Can Furnaces Catch Fire?

The return of cold temperatures raises your dependence on home heating equipment each 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 systems are a leading cause of home fires, contributing to nearly 50,000 blazes, 500 civilian deaths and more than $1 billion in direct property damage every year. Space heaters and fireplaces cause most of the fires affecting heating equipment, but central heaters, such as furnaces, are liable for around 12% of these blazes. Learn more about the primary causes of furnace fires and how to avoid them. 

Causes of Furnace Fires

Older furnaces are more exposed to safety hazards as they might 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 familiar with these causes of furnace fires. 

An Overheated Motor

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

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

Blocked Furnace Flue 

Yard waste, animal nests and other obstructions can clog the furnace flue, restricting oxygen. This results in soot accumulation and weaker ventilation, limiting efficiency and increasing the risk of flame rollout. Flame rollout is when fire gets out of the heat exchanger and burns the parts in your furnace. If this problem continues, your heating equipment can be seriously damaged, and the fire may even spread to areas outside the furnace. 

Obstructed Heat Exchanger 

The heat exchanger is a closed 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 impact as a blocked furnace flue—reduced performance and a bigger risk of flame rollout. 

Cracked Heat Exchanger 

Several problems can take place if corrosion cracks the heat exchanger. First, it lowers suction in this chamber, triggering less airflow and increased flame rollout. Second, it releases fumes, like carbon monoxide, into your home. Breathing CO gas can be deadly, so never neglect your carbon monoxide alarms. CO gas can also flash back to the source of the leak and ignite if a flame is found. 

Inadequate Gas Pressure 

Furnaces need a precise mixture of natural gas and air to ensure 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, increasing 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 various ways a furnace can combust, here are the steps you can take to prevent furnace fires: 

• Replace the air filter consistently: Check the filter monthly and change it when it appears dirty or every three months, whichever comes first. 
• Check the furnace flue: Periodically check the exterior vent for obstructions and clear out any you find. 
• Don’t store combustible items near the furnace: Things such as 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 component recognizes if a fire or hot exhaust gases are inside your furnace’s burner compartment. If the rollout switch triggers, have your furnace inspected as soon as possible to diagnose and repair the problem before it produces a furnace fire. 

• Schedule yearly furnace maintenance: It isn’t always easy to notice if your furnace is working 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 the reason, Service Experts Heating, Air Conditioning & Plumbing is here for you. Our HVAC experts can inspect, clean and test the system to provide safe operation. If anything looks out of place, we’ll suggest a repair or a modification, providing 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.