Cleaning the air conditioning system is not a complex process, but each job is unique. Whenever possible, access to the interior of ducts should be through existing openings, such as supply diffusers, return grilles, duct end covers, and existing service openings. Cleaning technicians may need to drill access holes in the ducts in order to access the interior with various cleaning tools. The creation of these service openings and their subsequent closure require skill and professional skills.
Moisture can enter the duct system through leaks or if the system has been improperly installed or maintained. Air duct cleaning service providers may suggest that they need to apply a chemical biocide to the inside of the ducts to kill bacteria (germs) and fungi (mold) and prevent future biological growth. This is because much of the dirt in the air ducts adheres to the surfaces of the ducts and does not necessarily enter the living space. On the other hand, if a service provider does not follow proper duct cleaning procedures, it can cause problems with indoor air.
Many modern residential air duct systems are manufactured with fiberglass plates or sheet metal ducts lined on the inside with a fiberglass duct coating. You might consider cleaning your air ducts simply because it seems logical that the air ducts will get dirty over time and that they should be cleaned from time to time. Manufacturers of products marketed to coat and encapsulate duct surfaces claim that these sealants prevent dust and dirt particles inside air ducts from being released into the air. Duct cleaning companies often advertise health benefits or suggest that duct cleaning will reduce energy bills by improving system efficiency.
Whether or not you decide to clean your home's air ducts, it's essential to commit to a good preventive maintenance program to minimize duct contamination. Most organizations that deal with duct cleaning, including the EPA, NADCA, NAIMA, and the National Association of Metal Plate Contractors and Air Conditioning (SMACNA), do not currently recommend the routine use of sealants to encapsulate contaminants in any type of duct. While the EPA states that cleaning the ducts is sufficient to treat mild episodes of mold, serious outgrowths often need to be replaced, especially if the ducts are rusty. In addition, the service provider may propose the application of chemical biocides, designed to remove microbiological contaminants, inside ducts and in other components of the system.
