How To Light A Furnace Pilot? Explained

June 30, 2025

Learning how to light a furnace pilot is a useful skill that can quickly restore your heat and comfort. However, when dealing with any gas appliance, safety must always be your first priority. So the experts at Accolade Heating will walk you through the process step-by-step.

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Before You Touch Anything, Safety First

If you smell gas, which is often described as a rotten egg or sulphur scent—DO NOT attempt to light the pilot. Do not operate light switches, use your phone, or create any kind of spark.

Leave your home immediately, get to a safe distance, and call your gas utility's emergency line.

The steps below should only be taken if you can safely do them and can confirm that you don't smell gas.

How to Check the Pilot Light on a Furnace

Before you can relight the furnace, you need to know where to look.

Here’s how to check the pilot light on a furnace:

  1. Locate the Access Panel: Find the front cover on your furnace unit. You may need to slide or lift it off.
  2. Find the Gas Valve Assembly: Look inside near the bottom of the furnace for a control box. You should see a knob with "ON," "OFF," and "PILOT" settings.
  3. Identify the Pilot Tube: There is a thin, often silver-colored line that leads to the main burners right next to this valve. Follow this tube to its end. If the pilot is lit, you will see a small and steady blue flame. If there is no flame, you can proceed to relight it.

How to Turn On a Furnace Pilot Light

These are general instructions that apply to most older furnaces. For specific details, always check for instructions printed on a label inside your furnace's access panel.

Step 1: Turn Off the Power and Gas
Set your thermostat to the lowest setting. Find the gas valve on your furnace and turn it to OFF.

Step 2: Wait 5 Minutes
This is an important safety step. Wait a full 5 minutes to let any leftover gas clear out.

Step 3: Set to "PILOT"
After waiting, turn the gas valve to the PILOT position.

Step 4: Hold the Reset Button
Press and hold the knob or nearby red reset button. This lets gas flow to the pilot.

Step 5: Light the Pilot
While holding the button, carefully light the pilot with a long lighter or match. You should hear a small “whoosh.”

Step 6: Hold for 60 Seconds
Keep holding the button for one full minute to heat the thermocouple (a safety sensor).

Step 7: Release and Turn to "ON"
Let go of the button. If the pilot stays lit, turn the valve to ON.

Step 8: Turn Up the Thermostat
Raise the temperature on your thermostat. If the main burners turn on, you’re good to go. Don’t forget to replace the furnace panel.

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What to Do If Your Furnace Pilot Light Is Out Again

You relit the pilot, but a short time later, your furnace pilot light is out once more. It means there’s a problem that needs professional diagnosis.

The common causes may include:

  • A Faulty or Dirty Thermocouple: This is the most frequent issue. If the sensor is failing or covered in soot, it won't detect the flame and will keep shutting off the gas as a safety precaution.
  • A Clogged Pilot Orifice: Debris can block the small opening. It leads to a weak flame that is easily extinguished by drafts.
  • A Strong Draft: Air blowing on the pilot from a poorly sealed chamber or nearby vent can extinguish the flame.
  • Problems with the Gas Regulator: An issue with the main gas supply can cause inconsistent pressure, affecting the pilot flame.

Stay Warm Safely

Knowing how to light a furnace pilot is a great skill for any homeowner with an older furnace. However, your safety is always the top priority. If you smell gas, are unsure about any step, or if the pilot light won't stay lit, put down the tools and pick up the phone.

For fast, reliable, and safe furnace repair and maintenance, trust an expert team like Accolade Heating.