Cross-section of a dirty air duct

Just like your own lungs, your heating and cooling system pulls air in and pushes air out of your living environment. It is the “lungs of your home”, pushing through the ducts of your heating, ventilation and air conditioning (HVAC) system in a network of branching tubes. These ducts, which can be made of fiberglass, sheet metal or other materials, transport the air from your central air conditioner and furnace to all the rooms of your house.

Just living in our homes, we produce a lot of air pollutants and contaminants, such as pet dander, chemicals and dust. Our HVAC systems then breathe these in, recirculating the air an average of 5 to 7 times during the day. Thus, as time passes, contaminants can build up in your duct work.

Almost 25 million people in the U.S., both adults and children, suffer with asthma. Hay fever, or allergic rhinitis, plagues another 50 million Americans. In fact, the CDC reports that allergies are 6th primary cause of chronic illness in this country. Mold, dust mites and other allergens, which are often found in air ducts, can trigger both asthma and allergic rhinitis.

With all of this in mind, wouldn’t it just make sense to want to clean you air ducts? The experts [Environmental Protection Agency (EPA) and National Air Duct Cleaners Association (NADCA)] agree that just cleaning the air ducts themselves isn’t enough and can result in recontamination of the whole system. The entire HVAC system must be cleaned to obtain the desired results, including:

  • Air ducts
  • Coils
  • Drain pan
  • Registers
  • Grills
  • Diffusers
  • Air plenum
  • Blower motor and assembly
  • Heat exchanger
  • Air filter
  • Air cleaner
  • Air handling unit housing

Should You Clean Your Air Ducts?

The benefit to indoor air quality of routinely cleaning your HVAC systems is the subject of continued research. A review was conducted in 2010 of scientific studies regarding duct cleaning by the National Institutes of Health, Office of Research Services, and Division of Occupational Health and Safety (DOHS). According to the study, there just isn’t enough evidence to come to any firm conclusions regarding the benefits to indoor air quality, HVAC system performance and energy usage, or occupational health. Still, the study found definite evidence supporting the fact that air ducts can become contaminated with dust and become a source of microbial growth with normal usage.

However, even if your ducts are extremely well cleaned, changes in indoor air quality vary greatly. Often, the amount of contaminates in the air is greater than before the air ducts were cleaned. The EPA adds that studies have not conclusively shown that contaminate levels go up due to dirty air ducts or decrease after they have been cleaned. A major reason is because any dirt that may collect inside air ducts can stick to the inside surfaces and not travel into the home. Dirty air ducts are only one potential source of pollutants in your home. Things like cleaning, smoking, cooking, or even just walking around can create higher levels of contaminants in your environment than dirty air ducts.

While cleaning air ducts alone has never been shown to prevent health problems, most professionals agree that you should do whatever you can to reduce dust if you have a heightened sensitivity.

When Should You Clean Your Air Ducts?

The EPA suggests doing so with caution so as not to cause more harm. If not done properly, more dirt, dust and contaminants could be released into your home, or your ducts or your heating and cooling system could even be damaged.

According to the DOHS, cleaning your air ducts should be your last resort. Cleaning should be done only after you have thoroughly inspected your system, found the source of any contaminants, and controlled it. If not, the system will just keep getting re-contaminated if not properly addressed. The DOHS goes on to point out that both the EPA and industrial hygienists agree that cleaning your air ducts or replacing them is the appropriate thing to do under the following conditions:

  • Permanent or continuing water damage in the air ducts
  • Observable slime or microbial growth (insulated air ducts that become wet or moldy can’t be cleaned and must be removed and replaced)
  • Build-up of debris in the air ducts that restricts the flow of air
  • Dust venting from the supply diffusers
  • Offensive odors coming from the HVAC unit or the air ducts
  • Infestation by rodents, insects or other vermin

Leading professionals note that if your home is over 10 years old and your ducts have never been cleaned; dust constantly collects regardless of how often you clean; you have allergy symptoms whenever you turn on your heating or cooling system, or your asthma is not being controlled by medication, then cleaning your air ducts is a wise option. If the source of any of these problems is not found and corrected, they will recur.

Professional vs. Do-it-Yourself Air Duct Cleaning

Cleaning your air ducts – actually, your entire HVAC system, really isn’t a DIY project. This is because special tools like high-powered vacuums and agitation equipment, such as rotary brushes, air whips, compressed air nozzles, and “skipper balls” are used to dislodge and remove dust, dirt and other contaminants. These aren’t tools readily available to the average homeowner, nor do they know how to properly use them. The equipment employed depends not only on the type of debris and contaminants, but also on what material the air ducts are made of. Some air ducts are sheet metal, or sheet metal lined with fiberglass insulation, while others are fiberglass board, or even “flex duct.”

Most homeowners would not be able to access their whole system. Sometimes access holes need to be cut in the ductwork which requires professional skill both in creating and closing these openings. Furthermore, the average homeowner does not possess the skills and knowledge necessary to clean their entire HVAC system. In instances where HVAC repair or replacement is necessary, Choice Home Warranty plays a major role.

If air ducts become infested with insects, rodents and other types of vermin that quickly become a serious problem requiring the intervention of a professional. Not to mention the fact that mold clean up presents its own health risks. If you plan on hiring a professional to perform the cleaning of your HVAC system, here are some things to consider according to the FDA:

  • There is no such thing as an FDA certified air duct cleaner. Don’t get scammed. The NADCA does certify air duct cleaners if they meet all their requirements.
  • Don’t allow them to use chemical biocides (to kill bacteria and mold) or treatments like sealants (to prevent dust and dirt from venting out of your air ducts) unless you completely understand all the pros and cons of doing so. Routine use of sealants in air ducts is not recommended. Very few chemicals have been registered with the EPA for use in your HVAC.
  • Be sure to check references and make sure no complaints have been made against them with the city, consumer affairs, or your local Better Business Bureau.
  • Interview any company you think you might hire and make sure:
    • They have experience working on HVAC systems, such as yours
    • They take precautions to protect people and pets in your home from contamination
    • They adhere to NADCA’s air duct cleaning standards and NAIMA recommendations if your ducts are fiberglass duct board or internally insulated with fiberglass duct liner
    • They have all required state licenses if needed
    • To get a written agreement with total cost and scope of work before beginning.

How to Clean Air Ducts

Although you won’t be able to reach all the way through your air ducts, there are still things you can do to help keep them clean.

Materials needed:

  • Vacuum cleaner – a heavy duty vacuum is best and you can rent one
  • Brush – a long-handled dust brush is just right for this. According to the EPA, a soft-bristled brush should always be used on fiberglass.
  • Screwdriver
  • Cleaning cloths and paper towels
  • Broom
  • Furnace filter

Air duct cleaning process

Man using a vacuum to clean air duct cover

  1. Cover the supply registers with paper towels by lifting them, wrapping the towel over them and replacing them. This prevents dust and debris from flowing into your home while you are working on other areas.
  2. Turn on the fan. Make sure the heating/cooling function is off.
  3. Make sure your furnace filter is in place so dirt and debris you dislodge doesn’t get sucked into the fan motor.
  4. Clean supply registers using a vacuum or broom, then use a long-handled broom to get deep into the piping system. Make sure the vacuum is running to catch all the dust.
  5. Clean return air registers, sweeping as far into the piping or cavity as possible.
  6. Turn off the power to the system.
  7. Access your air ducts by unscrewing air duct covers and grills. Using your cleaning cloths or soap and water, clean the grates.
  8. Vacuum out the air ducts as far as your hose will reach.
  9. Clean the blower compartment. With the power off, take off the panels on the front of your furnace to get at the return air boot and the blower compartment. Most of the dirt and dust will build up at the furnace and can cause clogging. Vacuum out the dirt and debris. Be careful not to damage the furnace fan.
  10. Replace furnace filter.
  11. Finally, if you have trouble with this process, you should call a professional.

How to Prevent Air Duct Contamination

The key to avoiding the expense of having your air ducts cleaned is prevention. According to the DOHS, prevention requires that you:

  • Routinely maintain your HVAC system by following your manufacturer’s guidelines for cleaning coils and other components as well as changing HVAC filters.
  • Prevent any dust or debris from renovations from getting into the HVAC system by sealing the ductwork.
  • Keep up good housekeeping practices in the occupied portions of your home.
  • Make sure that no contaminant sources are near any air intakes.
  • Consider having your air ducts routinely inspected.

In addition, homeowners can keep dust and debris from accumulating as fast by cleaning their vent covers routinely and changing air filters frequently. Maintaining less than 50 percent humidity in your home also helps, because humidity increases the risk of dust mites and mold.

Keeping dirt and water from getting into your system is the best way to keep it from becoming contaminated. Seemingly minor issues can make for air quality hazards. In addition to the steps listed above, you should:

  • Ensure no gaps exist around filters and none are missing.
  • Use the highest efficiency filters that your manufacturer recommends
  • Use HEPA filters on vacuums, if possible, or highest efficiency filtering bags recommended.
  • Keep all moisture out of your ductwork.

How often Should You Clean Your Air Ducts?

The NADCA recommends air ducts be cleaned every 3 to 5 years. According to the NADCA, “If your air ducts look dirty, they probably are.” When deciding for yourself when is best, take these factors into consideration:

  • Whether you have pets indoors
  • Whether there are smokers living in the house
  • Whether the house is extremely dusty
  • Whether there are occupants who have asthma, allergies or other respiratory problems
  • Whether your climate is excessively humid (could lead to mold or mildew)
  • Whether your air ducts may have leaks
  • Whether a lot of people live in your house
  • Whether there may be water contamination or water damage to your house or HVAC system
  • Whether your house has undergone renovations or remodeling
  • Whether you are about to move into a new home

Keep in mind that the EPA recommends that air ducts be cleaned only as needed, rather than on a routine basis.

Disclaimer: No recommendation is made herein for the do-it-yourself cleaning of air ducts. Air ducts are made of differing materials which can be damaged if not handled properly. If mold is present in the air ducts, the breathing of spores could present a health hazard. The preceding is for information purposes only.

Edison, NJ 08837
1090 King Georges Post Rd.