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How To Relight a Pilot Light on a Furnace

Cassie Pound, owner of Quality Heating, Cooling, Plumbing & Electric
Published by
Cassie Pound
January 20, 2024
How To Relight a Pilot Light on a Furnace

If you’re experiencing problems with the heating system in your Tulsa home, rely on the experts at Quality Heating, Cooling & Plumbing for help. Book an appointment now!

If your home uses a gas furnace to provide heat to the premises, it may have a pilot light. The pilot light or flame ignites the heating unit’s burners to combust natural fuel to produce heat.

Unfortunately, these flames can blow out for various reasons. So, knowing how to relight a pilot light on a furnace is necessary to keep the warmth flowing. 

As one of the top service providers for heating and air conditioning in Tulsa, Oklahoma, Quality Heating, Cooling & Plumbing regularly tends to gas furnaces. If you can’t properly heat your home due to the furnace’s pilot light going out, here are several tips on relighting it and possible blow-out causes.

Reasons a Furnace Pilot Light Goes Out

Age of the Heating Unit

Many furnaces facilitate the combustion process with a pilot light. When you turn on your home’s heat, the gas will travel through a valve to reach the pilot light. It’s a small blue flame that the system uses to ignite natural gas from the main burner.

Newer natural gas and propane furnaces lack a typical pilot light that burns constantly. Instead, they use an electronic ignition system that turns on only when necessary to burn fuel. Older furnaces 20 years old or older have traditional standing pilot lights. 

With a furnace that old, the system is likely to have worn, dirty components, reducing their inefficiency. As a result, the pilot light could struggle to stay lit. 

Ventilation Problems

A gust of air could also blow out the furnace’s pilot just like a lit match or candle. You might not realize that air could cause your pilot light to go out. Still, it’s common, especially if your heating unit ducts leak air. 

Gusts of wind are most likely the cause of your pilot light issues if your furnace flue has an incorrect installation or significant damage. Flue problems can also develop and affect your pilot light’s efficiency if the exhaust isn’t the right size for the furnace. In that case, the incorrectly sized flue could let in a draft that prevents the pilot light from staying lit. 

Thermocouple Issues

A thermocouple is a small safety valve that stops the flow of gas to the pilot light. Stopping the gas flow to the pilot light is necessary if the flame is no longer lit or is too small to ignite the gas in the main burner. 

The purpose of a thermocouple, which is directly over the pilot light, is to detect the flame. If the component is dirty or damaged and the flame goes out, the gas supplying the pilot light will continue seeping out. A gas leak is a serious problem, so a functional thermocouple is essential for your household’s safety. 

However, if the thermocouple has a problem, it could incorrectly shut off the gas supply to the pilot light. Without gas, the flame will not stay on. It’s not enough to know how to relight a pilot light on a furnace with a broken thermocouple; you’ll need a furnace technician to clean, repair, or replace the component to ensure it doesn’t prematurely cut the gas supply to the pilot light. 

Problems With the Gas Valve or Fuel Supply

Similar to a thermocouple, a functional gas valve is necessary for a pilot light on a furnace to stay on. If the gas valve doesn’t feed enough gas to the pilot light because of damage, it will blow out due to the lack of fuel. Even if the valve is operational, the pilot light will continue experiencing complications if the fuel supply is low. 

Broken Heat Exchanger

A furnace heat exchanger is a crucial component between the blower and combustion chamber that transfers heat from the furnace to the rest of your home. If your unit’s heat exchanger cracks, it will negatively affect the combustion chamber’s air pressure. As a result of the air pressure and venting changes, air can seep inside the chamber and blow out the pilot light. 

It’s best to hire a professional HVAC company to address an unlit pilot light if you suspect problems with the heat exchanger. 

5 Simple Steps To Relight the Pilot Light on a Furnace

While many homeowners feel comfortable enough to relight their furnace pilot lights if they go out, professional HVAC help is often necessary to address equipment issues that are causing the pilot light problems. Still, you can learn the basics of how to relight a pilot light on a furnace with this step-by-step guide.  

1. Check the Equipment’s Instruction Manual

Before doing anything to your furnace, you should familiarize yourself with its instruction manual. In the manual, you’ll find relevant information about your specific heating system, such as how to relight the pilot light and where to find “on,” “off,” and “reset” switches. 

Though different heating system models and brands may have varying setups and processes for relighting pilot lights, the general instructions tend to be the same. If you can’t find your furnace’s instruction manual, you can use the following steps to turn it back on. 

2. Locate the Furnace’s Reset Switch and Pilot Light Assembly

The pilot light assembly will most likely be at the bottom of the equipment. Near it, you may find a knob or switches with an “on,” “off,” and “pilot” setting. 

The knob should be fixed on the “pilot” setting once you locate it. Turn it to the “off” setting using your fingers. This adjustment stops the gas flow to the pilot light, making it safe to relight. 

3. Wait Several Minutes

You don’t want to immediately shift the knob from the “off” to the “pilot” positions to relight the pilot light. Instead, wait for at least five minutes. You must give the remaining gas time to dissipate from the combustion chamber to prevent igniting it. 

4. Relight the Pilot Light

After waiting for several moments, turn the knob or switch back to the “pilot” setting. Doing this will open the gas valve to the pilot light. 

Locate the furnace’s reset button. Next, light a long match or use a long-neck lighter to relight the pilot light while pressing the reset button. Keep your finger on the reset button until you see the pilot light burning steadily with a bright blue flame. 

5. Observe the Furnace’s Functions for Other Problems

Even after following these steps, the pilot light could go out again if there’s an unfixed problem blowing out the flame or preventing sufficient gas supply from reaching the pilot light assembly. If the flame blows out again, it’s time to call the professionals. 

Get Professional Help With Your Natural Gas Furnace Today

The pilot light on your gas furnace can blow out at any time, leaving your home in Tulsa, Oklahoma, without sufficient heat. It’s usually best to seek help from a qualified HVAC company, but knowing how to relight a pilot light on a furnace is still helpful in minor situations. 

At Quality Heating, Cooling & Plumbing, our crew of licensed and certified technicians can help with many systems and equipment around your home to improve your safety and comfort. Whether you need to reset your electronic ignition furnace, repair a water heater, or maintain your furnace to optimize its performance and improve indoor air quality, our team can help. 

As a locally owned and operated company, Quality Heating, Cooling & Plumbing’s team is responsive, experienced, and courteous. Call (918) 393-4577 for an appointment today. 

Cassie Pound, owner of Quality Heating, Cooling, Plumbing & Electric
Published by
Cassie Pound

Cassie Pound is the Vice President of Quality Heating, Cooling, Plumbing & Electric with locations in Tulsa, Glenpool, and Bartlesville, Oklahoma.