Choosing a Contractor
Hire a licensed contractor that specializes in mold remediation or duct cleaning if you have air pollution problems, such as a buildup of allergens in your duct system. Proper duct cleaning should take several hours and involve extensive preparation to ensure that mold spores are not being released inside the home.
Do not hire unlicensed contractors who claim that they can clean your ducts in an hour or two or who tell you that your ducts should be cleaned yearly. Properly working ducts should not require regular maintenance and should not be cleaned unless there appears to be a problem in the home.
Have your contractor place your entire duct system and home under negative pressure. The contractor uses a powerful vacuum as he cleans your ducts with brushes and cleaners.
Any debris removed will be sucked into the vacuum hoses and out of your home. Your contractor may vent the debris outside of your home or use a HEPA filter to trap the debris inside the vacuum unit for later disposal.
Sealants and Sanitizers
Consult the North American Insulation Manufacturers Association, the Environmental Protection Agency or the Sheet Metal and Air Conditioning Contractors' National Association for information regarding the use of sealants and sanitizers on your duct work. It is not recommended that you use these products on fiberglass or other porous surfaces, though you may be able to use them on bare metal ducts.
Because particles can become dislodged after being sealed, and because of the possibility of missing areas when sealing ducts, it is best to have a professional decide when and if to use these products on your duct work.