Lighting a pilot light on a furnace is a common maintenance task that many homeowners can perform safely, restoring heat to their homes. It involves carefully following a sequence of steps to reignite a small, continuous flame that ignites the main burners when the thermostat calls for heat.
Understanding Your Furnace's Pilot Light
A pilot light is a small, constant flame that serves as an ignition source for your furnace's main burners. In older or some specific modern furnaces, this tiny flame is essential for heating your home. If your furnace isn't producing heat, and you suspect it uses a pilot light, checking and potentially relighting it is often the first step in troubleshooting.
Safety First: Before You Begin
Working with gas appliances requires extreme caution. Prioritizing safety is paramount to prevent gas leaks, fires, or other hazards.
- Check for Gas Odor: If you smell gas, do not attempt to light the pilot light. Immediately open windows and doors, leave the premises, and contact your gas company or a qualified HVAC professional from a safe location.
- Turn Off Power: Before touching any furnace components, always turn off the electrical power to the furnace. This can usually be done at a dedicated switch on the furnace itself or at your home's main electrical panel.
- Locate Components: Identify the gas control valve, the pilot light assembly, and the igniter/reset button (often a button on the gas control valve itself).
Tools You Might Need
While sometimes a built-in igniter is available, it's good to have these on hand:
- Long lighter or matches
- Flashlight (for better visibility)
- Screwdriver (if you need to remove a small access panel)
Step-by-Step Guide to Lighting Your Furnace Pilot Light
Follow these instructions carefully to safely relight your furnace's pilot light:
-
Access the Pilot Light Assembly:
- Locate the furnace's main gas control valve. This is typically a knob or switch with settings like "OFF," "PILOT," and "ON."
- You may need to remove a small access panel or cover on the furnace to reach the pilot light assembly.
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Turn the Gas Control Knob to "OFF":
- Rotate the gas control knob to the "OFF" position. This stops any gas flow and allows any residual gas to dissipate.
- Wait at least 5 to 10 minutes to ensure any unburned gas clears from the area. This is a critical safety step.
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Turn the Gas Control Knob to "PILOT":
- After the waiting period, turn the knob to the "PILOT" setting. This allows a small amount of gas to flow specifically to the pilot light.
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Light the Pilot Light:
- On many furnaces, you'll need to push in and hold down the reset button (often integrated into the gas control knob itself) while lighting. This action allows gas to flow to the pilot.
- While holding the button down, bring a lit lighter or a long match to the pilot light's opening. You should see the pilot flame ignite.
- Keep the reset switch or knob depressed for about 30 to 60 seconds after the pilot lights. This allows the thermocouple (a safety device that senses the pilot flame) to heat up and signal to the gas valve that it's safe to keep the pilot lit.
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Verify and Release:
- Slowly release the reset button or knob. If the pilot light remains steadily lit, you've succeeded.
- If it goes out, repeat steps 3-5, holding the button down for a slightly longer period.
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Turn the Gas Control Knob to "ON":
- Once the pilot light is burning steadily, turn the gas control knob from "PILOT" to the "ON" position.
- Replace any access panels or covers you removed.
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Restore Power and Test:
- Restore electrical power to the furnace.
- Go to your thermostat and set it to call for heat (e.g., raise the temperature setting above the current room temperature). The main burners should ignite, and the furnace should begin heating.
Troubleshooting Common Issues
If your pilot light won't light or stay lit, here are some common reasons and solutions:
| Issue | Potential Cause | Solution |
|---|---|---|
| Pilot Light Won't Ignite | Gas supply issues | Ensure main gas valve to the furnace is open. Check if other gas appliances in your home are working. If not, contact your gas utility. |
| Clogged pilot opening | The small orifice where the gas exits for the pilot light can get dirty. Gently clean it with a thin wire (like from a paperclip, but avoid forcing anything). Turn off gas first. | |
| Pilot Light Lights But Goes Out | Faulty Thermocouple | The thermocouple is a copper rod that senses the pilot flame. If it's dirty, bent, or faulty, it won't signal the gas valve to stay open. It often needs cleaning or replacement. |
| Low gas pressure | Can be an issue with your home's gas line or utility supply. A professional can diagnose this. | |
| Pilot Flame is Weak or Yellow/Orange | Dirty pilot burner or thermocouple, low gas pressure | A healthy pilot flame is strong and blue. Clean the pilot burner and thermocouple. If it remains weak or discolored, it might indicate a gas pressure issue requiring professional attention. |
For a deeper dive into furnace troubleshooting, resources like Energy.gov's furnace maintenance tips can be helpful.
When to Call a Professional
While lighting a pilot light is often straightforward, there are times when it's best to call a qualified HVAC technician:
- You smell gas. (As mentioned, this is a critical safety hazard.)
- You've tried multiple times, and the pilot light won't stay lit.
- The main burners don't ignite after the pilot light is lit.
- You're uncomfortable or unsure about any step of the process.
- Your furnace shows signs of other malfunctions, such as strange noises or short cycling.
A professional can diagnose underlying issues, ensure proper gas pressure, and address any component failures, keeping your furnace running safely and efficiently.
