December 20, 2021
Furnace Repair in Festus, MO
Updated On: 1/19/2024

Now that chilly temperatures have arrived in Festus, MO, you’ll be depending on your heating system for relief. If you notice a burning smell once your heater turns on, you may feel alarmed and assume that something serious is wrong with the heating system. Burning smells aren’t always a reason for concern, and here are some of their causes and what they mean.

Dust on Heat Exchanger or Burner

If you smell a burning odor the first time you turn on your heater for the winter season, the cause is most likely to be dust buildup on the heat exchanger or burner. When the system isn’t in use, a small amount of dust will accumulate on those surfaces. Once the heat exchanger or burner gets hot for the first time, the dust ignites and burns off. The odor should go away after one or two heating cycles.

Heater burning smell

Dust and Debris in Ducts

Residential HVAC Duct Cleaning with a Power Brush
Dust and debris in your home’s ductwork may also cause a burning smell at the start of the heating season. After a few months of the ductwork not being used for heating or cooling, some dust gets into the system. Any debris, such as pollen, pet hair or rodent droppings or nesting material may also accumulate in the ducts. When the hot air is forced into the ducts by your heater, this debris also gets hot and may burn. We recommend duct cleaning every two to three years in order to remove the debris and keep your ductwork clean and free of obstructions.

Dirty Air Filter

A dirty air filter may release a burning odor when your heating system cycles. The air filter’s pores become filled with dust and debris after a month or two of use. If you smell a burning scent each time your heating system cycles, check the air filter. Replace it if it’s visibly dirty. Don’t wait more than three months between air filter replacements. Installing a new air filter will improve your home’s air quality and give your heating system’s efficiency a big boost. If you’re not sure where the air filter is located, your heating system’s owner’s manual will have a diagram. Our technicians at Bone Heating & Cooling can show you how to change the air filter during your annual heating system tune-up.
Home owner changing their dirty air filter.

Failed Motor Seal

Some causes of burning odors from heaters are more serious and require a professional inspection and prompt repair. One such reason is a failed motor seal. The indoor blower of a furnace or heat pump and the outdoor unit of a heat pump’s fan motor have seals. Over time, the rubber seals may crack or disintegrate. If the motor seal fails, oil can leak out of the system. The leaking oil may come into contact with the motor or electrical parts of your heater. When the oil gets hot enough, it may burn. If too much of the oil leaks, your heating system may need extensive repairs or even a replacement. You can check for oil leaks once per week by looking at the floor near the indoor unit or the ground near the outdoor unit. Any dark, oily or greasy substance is likely to be leaking oil.

Malfunctioning Transformer or Capacitor

HVAC Installer Strips Small Wires for a new Residential Furnace
Heaters have several electrical components. These parts include the transformer, capacitor, control board and wiring. Capacitors allow enough voltage to get to the motor and turn it on at the start of a heating cycle. They also deliver enough current to electrical heating elements in electric furnaces and heat pump auxiliary heating systems. A failing capacitor or transformer may get too hot and start to burn, which will cause a bad odor in your home. In a heat pump, the outdoor unit’s wiring is typically contained within a tube for protection from the elements. Corrosion or a failed seal may allow critters or moisture to damage the wiring and cause it to burn. If you see burn marks anywhere on your heating system, shut it down and call for an emergency repair.
Bone Heating & Cooling is the trusted heating repair company in Festus. We also offer air conditioner repairs and heating and cooling maintenance and installations. Our water heater, indoor air quality, ductwork, sheet metal fabrication, ductless mini-split and new construction services are designed with your comfort in mind. For more information about why you’re smelling a burning odor when your heater turns on, reach out to us at Bone Heating & Cooling any time.
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