Why Does My Gas Fireplace Keep Going Out?

Settling down in front of a warm glowing fire on a chilly evening is the definition of cozy. There is nothing like it. Unfortunately, there is nothing like having the fire suddenly go out, leaving you to shiver. 

Your gas fireplace keeps going out usually because a sensor or valve needs to be cleaned or replaced. The oxy pilot, which monitors fireplace oxygen levels, or the thermopile or thermocouple, which regulate the gas flow, are usually at fault. In rare cases, you may have a gas leak.

In this article, I’ll detail how you can troubleshoot and repair your gas fireplace yourself, and tell you when it’s time to call in the experts.

Let’s start by getting familiar with the inner workings of your gas fireplace.

Basic Components of a Gas Fireplace

Pilot Light

Most gas fireplaces have a pilot light that burns a very low flame even when the fireplace is not in use. It serves as an ignition source for the release of gas when the fireplace is lit.

Thermocouple

The thermocouple monitors the temperature of your fireplace. It keeps the tube sending gas to the pilot open. To function, it must always be in contact with the pilot light flame. 

Thermopile 

The thermopile functions similarly to the thermocouple but regulates the flow of gas to the fireplace. A thermopile generates more electricity than a thermocouple, so it can be used with a thermostat to regulate the heat.

Oxypilot

The oxypilot is a safety device that protects you and your loved ones from carbon monoxide. If there is not enough oxygen, the oxypilot stops the flow of gas to your fireplace.

If the oxypilot becomes clogged, it senses a drop in oxygen. This results in the flame changing shape, pulling away from the thermocouple, and triggering a shutdown of your fireplace by cutting off the gas flow.

Start With the Pilot Light

One of the most common fixes for a temperamental gas fireplace is to check the pilot light. If it is not lit you may have spotted your problem.

Located on a wall inside the fireplace or behind the logs, the pilot light may be operated with a key or a control panel.  

If you can’t find your key, you can purchase a replacement at most home improvement stores. You will have to check your owner’s manual to see what kind of key works in your fireplace.

Remove the front cover of your fireplace to access the control panel (or, in the key models, the gas valve knob).

If Your Fireplace Has a Key

1. Insert your key into the gas valve knob.  
2. Hold a long lighter up to the burner and ignite it.
3. With the key, turn the gas valve knob half a turn counterclockwise. Gas will be released, causing the pilot to light.

If Your Fireplace Has a Control Panel

1. Switch the control knob to “off.” Wait five minutes for gas to clear.
2. Turn the shutoff valve until it is parallel with the gas line.
3. When you’re ready to light the pilot light, move the control knob to the “pilot” position.
4. Press and hold the control knob down while pressing the ignition switch. Usually, the ignition switch is red. You may have to press it several times.
5. Hold the control knob at least 30 seconds or longer to give the thermocouple time to heat and register that the pilot is active.
6. Turn the control knob to “on.” This should keep the pilot lit.

Once your pilot is on, check its color. A healthy pilot light should be dark blue around the edges with a lighter blue center. If the flame is yellow or red, the gas is contaminated.  

Contaminated gas can come from burning rust, excess air in the system, oil, soot, or dirt. All these things can give off toxic chemicals. A yellow flame could also indicate a carbon monoxide leak. If you see a yellow flame, switch off the unit and use a carbon monoxide detector to ensure the air is safe to breathe.

Clean the Pilot Light

To clean the pilot light:

1. Turn off the gas supply to the fireplace.
2. Remove the pilot light and clean off any buildup with a wire brush.
3. For hard-to-reach places, use compressed air.

After cleaning the pilot light, try lighting it again. If the pilot does not stay lit, you probably have a problem with the thermocouple. If the pilot is lit but the fireplace isn’t, the problem may be the thermopile.

Checking Voltage on Thermopile and Thermocouple

If you have a multimeter, you can check the voltage on both the thermopile and thermocouple. 

Using the manufacturer’s guide, you can locate the electric contacts labeled TH/PT and PT and place the multimeter leads on each. If the thermopile voltage is below 300 millivolts, it should be replaced. A reading under 25 millivolts on the thermocouple means it should be replaced.

If it needs replacing, here’s how to do it:

1. Clean the device before replacing it.
2. You will find the thermopile or thermocouple near the pilot light. With a stainless steel brush or fine grain sandpaper, delicately clean away any dirt or soot.
3. Relight the fireplace. You may have fixed your problem. If the fire goes out, turn off the gas and check the oxy pilot.
4. Unscrew the oxy pilot (you may need pliers). Using a straw or compressed air, blow through each hole in the oxy pilot. Once all holes are clear, reinstall the device.
5. Light the fire again. If you’re still having trouble, clean out the pilot light’s gas entry using compressed air or a cloth.
6. If all of the above fails, it’s time to replace your sensors and oxy pilot.

When To Call a Professional

If you have some experience working on gas fireplaces and a good manual that will walk you through part replacement in a clear manner, you can try making your repairs yourself. However, for most of us, the risk of fire and the difficulty of finding the right parts makes calling a professional fireplace repair service the easiest solution.

To get free quotes from licensed fireplace repair professionals, you can fill out the form below. Our repair service partner will reach out to gas fireplace repair services in your area and tell them about your issue. You’ll receive a phone call from the services closest to you with free repair quotes and advice on the next steps you should take.

Other Reasons Your Gas Fireplace Keeps Going Out

I’ve covered the most common issues in this article, but there are rarer issues that may be at fault. If you’ve attempted the fixed covered in this article and still aren’t seeing results, I recommend contacting a repair service to check for any of the following issues:

• Gas pressure. If your gas pressure is not set correctly, your fireplace will not work as it should. A certified technician will need to make the right adjustments.
• Faulty gas valve.  Gas valve failure is rare, but when it happens, it is a fire hazard, and the valve should be replaced by a trained professional.
• Moisture in the gas line.  This is also rare. Water and gas do not mix, so this could cause the flame to go out in your fireplace.
• Blocked burner ports. Dirt, soot, and oxidation can buildup on burner ports, blocking gas flow to create the fire.

Note that routine maintenance can prevent most of the problems you might have with your gas fireplace. An annual cleaning is recommended.

What if You Smell Gas?

If you smell gas after turning on your gas fireplace, you should open the windows and doors to ventilate the house. If the smell is strong, leave your home immediately and call your natural gas provider; if you can not reach your gas company, dial 911 and report the emergency.  

Always err on the side of safety.

Conclusion

Your gas fireplace usually keeps going out because of dirty or faulty sensors. In most cases, a simple cleaning of the oxy pilot, pilot light, and/or thermocouple or thermopile will solve the problem. In some cases, those parts may have to be replaced. Remember, working with gas can be hazardous. If you feel out of your depth, don’t hesitate to call a professional.

Chris Hewitt

Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he’s not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.