Why My Rheem Water Heater Flashing Blue Light 7 Times [Reasons + Solutions]

Your Rheem water heater flashing blue light 7 times means the FVS (Flammable Vapor Sensor) goes into Lockout Mode. The defective FVS caused the lockout mode in your heater. And FVS become malfunctioning for the following reasons:

  • Cleaning agent 
  • Hydrocarbon solvent 
  • Dirt build-up in FVS
rheem water heater flashing blue light 7 times

Along with these factors, high temperature and physically damaged FVS can also cause this problem.

Quick Solution:

When a faulty FVS causes blue light to blink and shut down your heater, you must first reset the FVS. If resetting doesn’t fix the error, you must replace the sensor. 

However, throughout this writing, we will explain how you can do all these. So keep reading! 

Rheem Water Heater Flashing Blue Light 7 Times [Solved]

This troubleshooting guide will enable you to detect the culprit that makes the FVS non-functioning and cause 7 times blue light to blink. So let’s start:

What Is a Flammable Vapor Sensor

An FVS is a safety gadget in your Rheem water heater. When flammable vapors concentrate significantly in your Rheem heater, the FVS shuts down the gas valve to prevent a fire outbreak. So the main job of FVS is to detect the flammable vapor before a fire starts. 

Rheem water heater flammable vapor sensor

The FVS in your Rheem water heater is located beneath the jacket door at the bottom of the unit. The sensor communicates with the gas valve. When this sensor stops working, the blue light flashes 7 times on your heater with a 3 seconds pause. 

Flammable Vapor Sensor Issue [5 Easy Fixes]

Your first suspicion should go to the flammable vapor sensor when your water heater blinks blue light 7 times. FVS keeps tripping whenever it senses an extreme concentration of flammable vapor. And ultimately, the sensor goes into lockout mode.

Therefore the apparent part of this troubleshooting guide is to explain what causes bad FVS and how to solve it. Below we will explain that, so keep going:

1. Cleaning Agent

The FVS can stop functioning for different reasons, including using a cleaning agent. Surprisingly a little drop of the cleaning agent can easily set this sensor off. 

Thus if you place your heater near the laundry room, the sensor will go into lockout mode frequently. So we strongly recommend not putting your heater near the laundry room.

2. Hydrocarbon Solvents

Another reason for FVS malfunctioning is the use of hydrocarbon solvents. The hydrocarbon is volatile, and it can quickly ignite in the air. The FVS on your Rheem heater will start tripping within a minute of hydrocarbon solvents spilling.

So the easy solution is always to store the cleaning agents and oil-based paints (which contain hydrocarbon) away from your Rheem water heater.

3. Dirt Or Soot Build Up

The FVS can also get triggered by the dust or debris build-up on the arrestor screen. Grime accumulation on the arrestor screen prevents the free flow of air into your heater. As a result, the internal temperature increases. And thus, it triggers the FVS. 

So, obviously, cleaning the dirt from the arrestor screen is the prime solution to the above trouble. Removing the dust from the screen ensures sufficient airflow to your heater.

4. High Temperature

FVS works well in the selected temperature range (160°C – 200°C) of your water heater. But when the temperature in the combustion chamber increases compared to the standard thermal ratings, the FVS starts malfunctioning. 

Thus, to prevent FVS tripping, make sure your heater works in the selected temperature range.

5. Physically Damaged

Another apparent reason for FVS malfunction is that it is physically damaged. However, after checking the above issues and confirming the solutions, now visually check the FVS. If you find the FVS on your heater is damaged, you must replace it. 

How To Reset Rheem Water Heater Vapor Sensor

Of course, the first action to fix the 7 times blue light flashing on your heater is resetting the FVS, which is very easy. Well, now start the resetting process by identifying the gas control valve on your water heater. 

 rheem water heater vapor sensor

Most water heaters come with the Honeywell gas valve. Below we will explain the vapor sensor reset in the Honeywell gas valve. 

Step 1: Unplug your Rheem water heater from the electrical outlet. Wait 10 seconds. And then plug it back. After plugging back the unit, you will have only 30 seconds to complete the next step. 

Step 2: Hold the switch (pilot knob) of the gas valve. Now turn the knob from the “Vacation” setting to the “Very Hot” setting or “High-Low” setting. 

Step 3: To reset the FVS successfully, repeat this pattern 5-6 times, and the reset is done. 

How To Replace The Flammable Vapor Sensor

After completing the FVS reset, did you check your heater to see whether the blue light is still appearing or not? If yes, that means resetting is not enough to fix it. So, in this case, you must replace the FVS because it is defective. 

Following the simple steps, replace FVS on your Rheem water heater. 

Step 1: Go near your Rheem water heater. And you will find the FVS at the bottom of your heater.

FVS at the bottom of your heater

Step 2: A bracket is at the base of your Rheem heater. Remove the front cover of it. Now use the screwdriver to pull the FVS.

remove the front cover

Two white wires are attached to the sensor. Be careful while disconnecting the white cables. 

Step 3: Completely disconnect the FVS from your Rheem heater. Now use a multimeter to measure the voltage reading of the FVS. The volt reading between 7,000-25,000 ohms means the FVS works fine. 

FVS’s voltage reading

But the malfunctioning FVS’s volt reading will be below 7,000 ohms. Therefore, we recommend you replace the faulty FVS immediately. 

Step 4: Bring a brand new FVS to replace the bad one. Once you install the new sensor, your heater’s seven-times blue light blinking will be solved. 

new FVS of rheem water heater

Keep in Mind: For a mechanically expert person, replacing the FVS will be very easy. But you must contact a professional if you are not an electronically inclined person or fear dealing with an electrical appliance.

However, in case you face your Rheem water heater blinking red other than blue, you can also read our guide on why the Rheem water heater’s red light flashes 7 times and how to fix it


Do Rheem water heaters have a pilot light?

Yes! Your Rheem water heater has a pilot light. Through the viewing window, you can see the pilot light near the inner door of your Rheem water heater. 

Why does my pilot light keep going out on my Rheem water heater?

The pilot light keeps going out due to the dirt build-up in a pilot tube, insufficient gas supply, defective thermopile, faulty thermocouple, etc.

How do I reset my Rheem water heater?

Turn on your heater. Then open your heater’s front panel and find the button. Near the thermostat, you will find the red button. Press it to reset your heater and resume your heater’s regular operation. 

Why is my Rheem hot water heater not working?

Your Rheem water heater is not working because the unit is disconnected from the power source. Also, the other causes are a damaged extension cord, faulty safety switch, no gas supply, etc. 

How long does it take for a Rheem water heater to heat up?

For thoroughly heating the water, your Rheem water heater may need, on average, 30-40 minutes. 

Wrap up

Hopefully, this ultimate troubleshooting guide was helpful for you. And now you have a crystal clear idea of why your Rheem water heater flashes blue light 7 times.

When your heater starts flashing 7 times, first detect which problem is causing the FVS error and fix it. 

Don’t hesitate to comment if you want to know anything about your Rheem water heater. ASAP we will reply to you. 

About David

David is a man who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever he finds the perfect solutions to any issues of heating appliances after doing in-depth research, he loves to share them with his readers. In fact, his aim is to help his readers to fix the issues with their heating appliances easily.More about us .

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