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What Causes That Burning Smell When My Furnace Turns On?

HVAC technician inspecting furnace in basement

If you've ever turned on your gas furnace after a long break and been greeted by a burning smell, you're not alone. In fact, it's a pretty common occurrence. But what causes that burning smell? Is it something to be concerned about? Let's take a look.

The Most Common Cause: Dust

A few different things can cause your furnace to produce a burning smell when you turn it on. The most common is simply dust that has accumulated on the burner over several months (or even years). When you turn on the furnace, the heat from the burner ignites the dust, causing it to burn off and produce that characteristic smell.

The easiest way to solve this problem is to inspect, clean, and tune up your furnace before every heating season. During one of these standard maintenance appointments, the technician can remove most of the dust buildup while also performing other tasks like lubricating the motor and tightening and realigning loose components. These steps prep your furnace to operate as efficiently as possible.

Other Reasons Why You Might Smell Burning From Your Furnace

While dust burning off in your furnace is not cause for alarm, you want to make sure the burning smell goes away. If it doesn’t, you might be dealing with one of the following problems.

  1. A clogged air filter: The air filter is located in the air return grille (the big openings you see on the walls or ceiling where cold air enters the furnace). A dirty air filter can restrict airflow and cause the furnace to overheat, leading to a burning smell. To check the air filter, remove it from the furnace and hold it up to a light. If you can’t see light glowing through it, or if it’s been 90 days since you put the filter in, it’s time to replace it with a new one.
  2. Debris crowding the furnace: Sometimes, debris can build up around the furnace, blocking airflow and causing the equipment to overheat. Take a look at the area around your furnace and make sure nothing is blocking the vents or touching any part of the equipment.
  3. An electrical issue: If the burning odor is somewhat metallic or if it smells kind of like burnt rubber, there could be something wrong with your furnace’s electrical components.

If you’ve checked the air filter and there is no debris around the furnace, but you still smell a burning odor, it’s time to shut your system off and call a professional. There could be a problem with the ignition or electrical system that only a trained professional can fix safely.

Do you need furnace repairs in Milford, CT? Tri-City Heating and Cooling can help! Give our friendly technicians a call today at (203) 303-5700.