Frequently Asked Questions

Heating, ventilation, and air conditioning systems, also known as HVAC systems, have been shown to collect mold, fungi, bacteria, and dust particles that could be harmful to health. Getting rid of these contaminants from the HVAC system and home should be considered part of a plan to improve the air quality inside.

The best way to tell if the cleaning of the HVAC system was successful is to look at the system before and after the cleaning. During the visual check, if any dust or debris can be seen, the system should not be considered clean. You can do a visual check on your own with a flashlight and a mirror, but a professional cleaner should be able to give you better access to the system's parts and maybe even let you use special inspection tools. Also, following the steps in the Homeowner's Guide to Cleaning Air Ducts can help make sure the job is done well.

Frequency of cleaning depends on several factors, not the least of which is the preference of the homeowner. Some of the things that may lead a homeowner to consider more frequent cleaning include:

• smokers in the household
• pets that shed high amounts of hair and dander
• water contamination or damage to the home or HVAC system
• residents with allergies or asthma who might benefit from a reduction in the amount of indoor air pollutants in the home’s HVAC system
• after home renovations or remodeling
• prior to occupancy of a new home.

The most effective way to clean air ducts and ventilation systems is to employ source removal methods of cleaning. This requires a contractor to place the system under negative pressure, through the use of a specialized, powerful vacuum. While the vacuum draws air through the system, devices are inserted into the ducts to dislodge any debris that might be stuck to interior surfaces. The debris can then travel down the ducts to the vacuum, which removes it from the system and the home.

Some companies apply antimicrobial chemicals to the interior surface of the air ducts to treat microbial contamination such as fungi (mold), viruses or bacteria. Before any antimicrobial chemicals are used, the system should be thoroughly cleaned. It is critical that any antimicrobial treatment used in your system be registered by the U.S. Environmental Protection Agency specifically for use in HVAC systems. The use of antimicrobial chemicals is an additional service that is not part of a typical air duct cleaning project. 

You should interview as many local contractors as possible. Ask them to come to your home and perform a system inspection and give you a quote. To narrow down your pool of potential contractors, use the following pre-qualifications:

• See if the company has been in business long enough to have adequate experience.
• Get proof that the company is properly licensed and adequately insured.
• Ensure that the company will clean and visually inspect all of the air ducts and related system components.
• Avoid advertisements for “$99 whole house specials” and other sales gimmicks.
• Ask if the company has the right equipment to perform cleaning effectively and if the company has done work in homes similar to yours.
• Get references from neighbors if possible.

You can also use the Homeowner’s Guide to Air Duct Cleaning as part of the contractor selection process.

TAccording to the U.S. Environmental Protection Agency, "duct cleaning services usually cost between $525 and $1,000 per heating and cooling system," but this isn't always the case. It depends on the services offered, the size of the system to be cleaned, how easy it is to get to, where you live, how dirty it is, and what kind of duct material it is. People should be wary of air duct cleaning companies that make broad claims about the health benefits of cleaning ducts because these claims aren't backed up by evidence.

"Here-today and gone-tomorrow" air duct cleaning companies should also be avoided. Most of the time, these companies clean the heating and cooling systems poorly for a small fee. These businesses may also try to get customers to pay for services they don't need, with or without their permission. (If you know of a company that does "blow-and-go" air duct cleaning, you should call your local Better Business Bureau to report the company and your local, state, and federal elected officials to ask for laws to be changed.)

There are two main types of vacuum collection devices: (1) those mounted on trucks and trailers, and (2) portable units. Truck/trailer mounted equipment is generally more powerful than portable equipment. However, portable equipment can often be brought directly into a facility, allowing the vacuum source to be located closer to the ductwork. Both types of equipment will clean to ACR standards. All vacuum units should be attached to a collection device for safe containment prior to disposal. Any vacuum collection device which exhausts indoors must be HEPA filtered. A vacuum collection device alone will not get an HVAC system clean. The use of methods and tools designed to agitate debris adhered to the surfaces within the system, in conjunction with the use of the vacuum collection device(s), is required to clean HVAC systems. (For example: brushes, air whips and “skipper balls.”)

The U.S. Environmental Protection Agency's research has shown that cleaning an HVAC system may make it run more efficiently by removing dirt and dust from sensitive motor parts. Systems that are clean and work well are less likely to break down, last longer, and work better in general than systems that are dirty.