The basic steps to light a floor furnace pilot light

A floor furnace pilot light is a small, continuous flame that ignites the main burner when your thermostat calls for heat. If it has gone out, you can relight it yourself in most cases—it takes about five minutes and requires only a long lighter or long match. The process is the same whether your furnace is in a basement, crawlspace, or under a floor register: locate the pilot assembly, find the reset button or valve, and follow the manufacturer's sequence for ignition.

Before you begin, locate your furnace's model number and manufacturer name on the unit itself. You will need this if something goes wrong and you have to call a technician. Write it down or take a photo.

Key Takeaways

  • Most floor furnaces have a reset button or a manual ignition valve located near the pilot burner assembly.
  • The standard sequence is to turn the gas valve to "Pilot," press and hold the reset button, light the pilot with a long lighter, and hold the button for 30 to 60 seconds after ignition.
  • If the pilot will not stay lit after you release the button, the thermocouple (a safety sensor) may be dirty or failing, and you should call a technician.
  • Never force a stuck valve or button—if it does not move easily, stop and contact a professional.
  • If you smell gas and cannot light the pilot, leave the area and call your gas company's emergency line.

Locating the pilot assembly and gas valve

Open the access panel or door to your floor furnace. You will see the burner chamber and, near it, a small metal assembly with a tiny nozzle—this is the pilot burner. Just above or beside it is a control valve, usually a knob or lever labeled with settings like "Off," "Pilot," and "On."

Some furnaces have a separate red or black reset button near the valve. Others use the valve itself to control the pilot. Look for any labels or diagrams printed on the furnace body or on a sticker inside the door. If you cannot find clear markings, take a photo and call your furnace manufacturer's customer service line with your model number—they can walk you through the location.

Turning the valve to Pilot and pressing the reset button

Turn the gas control valve to the "Pilot" position. This reduces gas flow to only the pilot burner, making it safe to light. If your furnace has a separate reset button, press and hold it down. You should feel resistance—do not force it. The button may need to be held for several seconds before it catches.

If the button does not depress smoothly or feels stuck, stop when ready. A stuck button can indicate a mechanical problem, and forcing it may damage the valve. Call a technician instead.

Lighting the pilot with a long lighter or match

While holding the reset button down, bring a long lighter or long match to the pilot burner nozzle. You want the flame to reach the small opening where gas is flowing. The pilot should ignite within a few seconds. You may hear a small "pop" or see a brief flash.

If the pilot does not light on the first try, release the button, wait 30 seconds for any gas to clear, and repeat. Do not try more than three times in a row. If it still will not light, there may be a blockage in the nozzle or a gas supply problem, and you should stop and call a technician.

Holding the button and confirming the flame stays lit

Once the pilot is burning, keep holding the reset button for 30 to 60 seconds. This allows the thermocouple—a heat-sensing safety device—to warm up and signal the valve that the pilot is stable. After 60 seconds, slowly release the button. The pilot flame should remain lit.

If the pilot goes out as soon as you release the button, the thermocouple is likely dirty or failing. A thermocouple is a thin metal rod that sits in the pilot flame and generates a small electrical signal. When it is working, it tells the gas valve to stay open. When it is not, the valve closes as a safety measure. You can try gently cleaning the tip of the thermocouple with a soft cloth or fine steel wool, but if the pilot still will not hold, you will need a technician to replace it.

Turning the valve to On and testing the main burner

Once the pilot is holding steady, turn the gas control valve from "Pilot" to "On." This opens the main gas line. Set your thermostat to heat and raise the temperature a few degrees above the current room temperature. The main burner should ignite within 10 to 15 seconds. You should see a larger flame in the burner chamber and feel warm air beginning to flow from the registers above the furnace.

If the main burner does not ignite, turn the valve back to "Off" and wait a minute. Then repeat the pilot lighting process. Sometimes the ignition sequence needs a second attempt. If the main burner still will not light after a second try, stop and call a technician—there may be a problem with the ignition system or gas supply.

When to call a professional instead

Do not attempt to relight the pilot if you smell gas in the room or if the furnace has been leaking. Leave the area when ready and call your gas company's emergency line. Do not use electrical switches, lighters, or anything that could create a spark.

Also call a technician if the pilot will not light at all after three attempts, if it lights but will not stay lit even after you hold the button for a full minute, if the main burner will not ignite after the pilot is lit, or if you hear unusual sounds like hissing or popping from the furnace. A technician can check the thermocouple, clean the pilot nozzle, test the gas pressure, and inspect the ignition system—all things that require tools and training.

Frequently Asked Questions

How long should I hold the reset button before releasing it?

Hold it for 30 to 60 seconds after the pilot ignites. This gives the thermocouple time to heat up and signal the valve to stay open. If you release it too early, the pilot may go out. If you hold it longer, that is fine—it will not hurt anything.

What does it mean if the pilot lights but goes out when I release the button?

The thermocouple is not warming up enough to keep the valve open. This usually means the thermocouple is dirty, bent, or failing. You can try gently cleaning it with a soft cloth, but if the pilot still will not hold, the thermocouple needs to be replaced by a technician.

Can I light the pilot if I smell a little gas?

No. If you smell gas, do not light anything. Leave the area, open windows, and call your gas company's emergency line. A small gas smell can mean a leak, and lighting a flame could be dangerous.

How often do floor furnace pilots go out?

A healthy pilot should stay lit all season. If it goes out once or twice a year, it is usually due to a draft or a dirty thermocouple. If it goes out repeatedly, have a technician inspect the thermocouple, the gas valve, and the pilot nozzle for blockages or wear.

Do I need to turn off the furnace before relighting the pilot?

No. You can relight the pilot while the furnace is in "Off" mode. Just turn the gas control valve to "Pilot," light it, and then turn the valve to "On" when you are ready to heat. If the furnace is currently running, turn it off at the thermostat first, wait a minute, and then proceed with relighting.