November 10, 2020

Common Causes of Furnace Fires and How to Prevent Them

As a responsible homeowner, we know you take every precaution to prevent house fires. You keep flammable materials in a safe area, you don’t go to bed or leave the house while your dishwasher or dryer are running, and you change your smoke alarm batteries at least twice each year.

Right? (If you’re not doing the above, we won’t scold you but do strongly suggest in our strictest parent voice that you begin adhering to these safety measures).

Any house fire can be catastrophic, but there’s one potential house fire that many never even consider …a furnace fire.

Causes of Furnace Fires

A properly maintained furnace gives you peace of mind not only in providing comfort for your home, but for safety as well.

However, furnace fires can occur, unfortunately. Here are four causes of furnace fires:

Flame rollout:

If you have a gas furnace, there is a possibility of a flame rollout if your unit is past its prime and/or has not been maintained by a professional. Flame rollouts can occur when flammable combustion gases build up inside of the combustion chamber. They can be dangerous because not only will internal parts become damaged, but there could be other flammable objects nearby that could catch fire.


When air filters are not changed frequently enough, they can become excessively clogged and not allow air to pass through. Your furnace will need to work harder, the blower motor will run for extended periods of time, and this could cause it to overheat. The devastating effect of internal temperatures climbing is that components could catch fire.

Gas pressure

Safe and efficient combustion happens when correctly regulated gas pressure flows into the furnace’s combustion chamber. If this pressure is too little, condensation could collect inside the heat exchanger, which can lead to corrosion. However, if pressure is too high, this may lead to extremely high temperatures inside the unit, even forming soot on the walls of a heat exchanger, which can combust.

Wear and tear on heat exchanger

The heat exchanger serves as both a metal chamber and a passageway, heating air as it’s blown across the exchanger’s hot metal surface. Metal expands and contracts in the normal heating and cooling process; but over time, it can wear down and create small cracks or holes. When this happens, there could be dangerous gases such as carbon monoxide that leak, causing a health risk as well as a fire risk.

How to prevent furnace fires

If you haven’t seen a theme in these scary-but-serious possibilities of furnace fires, it’s that proper maintenance by trained HVAC technicians can all but eliminate the risk.

MoreVent’s Front-of-the-Line Family Plan gives West Chester area homeowners the comfort and security of knowing you will have regular maintenance performed by trained professionals, and your HVAC system will run safely and efficiently for years to come.

Additionally, as with most house fires, you can help prevent a furnace fire by keeping the area around your furnace free from dirt, dust and debris.

And for the earlier mentioned flame rollout, you can have MoreVent install a rollout safety switch onto your gas furnace as a safety precaution.

Keep in mind that should you have an equipment failure any time of day or night, contact us at 1-610-257-7702 for our 24-hour emergency HVAC service, and we’ll get your family back to feeling comfortable.

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