How to Light a Pilot Light on a Furnace: A Step-by-Step Guide

Have you ever woken up to a frigid house on a winter morning, only to discover your furnace is refusing to kick on? A common culprit behind a silent furnace is a pilot light that has gone out. While it might seem intimidating, relighting a pilot light is often a straightforward process that can save you time, money, and a whole lot of shivering. Understanding how to perform this simple task empowers you to quickly restore heat to your home without needing to call a costly HVAC technician for a minor issue.

A functioning furnace is essential for maintaining a comfortable and safe living environment, especially during colder months. Beyond simple comfort, reliable heat protects your pipes from freezing, which can lead to expensive and disruptive water damage. Knowing how to troubleshoot and address common problems, like a pilot light that needs relighting, allows you to proactively maintain your home and avoid potential emergencies. With a few easy steps and a healthy dose of caution, you can often resolve this issue yourself.

What tools do I need, and how do I relight it safely?

What safety precautions should I take before lighting a furnace pilot light?

Before attempting to light a furnace pilot light, the most critical safety precaution is to shut off the gas supply to the furnace. Then, thoroughly ventilate the area around the furnace for at least five minutes to dissipate any accumulated gas. Finally, check for gas leaks using a gas leak detector or soapy water before proceeding.

Before you even think about striking a match or pressing an igniter, ensuring adequate ventilation is paramount. Natural gas and propane are heavier than air and can accumulate in confined spaces, creating an explosion hazard. Open windows and doors in the vicinity of the furnace to allow any lingering gas to escape. If you smell a strong odor of gas even after ventilating, do not attempt to light the pilot. Evacuate the area and call your gas company or a qualified HVAC technician immediately.

Next, perform a thorough leak check. You can use a commercial gas leak detector, which is the safest option, or mix a solution of soapy water (dish soap works well) and apply it to all gas connections around the furnace, including the gas valve, pilot light assembly, and gas lines. Look for bubbles forming in the soapy water, which indicates a gas leak. If you find any leaks, tighten the connections if you are comfortable doing so, or call a professional for assistance. Never attempt to light the pilot light if you suspect a gas leak is still present.

Remember, safety is always the top priority. If you are uncomfortable with any part of the process or unsure about any steps, do not hesitate to call a qualified HVAC technician to light the pilot light for you.

Where is the pilot light located on my specific furnace model?

Unfortunately, I cannot tell you *exactly* where the pilot light is on *your* specific furnace model without knowing that model number. However, generally, the pilot light is located inside the burner compartment, usually near the gas valve and main burner assembly. You’ll typically need to remove an access panel or door to see it. Look for a small metal assembly with a tiny opening where the flame will be. Often, there will be labels or diagrams near the gas valve or on the inside of the access panel indicating the pilot light location.

Finding the pilot light necessitates a bit of careful searching. First, locate the main access panel on your furnace; this is usually at the bottom front of the unit. Before removing any panels, ensure the power switch to the furnace is turned OFF. Once you have the panel off, look for the gas valve. The pilot light assembly will almost always be in close proximity to this gas valve. Look for a small nozzle or burner that’s separate from the larger main burners; this smaller assembly is where the pilot flame originates. Keep in mind that some newer furnaces have electronic ignition systems and do not use a standing pilot light. Instead, they use an igniter or hot surface igniter to light the main burners directly. If you don’t see a typical pilot light assembly, or if you see something resembling a glow plug or a small sparking device near the main burners, it’s likely your furnace has an electronic ignition system and doesn’t require manual pilot light relighting. In such cases, you should consult your furnace’s manual or a qualified technician if your furnace is not igniting properly.

How long should I hold the reset button when lighting the pilot?

Typically, you should hold the reset button (often labeled “pilot”) for 30-60 seconds after lighting the pilot light. This allows the thermocouple, a safety device, to heat up and generate enough electricity to keep the gas valve open, ensuring the pilot light remains lit after you release the button.

Holding the button for the correct duration is crucial. If you release it too soon, the thermocouple won’t be sufficiently heated, and the pilot light will go out as soon as you let go of the button. This means you’ll have to repeat the lighting process. If you hold it for longer than 60 seconds, it usually won’t cause any harm, but it’s unnecessary. The precise time might vary slightly depending on the furnace model and the age of the thermocouple. If, after holding the button for a full minute, the pilot still won’t stay lit, the thermocouple itself may be faulty and require replacement. In that case, it is highly recommended to call a qualified HVAC technician. Trying to bypass safety features can be dangerous.

What if the pilot light lights but won’t stay lit?

If the pilot light ignites but fails to remain lit, the most common culprit is a malfunctioning or dirty thermocouple. The thermocouple is a small metal rod positioned near the pilot flame; its purpose is to sense the heat from the pilot and, when hot enough, signal the gas valve to remain open and continue supplying gas to the pilot. If the thermocouple isn’t generating sufficient voltage, the gas valve will shut off the pilot light as a safety precaution.

To troubleshoot this, first, ensure the pilot light flame is engulfing the tip of the thermocouple. If it’s not, a slightly bent pilot tube might be the issue, and gently adjusting its position could help. However, most often, the thermocouple itself is the problem. Over time, thermocouples can become dirty or corroded, hindering their ability to generate sufficient voltage. You can try gently cleaning the thermocouple with fine steel wool or emery cloth to remove any buildup. If cleaning doesn’t solve the problem, the thermocouple is likely faulty and needs replacement; these are relatively inexpensive and readily available at most hardware stores. If replacing the thermocouple doesn’t fix the issue, it could indicate a problem with the gas valve itself. The gas valve could be failing to receive or interpret the signal from the thermocouple, preventing it from staying open. While less common, issues with the gas line pressure could also contribute. However, diagnosing and repairing gas valve or gas line problems are best left to qualified HVAC technicians due to the inherent safety risks associated with gas appliances.