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Is it safe to add a Whole-Home Scent Machine to my HVAC unit?

Is it safe to add a Whole-Home Scent Machine to my HVAC unit?

Retailers know what I’m talking about. It’s not a coincidence that stores that employ air-scenting make customers linger and buy more.  Consider these facts:

  • A study done by Washington State University suggests that shoppers spend more time in stores with citrus scenting. Orange and lemon are two common citrus scents used in scent marketing. (Smells that Will Drive Your Sales)

  • A study run by Nike showed that adding scents to their stores increased intent to purchase by 80 per cent, while in another experiment at a petrol station with a mini-mart attached to it, pumping around the smell of coffee saw purchases of the drink increase by 300 per cent. (The smell of commerce: How companies use scents to sell their products)

  • A Washington State University study in 2012 found that shoppers in a scented shopping mall spent an average of 20% more. The study examined 400+ shoppers in Switzerland for more than two weeks. A group of 100 people who shopped in a scented space spent 20% more than the other test subjects. (10 reasons why you should scent your store)

Scents also apply to the real estate market.  Here are 2 examples (The Impact of Cleanliness on Final Home Sale Price):

  • A study conducted in the Phoenix, Arizona real estate market compared homes that underwent professional cleaning and deodorizing services with those that did not. The results were striking:

    • Homes cleaned and deodorized: Sold for an average of 5% above the asking price.

    • Homes not cleaned or deodorized: Sold for an average of 3% below the asking price.

  • A survey conducted by Zillow found that 80% of buyers are turned off by homes with strong odors, whether from pets, smoke, or cooking. Homes with neutral or pleasant smells, such as freshly baked cookies or a clean, fresh scent, tend to sell faster and for higher prices.

Even if you’re not selling your home or don’t work from home, these studies are telling us: there is a smell of success!  People want to bring these memorable fragrances in retail stores and even during their hotel stay on vacation, back to their home.  Home fragrances have evolved beyond candles and plug-ins to whole home, 24/7 scent strategies.  Homeowners are starting to use their HVAC system to distribute scents throughout the home, and there are mixed opinions on it.

According to Lelior, a luxury fragrance manufacturer, there are three main types of HVAC scent diffusers available on the market: fan-based, nebulizing, and evaporative. 

  • A fan-based HVAC scent diffuser uses a small fan to disperse fragrances throughout your home’s HVAC system. They are affordable and easy to install, but they don't have as strong of a scent throw as nebulizing or evaporative models.

  • Nebulizing diffusers: Nebulizing, or cold air diffusion, is a safe way to diffuse pure essential oils using advanced technology. Instead of heat, machines that utilize this method break down the oils into micro-particles using filtered air and distribute them throughout the area.

  • Evaporative diffusers: An evaporative fan diffuser works by using a fan to blow air from the room through a pad or filter that has essential oils dropped onto it. The air passing through the pad causes the oils to evaporate quicker than usual, and the air with the evaporated oil is then blown back into the room.

Out of these three, nebulizing diffusers are the most popular for their effectiveness in scenting large areas.

Although we know there are HVAC professionals who are very educated in Indoor Air Quality (IAQ) and those who are less educated, in general they do not seem to be in favor of these HVAC scent diffusers:

  • The oils used may degrade the coils and electronic equipment (fans, thermostats, etc.) in the system.  One tech posted the following observation: “Step two enjoy the refrigerant bill every 6 months when the evaporator coil leaks. I've never worked in a house with powerful fragrances that did not leak after a few years.  The new aluminum evaporators may have eliminated this problem but I am going to wait a few more years before I believe it.”

  • Another professional HVAC worker posted the following: “When I was young and just starting out on my own, I lived in a mobile home. I had this idea of using a pump spray air freshener to keep my house smelling fresh. Hey, for a single guy, I figured that would allow me slack off some on the house cleaning! When I figured out I could just spray a little into the return grille, well, that was even better! The whole house smelled good with very little effort. Then one day I realized that there was area on the return grille that had lost its paint and was rusting. Right where I usually sprayed that stuff! Oops! There was no sign of coil damage, that I could tell, but to this day I consider myself lucky on that. Sold that place a few years later. Don't know about later sign of damage, but I'll never do that again!”

  • (Undescribed poster) Absolutely horrible for IAQ. I have seen the REGULAR diffusers start to grow mold, as news flash: essential oils are made from organic material and will biodegrade like organic material. That means mold, fungus and bacteria. You are asking, BEGGING for mold to grow in your ductwork and on whatever surface the aerosolized oils land on.

  • HVAC equipment installer: Unless the unit has an electrical integration to sequence it's operation with the furnace/air handler, it's going to dump a lot of oil into the HVAC equipment or ductwork, and also not put out enough oil when the blower is running.

  • (“Elder on r/HVAC): A sarcastic comment for sure! “...breathing in oil particles definitely isn't harmful eventually for us. Seeing as we need to vent all cooking exhaust outside, which is basically also all oils, and that all eventually coagulates into nasty grease on the filters, I personally don't see the need to purposely put oils of any kind into my supply air.”

Just like our mission of replicating the natural outdoors, inside, if you’re going to add scents, we advise making it light and natural.  Here are some considerations:

  • Make sure that no one living/staying in the home on a permanent basis is allergic or sensitive to fragrances.

  • Be overly cautious and attentive when using the system with children and those with respiratory illnesses in the home.

  • Don’t add scents just to “cover-up” bad odors.  Like the above real estate research, “clean” is the best scent available.

  • HVAC scent diffusers need to be cleaned and maintained regularly in order to ensure they're working properly. 

  • The system must be wired into the fan motor control, so that it will not dispense oil when the fan is not running. 

  • Take care that vents/registers are not located near/directly over fish tanks and housing for other sensitive animals (birds, reptiles, etc.) as these could cause health issues (Scent diffusers and Fish tanks)

  • Consider only using natural oils, as research suggests that synthetic fragrances are harmful to our health (Why Conventional Perfume is Giving You a Headache)

Photo by No Revisions on Unsplash