September brings the first day of autumn and, with it, cooler weather. Whether you’ve already started to heat your house or are someone who sticks it out until all the leaves have fallen, your nose may pick up an odd smell when you first turn on your furnace.

There are a number of reasons furnaces might give off a peculiar smell when turned on after a long spell. Most of the time, the smell will disappear once normal dust is burnt off. According to Carrier, if the smell lingers for longer than an hour you should check the air filter and replace it if necessary. If that doesn’t work it could indicate a bigger issue. Discerning the smell can help identify the issue. The three smells to be aware of are:

  • Rotten Eggs

  • Smoke/Burning

  • Mildew

Your furnace may emit an odor when you first start heating your home in the fall.

Rotten Eggs

The smell of rotten eggs is not only unpleasant, but likely dangerous. Often when there is a gas leak present, the smell of rotten eggs is the detectable scent. In this case, it is critical everyone evacuate the home and an expert technician is called to investigate. Call your gas company first, and once the leak has been repaired our trusted team of HVAC experts can perform a service call for any additional repair needs. We suggest saving your gas company’s phone number as a contact for easy accessibility in the event of an emergency.

While gas leaks are sometimes detectable, carbon monoxide detectors are critical for catching odorless leaks. Make sure to regularly replace your carbon monoxide batteries (doing this at daylight saving time in the spring and fall make it easy to remember).



A smoky or burning scent might indicate overheating. Synonymous scents include burning plastic or hot metal. Fires are possible consequences of overheating and should be dealt with immediately. Turn off your HVAC if you identify this smell and immediately reach out to your HVAC team or your local fire department if necessary.



Mildew, or must, is associated with moisture buildup. When air conditioning units accumulate moisture, mold forms and produces a mildew smell. Long exposure to mold can lead to respiratory problems. A thorough cleaning will typically take care of mold. However, it’s important to identify the source of excess moisture to prevent a long-term problem. In most cases, this smell is not associated with turning on the furnace.

As a Complete Energy Company, Genove Oil & Air offers Energy Efficient Heating and Cooling options.

The best way to protect your furnace is to schedule annual maintenance. During annual maintenance, our friendly team will conduct a thorough review of your heating system to ensure your home is winter-ready.

Five reasons to schedule your Tune-Up?

  1. Keep your system running at peak efficiency to save on fuel costs. 

  2. Reduce unexpected and inconvenient service calls throughout the heating season.

  3. Gain peace of mind knowing that a safety inspection has been performed on your equipment.

  4. Prolong the life of your heating system.

  5. Increase the overall value of your home with equipment that is safe for your property and the environment

Schedule your tune-up today.

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If your question isn’t answered here, contact the friendly team at Genove Oil & Air, and we’ll find a solution for your home or business.

Whether you need home heating oil or Bioheat delivery, or installation and service of oil & natural gas systems for HVAC, heating, and cooling—call us at 781-893-9191 or email us.