In order to maintain acceptable indoor air quality levels, it is commonly recommended that mold, fungi, dust and other contaminants be cleaned out of the heating, ventilation and air-conditioning (HVAC) system. Cleaning HVAC systems provides many benefits. It lessens the likelihood of indoor air pollution in the building and may help to alleviate health and comfort complaints by occupants. In addition, clean HVAC systems can save customers money as they perform more efficiently, decreasing energy costs, and, most important, well-maintained mechanical components are more likely to last longer, reducing the need for costly HVAC system replacement or repairs.

Prior to the start of any cleaning, however, a thorough inspection of the system should be performed by a properly trained and certified HVAC inspector. This inspection will determine if a system needs cleaning and, if so, it will help to pinpoint what areas need particular attention. An inspection can also alert facilities managers to physical degradation of key HVAC system components and, the information gained can allow a facility manager to establish benchmarks that illustrate the HVAC system’s cleanliness and how it has been maintained.

What is the best way to clean a system?
If it is determined that the system needs cleaning, a specification should be drawn up detailing the work that is to be performed and the methods by which it will be completed. Until 1989, there were no industry guidelines setting forth the most effective methods for cleaning, but that changed with the formation of the National Air Duct Cleaners Association (NADCA). The organization creates standards and guidelines, but does not endorse or recommend any single method of cleaning or type of equipment. Rather, NADCA recommends the use of source-removal methods and equipment designed to clean HVAC systems according to Standard ACR 2002.

One factor that often dictates the type of cleaning methods to employ is the region or climate in which the project occurs. Regions with high humidity levels often see greater levels of microbial contamination, which can require more aggressive cleaning techniques.

Another factor is the type of ductwork found within the system. Less abrasive techniques such as contact vacuuming are used on fiberglass-lined or flexible ductwork, while air whips and brushes are generally used on standard, sheet-metal ductwork.

Selecting the HVAC cleaning method to be employed on any given project is an important factor toward the successful completion of the job. In some cases, customers may wish to specify the use of specific methods and/or equipment. However, it is often better for the contractor — an expert in HVAC cleaning — to choose the methods and equipment. The customers can negotiate an expected level of cleaning as well as a verification method.

Regardless of what cleaning methods or equipment are used, there is no guarantee or proof of success without some form of cleanliness verification. NADCA Standard ACR 2002 defines three separate cleanliness verification methods: Visual Inspection, Surface Comparison Testing and the NADCA Vacuum Test. At least one of these methods can be incorporated into any project specification.

Rick Crickenberger is president of the National Air Duct Cleaners Association. His company, Dusty Ducts, has been a member of the association since 1991.

Are You The Right Contractor For The Job?
With growing awareness of the dangers of indoor air pollution, public concern for the cleanliness of ventilation systems has led to a significant increase in demand for HVAC system cleaning services. However, because of this demand increase, a large number of unqualified or poorly trained individuals have entered into the industry.

Reputable duct-cleaning contractors should be able to provide their clients and the occupants of the facility to be cleaned with a clear understanding of the work to be undertaken and demonstrate that the project will be well managed.

Building service contractors should be prepared to answer the following questions to be able to let their clients know they’re the right firm for the job.

1) How long has your firm been cleaning HVAC systems?

2) What percentage of your business is dedicated to HVAC system cleaning?

3) Is your firm properly licensed to do work in your state?

4) Is your firm fully insured? Discuss liability insurance requirements if necessary.

5) What is your firm’s experience in cleaning systems similar to those in the client’s facility?

6) Does your firm have references of completed similar projects?

7) Who will be the on-site supervisor responsible for this project and what is the number of projects of a similar scope has he or she been responsible for?

8) Does your firm have a comprehensive in-house safety program with training for employees?

9) Is your firm knowledgeable about site-preparation issues for a project of this scope?

10) Is your firm’s equipment in good repair and working order?

A client may also ask you questions regarding the National Air Duct Cleaners Association (NADCA): if your firm is a Certified Regular Member; your familiarity of the Standard ACR 2002; and if a NADCA certified Air System Cleaning Specialist will oversee the project.