Is My Furnace Overheating?
TechXpert verified by Ken Kontra
Your furnace is likely overheating if you notice a burning smell, hear unusual sounds or loud humming noises, or if it’s cycling off without starting back up. If your furnace is overheating, you’ll want to have the issue fixed right away to keep your home safe and comfortable.
Signs of Overheating
As much as you want your furnace to keep delivering the heat, you can get too much of a good thing. Here’s what to look for when you suspect your furnace is overheating:
Burning smell from your vents: This can happen when you turn on your furnace for the first time in months, but when it comes seemingly out of the blue, you’ll want to pay close attention. This smell can indicate your heater has overheated, and burnt itself out.
Unusual sounds or humming noises: If you hear your furnace singing an unusual ballad, it’s likely because the blower motor isn’t functioning well, and as a result, the system is generating excessive heat from having to work harder.
Cycling off without starting back up: Many furnaces have a built-in safety shutoff that’s triggered if the furnace gets too hot. If you find yourself constantly resetting your furnace, it likely has an overheating issue that needs to be fixed.
Furnace Feeling the Burn
Keeping your furnace properly cleaned and maintained is the best way to prevent it from overheating. However, even a well-kept furnace can start to feel the burn for a number of reasons, like:
Restricted airflow: If your furnace’s air filters are clogged, it will be tougher for air to pass through to other parts of your unit, and that can cause it to overheat. You’ll also want to make sure your vents aren’t blocked by furniture or covered by rugs so that air can move freely into your home.
Dirt buildup: Dirty air filters can restrict airflow and cause contaminants to accumulate on the other parts of your furnace, like the blower motor. If your blower motor can’t work efficiently, it can overheat.
Short cycling: If you notice your furnace turning on and off repeatedly during its heating cycles, it’s likely overheating and that can stress the motors. You’ll want to have this issue fixed before your furnace burns out completely.
Mechanical failure: All the parts of your furnace are extremely important for the unit to work properly. If your furnace’s fan motors or other wiring components are under too much stress, they’ll cause the unit to overheat.
Old age: If your furnace is approaching 15 to 20 years in age, it’s smart to consider a replacement. As your furnace ages, it’s more likely to overheat and begins to struggle to keep up with your home. So, for the safety of you and your home, replace an old furnace before it has the chance to burn out as winter arrives.
Too Hot to Handle?
Even if you’re DIY savvy, repairing an overheating furnace yourself may not be a great idea. With all the moving parts and potential for injury that comes with heat and electricity, the safest way forward is to turn off the power to the unit and contact an HVAC technician to fix the issue right away.
FREE Virtual Home Repair
We'll diagnose your issue over call or video and virtually walk you through the repair — all for free if you're a new customer! .