Can Furnaces Catch Fire?

The return of cold temperatures increases your reliance on home heating equipment every fall. If your furnace isn’t functioning 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 start the majority of fires involving heating equipment, but central heaters, such as furnaces, are accountable for around 12% of these blazes. Learn more about the primary causes of furnace fires and how to avoid them. 

Causes of Furnace Fires

Old furnaces are more exposed to safety hazards because they might be configured 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. 

An 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 longer. Eventually, the motor may overheat, raising the risk of fire. 
• Dirt can collect around and insulate the motor, forcing it to hold heat, which can cause a fire. 
• Exposed or corroded wiring can cause the voltage to increase too much, increasing the likelihood of an electrical fire. 
• Overly tight or worn motor bearings can heat up when the furnace is on. Without the proper lubrication, the bearings can eventually catch fire. 

Blocked Furnace Flue 

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

Clogged Heat Exchanger 

The heat exchanger is a closed combustion chamber where the heat created by your furnace is moved 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 damages the heat exchanger. First, it affects suction inside this chamber, leading to less airflow and increased flame rollout. Second, it releases fumes, such as 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 an accurate 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 ignite. Such fires can easily spread to other areas. 

How to Prevent Furnace Fires 

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

• Change the air filter consistently: Check the filter once a 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 clear out any you find. 
• Don’t store 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. 
• 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 promptly to diagnose and repair the problem before it produces 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 taking care of a problem with your furnace? Whatever the case, Aramendia Plumbing, Heating and Air 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, providing you peace of mind that your furnace is unlikely to catch fire. For more info or to schedule furnace maintenance, please contact your local Aramendia Plumbing, Heating and Air office today.