Can Furnaces Catch Fire

The return of cold temperatures increases your reliance on home heating equipment each fall. If your furnace isn’t working correctly, it could develop into a fire hazard and threaten your family’s safety.

As reported by the National Fire Protection Association (NFPA), heating systems are a top factor of home fires, leading to approximately 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 involving heating equipment, but central heaters, including furnaces, are accountable for about 12% of these blazes. Find out more about the primary causes of furnace fires and how to avoid them.

Causes of Furnace Fires

Aging furnaces are more susceptible to safety concerns because they could be designed differently and settle into disrepair over the years. That being said, 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 various ways. Here are the biggest risks: 
  • A clogged filter can block airflow and force the motor to work harder. At some point, the motor can overheat, raising the risk of fire.
  • Dirt can gather around and cover up the motor, forcing it to retain heat, which can trigger a fire.
  • Exposed or corroded wiring can cause the voltage to increase too much, increasing the chances of an electrical fire.
  • Overly tight or worn motor bearings can heat up whenever the furnace runs. Without the appropriate lubrication, the bearings may eventually catch fire.

Obstructed Furnace Flue

Yard waste, animal nests and other materials can block the furnace flue, lowering oxygen. This results in soot accumulation and weaker ventilation, decreasing 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 can be severely damaged, and the fire can 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 moved 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 a higher risk of flame rollout.

Cracked Heat Exchanger

Several problems can take place if corrosion breaks the heat exchanger. First, it lowers suction inside this chamber, leading to less airflow and increased flame rollout. Second, it emits fumes, such as carbon monoxide, into your home. Breathing in CO gas can be lethal, 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 lit.

Improper Gas Pressure

Furnaces need a precise combination of natural gas and air to generate 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 within the heat exchanger, accelerating the rate of corrosion.
On the other hand, high gas pressure can lead to excessive heat in the furnace, which can cause the soot inside the heat exchanger to burn. Such fires can quickly spread to other areas.

How to Prevent Furnace Fires

Based on the various 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.
  • Check the furnace flue: Examine the exterior vent for obstructions and clear out any you find.
  • Don’t store combustible items around the furnace: Things like cardboard boxes, paper, clothing and other combustibles should be kept at a minimum 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 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 working unsafely. Whether you notice warning signs or not, prioritize furnace maintenance every fall.

Schedule Furnace Services Today

Is it time for your annual tune-up? Do you need help fixing a problem with your furnace? Whatever the case, Service Experts Heating & Air Conditioning is here for you. Our HVAC experts can inspect, clean and test the system to ensure safe operation. If anything doesn't seem right, we’ll perform a repair or a modification, giving 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 office today.