Do Furnaces Have Pilot Lights? What You Need to Know

If you’ve ever looked at your furnace and wondered whether that small flame should stay lit, you’re not alone. Do furnaces have pilot lights?

The answer is some do, but not all. Older gas furnaces commonly use a standing pilot light that stays lit continuously. Most modern gas furnaces use electronic ignition, which activates when the furnace needs heat.

Knowing your furnace’s ignition type helps you understand how it operates and recognize potential problems.

Do Furnaces Have Pilot Lights?

Some furnaces have pilot lights, while others don’t.

A traditional standing pilot light is a small gas flame that stays lit continuously. When your thermostat calls for heat, the pilot ignites the gas supplied to the furnace’s main burner.

Modern gas furnaces generally use electronic ignition instead. Depending on the furnace, this may involve a hot-surface igniter, direct spark ignition, or an intermittent pilot that operates only during the heating cycle.

Electric furnaces don’t have pilot lights because they don’t use gas combustion to generate heat.

Do All Gas Furnaces Have a Pilot Light?

No, not all gas furnaces have a pilot light. Many older gas furnaces use standing pilots, but newer models use electronic ignition. Another option is an intermittent pilot system that lights a small pilot flame only when heat is needed instead of burning continuously.

If you’re unsure what type of ignition your furnace uses, check the owner’s manual or furnace documentation. The model number can also help an HVAC professional identify the system.

What is a Furnace Pilot Light?

A furnace pilot light provides the ignition source for the main burner in a gas furnace.

In a standing-pilot system, the flame remains on between heating cycles. A thermocouple acts as an important safety component by sensing whether the pilot flame is present. If the flame goes out and the thermocouple cools, the gas valve can shut off the gas supply.

Because a standing pilot burns continuously, it uses a small amount of gas even when the furnace isn’t heating your home.

How Can You Tell If Your Furnace Has a Pilot Light?

To determine if your furnace has a traditional pilot light, look for a small flame that stays lit when the furnace isn’t heating.

If you have a pilot light furnace, you’ll typically see this standing flame near the burner assembly.

You can also:

• Check your furnace owner’s manual.
• Look at the manufacturer’s label and model number.
• Review the installation documentation.
• Observe the furnace during startup without removing or interfering with components.

If there’s no continuously burning flame, your furnace may use electronic ignition. That does not necessarily indicate a problem.

Why Does a Furnace Pilot Light Keep Going Out?

A standing pilot should stay lit. If it repeatedly goes out, there may be an underlying problem. Common causes include:

• Dirty pilot assembly: Dirt or debris can restrict the pilot orifice and weaken the flame.
• Faulty thermocouple: A malfunctioning or improperly positioned thermocouple can trigger the shutdown of the gas valve.
• Drafts: Strong airflow around the furnace can extinguish a small pilot flame.
• Gas supply problems: An interruption or pressure issue can affect the pilot flame.
• Gas valve problems: A faulty gas valve can interfere with proper gas flow.

If your pilot keeps going out, do not repeatedly relight it without finding the cause. A qualified HVAC professional can identify and fix the problem.

Is it Safe to Relight a Furnace Pilot Light?

If your furnace uses a standing pilot, the manufacturer’s instructions explain how to relight it. Always follow them exactly.

Never attempt to relight a pilot if you smell gas.

If you sense gas, hear hissing, or suspect a gas leak:

• Do not attempt to ignite the pilot.
• Avoid creating sparks or using electrical switches.
• Leave the area and follow your local gas utility’s emergency instructions.
• Contact the appropriate gas utility or emergency service from a safe location.

If there’s no gas odor and the manufacturer’s instructions provide a pilot-light relighting procedure, follow them carefully. If the pilot won’t stay lit or repeatedly goes out, contact a qualified HVAC professional rather than continuing to troubleshoot it yourself.

Frequently Asked Questions

Do modern furnaces have pilot lights?

Most modern gas furnaces don't use a continuously burning standing pilot. They generally use electronic ignition, although some systems use an intermittent pilot.

Do electric furnaces have pilot lights?

No. Electric furnaces don't burn gas, so they don't require pilot lights.

How do I know if my furnace has a pilot light?

Look for a small flame that remains continuously lit when the furnace isn't heating. You can also check the owner's manual or have an HVAC professional identify the ignition system.

When Should You Call an HVAC Professional?

A pilot-light problem may be more than a simple ignition issue. Contact a HVAC professional if:

• The pilot repeatedly goes out.
• The flame looks weak, unstable, or unusually yellow.
• The furnace won’t heat after the pilot is lit.
• You suspect a problem with the thermocouple or gas valve.
• You smell a gas-like odor or suspect a gas leak.
• You’re unsure how your furnace’s ignition system works.

Gas furnaces involve fuel, combustion, electrical components, and safety controls. If you’re uncertain about what you’re seeing, professional service is the safest option.

Need Help With a Furnace Pilot Light?

Not every furnace has a pilot light. Older gas furnaces commonly use standing pilots, while modern gas furnaces generally use electronic ignition systems.

If your furnace has a standing pilot that repeatedly goes out, the problem could involve the pilot assembly, thermocouple, gas supply, airflow, or another component. Don't ignore recurring problems, and never attempt to relight a pilot if you smell gas.

If you're unsure whether your furnace uses a pilot light or need help diagnosing a heating problem, Fahrenheit AC can help. Their qualified HVAC professionals can inspect your furnace, identify the cause of recurring pilot-light issues, and recommend the appropriate repair or replacement options for your home in South Florida.