First you notice a burning or “hot” smell coming from your furnace or vents. Or you hear odd noises coming from your furnace. Then, it shuts off entirely and won’t start up again. These are all signs that your furnace may be overheating — a situation that definitely needs attention!
But, what's causing this issue? Here are the most common reasons for a furnace to overheat and steps you can take to correct the problem.
Reduced or Restricted Airflow
If air is blocked from circulating properly throughout your system, it can cause furnace components to overheat. The most common cause of restricted airflow is a dirty filter. That’s why it’s so important to inspect and change your filer regularly throughout the heating season. Most professionals recommend checking your filter at least monthly and replacing as soon as it’s showing signs of dust and dirt. Also check to see if all warm air registers and return air grilles are open and unobstructed.
The furnace blower wheel and other components can also get grimy and dirty — also due to a dirty filter. The air conditioning coil may be plugged with dirt and lint. Either of these may prevent the furnace heat exchanger from rejecting the heat to the airstream, causing an overheat condition.
When a furnace turns off too soon in the heating cycle, it’s called short cycling. When this happens repeatedly, it can stress the furnace heat exchanger and blower motor, and may lead to overheating or burning out the motor entirely or failure of the heat exchanger. If you suspect your furnace is short cycling, you should contact your HVAC pro right away to get an inspection and any needed repair.
From electrical wiring to the fan blower to the motor itself, furnace components can fail. However, with proper inspection, tune-ups, and maintenance, this can often be avoided. Plan to have your system inspected annually to avoid costly repairs.
In general, with proper tune-ups and maintenance, today’s furnaces typically last 15 to 20 years. But nothing lasts forever, so if your system is getting on toward that 15-year mark, you may want to talk with your HVAC professional to learn about new options. Newer models are more efficient, usually run quieter, and have features that make your system easier and more convenient to use.
A furnace that overheats is not just an inconvenience, it can present a dangerous risk to you and your family. If you’re concerned that your furnace may be overheating, don’t wait, have it inspected by an HVAC professional as soon as possible.
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