When you turn your heat on in your home, you may have a foul smell coming from your vents. This makes it very difficult to be comfortable and happy in your home. There are several types of odors you may experience for many different reasons. Here are the reasons odors appear in your ducts and how you can effectively get rid of them.

Types of Odor

Different homes may have different odors coming from the vents. It all depends on the cause. The most common sources of the odor are mold/fungus and cigarette smoke residue.

Cigarette Smoke

Most people think that once the cigarette smoke dissipates, it is gone from their home. Unfortunately, the smell stays imbedded in furniture and ductwork; most smokers just can't smell it. If you recently quit smoking or just moved into a home that smokers lived in, the smell is probably very strong.

To eliminate the cigarette odors, there are a few different things that you can do:

  • Use air sanitizers
  • Change air filters
  • Wipe down your home
  • Have ducts professionally cleaned

Air sanitizers use chemicals to eat away at the odors in your home. If you don't want the chemicals, you can make natural odor eliminators. While you have the air sanitizers in your home, change the air filters. Air filters trap all of the contaminants that go through your ventilation system, so it is probably full of cigarette residue. They should be changed every couple months anyway.

Your air filter is probably in the ceiling. You'll see a large square area that looks like a grate or vent with small latches on the side. Flip down the latches and pull it off to reveal the air filter. The edge of the filter will have a size printed on it; you need to buy a replacement that is the same exact size. Stores carry scented ones as well.

If you are/were the smoker, all the particles are rested on your furniture and floors. Wipe everything down to remove as much of the residue as possible. It will keep all of the particles from going back through your ductwork. Once you have followed all these steps, your home may smell pleasant again. However, if the smell continues, you will need to call an HVAC contractor to professionally clean your ducts. A professional cleaning should be done on a yearly basis anyway.


Mold and fungus will thrive more easily if you have central air conditioning as well as heat. This is because the condensation from your air conditioner will make the inside of your ducts moist in certain areas. Both mold and fungus grow in wet environments. If mold or fungus is the problem, it will smell like mildew or must in your home.

If you see some fungus just inside a vent that is easy to reach, you can try to clean it yourself. A common household detergent mixed with water will do the trick. You can use either baking soda or borax as well. Mix the baking soda with water (2 parts water to 1 part baking soda) and a tablespoon of liquid detergent. If you use borax, mix it with 16 parts water.

Clean everything that you can see and reach with your heat and air conditioning off. Let it dry for about an hour, and then you can turn your air back on.

Mold can be very hazardous to your health and it isn't recommended that you try to clean it. This is because you don't want to ignore the possibility of mold being deeper inside of your ducts. If mold is the issue, or you still smell an issue after cleaning the fungus, call an HVAC contractor to do a professional cleaning.

Don't ignore the foul smells inside of your home. Change your air filters, use odor eliminators, and check your ductwork for anything growing inside of them. If you can't get rid of the smell, call a professional to come clean your vents for you. Continue here for more about this topic.