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Why Won’t My Furnace Pilot Light Stay Lit?

Is your furnace pilot light refusing to stay on? Gas furnaces have a pilot light that ignites the furnace burner whenever it’s in use.

When this pilot light refuses to stay lit, that also means your gas furnace won’t work—leaving you with a freezing home.

There are several reasons why your furnace pilot light won’t stay lit, the most common being:

  • A faulty thermocouple
  • A broken gas regulator
  • A corroded pilot tip
  • An unknown draft

Keep reading to learn more about what’s causing your pilot light problem and its corresponding fixes.

Reasons Your Gas Furnace Pilot Light Won’t Stay Lit

If you notice anything wrong with your furnace pilot light, it’s a great idea to get furnace repair services to help fix the issue. While you wait for services to become available, you can use the following quick fixes to temporarily correct the problem.

Reason #1: Faulty Thermocouple (Flame Sensor)

The thermocouple is a long copper tube that controls the gas valve inside gas furnaces. It’s often referred to as the flame sensor because it turns the gas flow on and off in the furnace whenever it senses heat.

A broken flame sensor can be dangerous as it means the gas valve won’t automatically shut off when it needs to. As a result, gas from your furnace will start flowing into your home, putting everyone at risk.

Symptoms of a Faulty Thermocouple

A visual inspection is needed to determine if the problem truly is a faulty flame sensor. You can contact a professional to do the assessment for you. Or you may also check it yourself using the following steps:

  1. Locate the flame sensor inside your furnace
  2. Look for signs of cracks, holes, or discoloration in the tubes
  3. Check for signs of corrosion in the wirings
  4. Check for bare wires or missing insulations
  5. Look for physical damages that could be affecting the reliability of the connectors

If there aren’t any obvious signs of a problem, the issue may lie elsewhere. This may be a great time to get in touch with an HVAC professional to check your furnace functionality.

How to Fix a Faulty Flame Sensor

There are two things you can do about a faulty gas furnace flame sensor: Cleaning or Replacement.

CLEANING A dirty flame sensor

Soot build-up can cause the flame sensor to stop working properly. A quick and deep clean should be able to help if that’s the case.

For this, you’ll need the following materials:

  • A screwdriver
  • Steel wool
  • Pencil eraser

After locating the dirty flame sensor, use the screwdriver to loosen it from the pilot assembly. Gently remove the soot from the flame sensor using a piece of steel wool.

DO NOT use any type of house cleaner on the flame sensor. This may cause unwanted damage to happen to the thermocouple.

Once you’re satisfied with the state of the probe, use the pencil eraser to clean the threaded end of the flame sensor.

Finally, reattach the thermocouple to the pilot assembly and see if the pilot light now works.

replacing a thermocouple

Gas furnace thermocouples come in different sizes. To ensure you get the right one, don’t forget to bring your broken thermocouple with you to the store.

If you’re unsure how to proceed with the process, getting a professional HVAC technician to help can save you from damaging your gas furnace further.

Reason #2: Broken Gas Regulator

If your pilot light refuses to stay lit, there could be something wrong with your gas regulator. This mechanism controls the gas pressure that flows to your furnace and other gas-powered appliances.

When this part is broken, gas pressure is reduced, resulting in your pilot light shutting down.

Symptoms of a Broken Gas Regulator

In cases where the gas regulator is the issue, signs can be observed in more than just one appliance in your home. Besides your gas furnace, make sure to check other gas-powered appliances such as burners, air conditioners, stoves, grills, and dryers.

If you notice that the gas pressure is low in any other appliance, it may not be getting enough gas from the supply.

How to Fix a Broken Gas Regulator

The best solution to a broken gas regulator is a complete replacement. Repairs can be done; however, experts advise against it since the risk of doing something wrong is high.

Contact your gas supplier or an HVAC technician to inspect your gas furnace and assist you with any necessary procedures.

Reason #3: Corroded Pilot Tip

Furnaces, especially older models, have something called a pilot light that ignites the furnace’s burners when in use. A healthy pilot light flame is normally blue with a strongly-shaped cone.

If the flame you see on your furnace pilot is yellow, you may have a corroded pilot tip in your hands. This type of problem can interrupt the gas flow and disrupt the furnace heating cycle.

Types of Furnace Pilot

Furnace pilots typically come in two forms:

  • Traditional Standing Pilot Light
  • Electronic Intermittent Pilot Ignition (IPI)

The standing pilot light is a traditional ignition system found in most older furnaces. They’re referred to as “standing” because they have flames that stay lit regardless of whether the fireplace is on.

On the other hand, an IPI uses a modern ignition system for the pilot burner that works only when the system is hooked into an electric power source. It doesn’t have a constant flame like the standing pilot light; instead, it needs you to manually ignite the pilot every time you use it.

How to Clean a Corroded Standing Pilot Light Tip

After confirming that your pilot light tip is corroded, you may want to clean the tip to try and fix the problem. Cleaning your furnace’s pilot is simple:

  1. Twist the gas valve to turn off the gas supply to avoid accidentally igniting the furnace pilot. If the pilot tip is still hot, give it around 30 minutes to cool down before proceeding to the next step.
  2. After cooling the furnace’s pilot, take a small pin or needle and use that to remove any debris or dirt from the pilot orifices.
  3. Use a small blower to remove loose bits of dirt and dust that you’ve managed to pry out of the pilot light.
  4. Turn on the gas supply and see if anything has changed with your pilot light.

Are you getting a bluer, healthier flame? Is the furnace staying lit?

If so, the process was successful and you don’t have to worry about it happening again anytime soon.

Unfortunately, there might also be cases when cleaning might not be enough to solve the issue. In that case, you may want to contact a professional to give your furnace a little once-over.

Reason #4: Unknown Draft

Another issue that might be preventing your pilot light from staying lit is an unknown draft. Cold air can flow through open doors and windows—it can even sneak in through cracks or holes in the walls.

Drafts can make it harder for your furnace to heat the air inside your home. Furthermore, drafts can blow out the pilot light flame without you even knowing about it until later.

How to Check Your Home for a Draft

The following techniques can help you determine if your home has an unknown draft that’s preventing your furnace burner from staying lit:

  • Stand close to your door and see if you can feel a soft breeze blowing on your skin. This means you probably have a draft somewhere near.
  • Carry a lit candle around your home and observe if it flickers or burns out. This means that a draft is nearby. Don’t forget to turn off appliances like fans and air conditioners. These appliances can cause disturbances in the air and can mask the presence of drafts in your house.
  • Take a coat hanger and hang a piece of plastic on one end of it. Hold it near your doors or windows and see if the bag blows up. If it does, this means there’s a draft somewhere near your windows or doors.

If none of these techniques work but you still suspect your home of having a draft, it might be time to contact a professional to do a complete sweep of your home. They’re more likely to have the right tools and materials to effectively spot drafts in your home .

How to Fix a Draft in Your Home

The only way to fix a draft in your home is to identify where the draft is coming from and seal it off permanently. If you’re not confident in your DIY home improvement skills, hiring someone to do the repairs for you is ideal.

Another thing you can do is get a barrier for your furnace. This barrier goes in front of your furnace and prevents air from blowing out the pilot light flame.

One-Stop Heating Helps You Determine and Fix Pilot Light Issues

To avoid experiencing pilot light issues, getting annual furnace maintenance is key. One-Stop Heating has all the services you need to keep your gas furnaces in tip-top shape throughout the year. Whether you need professional heating system installation or emergency AC repair, you can trust our technicians to get the job done.

Let us take care of your pilot light issues while you take care of your family!

Call (801) 355-9500