Can Furnaces Catch Fire?

The return of low temperatures boosts your reliance on home heating equipment in the fall. If your furnace isn’t functioning correctly, it may develop into a fire hazard and jeopardize your family’s safety. 

As reported by the National Fire Protection Association (NFPA), heating systems like furnaces are a major source of home fires, leading to approximately 50,000 blazes, 500 civilian deaths and more than $1 billion in direct property damage each year. Space heaters and fireplaces cause most of the fires affecting heating equipment, but central heaters, such as furnaces, are responsible for just about 12% of these blazes. Find out more about the leading causes of furnace fires and how to minimize them. 

Causes of Furnace Fires

Older furnaces are more vulnerable to safety problems because they could be designed differently and fall into disrepair through 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. 

Overheating Motor

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

  • A clogged filter can block airflow and force the motor to work harder. Sooner or later, the motor may overheat, elevating the risk of fire. 
  • Dirt can collect around and insulate the motor, forcing it to absorb heat, which can cause a fire. 
  • Exposed or deteriorated wiring can cause the voltage to get too high, increasing the risk of an electrical fire. 
  • Excessively tight or damaged motor bearings can heat up whenever the furnace is on. Without the proper lubrication, the bearings may eventually catch fire. 

Blocked Furnace Flue 

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

Clogged Heat Exchanger 

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

Cracked Heat Exchanger 

Numerous problems occur if corrosion cracks the heat exchanger. First, it reduces suction within this chamber, resulting in less airflow and increased flame rollout. Second, it produces fumes, like carbon monoxide, into your home. Breathing in CO gas can be deadly, so never dismiss your carbon monoxide alarms. CO gas can also flash back to the source of the leak and ignite if a flame is lit. 

Improper Gas Pressure 

Furnaces require a precise mixture of natural gas and air to produce 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 in the heat exchanger, accelerating the rate of corrosion. 

Conversely, high gas pressure can create excessive heat inside the furnace, which can cause the soot inside the heat exchanger to combust. Such fires can quickly 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: 

  • Replace the air filter regularly: Check the filter once a month and change it when it appears dirty or every three months, whichever comes first. 
  • Keep an eye on the furnace flue: Inspect the exterior vent for obstructions and remove any you find. 
  • Don’t keep combustible items around the furnace: Things like cardboard boxes, paper, clothing and other combustibles should be kept more than 3 feet away from the furnace and any other heating equipment. 
  • Install a flame rollout switch: This safety device recognizes if a fire or hot exhaust gases are inside your furnace’s burner compartment. If the rollout switch trips, have your furnace inspected promptly to diagnose and repair the problem before it causes a furnace fire. 
  • Request annual furnace maintenance: It isn’t always easy to notice 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 annual tune-up? Do you need help resolving a problem with your furnace? Whatever is happening, Service Experts Heating, Air Conditioning & Plumbing is here for you. Our HVAC professionals can inspect, clean and test the system to provide safe operation. If anything doesn’t seem right, we’ll perform a repair or a modification, offering 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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