How to Light the Standing Pilot Light on a Gas Furnace

Lighting the standing pilot light on a gas furnace is an important part of ensuring your heating system works properly and efficiently during the colder months. While most modern furnaces have electronic ignition systems that automatically light the gas burner, older models require manually lighting a standing pilot light which then ignites the main burner.

Relighting a standing pilot light is usually a quick and straightforward process, but it’s important to follow safety precautions. Gas leaks or improper lighting techniques can lead to risky situations. We’ll walk through the complete process in the steps below, but always refer to your specific furnace manufacturer instructions as well.

What You Need To Relight a Standing Pilot

Before getting started with relighting your furnace pilot light, make sure you have the proper supplies:

  • Long matches or lighter – Avoid using paper matches which may not reach far enough into the furnace. Use long fireplace matches or a long-necked lighter.
  • Flashlight – You’ll need to peer into the furnace to see the pilot light and burner. A flashlight is essential.
  • Manufacturer instructions – Consult the owner’s manual for your specific furnace model for lighting instructions. Instructions can vary.
  • Glasses and gloves – For safety, wear protective glasses and gloves.

Turn Off the Gas Supply Valve

The first step is to locate the gas supply valve for your furnace and turn it to the ‘off’ position. This valve may be on the side of the unit itself, or on the incoming gas supply line.

Turning this valve off cuts off the flow of gas to the furnace prior to lighting. This ensures no gas is accumulating in the combustion chamber while you work.

Gas Supply Valve

Locate the gas supply valve near the furnace and turn it off

Remove the Furnace Front Cover

Most gas furnaces have a removable metal cover on the front. Take off this cover to gain access to the burner chamber inside.

This usually only requires removing a couple screws or panels. The cover should lift off easily once loose.

Set the cover aside carefully so no wires or connections are strained.

Wait 5 Minutes

With the gas valve turned off and the front cover removed, wait 5 minutes before proceeding.

This allows any gas that may have accumulated in the combustion chamber to dissipate so there is no risk of ignition while you work.

Locate the Pilot Light Assembly

Now you can locate the pilot light assembly. It will be inside the burner chamber near the gas burner tubes.

Refer to your manual for the exact location. It may help to shine the flashlight inside to illuminate the small pilot light nozzle and igniter electrode.

Pilot Light Location

Use a flashlight to locate the pilot light nozzle inside the burner chamber

The pilot is a small tube with a nearby electrode that creates a spark. This is where you will apply the flame.

Turn Gas Valve to Pilot Position

With the pilot light assembly located, you can now turn on a small amount of gas flow.

Switch the gas control valve to the ‘pilot’ position. This allows gas to flow only to the pilot light, not the main burner.

Some valves have 3 positions – on, off, and pilot. Others have a knob or dial. Consult your manual for the proper valve control.

Depress and Light Pilot

Now comes the actual lighting steps:

  1. If your pilot has a button or switch to activate the igniter electrode, push it in. You should hear a sparking sound as the electrode sends a spark to the pilot nozzle.
  2. While depressing the igniter, apply flame to the pilot tube using your long match or lighter. Hold the flame to the pilot tube for about 60 seconds to heat the thermocouple.
  3. After holding the flame for a full minute, release your finger from the igniter button but keep holding the flame to the pilot. The thermocouple should now hold the pilot valve open.
  4. Remove the flame after another 30 seconds while still listening for the pilot to remain lit. Look for a stable, consistent flame at the pilot tube.
Lighting the Pilot

Depress the igniter while applying flame to the pilot tube

If the pilot does not stay lit, repeat the full sequence. Be patient while holding the flame to allow the thermocouple to heat up sufficiently.

If it fails to light after several tries, contact a professional service technician.

Turn Gas Control Valve to On

Once the pilot flame remains steadily lit, you can turn on the main gas supply to the furnace burners.

Switch the gas control valve from ‘pilot’ to ‘on’. This opens gas flow to both the pilot and the main burner tubes.

Listen as the main valve opens up. You may hear the gas igniting in the burners if the furnace is especially cold.

Replace Front Cover

With the pilot lit and gas valve on, replace the front cover on the furnace. Make sure all wires and tubes are clear and re-secure any screws or panels.

Set Thermostat to Call for Heat

The pilot is now ready to automatically ignite the burners when heat is needed.

Turn up your thermostat several degrees above room temperature so it calls for heat. Listen for the main burners igniting within a minute.

Confirm you feel warm air blowing from the ducts throughout your house.

Thermostat Calling for Heat

Set thermostat to call for heat

If the furnace does not ignite, reconfirm the gas control valve is set to ‘on’ and the pilot remains lit.

Troubleshooting Pilot Light Issues

If the standing pilot light fails to stay lit after releasing the igniter and flame, there are a few issues to troubleshoot:

  • Thermocouple connection – Check that the small thermocouple prong is tightly connected to the gas valve. Loosen and retighten this connection.
  • Drafts – Gusts of air across the pilot tube can blow out the flame. Seal any openings on the furnace front to block drafts.
  • Low gas pressure – A weak flame that goes out may indicate low gas supply pressure. Contact the gas company.
  • Old thermocouple – The thermocouple may need replacement after 5-10 years. Switch this inexpensive part out.
  • Clogged pilot orifice – Use compressed air to clear any possible blockages in the pilot orifice.

If troubleshooting does not resolve a stubborn pilot problem, it’s best to call a pro.

Safety Precautions When Relighting Pilot

When relighting the pilot, keep these safety guidelines in mind:

  • Turn off the gas valve and wait 5 minutes before starting. This prevents gas buildup.
  • Follow manufacturer lighting instructions exactly. Never improvise.
  • Keep your face and body as far away from the pilot area as possible during lighting.
  • Avoid excessive gas flow; turn off gas immediately if pilot fails to light within a minute.
  • Never leave the unit unattended when relighting. Stay until the pilot is stable.
  • Always replace the furnace front cover when done. Never operate without the cover securely in place.
  • Install a carbon monoxide detector near all gas appliances.

When to Call for Professional Assistance

While relighting a furnace pilot is usually straightforward, call for professional help in these situations:

  • If repeated attempts fail to light the pilot. There may be an underlying issue needing repair.
  • If you smell leaking gas. Shut off the valve and call the gas company.
  • If the burners fail to ignite after the pilot is lit. There could be a problem with the gas valve or burners.
  • If the pilot keeps going out, despite troubleshooting efforts. A persistent problem requires a pro.
  • If you lack the required tools or struggle with physical access to the furnace. Let a qualified technician handle it safely.

Maintaining the Pilot and Furnace

A few furnace maintenance tips involving the pilot light include:

  • Visually check the pilot flame each year. It should be blue in color and consistently 1-2 inches tall.
  • Listen for any unusual noises or smells from the furnace while operating. Anything abnormal could indicate a gas or combustion issue.
  • Have an HVAC technician inspect the gas control valve, heat exchanger, and burners annually. Ensure all components are in good shape.
  • Install a furnace filter reminder to replace filters per manufacturer recommendation, usually every 1 – 3 months.
  • Clear debris and combustible materials away from the furnace. Give the unit ample breathing room.

Moving to an Electronic Ignition System

Many homeowners eventually opt to upgrade their furnace to an electronic ignition system. This modern option offers:

  • Automatic ignition – No need to manually light pilots!
  • Added safety – No open flame constantly burning.
  • Energy savings – More efficient fuel use.
  • Reliability – Less prone to pilot outages.

While electronic ignitions involve an upfront cost, they can pay off in the long run through utility bill savings and reduced maintenance.


Manually relighting a furnace pilot light is a quick process if done safely and correctly. Pay close attention to manufacturer instructions and exercise gas safety precautions. Call a technician for assistance if trouble arises. With an aging furnace, consider upgrading to an electronic ignition for more convenience and efficiency.

Frequently Asked Questions About Relighting a Furnace Pilot

Relighting the standing pilot light in a gas furnace is usually straightforward. But questions can arise on proper lighting techniques and troubleshooting issues. Here are some common FAQs:

Q: How often does a pilot light need relit?

A: Most standing pilot lights only need to be relit if they go out unexpectedly. Otherwise they continuously burn all year long. Pilots can blow out due to gusts down the furnace vent, interruptions in gas supply, or age-related pilot assembly issues. Situations where a pilot is constantly going out likely indicate a larger problem needing service.

Q: Why does my pilot keep going out?

A: If a relit pilot won’t stay lit, potential causes include a weak thermocouple, excessive drafts near the furnace, debris or spider webs around the pilot clogging gas flow, or problems with gas supply pressure. Troubleshoot these possibilities before calling a pro for additional pilot diagnoses.

Q: Do I need a professional to relight my pilot?

A: Most homeowners can safely relight their standing pilot by following the manufacturer instructions closely. However, if you are unable to get the pilot going after several tries, or you smell gas at some point, call for professional assistance. HVAC technicians have experience troubleshooting stubborn pilot light issues.

Q: How long do I hold the flame on the pilot?

A: When lighting the pilot, hold the match or lighter flame to the pilot tube for at least 60 seconds. This heats up the thermocouple sufficiently to hold the gas valve open. Keep the flame in place another 30 seconds after releasing the igniter button before removing it. The pilot should stay lit at this point.

Q: What causes delayed ignition of the main burner?

A: If the main furnace burner does not immediately ignite after the pilot is lit, delayed ignition causes may include: low gas pressure, a dirty or faulty flame sensor, bad gas valve, or an issue with the hot surface igniter. A technician can diagnose the problem area.

Q: Can I upgrade my standing pilot system?

A: Many homeowners choose to upgrade their furnace to an electronically-controlled intermittent or hot surface ignition system. These modern ignitions eliminate having to manually light a pilot while also offering greater reliability, efficiency, and safety. Upgrading the ignition system costs more upfront but can pay off long-term.

Q: Why does my pilot have a yellow flame?

A: The pilot flame should burn bright blue. A yellow or orange colored pilot flame indicates contaminants or debris at the pilot orifice. Try clearing any dirt, spider webs, or oxidation with compressed air. If the yellow flame persists, the pilot assembly may need professional cleaning or replacement.

Q: Is it normal for the pilot flame to burn continually?

A: Yes, standing pilot flames are designed to burn 24/7 throughout the heating season. The nonstop flame provides a ready ignition source for the main burners while also establishing a draft in the vent. Some gas escapes up the flue when not firing. While not ideal, it’s standard for this older system. Upgrading to an intermittent pilot would improve efficiency.

Q: Where is the thermocouple on a furnace pilot?

A: The thermocouple is the small metallic rod located right in the flame path of the pilot. When heated by the flame, it generates a small electrical signal that holds the pilot gas valve open. If the pilot blows out, the thermocouple cools and closes the valve shutting off the gas. The thermocouple allows self-regulation of the pilot flame.

Q: Can I temporarily turn off my pilot light to save gas?

A: Turning off the pilot during a time when furnace heat is needed is not advisable. You would have to relight it again later, which creates an unnecessary hassle and safety issue. The small amount of gas saved is minimal. Also, turning off the pilot can lead to corrosion build up inside the gas line over time. Leave pilot lit during heating season.

Q: Why does my furnace pilot emit a sulfur smell?

A: The rotten egg odor of sulfur from a pilot indicates there are contaminants or impurities in the natural gas supply. Usually this is temporary. Contact the gas company if the issue persists more than a few days. In rare cases, a problem with gas regulators may need resolved.

How to Maintain Proper Furnace Pilot Operation

Keeping your standing pilot furnace system in top shape requires some periodic maintenance. Here are tips for optimal pilot operation:

Inspect the Flame

At the start of each heating season, visually inspect the pilot flame. It should burn bright blue, with minimal orangish-yellow tipping. The flame should be steady and reach 1 to 2 inches tall.

A weak, lifting, or lazy flame can allow the pilot to blow out. A dirty orifice may cause an overly yellow flame.

Good Pilot Flame

A healthy pilot flame is predominantly blue and 1-2 inches in height

Adjust the Pilot Flame if Needed

If the flame needs adjusted, turn the adjusting screw on the pilot gas supply line. Turn clockwise to reduce gas flow and shrink an overly large flame. Turn counter-clockwise to increase gas if the flame is too small. Make adjustments gently.

Adjusting Pilot Flame

Turn pilot adjustment screw clockwise to reduce flame, counter-clockwise to enlarge

Keep Air Vents Clear

Ensure all combustion air vents on the furnace are clear and unobstructed. Blocked vents can choke air flow to the burners. Keep a 12-18 inch clearance around the furnace.

Clean the Pilot Orifice

Over time, oxidation and small debris can clog the pilot orifice hole. Use compressed air to clear out any obstructions through this small opening. Blow air through straw attached to the air nozzle.

Replace Thermocouple When Needed

The pilot thermocouple should be replaced every 5-10 years. These inexpensive parts wear out over time. A weak thermocouple allows the pilot to go out.

Have a Professional Cleaning

HVAC technicians can perform a professional deep cleaning of the pilot assembly, burners, heat exchanger, blower, and gas valve. Buildup in these components can reduce furnace performance and lifespan. Schedule professional cleanings as manufacturer recommends, usually every 2-3 years.

Replace Furnace Filter Regularly

A dirty filter forces the blower to work harder to draw sufficient air across the heat exchanger. Replace filters as recommended, generally every 1-3 months depending on type. Set a reminder to swap filters seasonally.

Arrange Annual Inspections

Have an HVAC professional inspect your standing pilot furnace before each heating season. They check all components for wear, corrosion, carbon buildup, rust, cracks, leaks, and proper operation. These inspections help keep the furnace running safely and efficiently for years to come.

Upgrading to an Electronic Ignition System

Standing pilot furnaces date back generations. Eventually, the pilot assembly components wear out. Repairs can become frequent. Efficiency declines over decades of use.

When repair costs mount, many homeowners choose to upgrade their old furnace to a modern electronically controlled model. Here are pros and cons when considering this upgrade:

Benefits of Electronic Ignition

  • Automatic – No manually lighting pilots required. The igniter automatically switches on when heat is needed.
  • Modern convenience – New models have programmable thermostats, WiFi controls, and advanced features.
  • Efficiency – No gas wasted heating a constant standing pilot. Electronic ignitions only use gas when firing the burner.
  • Reliable – Electronic ignition systems are very dependable starts. Standing pilots can blow out.
  • Safe – No open flame burning 24/7 during winter. Electronic ignitions have fewer safety risks.
  • Reduce energy bills – More efficient fuel use directly saves money on natural gas or propane each month.
  • Environmentally friendly – Less wasted gas benefits the environment long-term.

Drawbacks of Electronic Ignition Upgrades

  • Cost – Replacing the entire