Can Furnaces Catch Fire?

The return of cold temperatures increases your reliance on home heating equipment every fall. If your furnace isn’t working properly, it could become a fire hazard and endanger your family’s safety. 

As reported by the National Fire Protection Association (NFPA), heating systems are a leading cause of home fires, causing approximately 50,000 blazes, 500 civilian deaths and more than $1 billion in significant property damage annually. Space heaters and fireplaces cause most of the fires concerning heating equipment, but central heaters, including furnaces, are accountable for just about 12% of these blazes. Learn the most likely causes of furnace fires and how to prevent them. 

Causes of Furnace Fires

Old furnaces are more vulnerable to safety problems as they could be manufactured differently and settle into disrepair over the years. That being said, whether your furnace is more than a decade old or brand new, you should be aware of these causes of furnace fires. 

An Overheated Motor

A furnace motor can overheat in different ways. Here are the most common risks:  

  • A clogged filter can block airflow and force the motor to work longer. Sooner or later, the motor might overheat, increasing the risk of fire. 
  • Dirt can collect around and cover up the motor, forcing it to hold heat, which can trigger a fire. 
  • Exposed or damaged wiring can cause the voltage to increase too much, increasing the chances of an electrical fire. 
  • Overly tight or worn motor bearings can heat up when the furnace is on. Without the proper lubrication, the bearings may eventually light on fire. 

Blocked Furnace Flue 

Yard debris, animal nests and other materials can block the furnace flue, lowering oxygen. This leads to soot building up and weaker ventilation, decreasing efficiency and increasing the risk of flame rollout. Flame rollout is when fire gets out of the heat exchanger and burns the parts within your furnace. If this problem continues, your heating equipment can be severely damaged, and the fire may even spread to areas outside the furnace. 

Clogged Heat Exchanger 

The heat exchanger is a restricted combustion chamber where the heat generated by your furnace is exchanged to the air circulating through your home. A heat exchanger clogged up with soot or corrosion has the same effect as a blocked furnace flue—reduced performance and a bigger risk of flame rollout. 

Cracked Heat Exchanger 

Several problems occur if corrosion breaks the heat exchanger. First, it affects suction in this chamber, triggering less airflow and increased flame rollout. Second, it emits fumes, including carbon monoxide, into your home. Breathing in CO gas can be deadly, so never dismiss your carbon monoxide alarms. CO gas can also return to the source of the leak and ignite if a flame is lit. 

Inadequate Gas Pressure 

Furnaces depend on an accurate mixture of natural gas and air to generate safe and efficient combustion. Too little pressure is often the result of clogged burner orifices. This problem makes the burner flames more likely to roll out. It also leads to unwanted condensation inside the heat exchanger, accelerating the rate of corrosion. 

Conversely, high gas pressure can produce excessive heat within the furnace, which can cause the soot inside the heat exchanger to ignite. Such fires can readily spread to other areas. 

How to Prevent Furnace Fires 

Based on the different ways a furnace can catch fire, here are the steps you can take to avoid furnace fires: 

  • Change the air filter on a regular basis: Check the filter once a month and change it when it appears dirty or every three months, whichever comes first. 
  • Check the furnace flue: Inspect the exterior vent for obstructions and take care of any you find. 
  • Don’t keep combustible items close to the furnace: Things like cardboard boxes, paper, clothing and other combustibles should be kept at a minimum 3 feet away from the furnace and any other heating equipment. 
  • Add a flame rollout switch: This safety device detects if a fire or hot exhaust gases are inside your furnace’s burner compartment. If the rollout switch triggers, have your furnace inspected right away to diagnose and repair the problem before it results in a furnace fire. 
  • Request yearly furnace maintenance: It isn’t always easy to tell if your furnace is performing unsafely. Whether you notice warning signs or not, don’t forget furnace maintenance every fall. 

Schedule Furnace Services Today 

Is it time for your yearly tune-up? Do you need help taking care of a problem with your furnace? Whatever is happening, Service Experts Heating, Air Conditioning & Plumbing is here for you. Our HVAC pros can inspect, clean and test the system to ensure safe operation. If anything looks out of place, we’ll perform a repair or a modification, providing you peace of mind that your furnace is unlikely to catch fire. For more information or to schedule furnace maintenance, please contact your local Service Experts Heating, Air Conditioning & Plumbing office today. 

  • Zoning Systems: Customized Comfort in Every Room

    Central heating and cooling systems have revolutionized home comfort and made it possible to stay completely comfortable in any season or climate. However, while centralized systems are a handy way to manage the temperature, they occasionally fall short when it comes to evenly distributing heated... Continue reading

  • Eight Popular Heating Myths Debunked

    There are lots of myths out there about home heating that lead to confusion and inefficient furnace usage. It’s time to set the record straight. Here, the heating authorities at Service Experts Heating, Air Conditioning & Plumbing debunk the eight most common myths to keep your home... Continue reading

  • Eight Ways to Upgrade Your HVAC System

    During the cold winter months in the U.S., there’s no better way to improve your home’s comfort than with a few effective upgrades. It’s not only about keeping the house toasty warm as the snow begins to fall—it’s about enhancing efficiency and removing pollutants from the very air you... Continue reading