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New odors in your home can be annoying to get rid of but they can also give you a clue to what is going on within the structure of the house. Many times we turn on the heat when the temperature starts to drop and strange smells accompany the hot air coming into your rooms. Knowing what different furnace smells mean can help you determine where the smell is coming from and if it is something to worry about. If you are worried about a smell and want to check for maintenance, VA Reliance Home is here for you. Here is what to sniff around for:

Types of Odors

Okay Furnace Smells

Dust smell

Dust, dander, pollen, and other airborne particles float throughout your home all year, and they can settle within your furnace and HVAC system. It is normal to smell something dusty when you turn on the heat for the first time. While dust is not an immediate danger, like other things, it can impact your health in the long run by irritating people with respiratory issues. Contact Reliance Home Comfort to schedule seasonal cleaning – once in the fall before turning on the heat, and once in the spring before switching to a/c.

Dangerous Furnace Smells

Gas aka Mercaptan/Rotten Egg smell

Natural gas is odorless and colorless, which makes a leak difficult to detect. Gas companies are required to add mercaptan to the gas, which is what causes the sulfur or rotten egg smell. If you ever think you can smell sulfur or rotten eggs, you need to act immediately. Turn off any gas-powered appliances right away. Evacuate any people or pets from your home. Quickly exit, but leave open exterior doors or windows to air things out. Call 911 as soon as everyone is out of the building and a safe distance away. The dispatchers will contact the gas company to shut off the source and send emergency personnel to investigate the potential leak. Do not go back into the home until you get the all-clear from the emergency response team.

Burning plastic

If you have a new HVAC system, it may emit the smell of burning plastic the first time or two that it runs. However, if the smell persists, it could be a sign of a problem. Burning plastic smells in units that are not new could mean that the system is overheating or that parts are rubbing against each other and creating heat in areas that aren’t supposed to. If you notice a smell like burning plastic, contact an HVAC specialist immediately to check things out and diagnose the problem.


If the furnace smell is something that reminds you of rotting wood or wet, dirty socks, you might have a mold or mildew problem. Sometimes it can be difficult to distinguish between a musty smell, or something more sinister, like mold or mildew. Generally the smell of mold or mildew will be much stronger than a musty smell and it will linger until the source is taken care of. If you smell something moldy, it could be coming from a multitude of places: the filter for your furnace humidifier, the condensate drain line of your air conditioner, or actual mold or mildew growing inside the HVAC unit or in the air ducts. People who are consistently breathing in mold or mildew spores can exhibit symptoms such as wheezing, itchy eyes, runny nose, coughing, fatigue, headache, and difficulty breathing. If you don’t take care of the issue, it could spread and become much worse. It can also impact the health of loved ones – repeated exposures can lead to more severe reactions. If you suspect a mold or mildew problem, contact your HVAC specialist to have the problem pinpointed and get it taken care of.

With cold weather, we often have our doors and windows shut for months at a time and this can trap in smells and pollutants. The EPA has reported that indoor air can actually be 2 to 5 times more polluted than outdoor air because irritants and particles are trapped and recycled through our HVAC systems. Noticing new or unpleasant smells can help you to identify any problem and to resolve them before they can become bigger and more costly – in terms of dollars and health. In order to keep your HVAC system running at its best, you should be working with an HVAC specialist at least twice a year for maintenance. If you notice any of the odd furnace smells described above, contact Reliance Home Comfort right away to schedule an appointment and have it taken care of.