The Furnace Pilot Light Keeps Going Out
Posted by Sumant JHA
HVAC Basics
The furnace pilot light is the starting point for heat in your home. But if it keeps going out, it can become more than an annoyance.
Here we’ll go over what a pilot light is, why it may keep going out, and how to relight it.
What is a Pilot Light
It’s the small, continual flame inside a gas-powered furnace. The gas line provides a constant flow to the pilot opening, also called an orifice. When the thermostat tells the furnace to start producing heat, the pilot light ignites the burners.
Reasons Pilot Light Keeps Going Out
Be careful using your furnace if the pilot light keeps going out. It’s not entirely uncommon for this to signal a larger issue within the furnace.
Pilot Light is Dirty
You can tell if the pilot opening is dirty by looking at the flame color. An orange or yellow flame means there’s something blocking the full gas flow, such as dirt or soot. Since the pilot opening is small, it doesn’t need much to block and cause the flame to go out. The flame is blue with a green tint when the opening is clear.
Thermocouple Fails (broken, dirty, off center)
The thermocouple is a copper rod connected to the gas valve and acts as a safety device in the furnace. Its position next to the pilot light allows the flame to fully engulf the thermocouple, sending voltage through the rod to the gas valve. The voltage tells the valve to stay open.
However, if the flame can’t fully engulf the thermocouple — when the pilot opening is dirty, for example — the voltage isn’t enough to keep the valve open and the gas flow shuts off.
Other reasons include:
Broken: The expansion and contraction cycle from heating and cooling eventually wears the copper rod to the point of breaking or burning out.
Dirty: Since the furnace uses gas, the combustion process creates dirt, soot, and ash that coats a lot of internal components, including the thermocouple.
Misaligned: If the thermocouple bends or somehow moves out of alignment with the pilot light, it’ll trigger the gas shutoff. It’s possible to bump the rod by accident, such as when relighting the pilot light, enough to move it out of place.
Drafty Basement or Attic
Between the furnace unit and associated ductwork, an attic or basement usually has the necessary amount of space. Unfortunately, these two rooms in a home are notorious for air leaks and drafts, sometimes strong enough to extinguish a pilot light.
We recommend periodically checking for drafts and other phantom air leaks around the furnace and making repairs as soon as possible, if necessary.
How to Re-Light Pilot Light
While relighting a furnace pilot light is relatively easy, if you suspect the issue is caused by something else, don’t attempt to relight. Instead, contact a trained HVAC technician.
< Check the Manual Check your furnace’s owner’s manual for the best instructions on how to relight the pilot light. If you can’t find it, see if the manufacturer’s website has a digital version available for download. Turn off the Gas Begin by turning off the gas line with the dial at the bottom of the furnace. Next, turn off the power supply, usually at its source or the circuit breaker. The gas should be off for at least five minutes to let the leftover gas inside the line and valve to dissipate. Reset the Gas and Light the Pilot Light To reset the gas, turn the flow back on then the power supply. Turn the dial to the pilot setting; gas will resume flowing to the pilot opening. Find the furnace’s reset button then press and hold it. Relight the pilot with a long lighter, such as one used for a cooking grill, and release the reset button when a flame appears in the opening. Don’t use a cigarette light or match as both will have your hand too close to the gas flow and flame. Pilot Light Safety and Maintenance Tips Schedule Routine Tune-Ups and Maintenance One of the best ways to stop a pilot light from continually going out is regular furnace maintenance. Gas appliances, such as a furnace, should be inspected at least once a year by a qualified HVAC technician. They go through an extensive checklist, looking at all parts, such as: Vents and ductwork: Appropriate venting and ductwork carries toxic fumes and other byproducts out of the home, keeping your family safe. Heat exchanger: This crucial part is known to crack or become damaged with age, potentially releasing deadly carbon monoxide (CO) into the home. Make sure to Change Your Air Filter The air filter should be changed every two to three months, or sooner if you live in a dusty environment. The filter keeps hair, dust, fur, and other allergens from entering the furnace and returning with warm air. Place Carbon Monoxide Detectors in Bedrooms Because CO is odorless and tasteless, it’s extremely important you keep CO detectors in every room, especially bedrooms. This way, if a leak occurs, you and loved ones will have ample notice to leave the home at any time of day. It’s recommended to change the batteries twice a year, such as when you change clocks. While pilot lights are straightforward to relight, if yours continues to go out, contact an HVAC technician as soon as possible. Schedule a furnace tune-up today with Moore Home Services.
