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why would my gas furnace stop working
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Do you feel the chill of winter creeping into your home and can’t figure out why? One thing it might be is a broken gas furnace. A malfunctioning gas furnace can send chilly drafts through the house during cold weather, leaving everyone uncomfortable. It can increase electricity bills as you attempt to offset them with other heating means.

In this blog post, we will go over some common causes for why a faulty gas furnace that suddenly stopped working may have occurred and provide actionable information on how to get things back up and running in no time. So if you feel like winter has come early, or your utility bills keep climbing higher than normal, read on to find out what could be the root cause and how to remedy it quickly!

Lack of Maintenance

Your gas furnace is essential to your home’s HVAC system, keeping you warm and comfortable during the cold winter months. However, like any other machine, it can break down over time, causing frustration and discomfort. A lack of maintenance is one of the most common reasons for a gas furnace to stop working.

When it comes to any type of mechanical equipment, lack of maintenance can cause various issues to occur. Over time, a gas furnace accumulates dust and debris, leading to clogs and restricted airflow. This clogged air filter can cause the furnace to work harder, potentially leading to overheating and a reduced lifespan. Worn-out belts and thermostats are also an issue in poorly maintained furnaces, leading to problems with your furnace’s control system. By taking care of your furnace, you can help to avoid these issues altogether.

The accumulation of dust and debris can clog the air filter and have various effects. For example, if the air filter is clogged, the furnace has to work harder to suck in the air, leading to higher energy bills and wear and tear on the furnace. Additionally, a clogged air filter may cause the furnace to overheat, damaging the furnace’s components and leading to further repairs. Moreover, a poorly maintained furnace may also have problems with the system’s belts, leading to problems with the furnace’s control system.

Pilot Light Issues

The pilot light is a small flame that burns continuously to ignite the gas burners in your furnace. The piezoelectric ignition system ignites the flame, which sends a spark to the pilot gas line. Once lit, the pilot light remains on, waiting to ignite the main gas burners once the thermostat signals a heating call. The pilot light is typically located near the main burners inside your furnace.

Several reasons can cause the pilot light to go out, including a gas leak, a dirty pilot light, or a faulty thermocouple. A gas leak around the pilot light can cause a draft, extinguishing the flame. A dirty pilot light is caused by debris or dust obstructing the gas flow, quenching the flame. Additionally, the thermocouple, which senses the presence of the pilot light, may wear out, resulting in a system shutdown.

To relight the pilot light, follow the instructions in your furnace user manual. Typically, you’ll need to turn off the gas supply for a few minutes and turn the knob back to the pilot position later. You can ignite the pilot flame using a lighter and pressing the reset button on your furnace. Then, you should keep holding down the knob for 30 seconds to warm the thermocouple, enabling it to send an electric signal to keep the valve open, allowing gas to flow to the burners.

Faulty Ignition System

The ignition system of a furnace is responsible for lighting the gas burners that generate heat for your home. It comprises several elements, including the control board, the gas valve, and the igniter. The control board signals the gas valve to allow gas to flow into your furnace, where the igniter will ignite it, lighting the burners. Once the burners run, they will continue generating heat until the thermostat reaches your desired temperature.

A faulty control board is one of the most common reasons for issues with the ignition system. The control board sends a signal to the gas valve, allowing gas to flow into the furnace. If the control board malfunctions, it may fail to send the correct signals to the gas valve, leading to your furnace failing to ignite or to stay lit. If you suspect your control board is malfunctioning, it’s essential to contact a professional HVAC technician for diagnostics.

Gas Valve Issues

The gas valve regulates the flow of gas into your furnace’s burners. It maintains the proper gas-air mixture so your furnace operates safely and efficiently. Without a properly functioning gas valve, your furnace will fail to produce the heat needed to warm your home comfortably. The gas valve is a crucial part of your furnace’s heating process.

Dirt and debris can accumulate around the gas valve, leading to malfunctions in its internal components. When debris interferes with the valve’s opening and closing mechanism, it may become stuck in an open or closed position, preventing it from correctly controlling the gas flow. Additionally, a damaged valve can cause gas leaks, leading to a potentially dangerous situation. Gas leaks can cause enhanced health and safety hazards and should be taken seriously.


While there are many reasons why your gas furnace may stop working, lack of maintenance, pilot light issues, faulty ignition systems, and gas valve issues are some of the most common. If you experience any of these problems, fixing the issue is essential. A professional HVAC technician can diagnose and repair the problem, ensuring your furnace works correctly and efficiently. Remember to have your furnace inspected regularly to avoid any unexpected issues, and consider scheduling a maintenance visit for your system every year.

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