This Simple Furnace Trick Can Refresh Your Entire Home

If you’re not in the mood for baking cookies or sautéing onions and garlic, another great choice for making your home smell welcoming is essential oils. Think zesty lemon, calming lavender or woody incense. There are many ways to disburse those around your home, but if you have a central HVAC system, one of the easiest is with this furnace air freshener hack, which simply involves putting a few drops in your furnace filter.

“This is actually a good hack,” says Randy Huckstadt, a licensed HVAC expert with JustAnswer. “My wife loves this hack and has used it for years.”

Using essential oils is also preferable to air fresheners with synthetic fragrances, since many of those contain chemicals and VOCs that can cause health problems.

If you’re looking to add a little easy cheer to your home, here’s what to know to successfully pull off the furnace air freshener hack.

Furnace Filter Air Freshener Hack, Explained

When your furnace or air conditioning system is not running, remove the filter and place several drops of essential oil on its pleats. Take care to reinstall the filter properly so the airflow is going in the proper direction, as per the little arrows on the filter. Once the HVAC system kicks on, it will spread the fragrance throughout the house.

“Any great smelling essential oils that you like will work well,” says Huckstadt. “Depending on how large your system is depends on how many drops and how long it will last. This is where experimenting comes in to find out what works best for you.”

Customization Tips & Tricks

The furnace filter air freshener hack can be tailored to match your mood and the season, for example, by using peppermint during the winter holidays and roses around Valentine’s Day. It’s such a tempting idea that 3M even developed a product line around it, says Andy Fox, a filtration and indoor air quality specialist at 3M. To increase its efficacy, he suggests running the HVAC fan at a continuous low speed.

“On the positive side, this approach will help spread some scent through the home,” says Fox. On the negative side, nearly every residential filter above MERV 8, and even some lower, use an electrostatic charge to boost the filter’s performance without impacting airflow.” That means that anywhere the oil contacts the filter, media will be discharged, reducing the smell’s potency.

Will This Hack Damage My Furnace?

Usually, this hack is safe for furnaces. However, some oils might break down the filter material, so have a backup filter handy just in case, says Glenn Wiseman, a certified home air technician with Top Hat Home Comfort Services.

“If you want to try this, stick to just a few drops and let the filter dry a bit before putting it back,” he says. “I’d recommend checking the filter regularly to make sure it’s still in good shape.”

Also, refrain from soaking the filter or adding enough oil over time to cause it to start leaking, says Fox. “If it’s only a few drops, I don’t anticipate any damage,” he says. But keep in mind that “oil will wet out most filter media, meaning it will creep along the fibers and discharge a larger spot than just the area where the drops are placed.”

Is The Furnace Filter Hack Safe?

This hack is generally safe, but only use essential oils intended for indoor use and in quantities according to their use guidelines. Although essential oils are generally considered safer for human health than synthetic air fresheners, they still contain volatile organic compounds (VOCs). They can aggravate respiratory problems like asthma and COPD, according to the American Lung Association.

“Air quality could be a concern, especially if you have pets or people with allergies, so just make sure to use caution when trying this for the first time,” says Wiseman. “Use the oil sparingly just to make sure you don’t damage any parts of the furnace and to prevent too much of an overwhelming scent.”

Also, never combine essential oils, as there is little research about their interactions. According to the American Lung Association, combining some VOCs can create secondary pollutants, including formaldehyde, which can irritate the nose, throat and lungs.

All About Furnace Filters

Learn what you need to know about furnace filters to properly use and maintain them.

• Best Furnace Filters for Allergies, Dust, Pet Owners and More
• How to Change a Dirty Furnace Filter
• Furnace Filter Myths
• Why High-Performance Furnace Filters May Ruin the Blower

About the Experts

• Andy Fox is a division scientist in the Home Improvement & Consumer Wellbeing segment of Consumer Business Group at 3M, where he’s worked for more than 20 years. He specializes in filter media and filtration systems development and holds 56 issued U.S. patents.
• Randy Huckstadt is a licensed HVAC contractor and indoor air quality specialist with nearly 20 years of experience. He also works as an HVAC expert at JustAnswer.
• Glenn Wiseman is an HRAI-certified residential air system design technician as well as the sales manager at Top Hat Home Comfort Services in Ottawa, Ontario. He specializes in home comfort solutions, including HVAC systems, fireplaces and insulation.