If Pilot Light Goes Out On Furnace Is It Safe In The House?

Having a furnace is nice. When it’s cold out, it’s toasty-warm inside, and everyone is happy. Since it works with gas, some people worry that there could be safety issues, and questions naturally arise. For instance, if pilot light goes out in a furnace, is it safe in the house?

Today we’ll address the pilot light and your furnace in detail and answer some of the most common questions about them so that you can know what’s going on and what you can do should that pilot light go out. So let’s talk about your furnace and its pilot light!

If the pilot light goes out on a furnace, is it safe in the house?

Yes, if the pilot light goes out in your furnace, you are completely safe. This is because the tube which moves the gas into your main burner is fitted with a thermocouple. The thermocouple is there to stop the gas flow if your pilot light goes out so that it doesn’t build up in your furnace. It’s a standard feature that is there to keep you safe.

What is the Purpose of a Pilot Light in Furnaces?

A pilot light is a small flame that stays perpetually lit inside many gas appliances, such as your furnace, gas stove, or water heater. When you turn on your appliance, that little flame is there to ignite the gas in the main burner so that your appliance can heat up and do what it is designed for.

Do I need to Turn the Gas off if the Pilot Light goes out?

The thermocouple in your appliance will shut off the gas if your pilot light goes out, so you don’t have to switch off the gas immediately. The thermocouple safety feature is inside your appliance for exactly such situations.

Now, you certainly CAN turn off the gas, and you will eventually need to for the next steps. Your pilot light is supposed to be lit all of the time, after all, so if the pilot light goes out and you want to shut off the gas, you certainly can do that as it will be a necessary step for the process of relighting it.

Should the Pilot Light always be on in a Gas Furnace?

Leaving the pilot light on is a good idea. While you won’t be using your furnace in the summer, for instance, the gas consumption for keeping the light on is minimal – probably about $7 to $10 per month. The main reason that you want to keep it on is a little creepy but stay with us.


We don’t specifically know why they like it, but spiders are attracted to an additive gas company put in their gas. This is called mercaptan. When your pilot isn’t on, they can still smell traces of it, and they like to build their webs in there. This can get in the tubes and is not suitable for the overall functionality of your furnace.

That pilot light also serves a practical purpose, and that is keeping corrosion at bay. While it’s lit, it helps to reduce the level of moisture in the air, which helps to keep corrosion away from that part of your gas furnace interior.

What Causes A Pilot Light To Go Out?

When your pilot light goes out, there is generally a straightforward solution. Furnaces are fairly straightforward in how they function, so if you know a little about how they work, you can often fix the simple problems yourself if you are so inclined.

We’ll give you an overview of the 5 most common reasons below:

  • There could be a draft
  • Dirt in the pilot orifice
  • Gas regulator could need replacing
  • The thermocouple is having issues
  • Gas fluctuations unrelated to the furnace

1. There could be a Draft

If your pilot light seems to go out overnight fairly often, and lately, it’s been very windy, you might have a draft issue. This is usually caused by a leak inside the output duct of your furnace, and if this is the case, you can keep all of your intake registers in your home open to help minimize the chances of a draft blowing out your pilot light.

2. Dirt in the Pilot Orifice

Try lighting your pilot and once it ignites, take a look at the color of the flame. It should be blue, but if it is yellow and looking kind of weak, then you might have some dirt in the pilot orifice. This means that the pilot orifice will need to be disassembled and cleaned, generally with spray air.

If you aren’t comfortable taking apart the furnace, it’s good to get a professional to help you out. It’s a quick job for a pro, and that way, you don’t have to worry about voiding your warranty.

3. Gas Regulator could need Replacing

If you are noticing problems with all of your gas appliances in the house, it could mean that your outside meter has a bad gas regulator. This is something that the gas company will need to fix, so it’s out of your hands. Give them a call, and they can get it checked out for you to rule this issue out.

4. The Thermocouple is having Issues

Your thermocouple has a pretty simple job. It keeps the flow open if it detects the flame, but it shuts down the gas flow if it doesn’t detect your pilot. It is easy to replace if it’s broken if you are mechanically inclined but always call in a pro if you are uncertain.

Sometimes it’s just dirty, however, due to the accumulation of soot. In cases like that, you can remove the thermocouple and brush it out with an old toothbrush or, even better, a wire brush. The slightest amount of soot in there can cause it to stop functioning, so you might want to Google’ thermocouple maintenance’ so that you can learn how this is done.

Finally, if the thermocouple is not properly lined up in your furnace, then it doesn’t know when the flame is on. This is a case best suited for a pro to fix.

5. Gas Fluctuations Unrelated to the Furnace

Finally, if gas consumption is very high in your area, it can reach its peak, and your gas company might be lowering the pressure intermittently. This can cause the pilot to die out at seemingly random times. Contact your gas company to see there is a local issue.

What to Do When Your Pilot Light Goes Out on a furnace

If your pilot light goes out in the furnace, you’ll need to reignite it, and the process is relatively easy. So let’s go through the steps to prepare for the next time the pilot light goes out.

Relighting a Furnace Pilot Light

Check your furnace’s manual just in case, as steps may vary, but this is generally what you will want to do:

  • Turn off your gas valve and wait about 3 minutes
  • Switch the valve to ‘pilot’ and press your ‘reset’ button down
  • With reset pressed down, hold a lit match into the pilot light aperture until the pilot light ignites
  • If it doesn’t stay lit, then you may need to do some troubleshooting from our steps or contact a local professional to help


This concludes our deep-dive into the pilot light and what it does in your furnace. As you can see, its functionality is pretty straightforward, so if something goes wrong, you now know the most common reasons so that you may deal with them or get some help from a pro to get the issues resolved.

We wish you a healthy furnace and a warm winter!