Everyone likes the air in their home to smell fresh and clean. Many even want it to smell apple-ish, or lavender-ish, or even patchouli-ish, but no one I've ever known has said, "I love the musty smell my furnace provides." Look no further than the candle and air freshener market these days for proof that people like things to smell good. There are whole stores dedicated to making your surroundings smell better, however not all issues can be solved by making a trip to Yankee Candle. Your furnace and duct work are a couple of those issues.
Knowing some of the common causes of furnace odor may help in resolving your issue, so let's take a look at some of the things that cause these unpleasant smells in our home.
Aside from the fact that dust itself has an odor, when the furnace runs it burns that dust that has built up in the off season and blows it through the air ducts.
Having your furnace and evaporator coil cleaned before fall cold arrives.
Animals like to be warm. More than a few birds and chipmunks have met their end in chimneys and inducer fans as well as mice and other rodents looking to make nesting material out of filters, wiring, and flexible air ducts.
Remove dead animal. Most commonly found in the flue pipe, inducer fan, blower compartment, and occasionally the ductwork itself. Signs of damage can help you locate the deceased if there is one.
Mold / Mildew
Most often found in underground ductwork, mold and mildew are a very common cause of bad household smells. Time often allows water to leak into these systems and create all kinds of bad odor as well as health concerns. Evaporator coil drain trays and drains can contain mold and mildew as well as unattended humidifiers with old water panels.
Having your humidifier, evaporator coil, and ducts cleaned is the most surefire way to handle this problem however if you have an underground system, it's not nearly that simple and you may have to consider having your ducting lined or sealed by a professional since once they leak, they always will.
When electrical parts fail they often overheat or "burnout" thus creating the distinct odor of melting plastic or burnt wires.
Even if your unit is working, you may have a motor or other electrical part overheating and getting ready to fail. Have this checked out before it's an issue.
Did You Know...
...if you lay a few dryer sheets on top of, spilled milk for example, then place coffee grounds on top of them it will help absorb the spill and odor that tends to linger?
HVAC technology offers homeowners a lot of product options for improving the quality and smell of the air in our homes. These IAQ products have drawn extra attention in today's world where our homes are sealed up so tightly. Let's start by taking a look at some of the products available to us that can be installed in our HVAC systems.
This is an example of a media filter. Filter replacements aren't as cheap as your standard 1" filter and installation will likely require some modification to your return duct.
These are filter cabinets installed in our return air duct with a larger (wider) surface area that catch much more dust than the typical 1" wide filters most of us use.
Much lower amounts of dust in a home compared to a home with a standard 1" filter.
Filter replacements are more expensive and ductwork may need modified to accomodate air flow restriction and installation.
Electronic Air Cleaners
Providing the same advantages as a media filter, these also use electricity to zap dust particles as well.
Provides the best dust control of air filtering products.
Initial costs is higher than other air cleaners and routine maintenance is required to keep it functioning at full capacity. Electrical components mean there is potential for breakdowns.
Lamp installed onto / into your duct work, typically above the evaporator coil, lights up the inside of the duct with UV light.
Provides healthier air in the home by using UV to kill pathogens and microorganisms..
Requires some maintenance including bulb replacement from time to time and only treats the area exposed to the light.
A small ion producing unit usually wired into the blower and sits in the furnace cabinet.
Provides the benefits of other IAQ products in one unit that requires little to install and no maintenance.
Cost. These are not cheap.
A separate unit tied into your ductwork requiring it's own space and duct to outside of home.
Fresh outdoor air is filtered and brought into the home as well as exhausting stale, perhaps radon or VOC filled air.
Cost. These units are not cheap either and require a fairly extensive process to install. Maintenance and filter changing is a must.
Did you know....
...running your furnace fan continuously (in "fan" mode) will keep the air in your home circulating, thus passing through the filter and in turn provide cleaner air? This helps even out the temperatures of the house as well.
Not everything you do to improve your home's air quality and smell has to cost you a bunch of money. There are a few tricks I've learned and some rather easy things anyone can do for themselves that can make a significant difference in this arena.
Keep in mind these aren't permanent fixes of underlying problems (such as not removing a dead critter or treating mold and mildew issues) but they're great for maintaining a pleasant atmosphere at little to no cost.
Sometimes no matter what you do, or how clean you get the ducts, you still have bad smells that just won't go away. These smells built up over time in all the crevices and cracks throughout your system.
When nothing else works, a lot of us in the HVAC industry are now starting to use this ClenAir Odor Neutralizer. In fact, we use this extensively on restorations after fire or flood damage to get out the last bit of remaining smell. Just stick it in the air return and it'll do the rest.
Getting rid of nasty odors in our home is obviously something we all want to do if we are experiencing this type of thing but the underlying truth here is that if you have bad odors in your duct work, your entire home is affected and it's usually not without cause. These causes not only make things smell bad but they often can jeopardize our health as well.
I hope you found something here that not only helped create a more pleasant smell in your home but maybe even provided a healthier atmosphere for you and yours.
~ We're all in this together ~
© 2018 Dan Reed
Shelly on August 24, 2018:
Dan Reed (author) on June 06, 2018:
Rich - I don't recommend doing this. Lysol disinfectant contains very harmful chemicals. It is flammable and dangerous to inhale. If you look up "Lysol disinfectant spray warnings" you'll see this for yourself. I'm not a big fan of the product. I know you've been using it but once you read up, you may change your mind about continuing this practice.
Rich on June 05, 2018:
Annually I spray a generous amount of Lysol disinfectant directly up through my evaporator coil with just the fan running to distribute it through the ductwork. Then I turn off the fan and let it sit for an hour before turning the fan back on with all windows open to ventilate the house. This seems to get rid of moldy, musty odors from our attic ductwork.