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Too Hot To Handle: What To Do If Your Furnace Overheats

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You expect your furnace to keep your home nice and toasty, but not at the expense of overheating your furnace. Believe it or not, it's possible for your furnace to get too hot as it attempts to keep your home warm. An overheating furnace can cause a wide variety of problems, including unexpected heat exchanger failure, and even create a serious fire hazard. The following takes an in-depth look at the typical symptoms associated with an overheating furnace and what you can do to resolve those issues.

Common Symptoms of an Overheating Furnace

One of the most noticeable indicators of an overheating furnace is when it suddenly shuts down and is unable to be restarted for some time. Nearly all modern furnaces are equipped with thermal protection devices that disable the unit when it exceeds safe operating temperatures. This keeps the heat exchanger and other furnace components from being damaged due to the extreme temperatures. The thermal protection device shuts the furnace down until the affected component is able to cool down.

Short cycling is another common sign of an overheating furnace. Short cycling occurs when the furnace cycles on and off for extremely short periods in an attempt to maintain your thermostat's temperature set point. Overheating furnace components can prompt a round of short cycling, resulting in added wear and tear to your furnace.

The smell of hot metal, hot plastic or burning rubber can also indicate an overheating issue. If you smell these odors, then you'll want to shut your furnace off immediately and check for any signs of fire or smoke.

Quick Remedies to Try

Most overheating problems are caused by airflow blockages within the furnace itself. Without enough air flowing through the furnace, it's easy for the heat exchanger and other components to be overwhelmed by the sheer heat that's normally carried away into the supply air ductwork. Fortunately, you can resolve most of these issues on your own with the following tips:

  • Change your air filter - A clogged furnace air filter can actively block most of your furnace's airflow and set the stage for overheating issues. You should change your air filter immediately and remember to change it on a monthly basis.
  • Move your rugs or furniture away from your vents - These and other obstructions can block airflow, leading to overheating issues.
  • Remove dust from supply and return air vents - Dust and debris buildup on wall and ceiling vents can also block airflow. Use a wet/dry shop vacuum with a soft brush attachment to remove this buildup.
  • Check the blower fan motor for dust buildup - Heavy dust buildup on the blower fan motor can cause this component to overheat and shut down, which in turn could cause your furnace to overheat and shut down. Use your shop vacuum to remove this buildup from the fan motor as well as the fan blades.
  • Check the evaporator coil - If your furnace is integrated in the same indoor cabinet as your central air conditioner, it's not unusual for dust and debris buildup on the evaporator coil to affect your furnace's airflow. Take a moment to carefully clean the evaporator coil before restarting your furnace.

When in Doubt, Call a Professional

While taking a hands-on approach to your furnace maintenance can resolve most of your furnace overheating issues, there are some issues that are best handled by your HVAC specialist. These include damaged or shorted wiring, defective thermal protection relays and even some thermostat issues. Your HVAC specialist will be able to tackle the tougher tasks and make any in-depth repairs that are needed for your furnace.

For more information, contact a business such as Dick  Kearsley Service Center.