How To Light Pilot Light On Furnace

Many older furnaces rely on a pilot light, a small, continuous flame that ignites the main burner when heat is needed. If your furnace isn't firing up, a blown-out pilot light is often the culprit. While newer furnaces have electronic ignition, knowing how to relight a pilot light can save you a call to a professional and restore heat to your home. This guide provides step-by-step instructions and essential safety information to help you safely relight your furnace pilot light.

Understanding Your Furnace

Before you begin, it's crucial to understand the basic components and how they work together. Here's a simplified overview:

Gas Valve: This controls the flow of natural gas or propane to the furnace. It's usually a rectangular box with pipes connected to it. Look for a dial or lever on it.
Pilot Light Assembly: This small assembly houses the pilot light, a small nozzle that releases gas to feed the flame, and a thermocouple (or sometimes a flame sensor).
Thermocouple (or Flame Sensor): This safety device detects the presence of the pilot flame. If the flame is present, it allows the gas valve to stay open, supplying gas to the main burner when heat is called for. If the pilot light goes out, the thermocouple shuts off the gas supply to prevent a dangerous gas leak. Think of it as a 'gatekeeper' for the gas.
Main Burner: This is where the main combustion happens, producing the heat that warms your home.
Igniter: In some furnaces, after the pilot lights, there is an igniter that glows red hot to ignite the main burner.

Important Safety Note: If you smell a strong odor of gas, do not attempt to light the pilot light. Immediately evacuate the building and call your gas company or fire department from a safe location.

Gathering Your Supplies

You won't need many tools, but having these items on hand will make the process smoother and safer:

Long-handled lighter or match: A long-handled lighter or match is crucial for safely reaching the pilot light assembly without burning yourself. Standard short lighters are not recommended.
Flashlight or headlamp: Furnaces are often located in dimly lit basements or utility closets. A good light source is essential for seeing what you're doing.
Screwdriver (possibly): Some furnace access panels are secured with screws.
Owner's Manual: Your furnace owner's manual contains specific instructions for your model, including the location of the pilot light and the gas valve controls. Always refer to your manual first.
Safety Glasses: Protect your eyes from any debris or unexpected flare-ups.

Step-by-Step Instructions for Relighting the Pilot Light

1. Turn Off the Furnace:

Locate the power switch for your furnace and turn it to the "off" position. This is usually a standard light switch located on or near the furnace. This step is crucial for safety.

2. Locate the Gas Valve Control:

Find the gas valve control, usually located on the gas valve itself. It will typically have three positions: "On," "Off," and "Pilot." Sometimes, instead of positions it will have a push button for pilot. Note: some furnaces use electronic pilot ignition, so consult your manual.

3. Turn the Gas Valve to the "Off" Position:

Turn the gas valve control to the "Off" position and wait for at least five minutes to allow any accumulated gas to dissipate. This is a critical safety precaution to prevent a flash fire. Patience is key!

4. Locate the Pilot Light Assembly:

The pilot light assembly is usually located near the bottom of the furnace, often behind a small access panel. Your owner's manual will show its exact location. It's usually a small metal enclosure with a small opening to view the pilot light.

5. Turn the Gas Valve to the "Pilot" Position:

After waiting the required five minutes, turn the gas valve control to the "Pilot" position. On some models, you may need to press and hold down the reset button while in the Pilot position. This button manually allows gas to flow to the pilot light.

6. Light the Pilot Light:

While continuing to hold down the reset button (if applicable), use your long-handled lighter or match to light the pilot light. Insert the lighter or lit match through the opening in the pilot light assembly and position it near the pilot light nozzle.

7. Hold the Reset Button (If Applicable):

This is a crucial step. Continue holding down the reset button for 20-30 seconds after the pilot light ignites. This allows the thermocouple to heat up and generate enough electricity to keep the gas valve open. If you release the button too soon, the pilot light will go out.

8. Release the Reset Button:

After holding the reset button for 20-30 seconds, slowly release it. The pilot light should remain lit. If it goes out, repeat steps 5-7. If it continues to go out, there may be a problem with the thermocouple (see troubleshooting section below).

9. Turn the Gas Valve to the "On" Position:

Once the pilot light is burning steadily, carefully turn the gas valve control to the "On" position.

10. Turn the Furnace Back On:

Turn the furnace power switch back to the "On" position.

11. Test the Furnace:

Increase the thermostat to a temperature higher than the current room temperature. The main burner should ignite, and the furnace should start producing heat. If it doesn't, consult the troubleshooting section below.

Troubleshooting Common Problems

If you encounter problems while relighting the pilot light, here are some common issues and solutions:

Pilot Light Won't Stay Lit:
- Faulty Thermocouple: This is the most common cause. The thermocouple may be dirty, loose, or damaged. Try cleaning it gently with fine-grit sandpaper or steel wool. If that doesn't work, it likely needs to be replaced. A thermocouple is a relatively inexpensive part and can be replaced by a qualified technician.
- Dirty Pilot Light Orifice: The small opening that supplies gas to the pilot light can become clogged with dust or debris. A qualified technician can clean this orifice with specialized tools.
- Weak Gas Pressure: Low gas pressure can prevent the pilot light from staying lit. Contact your gas company to check the pressure.
- Drafts: Strong drafts can blow out the pilot light. Ensure the furnace area is well-ventilated but protected from direct drafts.
Pilot Light Won't Light:
- No Gas Supply: Make sure the gas valve is turned to the "Pilot" position and that you are holding down the reset button (if applicable).
- Clogged Pilot Light Orifice: A clogged orifice can prevent gas from flowing to the pilot light.
- Faulty Igniter: Some furnaces use an igniter to light the pilot. A faulty igniter will not produce a spark or glow.
Furnace Still Doesn't Work After Relighting Pilot:
- Check Thermostat: Make sure the thermostat is set to "Heat" and is set to a temperature higher than the current room temperature.
- Dirty Flame Sensor: A dirty flame sensor (found in some furnaces instead of a thermocouple) can prevent the main burner from igniting. Clean it gently with fine-grit sandpaper or steel wool.
- Faulty Igniter (Main Burner): If the pilot light is lit but the main burner doesn't ignite, the igniter for the main burner may be faulty.
- Blocked Flue: A blocked flue can prevent the furnace from operating safely. This is a serious safety hazard and should be addressed immediately by a qualified technician.

When to Call a Professional

While relighting a pilot light is often a simple task, there are situations where it's best to call a qualified HVAC technician:

You Smell Gas: If you smell a strong odor of gas, do not attempt to light the pilot light. Evacuate the building immediately and call your gas company or fire department.
You Are Uncomfortable: If you are not comfortable working with gas appliances, it's always best to err on the side of caution and call a professional.
Pilot Light Won't Stay Lit After Multiple Attempts: If you've tried relighting the pilot light several times and it still won't stay lit, there may be a more serious problem with your furnace that requires professional attention.
You Suspect a Gas Leak: If you suspect a gas leak, even if it's a small one, call your gas company or fire department immediately.
You Are Not Able to Find the Components: If you are unable to identify the gas valve, pilot light assembly, or other key components, consult a professional.

Preventative Maintenance

To help prevent your pilot light from going out and ensure your furnace operates efficiently, consider the following preventative maintenance tips:

Schedule Annual Furnace Inspections: A qualified HVAC technician can inspect your furnace, clean its components, and identify potential problems before they become major issues.
Replace Air Filters Regularly: Dirty air filters restrict airflow, which can cause the furnace to overheat and shut down. Replace your air filters every 1-3 months, or more often if you have pets or allergies.
Keep the Furnace Area Clean: Keep the area around your furnace clean and free of clutter to ensure proper airflow and prevent dust and debris from accumulating.

By following these steps and taking proper precautions, you can safely relight your furnace pilot light and restore heat to your home. However, remember that safety is paramount. If you are ever unsure about any aspect of the process, don't hesitate to call a qualified HVAC technician.