Rheem Water Heater Flashing Red Light 2 Times [3 Easy Fixes]

Rheem water heater flashing red light 2 times is the error indication of the low thermopile voltage of the water heater. The leading reasons for this system error include improper thermopile connection to the gas combination valve, worn-out thermopile wiring, and defective thermopile connector. 

rheem water heater flashing red light 2 times

To assuring all the above faults on the thermopile, you need to inspect the pilot assembly and check each part. Also, testing the thermopile voltage through a multi-meter is a must to ensure whether the device needs replacement or not.

Read through the below article to get a comprehensive guide on the Rheem water heater status light blinking red 2 times.

Rheem Water Heater Flashing Red Light 2 Times [3 Easy Fixes]

Before moving to the details factors, let’s have a glimpse of thermopile and all about its functions in a water heater. 

Note: You can also read how to fix Rheem Water Heater’s red light flashing 7 times.

What Is Thermopile And How Does It Work

Thermopile is an essential part of the water heater that is featured with several thermocouples. The core function of this element is converting thermal energy into electrical energy. 

When the fact comes to the hot water heater, it continues an electronic system to control the temperature of the outgoing water. This electric system has done through a circuit board that needs a specific amount of current. 

Thermopile is such an element that produces the needed current to continue the ignition. Here basically, the pilot light heats the thermopile. Once the thermopile heats up, it produces a small voltage of electricity and passes it over to the gas control valve. When the gas control senses this electricity, it allows the gas supply to the burner.

What Does Low Thermopile Voltage Mean In Rheem Water Heater

To continue the water function, the thermopile should work properly. The thermopile is the combination of many thermocouples that produce enough current to power up the circuit board. Without sensing electricity and powering up the small circuit board, the heater will fail to heat the water.

But in many cases, the thermopile voltage becomes low, which interrupts its function. Low voltage means there is some problem with the thermopile system. Once the thermopile voltage is turned low, the pilot light will go out. 

If the pilot light is out, the gas valve shuts down and turns off the gas supply until the pilot light is relit. In short, the thermopile works as a switch to control the gas flow from the gas supply valve.

When this happens, the controller system catches it as an error and flashes two times, blinking the red status light. The error signifies that you would not get the correct water supply because of a faulty thermopile system.

What Causes Low Voltage In Thermopile And How To Fix It

There are some major reasons which cause low voltage in the thermopile. Extinguished pilot light is the leading reason for this. The pilot light goes out because of the high winds. 

Also, incorrect venting settings or failing chimney caps allow too much airflow inside the heater which caused the pilot to be extinguished. Once the pilot light is out, the thermopile voltage becomes low. 

Besides, damaged thermopile wiring, improper thermopile connections to the gas valve, damaged connectors, or defective thermopile are highly responsible for this. Read the below section to know more about this and how how to fix the water heater thermopile voltage low.

1. Improper Thermopile Connection To The Combustion Gas Chamber

As you have read above, the Rheem water heater’s red light flashing 2 times every 3 seconds means there is a low voltage on the thermopile of your water heater. Incorrect thermopile connection to the combination gas control is the leading reason for occurring such errors. 

Thermopile is an essential part of the water heater’s burner assembly which is located next to the pilot light. Basically, it connects to the combination gas control valve through a connector on the outside of the water heater. 

If the thermopile connector is not properly connected to the gas control valve, it causes several malfunctions to the thermopile. Besides, you will find copper lead wires that connect to the gas valve. 

Damaged thermopile wiring is another responsible factor for low thermopile voltage. If the wires are worn out or have any sign of corrosion like missing insulation or a bare wire, it will fail to send electrical power to the gas control. So, now you need to do a visual inspection to check the connectors and wiring.


  • Before checking, turn off the gas supply.
  • Move to the combination gas control valve.
  • Check the thermopile connector connection with the gas valve.
  • You have to check the connectors for physical damage. Replace the bad connector.
  • Also, ensure it is not loosened and fully seated or clicks to the combination gas control. 
  • Now check the wiring for any signs of wear or corrosion. You need to replace the damaged wires.

2. Test The Thermopile

After checking the thermopile connector and wiring connection, you need to test the thermopile.

test the thermopile 

The test result will define whether the thermopile is bad or it needs to replace. 

How To Test Thermopile On Water Heater

Follow the steps we have mentioned below to test a thermopile.

  • To test the thermopile, you will need a multi-meter that can read for millivolts.
  • Then, you have to set up the multi-meter for direct current. Then, set the range to millivolts or for less than one volt.
  • Now, remove the thermopile wiring connector from the gas control valve connection. To disconnect the thermopile, wiggle it a bit before it becomes loose.
  • Then, connect the red positive lead to the red thermopile wire. Attach the black negative lead to the white wire. 
  • After that, set the gas control to the pilot lighting setting. Follow the manufacturer’s instructions and light your pilot light.
  • After lighting the pilot, the voltage reading on your multi-meter will start to increase.
  • Now, press the gas control’s thermostat knob. You need to hold the knob until the maximum voltage is reached.
  • Once the multi-meter has finished the reading process, the multi-meter would slow down.
  • It will take 2-3 minutes. A healthy thermopile will show a voltage reading of 650 to 850 millivolts or somewhere in between.
  • If you are getting a reading below 400, be sure the thermopile is defective and needs a replacement.
  • Follow the below section to get a complete guide on this. 

3. Replace The Bad Thermopile

After confirming the low voltage on the thermopile, you need to replace the thermopile to get the heater back into operation.

replace the bad thermopile

The process of replacing a thermopile is simple and straightforward but fairly lengthy. 

How To Replace A Thermopile On The Gas Water Heater

Here, we have included the step-by-step guide to replacing the thermopile. 

  • First, shut off the gas supply to the water heater. Turn the gas control knob to the off position.
  • Disconnect the igniter and thermopile wires from the connection. You may need to wiggle to remove the connection. Here take enough precautions to disconnect all the attachments.
  • Now, you will find two screws that hold the manifold door assembly in place. Unscrew the screws and take them aside.
  • Remove the burner assembly from the chamber to access the thermopile.
  • Then, remove the retaining clip from the manifold door and the screws that hold the pilot assembly in place. 
  • After disconnecting the thermal switch wiring, remove the pilot assembly.
  • Now, connect the new thermopile wire into place, and it is fully seated in the manifold door.
  • Also, connect the retaining clip in place securely.
  • Attach the pilot tube and the new thermopile wire through the manifold door. Make sure you are not bending the pilot tube.
  • Screw the pilot assembly and set up the Manifold component. Here you will have to add a few screws and ensure a snug connection of all screws.
  • Then, reconnect the thermal switch wiring. Reattach the manifold door as well.
  • A click sound will ensure you a tight connection if the manifold door will tightly connect.
  • Connect the pilot tube back and the manifold tube. Also, connect the thermopile wiring to the place.
  • Besides, plug the igniter wire back into place.
  • Turn on the gas supply and turn the control knob to the pilot position. 
  • Finally, adjust the temperature as you would like to.
  • Great!! You have successfully replaced the bad thermopile from your water heater. 


Why is my water heater not producing hot water?

If your water heater is not producing hot water, be sure there have degradation in the power supply to the heater. Either the fuse has blown, or the circuit breaker has tripped. Also, defective heating elements can cause this.

How do I know if my water heater thermostat is bad?

There are a few signs to identify that the thermostat is not working. That includes water not getting hot, not enough hot water, slow-to-heat water, water getting too hot, or tripping the high-limit switch.

Wrapping Words

At the end point of this guide, hopefully, now you are clean to all the aspects for 2 times error blinking on the Rheem water heater red light. Also, you can easily erase the error from your water heater by following the above solution methods. 

Still, if you have any questions on any facts, don’t hesitate to ask us through comments. We will get back to you ASAP.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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