Can Furnaces Catch Fire?

The return of low temperatures raises your dependence on home heating equipment every fall. If your furnace isn’t working correctly, it could develop into a fire hazard and jeopardize your family’s safety. 

According to the National Fire Protection Association (NFPA), heating systems are a top cause of home fires, leading to approximately 50,000 blazes, 500 civilian deaths and more than $1 billion in significant property damage annually. Space heaters and fireplaces generate most of the fires affecting heating equipment, but central heaters, such as furnaces, are liable for just about 12% of these blazes. Learn the leading causes of furnace fires and how to prevent them. 

Causes of Furnace Fires

Older furnaces are more vulnerable to safety problems since they could be designed 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. 

Overheated Motor

A furnace motor can overheat in different ways. Here are the biggest risks:  

• A clogged filter can restrict airflow and cause the motor to work harder. At some point, the motor may overheat, increasing the risk of fire. 
• Dirt can collect around and coat the motor, forcing it to absorb heat, which can lead to a fire. 
• Exposed or deteriorated wiring can cause the voltage to get too high, increasing the risk of an electrical fire. 
• Overly tight or damaged motor bearings can heat up whenever the furnace starts. Without adequate lubrication, the bearings could eventually light on fire. 

Clogged Furnace Flue 

Yard debris, animal nests and other materials can clog the furnace flue, reducing oxygen. This leads to soot accumulation and weaker ventilation, limiting efficiency and increasing the risk of flame rollout. Flame rollout is when fire escapes the heat exchanger and burns the parts in your furnace. If this problem persists, your heating equipment can be severely 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 is exchanged 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 a higher risk of flame rollout. 

Cracked Heat Exchanger 

Numerous problems occur if corrosion cracks the heat exchanger. First, it affects suction within this chamber, leading to less airflow and increased flame rollout. Second, it produces fumes, including carbon monoxide, into your home. Breathing CO gas can be lethal, 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 present. 

Improper Gas Pressure 

Furnaces depend on a precise combination 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 causes unwanted condensation inside the heat exchanger, accelerating the rate of corrosion. 

Conversely, high gas pressure can produce 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 light on fire, here are the steps you can take to avoid furnace fires: 

• Change the air filter regularly: Check the filter each month 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 take care of any you find. 
• Don’t store combustible items close to the furnace: Things like 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 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 promptly to diagnose and repair the problem before it causes a furnace fire. 

• Schedule annual furnace maintenance: It isn’t always easy to tell if your furnace is performing unsafely. Whether you notice warning signs or not, remember 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 looks out of place, we’ll suggest 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.