Can Furnaces Catch Fire?

The return of low temperatures raises your reliance on home heating equipment each fall. If your furnace isn’t working properly, it could develop into a fire hazard and endanger your family’s safety. 

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

Causes of Furnace Fires

Aging furnaces are more susceptible to safety concerns since they could be configured differently and fall into disrepair through the years. Nevertheless, 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 most common risks:  

  • A clogged filter can impede airflow and cause the motor to work harder. At some point, the motor may overheat, elevating the risk of fire. 
  • Dirt can accumulate around and coat the motor, forcing it to hold heat, which can cause a fire. 
  • Exposed or damaged wiring can cause the voltage to elevate, increasing the chances of an electrical fire. 
  • Exceedingly tight or damaged motor bearings can heat up as the furnace is on. Without the proper lubrication, the bearings could eventually catch fire. 

Obstructed Furnace Flue 

Yard debris, animal nests and other materials can obstruct the furnace flue, restricting oxygen. This causes soot building up and improper ventilation, decreasing efficiency and raising the risk of flame rollout. Flame rollout is when fire reaches past the heat exchanger and burns the parts in your furnace. If this problem remains, your heating equipment could be severely damaged, and the fire can spread to areas outside the furnace. 

Obstructed Heat Exchanger 

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

Cracked Heat Exchanger 

Numerous problems can happen if corrosion damages the heat exchanger. First, it lowers suction inside this chamber, triggering less airflow and increased flame rollout. Second, it produces fumes, like carbon monoxide, into your home. Inhaling CO gas can be lethal, so never neglect your carbon monoxide alarms. CO gas can also return to the source of the leak and ignite if a flame is found. 

Improper Gas Pressure 

Furnaces require a precise 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 leads to unwanted condensation in the heat exchanger, increasing the rate of corrosion. 

On the other hand, high gas pressure can create excessive heat in the furnace, which can cause the soot inside the heat exchanger to burn. Such fires can easily spread to other areas. 

How to Prevent Furnace Fires 

Based on the various ways a furnace can combust, here are the steps you can take to avoid furnace fires: 

  • Change the air filter regularly: Check the filter once a month and change it when it looks dirty or every three months, whichever comes first. 
  • Check the furnace flue: Examine the exterior vent for obstructions and remove any you find. 
  • Don’t store combustible items around the furnace: Things like cardboard boxes, paper, clothing and other combustibles should be kept at least 3 feet away from the furnace and any other heating equipment. 
  • Install a flame rollout switch: This safety system recognizes 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 produces a furnace fire. 
  • Schedule yearly furnace maintenance: It isn’t always easy to recognize if your furnace is operating unsafely. Whether you notice warning signs or not, don’t forget furnace maintenance every fall. 

Schedule Furnace Services Today 

Is it time for your annual 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 doesn’t seem right, we’ll recommend a repair or a modification, giving you peace of mind that your furnace is unlikely to catch fire. For more info or to schedule furnace maintenance, please contact your local Service Experts Heating, Air Conditioning & Plumbing office today. 

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