The Ultimate Guide to Air Duct Cleaning- Know More About It!


Air duct cleaning is critical to maintaining indoor air quality and maximum efficiency of the HVAC system. According to the Environment Protection Agency, indoor air is two to five times more polluted than outdoor air. 

Air impurities recirculate via the air ducts every time the heating system is on. Such contamination compromises indoor air quality. This guide answers all your questions about air duct cleaning.

What Is Duct Cleaning?

Duct cleaning is the process of cleaning the heating and cooling system components, including the supply and returns, grilles, heat exchangers, diffusers, fan motor, housing, and condensate drain pans. 

The components accumulate dust over time hence the need for professional cleaning. They may also develop microbiological growth if some parts get moisture. Spores from such growths can be released into a home’s living space leading to allergic reactions and respiratory issues.

How Effective Is Air Duct Cleaning?

The primary objective of air duct cleaning is to keep the HVAC system clean and clog-free while keeping a home free of pollutants. A study to determine the effectiveness of vent cleaning in improving indoor air quality was conducted on eight homes using three methods: contact method, air sweep method, and rotary brush method.

At the end of the study, the researchers found that particle count readings were higher during the cleaning process than before and after cleaning. This finding results from dirt particles and other pollutants becoming more airborne during disturbances caused by the cleaning process.

However, the particle count readings significantly reduced a day or two after cleaning. Beyond improving indoor air quality and cleaning HVAC parts, duct cleaning allows professionals to identify air leaks in the ductwork. Leaks and tears allow pollutants to enter the heating system and compromise its ability to heat and cool homes effectively.  

How Necessary Is Air Duct Cleaning?

While home ventilation cleaning is associated with potential health benefits, no independent organization can substantiate the claims. The Environment Protection Agency recommends duct cleaning if:

  • The system has developed substantial microbial growth inside the hard surface ducts or other heating and cooling system components. The service provider should provide evidence of the mold growth before starting the cleaning process. 
  • The vents get clogged with large amounts of dust and debris.
  • The system is infested with rodents or insects.

The EPA argues that households have different living conditions making it difficult to conclude that duct cleaning is essential. If the occupants don’t have allergies, duct cleaning might not be necessary, especially if there’s no indication of dirty ducts. 

In addition, dirt particles and pollutants enter a home from outdoor and indoor activities like cleaning, cooking, and exposing a living space more to contaminants than dirty air ducts. Also, there’s no evidence that household dust accumulating in air ducts can cause health problems.

Although return registers become dusty over time, it doesn’t mean that the air ducts have heavy dust deposits. Professionals can vacuum them separately without interfering with the air ducts. As such, air duct cleaning should be part of occasional HVAC cleaning, i.e., because air ducts are dirty, not to prevent health problems.

What Are the Advantages of Air Duct Cleaning?

Some benefits of duct cleaning include:

Improved Air Quality

Activities like smoking and cooking generate air pollutants and contaminants, which are pulled into the HVAC system, accumulating on the ducts.  

The National Air Duct Cleaners Association estimates that dirty air ducts recirculate contaminants and air pollutants five to seven times daily. Duct cleaning removes the dirt particles helping the HVAC system to circulate clean air. 

Reduced Allergies

Duct cleaning is essential during spring because of the increased allergens and pollen in the air. During winter, mold, pet dander, rodents, and insects may have lodged in the ducts, wreaking havoc.

As a result, people with airborne allergies develop breathing problems due to reduced indoor air quality. Duct cleaning helps remove such pollutants, improving the air quality in your home.

Energy Savings

According to ENERGY STAR, 20% of cool air circulating through an HVAC system is lost through the duct system due to dirty and poorly connected ducts, leaks, and holes. As a result, the air conditioning system becomes inefficient, leading to high utility bills. 

Also, the heating and cooling system works harder, shortening its life. Duct cleaning, among other repair efforts like proper duct installation, keeps the system efficient.

Reduced Odor

Mold growth in the ductwork causes unpleasant odors every time the HVAC operates. Rodents living in the HVAC system may also leave droppings and sometimes die inside the equipment. Professional duct cleaners identify all such problems when taking the components apart, removing the pollutants causing the foul odor. 

How Do I Know If My Air Ducts Need to Be Cleaned?

We had highlighted conditions necessary for duct cleaning, but we explain them in detail in this section:

Substantial Mold Growth

The central air system may develop condensation during the warm season leading to mold growth in the ductwork. Mold growth in the air ducts is challenging to identify visually, hence the need to engage an expert. Air duct cleaning technicians can quickly identify and remediate the mold problem and implement measures to prevent its return.

Rodent Infestation

Mice and insects lodge into your air ducts, causing problems. They leave droppings and fecal spores along the ducts contaminating the air quality. Rodents are also notorious for destroying ductwork and can quickly access other parts of the HVAC system.

Some telltale signs of rodents in ductwork are a foul odor, droppings, and damaged pipes.

Dusty Surfaces

If your home still has a layer of dirt even after thoroughly cleaning the surfaces, the ducts probably need to be cleaned. Some vents are so dirty; you might notice dust coming out of the HVAC system when it’s in operation. 

A quick glimpse of the air supply and return vents should tell you if the ducts need cleaning. Besides cleaning the ductwork, you may need to replace the air filters. They trap dust before entering the airway causing the air conditioning to circulate dirt particles.

Changing Filters Frequently

Your furnace filters should be changed out quarterly to maintain a healthy HVAC system. When you start to change out your filters more frequently, it is usually a good sign that your air ducts need to be cleaned. 

Rising Energy Costs

The ductwork may accumulate lots of dirt, clogging the HVAC system. As a result, the air conditioner and furnace work harder to maintain the desired temperature. The additional energy required to run the AC translates into high energy bills.

The HVAC system may also deliver varying temperature levels in some parts of the home. Such temperature fluctuations also lead to high utility bills. 

Renovation or Construction

The ductwork may also accumulate dirt after a major renovation or construction. Unless the HVAC is covered and switched off, it’s bound to get dirty. Construction dirt often contains particulate matter, likely to cause respiratory problems if the air ducts aren’t cleaned. Drywall dust is the number one culprit! Breathing in this hazardous material is terrible on your respiratory system. If you recently had home construction, hire an air duct cleaning company to inspect your duct work. The chemicals used in drywall compounds are hazardous to your health. 

Uneven Airflow

Ducts are designed to deliver a certain amount of air to a specific space. Any changes in its configuration can disrupt its ability to disperse the correct amount of air. Clogged air ducts change, restrict, and cause uneven airflow.

Does Air Duct Cleaning Increase Heating Efficiency?

The heating system uses a series of ducts to circulate air throughout a home. A dirty home air duct disrupts airflow, impeding the system’s ability to cool or heat a space.

The HVAC system must then work harder, causing it to use more energy to keep a home comfortable.

Residential air duct cleaning removes clogs, dirt, and debris, allowing the equipment to operate normally, thus enhancing energy efficiency.

How Are HVAC Air Ducts Cleaned?

A thorough duct cleaning involves cleaning all the system’s components to avoid re-contamination. Typically, a duct cleaning service uses special tools to dislodge the parts, then vacuums them using powerful vacuum cleaning equipment. Sometimes the ducts are cut to allow tool access and resealed. 

The cleaning process includes the following steps:

  1. Pre-inspection

The professional must inspect the air duct system to assess its condition and determine a suitable cleaning technique. The inspection also helps identify any damaged parts. The technician may repair or replace them at an extra cost.

  1. Air Duct Cleaning

The technician then sets up the vacuum unit to create the negative air pressure that prevents dirt and debris from spreading in the house. The service may use any of the following duct cleaning methods:

Shop-Vac Method

This next method is not ideal in any situation. The vacuum can only clean a few feet down each opening, leaving most ductwork untouched.

Vacuum and Brush Method

Experts use longer hoses and a spinning brush to clean the ducts. The hose pushes through the vent while the brush loosens the debris. The vacuum and brush method is more effective than shop-vac air duct cleaning. The only flaw is that the vacuum might not produce enough suction to lift and pull-out clogged debris.

HEPA Vacuum Method

Duct cleaners using this method utilize a larger duct vacuum equipped with a HEPA air filtration system. The vacuum has a greater suction (2000-5000 cubic feet per minute) to remove heavy debris. 

The technician connects the vacuum to the ductwork. The forced air then flows into the equipment, allowing dirt and debris to flow into the vacuum. The use of HEPA filters prevents dust from re-entering the house.

  1. Final Inspection

The professional must perform another inspection to ensure they have thoroughly cleaned the ducts. Check the system to verify that the parts are clean and tightly fit.

Cooling components like coil fins should be clean, straight, and evenly spaced, while the air vent registers must be firmly reattached to the floors and walls. Ask for before and after pictures to ensure you received a quality cleaning.

How Much do Air Duct Cleaning Services Cost?

HomeAdvisor estimates the cost of air duct cleaning to be $269- $486. Homeowners with larger homes might pay more. The cost varies based on several factors:

  • Inspection:

    This cost is often on top of the cleaning cost. An extra fee may apply if the company uses special equipment, e.g., a camera to inspect the ductwork.

  • The ductwork size:

    It measures the number of vents making the HVAC system or the square footage. The cost may range from $25 to $35 per vent based on the service company.

  • Contamination level:

    If the system needs mold removal, the service company may charge an extra $600-$2000. Such elements need special equipment to remove them, and sometimes a specialist. Make sure the company is a certified remediation company!

  • Accessibility:

    Most homes have entry points in the utility room or basement that allow access to the duct system. If the system is in hard-to-reach areas, the service company charges extra. 

How Long Should Duct Cleaning Take?

Duct cleaning takes two to five hours, depending on the size of the HVAC system and your home, the type of ventilation used, the contamination level and how many employees are on the job. This time frame includes cleaning the blower compartment, the return and supply-side, and the blower wheel.

What Is the Best Machine for Duct Cleaning?

When buying duct cleaning equipment, the vacuum plays a significant role in your decision. Typically, there are two types of vacuum collection devices: portable units and those mounted on trucks. Truck-mounted vacuums are more powerful only if the amount of tubing they use is less than 50 feet. If the truck mount duct cleaning company is using more than this, then they are losing suction power and is no better than a portable vacuum.

Since they are attached to a collection device, waste disposal is easier. Note that a vacuum collection device doesn’t clean the duct system alone. Technicians need other tools to remove debris attached to the surfaces. They include:

  • Air washing tools:

    These include the forward skipper line (used to blow dirt and debris forward), a blowgun for more precise air washing, and a reverse skipper line for blowing dirt backward. They produce high-pressure air through an air compressor to dislodge dirt and debris.

  • Air whipping system:

    It consists of duct ball support assembly, a set of five-foot flexible and non-flexible rods, three or more whip heads, as well as forward and reverse air nozzles. Air whips use high-pressure air generated by the air compressor to thrash the interior of the duct to remove debris.

  • Flexible cable brush system:

    It consists of a 15′ or 25′ flexible cable, silica carbide brushes, and nylon brushes. Silica carbide brushes clean hard surfaces, while nylon brushes work well on any duct surface.

Does Air Duct Cleaning Make a Mess?

Duct cleaning is messy regardless of how cautious a technician is. Preliminary precautions are critical to minimizing the mess involved. Here are some tricks professional’s use:

  • They spread tarps to protect the floor from the vacuum hose connecting the truck and the HVAC system. Some technicians may fit corner guards to protect the wall corners from damage.
  • The professionals cover the vents with magnetic vent covers or adhesive to reduce the dust level when cleaning the ducts. The covers also create extra suction power.
  • Use negative pressure to reduce the blow-back of dirt into the house. It ensures that all the pressure exerted by the tools flows directly toward the vacuum. Vent covers also aid this process by creating more suction and preventing debris from escaping through the vents.

Sometimes debris still escapes even after taking all the precautions. For example, homes with extensions or retrofitting may have new vents installed too close to existing ones. Such unconventional installation may cause dust to escape through the vents when cleaning the vents.

Another scenario that may cause a mess is duct cleaning on a unit that needs high-level cleaning. The dust may be too much for small tools making most of it escape. Also, bent, cheap, or an ill-fitting filter may allow dirt to bypass the filter when cleaning the returns. It enters the supply line, escaping through the supply vents. 

Why Does My House Get So Dusty?

Even after sealing cracks and replacing filters of an HVAC system, your house may still accumulate dust. There are several reasons for the problem: 

  • The ductwork has gaps and openings where air escapes. As a result, air enters the living space without going through the filter, leaving it dusty.
  • There isn’t enough clean air flowing in your home, allowing dirt to settle. Increasing the airflow helps reduce dirt. You can check the thermostat to ensure the fan is on. 
  • Check the registers to ensure they are open. If the registers can’t deliver adequate air, the blower motor might be faulty.

Will Air Duct Cleaning Damage My Air Ducts?

As much duct cleaning improves indoor air quality, it’s invasive and can damage some parts of the duct system. What’s more, some duct types are more prone to damage. Flex ducts and fiberglass ducts are a perfect example of fragile systems likely to get damaged when cleaning.

The system has a spring wrapped with a delicate plastic layer and insulation that blocks heat from getting in or out of the duct. Around the insulation is the vent itself.

If your HVAC is old, the plastic layer has likely become even more fragile due to the heat inside your home’s walls. If you try to clean it, the delicate plastic will break.

The duct cleaning method may also damage the air ducts. Vacuum cleaning, for example, involves a rapid increase or decrease of pressure inside the chimney hence likely to destroy old duct systems. Similarly, brush cleaning can damage the interior of the ducts because it’s incredibly fragile.

Can I Clean My Air Ducts Myself?

Although the internet provides many DIY resources on cleaning air ducts, it’s best to engage a professional. What’s more, the job involves using high-powered vacuum equipment and rotary brushes you might not have a home. You may end up cleaning or damaging some parts, leading to expensive repairs.

What Are the Best Questions to Ask an Air Duct Cleaning Company Before Hiring Them?

Finding a reliable service provider can be an uphill task with many air duct cleaning companies. It’s best to consult at least three service providers and ask for the estimates before hiring one. They should also show the contamination to justify having the air ducts cleaned. Here are some questions you should ask:

  • How long have you been in operation?

    An established company with industry experience is likely to be well-versed in handling any ductwork. The professionals also know the tools and materials required. 

  • What does the quote include?

    The company should explain if it charges services at a by the vent level, or by square foot. Be sure to request a quote showing the cost of all duct cleaning services.

  • What equipment are you using?

    There are different air duct cleaning methods, and some are more effective than others. The service provider should explain the method they intend to use. You must also ensure the company isn’t using chemical biocides, which the EPA (Environmental Protection Agency) doesn’t approve.

  • What other charges should I expect?

    Many factors increase the cost of air duct cleaning service. For example, if a home is a few miles from the company’s service area, has many vents, more than one HVAC system, or the square footage exceeds the threshold, the company may charge extra.

  • Will the technicians check other parts of the system?

    The technician should check other system components because the air ducts work in sync with the furnace and AC. If one part of the system is dirty and the air duct system is not cleaned in isolation, it might cause cross-contamination.