Can Furnaces Catch Fire?

The return of low temperatures boosts your dependence on home heating equipment in the fall. If your furnace isn’t functioning properly, it might become a fire hazard and endanger your family’s safety. 

As stated by the National Fire Protection Association (NFPA), heating systems are a major cause of home fires, leading to approximately 50,000 blazes, 500 civilian deaths and more than $1 billion in significant property damage each year. Space heaters and fireplaces cause most of the fires involving heating equipment, but central heaters, like furnaces, are responsible for around 12% of these blazes. Learn more about the primary causes of furnace fires and how to prevent them. 

Causes of Furnace Fires

Older furnaces are more susceptible to safety problems since they could be designed differently and settle 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. 

An Overheated Motor

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

  • A clogged filter can restrict airflow and cause the motor to work longer. At some point, the motor may overheat, elevating the risk of fire. 
  • Dirt can accumulate around and insulate the motor, forcing it to absorb heat, which can cause a fire. 
  • Exposed or corroded wiring can cause the voltage to increase too much, increasing the chances of an electrical fire. 
  • Overly tight or damaged motor bearings can heat up when the furnace is on. Without the proper lubrication, the bearings may eventually light on fire. 

Clogged Furnace Flue 

Yard waste, animal nests and other materials can obstruct the furnace flue, reducing oxygen. This causes soot buildup and improper ventilation, decreasing efficiency and raising the risk of flame rollout. Flame rollout is when fire escapes the heat exchanger and burns the parts within your furnace. If this problem continues, your heating equipment can be badly damaged, and the fire could spread to areas outside the furnace. 

Obstructed Heat Exchanger 

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

Cracked Heat Exchanger 

Several problems can take place if corrosion breaks the heat exchanger. First, it lowers suction inside this chamber, resulting in less airflow and increased flame rollout. Second, it produces fumes, including carbon monoxide, into your home. Breathing CO gas can be lethal, 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 lit. 

Inadequate Gas Pressure 

Furnaces require an accurate mixture of natural gas and air to produce safe and efficient combustion. Too little pressure is often because of clogged burner orifices. This problem makes the burner flames more likely to roll out. It also produces unwanted condensation in the heat exchanger, accelerating the rate of corrosion. 

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

How to Prevent Furnace Fires 

Based on the listed 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 each month and change it when it seems 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 keep combustible items around the furnace: Things including cardboard boxes, paper, clothing and other combustibles should be kept at least 3 feet away from the furnace and all other heating equipment. 
  • Put in 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. 
  • Request yearly furnace maintenance: It isn’t always easy to tell if your furnace is performing 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 reason, Service Experts Heating, Air Conditioning & Plumbing is here for you. Our HVAC pros can inspect, clean and test the system to provide safe operation. If anything seems off, we’ll suggest a repair or a modification, giving you peace of mind that your furnace is unlikely to catch fire. For more details or to schedule furnace maintenance, please contact your local Service Experts Heating, Air Conditioning & Plumbing office today. 

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