low water flowClean the aerator on the hot water tap and the inlet filters of your unit. Also, adjust the temperature to higher settings.
10False flame detectedEnsure the vent and flue inlet are not clogged.
16Over temperature warningCheck that the heat exchanger is allowed.
29The heat exchanger outlet temperature is too lowClean the heat exchanger air inlet

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