Constantly relighting the furnace pilot light is a hassle and usually signals a larger issue to resolve. We’ll go over common reasons it goes out and how to relight the pilot.

What is a Pilot Light

It’s the small flame that is visible inside a gas-powered furnace and stays lit thanks to a continuous feed from the gas line. It’s responsible for igniting the burner when the thermostat tells the furnace to begin producing heat.

Reasons Pilot Light Keeps Going Out

While there are several common reasons for a pilot light to extinguish, it’s important to use care and caution until it’s resolved, or another furnace issue is repaired.

Pilot Light is Dirty

The pilot light flame sits on the pilot orifice or opening. It’s easy to tell if this opening is dirty — a blue flame with tinges of green means it’s clean. A yellow or orange flame means something is impeding the gas flow, such as dirt, soot, or ash. When enough collects in the opening, the pilot light goes out and stays out until the opening is cleaned.

Thermocouple Fails

Every gas furnace uses a thermocouple, the copper rod next to the pilot light. It connects to the gas valve and when the full pilot light flame engulfs the thermocouple, it sends enough voltage through the rod to keep the gas flowing. The thermocouple also acts as a safety device for the furnace.

  • Broken or burned out: Because the rod expands and contracts with heat, this cycle steadily wears out the thermocouple until it eventually breaks or burns out.
  • Dirty: Because of its proximity to the burners, the thermocouple can become covered or coated with ash, soot, dirt, and other debris. This collection inhibits its ability to properly sense when the pilot light is lit; if it thinks the light is out, the gas flow stops to the pilot and the flame goes out.
  • Off-center: The pilot light needs to fully engulf the thermocouple rod. If the rod is bent or otherwise off center, the misalignment triggers the gas shutoff and causes the pilot light to extinguish.

Drafty Basement or Attic

The attic and basement of a home are known for drafts and other air leaks. But, because of their often unused space, these rooms are common installation spots for a furnace. If the pilot light keeps going out, check the basement or attic for air leaks, such as around window casings. Another place to look, and one that might require an HVAC technician, is the furnace duct. Sometimes a backflow develops and blows out the pilot light.

How to Re-Light Pilot Light

If there isn’t a bigger problem within the furnace, relighting the pilot is relatively easy and doesn’t take too much time.

Check the Manual

Begin by finding and reading through the owner’s manual for your specific furnace make and model. The manual will have the best instructions whereas the following are a generalization. If you can’t find the manual, check the manufacturer’s website — many have started including PDFs of support materials.

Turn off the Gas

For your safety, turn off the gas using the dial at the bottom of the furnace and its power supply at the source, usually the circuit breaker. Leave the gas off for at least five minutes before proceeding to allow the residual gas to dissipate. This time should be enough to allow leftover gas in the valves to dissipate.

Reset the Gas and Light the Pilot Light

Turn the gas and power back on then turn the dial to pilot; this allows gas to flow to the pilot opening. Press and hold the reset button, then using a long lighter, relight the pilot light by holding the lighter’s flame over the pilot opening. Release the reset button when the flame appears.

Pilot Light Safety and Maintenance Tips

Schedule Routine Tune-Ups and Maintenance

Regular furnace maintenance and timely repairs are crucial for the unit’s efficient operation and the safety of everyone in your home. This appointment is usually made before the furnace is needed and takes a couple of hours to complete. An HVAC technician works methodically with an extensive checklist of items such as:

  • Looking at the vent system: Proper venting keeps toxic gas fumes from entering your home. The technician will also remove any debris and make repairs if necessary.
  • Checking the heat exchanger: The heat exchanger is where carbon monoxide (CO) forms as a byproduct of burning gas. It may crack or become damaged as it ages, setting the stage for carbon monoxide (CO) to enter the home with the warm air.

Make sure to Change Your Air Filter

The air filter keeps airborne debris, such as dust, hair, and fur, out of the furnace which keeps the unit working efficiently and improves your indoor air quality. But, a clogged air filter won’t allow enough air into the furnace and affects how much warm air your home has. It’s recommended to change the air filter every two to three months.

Place Carbon Monoxide Detectors in Bedrooms

CO is an odorless and tasteless gas; many homeowners won’t realize there’s a problem until it’s a dangerous and life-threatening situation. That’s why it’s strongly recommended to keep CO detectors in every room, especially bedrooms. If a detector goes off at night, you and others will know and have enough time to leave the home to call 911.

Change the batteries in the CO detectors when you change clocks in the spring and fall. And, periodically test them by pressing the test button; throw away and replace any that fail to test.

Furnace pilot lights are easy to relight, but if they continue to go out, contact an HVAC technician to dig deeper into the cause. Need help with your furnace? Call JW Plumbing, Heating and Air today!

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