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Concerned man puts his face close to his home air vent.

Why Your Heater Smells Like It’s Burning

First time firing up your heater this season? Find out what furnace smells are normal and when to get expert help.

October 10, 2023

As the chilly embrace of winter approaches, homeowners across the country prepare to combat the cold by firing up their furnaces. It's a familiar ritual – you adjust the thermostat, eagerly anticipating the warmth that will soon envelop your home. However, instead of the cozy comfort you expect, an unpleasant burning smell wafts through the air. If you find yourself in this situation, don't panic! While a burning odor from your heater can be disconcerting, it's not always a cause for alarm. In this comprehensive guide, we'll take a closer look at the various reasons your heater smells like it's burning and outline steps to address each situation safely.

What's Behind That Burning Smell from My Furnace?

When your heating system emits a suspicious odor upon activation, your heater smells like it's burning, or the furnace smells like burning plastic, several culprits could be to blame. While major issues should always prompt a call to an HVAC professional, you can attempt some troubleshooting on your own to identify the source of the burning smell.

Dust Accumulation on the Furnace

A common reason for a burning smell when you initially turn on your heater is dust buildup on the furnace. If you live in a region with fluctuating seasons, such as the Mid-Atlantic, your furnace may sit dormant for months, allowing dust to accumulate. When you finally switch it on after an extended hiatus, this accumulated dust ignites, often resulting in a burning plastic smell permeating your home.

What Can You Do?

Fortunately, dust buildup on your furnace usually isn't a cause for concern. After the dust burns off, the smell typically dissipates. Inspect your unit, but avoid touching it. If you suspect dust is responsible for the odor, let the unit run for about 10 minutes. If the smell diminishes or vanishes, you're likely in the clear. However, if the odor persists or worsens, turn off your unit and seek assistance from an HVAC professional.

Debris Trapped in the Heating System

During periods of inactivity, it's possible that foreign objects found their way into your HVAC device or ductwork, especially if you have a central heating and cooling system with multiple vents throughout your home. If you can pinpoint the burning smell to a particular room, there may be an object trapped inside the vent causing the issue.

What Can You Do?

If you identify the room emitting the smell, attempt to access the vent. Carefully open it or peer inside. You might discover a toy, a component of the heating system, or another object lodged within. Safely remove the object, if possible, and wait to see if the burning smell subsides. If you can't safely remove the object or the odor persists, contact an HVAC professional for assistance.

Dirty Furnace Air Filters or Air Vents

Proper maintenance of your gas furnace is crucial to preventing burning smells emanating from your heater. Dirty furnace air filters or clogged air vents can lead to mold or mildew growth inside the heating system or ductwork, resulting in an unpleasant musty odor when the system is activated.

What Can You Do?

If you detect a musty scent emanating from your furnace, turn off the unit completely. Have your filters cleaned or replaced inside your unit, and then attempt to run it again. If a freshly cleaned furnace air filter doesn't eliminate the odor, consult an HVAC professional to inspect your unit and ductwork.

Damaged Electrical Wiring

A burning electrical odor emanating from your heater could indicate a severe electrical problem. Over time, general wear and tear or improper installation can damage your system's electrical wiring. Such damage can lead to a cracked heat exchanger, overheating blower motor, or a range of other serious issues that require immediate attention from a licensed HVAC professional.

What Can You Do?

If you suspect an electrical issue is causing the burning smell, immediately turn off your unit and contact a licensed HVAC professional to address the problem.

Accumulated Pet Hair and Dander

If you have pets in your home, especially furry ones, their hair and dander can accumulate within your heating system over time. When you turn on the heater, this buildup can heat up and emit a burning odor.

What Can You Do?

To address this issue, start by regularly cleaning or changing your furnace filters. Consider using filters designed to capture pet hair and allergens, like the Trane CleanEffects® Whole Home Air Cleaner. Additionally, vacuum and dust your home regularly to reduce the amount of pet hair and dander circulating through your HVAC system. If the odor persists, consult an HVAC professional to ensure there's no deeper issue within the system.

Chemical Odors from a New Furnace

If you've recently had a new furnace installed, it may emit a chemical odor that smells like burning plastic when first used. This smell can be alarming, but it's often a result of the manufacturing process and protective coatings on components.

What Can You Do?

To alleviate this issue, allow your new furnace to run for a few hours with windows open to ventilate your home. Ensure proper ventilation in the area where the furnace is installed. If the odor doesn't dissipate after several hours of use, contact the HVAC installer to verify that the furnace is functioning correctly and that there are no unusual issues causing the smell.

When to Seek Furnace Repair

While many of the potential odor problems mentioned above have quick fixes, there are situations where a comprehensive furnace repair may be necessary. If the burning smell persists for over an hour despite your troubleshooting efforts, a more significant issue may be at play, and you should promptly enlist the help of an HVAC professional.

A heater emitting a burning smell could indicate significant electrical problems, structural damage to the unit, or a malfunctioning component. In any of these scenarios, an HVAC technician may need to repair or replace parts of your furnace before you can safely heat your home again.

Preventing a Burning Smell

The best way to prevent unwanted smells coming from your furnace is to schedule regular maintenance for your unit with an HVAC professional. Furnace maintenance should occur at least once a year, and some units may require semi-annual service. During these maintenance visits, technicians will clean your furnace, mitigating the risk of burning smells caused by dust buildup. Additionally, they will inspect your unit for serious electrical issues.

Regular maintenance that you can perform yourself, such as replacing furnace air filters every three months, contributes to the smooth operation of your unit and helps keep your home free of unwanted odors. While regular maintenance isn't foolproof, it is the most effective measure you can take to avoid encountering this issue each winter when you turn up the thermostat.

Eliminate Furnace Smells: Contact a Trane Comfort Specialist

Any furnace smell, and particularly a burning smell from your heater, can be unsettling, but it doesn't always signal a major problem. By identifying the potential causes and taking appropriate action, you can often resolve the issue on your own. Regular maintenance remains the best preventative measure, ensuring that your heater keeps you warm and cozy all winter long without any unpleasant surprises. However, if the odor persists or you suspect a more serious problem, don't hesitate to contact a Trane Comfort Specialist.

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