All About Your Furnace Pilot Lights

As homeowners, we tend to only think about our pilot lights when it’s clear there is a malfunction. One has only to search the internet to see the bevy of requests for information on re-lighting pilot lights or common problems associated with them.

Demystifying the potential problems around the pilot light in your furnace becomes especially important as cold seasons set in. If you suspect there may be an issue with your furnace lighting up, read on to learn more about pilot lights, their function, and how to best approach an issue with your furnace.

What Are Pilot Lights?

A pilot light is an ignition device that is found in many older furnace models. The original version of a pilot light is a simple natural gas flame. If your HVAC system is electric, you won’t use a pilot light to heat your water and air.

The gas flame serves as an ignition catalyst for larger burners that are located inside your main furnace casing. As your thermostat calls for heat, it signals the furnace to turn on, firing up the burners to provide heat to your home. Larger burners responsible for heating air or water will not light unless the initial pilot light flame is working properly.

Are Pilot Lights Protected From Outside Interference?

With any natural gas system, there are always measures put in place to ensure the safe operation of your HVAC system. These sensors exist to tell your system to turn off the gas supply if your pilot light is not heating. Should the safety sensors fail, your home could potentially fill up with natural gas and cause an explosion. Noticing that your pilot light is not working is a call for immediate action to maintain the safety of your home and your loved ones.

Safety Measures for Pilot Lights

There are a few common types of safety measures implemented in natural gas furnaces to ensure that they are operating as they should, reducing your risk of injury or harm when dealing with your system.

Flame Sensors

A flame sensor is used on gas systems with an electric igniter. The flame sensor is able to detect whether or not your large furnace burners are working properly. This sensor is for the burners themselves, not your pilot light.


Thermocouples are also sometimes called flame sensors, though they function differently than the aforementioned devices. Thermocouples are small copper rods that interact with the flame from your pilot light. If the light and heat from your gas source do not hit the thermocouple, it will initiate a response known as a safety trigger. This will cut off the gas supply to your whole system so your house does not fill with natural gas.

Why a Pilot Light Goes Out

There are various reasons why a pilot light goes out. Here are some of the more common causes that you could be dealing with, regarding the issue of a faulty furnace.

Dirty Pilot Light

The shaft that houses a pilot light may become dirty or caked with debris. This directly interferes with the flame’s operation. Dirty pilot light shafts cause noticeable flickering or changes in color, with part of a flame burning yellow. The color of a strong, functional pilot light is bright blue. Any portion that struggles to light or fails to retain its brilliant blue color is indicative of a problem.

Malfunction of the Thermocouple

Furnace components do deteriorate over time. Simple wear and tear due to continuous use cause mechanical parts to break down. Thermocouple malfunction is a common cause of pilot light failure, although a failure in a thermocouple does not necessarily mean big repairs. It could be a bit off-center, or it could need to be cleaned thoroughly before successfully sensing the pilot light again.

Strong Drafts or Crosswinds

Basements and utility closets can be subject to strong cold drafts that can compromise your pilot light’s function. If a draft is strong enough, it’s likely to blow the entire light out. In cases where the pilot light has gone out completely, it is unwise to attempt to light it yourself. You don’t know how long natural gas has been flowing into your utility space, so attempting to ignite a flame in an area saturated with natural gas could have catastrophic consequences.

Low Gas Supply

At times, the gas supply to your home can become compromised. This may be due to issues with the gas supply itself, or you may be dealing with a partially obstructed line coming into your home or into your appliances. If this is the case, you’re likely to see issues with all of your gas appliances. If your pilot light isn’t the only thing that has become compromised, it’s time to call your utility company to assess the root cause of your low supply.

Relighting the Pilot

Unless you are trained to handle all aspects of natural gas service and repair, it is unwise to attempt to diagnose and treat a pilot light issue on your own. Calling in a professional who can safely target your issue, and work to correct it, is the best course of action for getting up and running again. Your technician will likely follow these steps.

Initial Inspection

Upon entering your home, a technician will perform a quick visual inspection of the HVAC components in your system. If anything is found that might compromise the safety of people in your home, you’ll be asked to relocate family members and pets until work has been performed and your home has been determined safe for reoccupation.

Shutting Off Gas Supply

Your technician will then shut off the gas supply to your unit, and possibly the entire building if it is found that more detailed repairs need to be performed. The repair person will allow gas to dissipate in the workspace before attempting to reboot your system.

Resetting and Relighting

After enough time has passed, your technician will turn the gas back on to allow for a slow release back into the pilot light shaft. Most systems have a regulation dial that prevents too much gas from entering your system at one time. Once your HVAC system has been reset, a flame can be immersed into the gas supply in the shaft to reignite the pilot light. Once lit, your system will begin heating either air or water again for the purpose of reheating and regulating your home.

The Importance of HVAC Care and Maintenance

Regular care, maintenance, and inspection of your HVAC unit will allow for optimized function and performance of all its parts, including your pilot light. As your pilot light is an essential part of your system, it often determines whether your system can efficiently heat your home. Bel-Aire Heating & Cooling has strategies and services for keeping your HVAC system in tip-top shape during all seasons. We provide heating and cooling services, air quality inspection services, and repair and replacement for all types of units. We proudly serve valued customers in West Michigan and the surrounding area. If you notice that your HVAC system isn’t performing like it used to, contact our trusted professionals today. We’ll get your system in working order again.

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