Can Furnaces Catch Fire?

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

According to the National Fire Protection Association (NFPA), heating equipment is a leading cause of home fires, causing nearly 50,000 blazes, 500 civilian deaths and more than $1 billion in direct property damage every year. Space heaters and fireplaces cause the majority of fires involving heating equipment, but central heaters, including furnaces, are responsible for about 12% of these blazes. Learn the primary causes of furnace fires and how to prevent them. 

Causes of Furnace Fires

Older furnaces are more vulnerable to safety hazards because they may be designed differently and fall into disrepair over the years. Still, whether your furnace is more than a decade old or brand new, you should be aware of these causes of furnace fires. 

Overheated Motor

A furnace motor can overheat in several ways. Here are the biggest risks:  

  • A clogged filter can restrict airflow and cause the motor to work harder. Eventually, the motor may overheat, raising the risk of fire. 
  • Dirt can collect around and insulate the motor, forcing it to retain heat, which can cause a fire. 
  • Exposed or corroded wiring can cause the voltage to get too high, increasing the chances of an electrical fire. 
  • Overly tight or worn motor bearings can heat up when the furnace runs. Without the proper lubrication, the bearings may eventually catch fire. 

Blocked Furnace Flue 

Yard debris, animal nests and other obstructions can block the furnace flue, restricting oxygen. This leads to soot buildup and improper ventilation, decreasing efficiency and increasing the risk of flame rollout. Flame rollout is when fire escapes the heat exchanger and burns the parts inside your furnace. If this problem persists, your heating equipment could be severely damaged, and the fire could spread to areas outside the furnace. 

Clogged Heat Exchanger 

The heat exchanger is a closed combustion chamber where the heat produced by your furnace transfers to the air circulating throughout your home. A heat exchanger clogged with soot or corrosion has the same effect as a blocked furnace flue—reduced performance and an increased risk of flame rollout. 

Cracked Heat Exchanger 

Several problems occur if corrosion cracks the heat exchanger. First, it reduces suction inside this chamber, leading to less airflow and increased flame rollout. Second, it releases fumes, including carbon monoxide, into your home. Inhaling CO gas can be fatal, so never ignore your carbon monoxide alarms. CO gas can also flash back to the source of the leak and ignite if a flame is present. 

Improper Gas Pressure 

Furnaces require a precise combination 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 causes unwanted condensation inside the heat exchanger, accelerating the rate of corrosion. 

On the other hand, high gas pressure can lead to excessive heat inside the furnace, which can cause the soot inside the heat exchanger to combust. Such fires can easily 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 prevent furnace fires: 

  • Change the air filter regularly: 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 remove any you find. 
  • Don’t store combustible items near the furnace: Things like cardboard boxes, paper, clothing and other combustibles should be kept at least 3 feet away from the furnace and all other heating equipment. 
  • Install 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 trips, have your furnace inspected right away to diagnose and repair the problem before it causes a furnace fire. 
  • Schedule annual furnace maintenance: It isn’t always easy to tell if your furnace is operating unsafely. Whether you notice warning signs or not, prioritize furnace maintenance every fall. 

Schedule Furnace Services Today 

Is it time for your yearly tune-up? Do you need help fixing a problem with your furnace? Whatever the case, Service Experts Heating, Air Conditioning & Plumbing is here for you. Our HVAC experts can inspect, clean and test the system to ensure safe operation. If anything looks out of place, we’ll recommend a repair or a modification, giving 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. 

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