Why Does Your Heater Smell Like Burning

If you're like most people, you ignore your heating system for most of the year until the winter months hit, and you rely on it to keep you warm and cozy. When you feel the first chill of the season and turn your heater on, you might notice that a heater smell like burning. You might even notice a burning smell that lingers for days or one that shows up unexpectedly halfway through the season. 

In some cases, a burning odor will fix itself, but an odor might indicate a serious issue in other cases. Your heater can emit different types of burning smells, and these odors can have several different causes.

Is a Burning Smell From My Heater Normal?

A burning smell from your heater is normal if it's due to dust buildup after a long warm season, but it can also be cause for alarm if there is another reason for the burning smell. It's normal to smell a burning odor when you first turn your heater on after it has been dormant for several months, but if you notice a recurring burning odor throughout the cold months, there could be an issue that you need to address. 

While some associate the burning smell with the joy of the winter season and winter holidays, it can be slightly unpleasant to others. If a burning odor occurs when you first turn on your heater after a dormant period, the smell should dissipate within an hour, but it's okay if it lasts longer as long as it lingers for less than a day. Some smells indicate a simple problem with an easy fix, while other odors can indicate a more severe and sometimes life-threatening issue.

How Do I Prevent a Burning Smell?

If your heater or furnace gives off a burning smell from dust buildup each winter, you can try several different methods to minimize or avoid the odor before turning it on this season. You can schedule a furnace tune-up from your local HVAC professional, including cleaning your heater's internal components. This will remove any dust or debris that can cause a burning smell when you first turn your heater on. You can also change your filter to catch more dust particles and prevent them from circulating throughout your vents and house.

Causes of Burning Smell From Your Heater

When your heater or furnace smells like it's burning after being dormant during the warmer months, it's most likely due to burning dust. This is normal and is no cause for alarm. However, if you notice a distinct smell or a smell that lingers longer than a day, you may need to call an HVAC specialist.

A burning smell from a heater can have one of several causes that include the following:

Burning Dust

It's normal for your heater to give off a burning smell when you first turn it on after the warm seasons are over. While you were enjoying the sunshine and warm weather of spring, summer and fall, your heater was collecting dust. This dust forms a fine layer in your heater due to air circulation even when you've turned the system off. 

The burning smell that you experience when you turn your heater on is this layer of dust burning. Once the dust and debris have burned and the smell dissipates, you can eliminate the odor from your home by opening some windows and letting some air flow through.

Clogged Air Filter

If you notice a recurring burning smell from your heater, it may be due to a clogged air filter. When dirt and debris clog an air filter, it will burn off and emit a burning odor. The burning smell can also occur due to overheating because the blower motor has to work harder when the air filter is clogged.

If your heater gives off a burning smell and you notice that the air filter is clogged, you can easily eliminate the burning odor by changing the air filter. Most people need to replace their air filters once every two to three months, but you will need to replace your air filter once a month if you use your heater frequently, smoke cigarettes inside the house or own pets.

Proximity of Objects

A burning smell can also result from any objects that are too close to your heater. Objects can fall and land near your heater, or you may have placed items on or around your heater when it wasn't in use and forgotten about them. These objects can include blankets, your children's toys, clothing, misplaced devices and other objects. If flammable materials are near your heater, they pose a safety threat. 

Plastics, fabrics and other materials can emit dangerous fumes or catch fire, so it's essential to check for any objects near your heater or register vents and remove them immediately if they are in close proximity. The smell should dissipate once you remove the item away from your heater, but if it persists, you will need to contact an HVAC specialist for help.

Smells to Watch For

Your heater can emit different types of burning smells. Each smell can indicate a different issue or cause for the burning smell, and it's important to know which smells mean minor issues with easy solutions and which smells signal serious problems with safety concerns that you need to address immediately. The following distinct smells can help you identify why your heater is giving off a burning smell:

Musty Smell

A moldy or musty smell can be normal when you first turn your heater on after it has been dormant, but it can also indicate that the HVAC system needs repairs. A musty smell can mean that moisture is trapped in your heater. If this is the case, the smell should be faint or dissipate soon after turning your heater on. If the smell dissipates after an hour or in less than a day, there is no reason to be alarmed. 

If the smell lingers, you might have a clogged air filter that you need to replace, or you may have mold growing inside your heater. If your air filter is clogged, you can easily amend the situation by replacing the filter. However, if mold is present, it poses a health risk. Some types of mold, such as black mold, can be toxic to inhale and cause health problems that include the following:

  • Headaches
  • Fatigue
  • Chronic sneezing and coughing
  • Irritated eyes
  • Rashes
  • Breathing problems
  • Irritation in the nose and throat
  • Nausea and vomiting
  • Diarrhea
  • Trouble concentrating

In addition to a musty odor and health symptoms of mold exposure, the presence of black dust around your air vents can also indicate that black mold is growing in your heating system. If you believe that you and your family may be exposed to toxic mold because of your heating system, it's important to remove the contamination. Contact an HVAC professional for assistance.

Electrical Burning Smell

An electrical burning smell can indicate a serious electrical issue that needs immediate repair. Electrical problems are one of the top causes of house fires in the United States. The Federal Emergency Management Agency (FEMA) reported that electrical malfunction caused 6.8% of fires in 2019. If you notice an electrical burning smell coming from your heater, turn it off immediately. 

Most heaters have a safety feature that shuts the heater down when it malfunctions or overheats. Sometimes, the safety feature can fail to work if there's an issue with the heat exchanger or blower motor, which means that any electrical burning within the heater will continue until you shut the unit down. Overheating can also cause a metallic or chemical smell, and some people compare it to the smell of formaldehyde. 

Electrical damage can result from damaged or faulty wiring, an overheated blower motor or a cracked heater exchange. These issues pose dangerous fire hazards, so it's critical to fix them immediately or call an HVAC professional for assistance.

Burning Plastic Smell

If you smell an odor of burning plastic, there is cause for alarm. It could mean that something is lodged in your heater and melting. This could be any object, from a lost pen to a child's toy that fell. A burning plastic smell can also occur when parts of the heater wear out or break. 

A burning plastic odor is dangerous because it can emit fumes that are toxic to inhale. Burning plastic releases particulates and toxic chemicals, such as dioxins, hydrochloric acid, heavy metals, sulfur dioxide and furans. These fumes can damage the respiratory and immune systems and cause cancer. When plastic melts on or in your heater, the fumes can circulate throughout your whole house through your HVAC system, so it's essential to turn your heater off immediately if you smell burning plastic. 

Once you turn off your heater, you can check if any objects are stuck or if any parts of the heater are broken. Check all parts of the heater, including the ductwork. If any parts of the heater are broken, you need to replace them before turning it back on. If you remove an object but the smell persists, seek assistance from an HVAC professional before turning your heater back on.

Rotten Egg or Sulfur Smell

A sulfur or rotten egg smell is dangerous because it may indicate a gas leak in your home. Natural gas is odorless, so it contains the added chemical mercaptan to add an odor to the gas. This chemical is harmless, but its scent allows you to detect when a dangerous gas leak occurs. 

If you notice this smell coming from your heater, turn it off right away and unplug any appliances in your house. Abstain from inhaling the air because it could be toxic to your lungs. Exit your home immediately and call your local fire department for emergency assistance. Gas leaks can cause fires and explosions, so you must evacuate your house immediately if you notice a sulfur smell coming from your heating system. 

The National Fire Protection Association (NFPA) reported that fire departments responded to approximately 125,000 gas leaks annually between 2012 and 2016. Natural gas causes about 4,200 house fires per year on average.

Gunpowder Smell

A gunpowder odor can indicate that the circuit board or fan motor overheated. If you hear a humming sound or other noises coming from your heater, or if your heater shuts down on its own, these can also be signs of an overheated fan motor. If you notice a gunpowder smell, turn your heater off immediately and call an HVAC professional to repair any overheated or damaged parts. Leave your heater turned off until an HVAC professional tells you that it's safe to turn it back on.

Dirty Sock Smell

If you notice a dirty sock smell coming from your furnace, it could indicate that bacteria is building up due to condensation. You can eliminate this smell by turning the furnace off to clean it thoroughly and replacing the air filter. If the odor lingers, the issue could be in the air ducts. If this is the case, you will need professional assistance to clean the air ducts.

Burning Oil Smell

If your furnace smells like burning oil, it could indicate a clogged filter or an oil leak. You should replace your filter every few months, but if excessive dust, pet hair or cigarette smoke is present in your house, the filter can become clogged faster. If this is the case, you can eliminate the smell by replacing the filter. However, if the smell lingers, it could indicate an oil leak, which requires professional assistance.

Know When to Be Concerned About a Heater Smell Like Burning

A burning smell from your furnace or heater can occur due to the simple issue of dust buildup over the warmer months, or it could be due to a more severe problem. It's important to know when to be concerned so you can fix the issue before it becomes a safety or health hazard. 

If you just turned your heater on for the first time after a long stretch of warm weather and you notice a burning odor that dissipates within a few hours or a day, there's no need to be alarmed. However, if the odor lingers, it may be time to look into other causes for the odor. You should also look into more serious problems that could be present if you notice a more distinct odor, such as a burning plastic or sulfur smell. 

Specific smells can indicate the presence of harmful mold or bacteria, a dangerous electrical problem or safety hazards that you need to address. You can easily resolve some issues on your own, but for more serious concerns, you should contact an HVAC specialist to help you make any needed repairs and determine when your heater is safe to use again.

If you need a new heating system or want to upgrade to a better system, shop Ingram's Water & Air for all of your heating needs. We carry quality heating and air conditioning systems that will save you money and time. We offer fast and easy shipping and technical assistance for installation and maintenance.

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