Can Furnaces Catch Fire?

The return of cold temperatures increases your dependence on home heating equipment every fall. If your furnace isn’t functioning properly, it might become a fire hazard and endanger your family’s safety. 

According to the National Fire Protection Association (NFPA), heating equipment is a leading factor of home fires, contributing to approximately 50,000 blazes, 500 civilian deaths and more than $1 billion in direct property damage annually. Space heaters and fireplaces generate the majority of fires concerning heating equipment, but central heaters, such as furnaces, are responsible for about 12% of these blazes. Learn the most likely causes of furnace fires and how to prevent them. 

Causes of Furnace Fires

Older furnaces are more vulnerable to safety problems as they may be manufactured differently and settle into disrepair through the years. That being said, whether your furnace is more than a decade old or brand new, you should know about these causes of furnace fires. 

An Overheated Motor

A furnace motor can overheat in several ways. Here are the main risks:  

• A clogged filter can restrict airflow and cause the motor to work harder. Eventually, the motor can overheat, raising the risk of fire. 
• Dirt can accumulate around and coat the motor, forcing it to retain heat, which can lead to a fire. 
• Exposed or corroded wiring can cause the voltage to increase too much, increasing the chances of an electrical fire. 
• Overly tight or damaged motor bearings can heat up as the furnace starts. Without adequate lubrication, the bearings may eventually catch fire. 

Clogged Furnace Flue 

Yard debris, animal nests and other obstructions can block the furnace flue, restricting oxygen. This results in soot building up and weaker 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 severely damaged, and the fire may even spread to areas outside the furnace. 

Clogged Heat Exchanger 

The heat exchanger is a restricted combustion chamber where the heat produced by your furnace is exchanged to the air circulating within your home. A heat exchanger blocked 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 

Several problems can take place if corrosion cracks 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. Breathing in CO gas can be lethal, so never dismiss your carbon monoxide alarms. CO gas can also return to the source of the leak and ignite if a flame is lit. 

Inadequate Gas Pressure 

Furnaces require a precise mixture 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 produces 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 burn. Such fires can easily spread to other areas. 

How to Prevent Furnace Fires 

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

• Change the air filter on a regular basis: Check the filter each month and change it when it seems 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 place combustible items close to the furnace: Things such as cardboard boxes, paper, clothing and other combustibles should be kept more than 3 feet away from the furnace and any other heating equipment. 
• Add 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 triggers, have your furnace inspected promptly to diagnose and repair the problem before it results in a furnace fire. 

• Request annual furnace maintenance: It isn’t always easy to tell if your furnace is operating 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 the reason, 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 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 info or to schedule furnace maintenance, please contact your local Service Experts Heating, Air Conditioning & Plumbing office today.