Air duct cleaning: Understanding the basics


Recent research shows indoor air contains more pollutants than outdoor air. Consequently, indoor air pollution is becoming a growing concern for households and businesses alike.

In fact, it has been proven that people who live or work in homes or buildings with poor air quality often experience Sick Building Syndrome (SBS), a condition in which occupants of a building experience acute health problems directly linked to time spent in that space. SBS symptoms include headaches, dizziness, nausea, fatigue, itchy and watery eyes, nose or throat irritation, dry cough, dry or itchy skin, difficulty concentrating, allergies, cold, flu-like symptoms, increased incidence of asthma attacks and mood swings.

The cause of the symptoms has yet to be proven, but it is suspected that dust, mould and bacteria that collect and breed in air duct systems and are redistributed into homes or buildings are responsible and need further investigation. Additionally, when moisture is present, the potential for mould growth increases, and the resulting spores are released into living or working spaces. What is certain is that these symptoms reduce work efficiency and increase absenteeism. Most people suffering from SBS report relief soon after leaving the building. Surprisingly, such problems are not limited to industrial buildings. Dust and particles in the air throughout your house can cause the same symptoms. People with respiratory problems or weak immune systems may find themselves getting sick more frequently.

The good news is that this problem can be fixed. A duct cleaning professional can rid your home of undesirable airborne particles and restore air quality to healthy standards. Duct cleaning generally refers to the cleaning of various heating and cooling system components, including supply and return air ducts and registers, grilles and diffusers, heat exchangers, heating and cooling coils, condensate drain pans, plenums, fan motor and fan housing, and air handling unit housing. When these components are not properly installed, maintained, or operated, they can become contaminated with an array of pollutants and contaminants and turn into a fertile breeding ground for mould. Exposed to them, some of these contaminants may cause many of the symptoms mentioned above.

What to do next

Once you decide to have your heating and cooling system cleaned, look for a duct cleaning company that is qualified and willing to clean each and every component of your system. When it comes to duct cleaning, no step can be skipped, and the pollutants or contaminants that accumulate in your duct system need to be eradicated 100 %, otherwise you risk re-contamination of the entire system. Most air duct cleaning companies recommend that you have the cleaning procedure done once every three years, particularly if you own a HVAC duct system since they are more likely to clog quickly with mildew and mud during seasons when they are not in use. Neglecting required duct cleaning can lead to problems that are best avoided.

Methods used

Different providers use different cleaning methods, although certain standards have been established by industry associations such as the National Air Duct Cleaners Association (NADCA). Typically, a service provider uses specialized tools to dislodge and then extract dirt and other debris in ducts, then vacuum them out with a high-powered vacuum cleaner.

Heads up

As they are hidden above ceilings or beneath floorboards, heating and cooling ducts are often overlooked for maintenance and cleaning, especially in homes. Heating and cooling ducts are the perfect breeding ground for germs and bacteria. Health experts now believe that fungi and bacteria in air duct systems account for approximately one in six people suffering allergies. A number of illnesses, such as Legionnaire´s disease, asthma, hypersensitivity pneumonitis, and humidifier fever, have been directly traced to poor maintenance of duct systems. However, there are other considerations for having air ducts properly cleaned. In most industrial buildings, dust and dirt in the heating or cooling system are a primary cause of system break-down. Proper cleaning helps eliminate breakdowns and avoid unscheduled repairs. A clean system can also benefit home owners as they can reduce heating and cooling costs by up to 20%.

What to look for in a duct cleaning company

As mentioned above, when looking for a professional air duct cleaning company, the first consideration is a company qualified and willing to clean each component of the heating or cooling duct system in order to avoid re-contamination. The second thing to be aware of is that there are different types of air duct designs requiring different cleaning procedures and products. Duct design is a critical part of the air duct system. There are primarily four major types of ductwork that distribute and intake air in a Heating Venting and Air Conditioning (HVAC) system. The trunk and branch method, the radial method, the spider method and the perimeter loop all perform this task in different ways, and usually correspond to a particular building type.

Look for an air duct cleaning service that is both affiliated with an HVAC contractor and belongs to a trade association, such as the National Air Duct Cleaning Association (NADCA). Choosing a NADCA member to perform the work will ensure that your facility receives a thorough source removal cleaning in accordance with the association’s mandatory performance standard. They should be able to maintain, repair, clean or replace various heating and cooling system components, including the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils, condensate drain pans, plenums, fan motor and fan housing, and the air handling unit housing. These types of contractors will most likely fine tune and service all parts of your air duct system.

Also, make sure your service provider is licensed and insured. This will guaranty that the technicians have been properly trained to perform the work you need done and that, in the unlikely event something goes wrong, the business has insurance to protect damage to your property. An unlicensed contractor may quote you a lower price to service your heating and air conditioning system, but you’ll end up paying many times over if the job turns into disaster and there is no coverage for damages to your home.

Avoid flashy advertising and special offers that are too good to be true. There are standard costs usually based on the size and type of duct system. Other variants may include the accessibility to the system, the timeframe and the level of contamination and whether you are dealing with a commercial or private duct system.  If the service provider charges by the hour, request an estimate of the number of hours or days the job will take. Make sure the duct cleaner you choose will provide a written agreement outlining the total cost and scope of the job before work begins.

Make sure that any chemicals used in the cleaning process are EPA registered for the intended application. You may also request a Material Safety Data Sheet (MSDS). Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs), and fungi (mould) and prevent future biological growth. Be wary of any service provider who wants to apply a disinfectant or biocide to the entire system by spraying or fogging the ducts after completion of work. Under Canada’s Pest Control Products Act, no such products have been registered or approved for duct cleaning purposes. Current research shows that broadcast spraying of biocide products in a home is unacceptable.

Heads up

Be careful when picking an air duct cleaning company, and never let price influence your decision. Search the Internet for relevant information about air duct cleaning companies that work in your region. A lot of information to help guide your decision can be found on the EPA Website (www.epa.gov). Also, always look for a company that only hires properly trained technicians. Hiring someone with little training or experience can be costly and lead to other problems. Each home is different and each ductwork system is unique. It takes years of training and experience to have the know-how to perform a thorough cleaning job. Do not trust companies that recommend services that you don’t need. Not every air duct system needs to be cleaned. Some degree of dust and dirt is normal. Be concerned if there is excessive dust and dirt or other more harmful contaminants.

Knowing when to clean your ducts

Research has yet to prove the potential benefits of air duct cleaning, and although it has been somewhat linked to indoor air quality, the jury is still out on the importance of duct cleaning. There are however certain times and situations where duct cleaning should be given serious consideration. The objective of this article is to provide certain indicators for having home ducts professionally cleaned. One thing is certain; you should always contact an honest and reputable air duct cleaning company before making your decision. Your air duct system may seem dirty at first glance, but it doesn´t necessarily mean it needs to be cleaned. A certain amount of dust and particles is normal and will not necessarily affect interior air quality.  

Remember that when it comes to indoor air quality, your five senses and general health are the best tools in determining whether you have problem or not. If no one in your household suffers from allergies, unexplained symptoms or illnesses; if you do not detect a mould or mildew smell or haven´t noticed large quantities of dust or mould, there is no real reason for having your air ducts cleaned. There are however certain cases where air duct cleaning should be considered:

Presence of mould: Your visual inspection has revealed large deposits of mould or mildew on the sheet metal inside your ducts or on other components of your heating and cooling system.

Clogged ducts: Without proper cleaning, air ducts can become overrun with dander, dust, and other allergens and spread them throughout the home or building. Not only does this decrease indoor air quality, but the HVAC system needs to work harder in order to maintain the level of comfort inside the building. As a result, energy bills rise and companies end up spending more to run the system than it would cost to clean it. Clogged air ducts can also prove a safety hazard in cases of fire.

Rodents and insects: This is one of the cases where duct cleaning should be a priority. If insects or rodents have taken residence in your ducts, you need to act fast. Fecal matter and other potentially harmful microorganisms and material will be blown into the living space and cause serious health hazards.

Energy savings: Most air heating and cooling systems fail or breakdown due to a lack of effective duct maintenance. Costs for repairing heating or cooling systems can be quite expensive and total replacement can cost thousands of dollars.

Purchasing or moving into a new home: If you have recently purchased a previously owned home, you should consider having your air duct system cleaned. Since you don´t know the lifestyle of the previous occupants, you shouldn´t take any chances. Additionally, foreclosed homes may have idled for a long period, allowing time for bacterial growth to occur inside the ducting.

Bad odours: If you have noticed a musty or mouldy smell, there is a good chance that mould has already contaminated your air ducts and air fresheners won’t solve the problem. Professional air duct cleaning can remove bad odours with great success in a very short time.

Home improvements: Room additions, removing walls and making major changes inside a home can create drywall dust, fibreglass pieces, and sawdust and other construction debris that can restrict air flow. It also can stir up major amounts of dust and particles that get into the ducts. A thorough cleaning afterwards removes debris.

Heads up

Along with considerations mentioned above, you may want to have your air ducts cleaned simply as a precaution. Like any other system in your home or office, air ducts get dirty over time and should occasionally be cleaned. Although the negative impacts of neglecting air duct cleaning have yet to be proven, no evidence suggests that such cleaning would be detrimental. Indeed, ducts left unattended for long periods of time present risks to office personnel or household occupants. It is important to remember that duct systems are first and foremost air distributors, which can serve as a vehicle to distribute all sorts of contaminants. The important thing however is not to overreact in the presence of small quantities of dust and dirt. Remember that a small amount of dust in air ducts is quite normal and not necessarily a cause for alarm. Again, although research continues to evaluate the potential benefits of air duct cleaning, there certainly is no harm in keeping your air ducts clean.

Cleaning air ducts yourself

You have inspected your air duct system and are not too thrilled by your discoveries. You decide that a good cleaning is in order and you wish to do it yourself. Regardless of your reasons (distrustful of duct cleaning companies, budget, challenge, etc.) you need to understand exactly what is meant by air duct cleaning and the scope of such an operation. First, cleaning air ducts means cleaning an entire system of cooling and heating components. This includes all the components of forced air systems such as air supply and air return ducts, registers, grills, diffusers, cooling coils, heat exchangers as well as drip pans, and housing units. The list may seem long, but you need to know exactly what you are getting into so that things are done right. Never forget that when it comes to duct cleaning, no step can be skipped, and the pollutants or contaminants that accumulate in your duct system need to be eradicated 100 %, otherwise you risk re-contamination of the entire system.

Getting started

Like any other home improvement operation, you need to get the right tools before you begin. Here are the essentials:

  • Protective gloves and mask
  • Bucket of water
  • Rags and towels
  • Mop
  • Vacuum cleaner with hose attachment
  • Duct tape
  • Broomstick
  • Long handled brush
  • Sturdy ladder
  • Screwdriver


  1. Before the ducts are cleaned, each heat vent in the home is covered with a plastic bag. This barrier will protect the home from any dust stirred up during the cleaning process and will also provide a visual cue to see that there is proper suction to the duct cleaning machine.
  2. Air ducts with openings in walls, floors and ceiling of your home have vent covers, return-air grilles or registers on them. First, remove the air duct cover plates using a ladder when necessary and check the walls inside to make sure there aren’t any unexpected surprises such as dead rodents or accumulated mould.
  3. Cleaning registers is important, as they act as filters that trap allergens and other contaminants. Place the registers on a newspaper that is spread on the floor. Soak the rag or towel in a household cleaning solution of hot water and detergent, and clean the dirt off the grille or the registers. Let them dry in the sunlight to get rid of all traces of moisture. Immediately dispose of the newspaper.
  4. Use the vacuum cleaner, hose and brush to clean the actual air ducts. When this is done, wet a sponge with the household cleaning solution and clean the inside of the air duct. Reach your arms as far as possible inside the air duct. Don’t forget to wear gloves. Hand gloves prevent injuries usually caused by razor-sharp sides or even screws present within the duct function. Repeat the entire process with each vent and ductwork section. Once all of the filters and vent covers are back in place, flip the breaker back on, turn on your central air conditioning unit and allow the fan to run for at least an hour.
  5. Put all vents and fastening devices back in place and tighten any screws with the screw driver. If you are cleaning the ducts that go to your air/heat system you should also replace any filters at this time.

Heads up

One of the major reasons you should hire a professional air duct cleaning company is the equipment they have. Indeed, professionals have the necessary hardware to efficiently remove debris without making a mess in the process. While basic cleaning operations are easy enough to do, if you want to make sure they are done right, your best bet is dealing with a specialist. They have the knowledge and equipment to do a thorough job in a reasonable amount of time. Most serious air duct cleaning companies are equipped with powerful vacuuming machines that suck debris out of the ducts while keeping it from being blown throughout the home. They have powerful tools to remove pet hair, dander, dust, rodent droppings and other small garbage that fall into the vents.

Air duct cleaning – FAQ

Do I need to clean my air ducts if my home is brand new?

Surprisingly, yes. Construction debris is one of the most common types of contamination that we find in air duct systems. Fine particles, such as drywall dust or sawdust, as well as other materials can make their way into your system when the construction crews are cleaning up. The only way to thoroughly remove all of these pollutants from your system is through professional cleaning.

What are the health benefits to having this service performed?

Dust, fungi and bacteria have been shown to collect in the ventilation system. These contaminants are widely believed to be potentially harmful to your health, possibly irritating or triggering certain allergies. The removal of these contaminants from your HVAC system should be viewed as one step in improving the overall quality of air in your home.

Will having my air ducts cleaned reduce my energy bills?

Dirt and debris may collect in your ventilation system, blocking ductwork and key components of the furnace, including the evaporator coil and blower. Build-up of these contaminants in the furnace can restrict airflow, causing your system to work harder and longer, thus requiring more energy. By cleaning the entire HVAC system, you may not only see an increase in system efficiency (and thus lower energy bills), you can also extend the life of your furnace or air conditioning system by reducing wear and tear.

How frequently should air ducts be cleaned?

There are a number of factors that affect how long your HVAC system can go between cleaning, including the type of floor coverings in the home, how often these floor coverings are vacuumed, the type of filters used in the HVAC system, the presence of pets, etc. The general rule of thumb is to have the system thoroughly cleaned every 2 to 3 years.

How long does it take to clean an average ventilation system?

On average, it takes approximately two hours to clean a ventilation system with a single air-handling unit. This time can vary based on the size of the ventilation system, the number of air-handling units in your home, the number of vents and the condition of the system.

How do I know if my system needs to be cleaned?

There are some basic questions you can ask yourself that will help you determine whether or not you should have your air ducts professionally cleaned. Here are a few examples:

-Do you have smokers in the house? And if so, how many of them smoke on a regular basis?
-Do you have pets?
-Have you noticed dust trails coming out of your registers?
-Are you constantly dusting bookshelves, furniture with little or no result?
-Does anyone in your family suffer from the following symptoms: headaches, dizziness, nausea, fatigue, itchy and watery eyes, nose or throat irritation, dry cough, dry or itching skin, difficulty concentrating, allergies, cold, flu-like symptoms, increased incidence of asthma attacks and mood swings?
-As it been more than 3 years since your last air duct cleaning?
-Are you having problems with furnace airflow?
-Have you recently moved into a new home?

If you answered yes to any of these questions, then it may be time for you to consider having your air duct system professionally cleaned!

How long does an air duct cleaning take?

The length of time it takes to clean out your air ducts will depend on a number of factors. The ducts in most average sized houses can be done in four to eight hours, but complicating factors like difficult to reach areas and a large amount of debris can certainly add time to the process.

How often do my air ducts need to be cleaned?

There’s no industry recognized standard for how often your air ducts need to be cleaned. Except in extreme circumstances, there is no reason your ducts would need to be cleaned more than once a year. In fact, many people can easily go two years between cleanings, especially if they take other precautions to prevent debris from getting into the ducts to begin with. The best thing to do is to sit down with a reputable duct cleaning professional and establish a cleaning schedule suitable for your home.

Can I clean my air ducts myself?

There are certainly things you can do to help your air ducts function properly. Changing your air filters regularly and cleaning off the grills at the end of the air ducts are good steps to take in this regard. But because so much of your air duct system is difficult to reach, you will never be able to do a thorough job on your own. Professional duct cleaners have specialized equipment that allows them to inspect and clean even the hardest to reach places in your air duct system. Because of this, it’s a good idea to have a professional come in from time to time to complete a thorough cleaning in addition to whatever you are able to do on your own.

Will HVAC system cleaning reduce our home energy bills?

Research by the U.S. EPA has shown that HVAC system cleaning allow systems to run more efficiently. Thus, they are less likely to break down, have a longer life span, and result in energy savings for homeowners. When HVAC system components become clogged with dust, dirt or debris, they need to work harder to reach set temperatures, which results in hundreds of dollars on heating and cooling bills.

Is it true that indoor air is dirtier than outdoor air?

According to the EPA, there is a growing body of scientific evidence indicating that the air within homes and other buildings can be more polluted than the outdoor air in even the largest and most industrialized cities. There have been studies showing that the levels of indoor pollutants can be up to 60% higher than the levels of outdoor toxins. These interior impurity levels can even get up to one hundred times higher than the outdoor levels.

Are there health benefits to air duct cleaning?

While the EPA says that duct cleaning has never been shown to actually prevent health problems, removing the contaminants commonly found in homes’ HVAC systems (including mould, fungi and bacteria) certainly will help protect your family’s health. The furnace and air ducts act as a home’s ‘respiratory system’. If the system becomes congested with contaminants and debris, air quality may be compromised and the system won’t be able to breathe and function properly. When it comes to air quality, there is no doubt that a clean HVAC system is better than a dirty one.

What are the sources of air duct contamination?

All indoor air was once outside air, so all of the dust, chemicals, pollen, insects and mould spores in the outside air can be pulled into the air system. People shed millions of tiny dead skin cells every hour. Cooking smoke, household insect sprays, personal care products are also a source of pollutants. Many construction materials, carpets, wood products and plastics give off pollutants as well. During construction or remodelling activities, many types of dust are produced and find their way into the duct work. If the duct components were stored outside prior to construction, they may have collected dust, rain water and even mould before they were installed in a system.

See how Steamatic Canada is changing lives

The workers Luc, Tommy, David and Maxime were polite, helpful and efficient and the work well done.

Mrs Laursen - Steamatic Vaudreuil-Salaberry