Air duct cleaning is done by heating, ventilation and air conditioning (HVAC) professionals. The pros use industrial-strength, truck-mounted vacuums and powerful brushes and hoses to clean inside the metal ducts that make up your forced air heating and cooling system. The Environmental Protection Agency recommends duct cleaning if there is “substantial visible mold growth inside hard surface ducts, ducts that are infested with vermin such as rodents or insects, or ducts that are clogged with excessive amounts of dust and debris and/or particles are actually released into the home from your supply registers.”
Chemical biocides are regulated by EPA under Federal pesticide law. A product must be registered by EPA for a specific use before it can be legally used for that purpose. The specific use(s) must appear on the pesticide (e.g., biocide) label, along with other important information. It is a violation of federal law to use a pesticide product in any manner inconsistent with the label directions.
Another sketchy claim made by most duct-cleaning operations and their trade association is that dirty ducts and equipment overburden heating and cooling equipment, which wastes energy. Again, it intuitively makes sense that a cleaner system will run smoother and last longer — after all, that’s why we and HVAC-equipment manufacturers and repair services recommend that you regularly change your filters. But the page “Benefits of HVAC Cleaning” on the National Air Duct Cleaners Association (NADCA) website stretches this benefit too far by stating: “According to the U.S. Department of Energy, 25 to 40 percent of the energy used for heating and cooling a home is wasted.”
I was hesitant to have him do that for the price he quoted me. It would have been an extra $275+ for additional cleaning!! I certainly wasn't prepared for that, so I declined the offer. After his assistant started to use the shop vac to get some debris out of the vents, he came back in and said he was just on the phone with the office and he can lower the price of the additional service for me. He wrote up an estimate for me and said that I could call him if I'd like to do the service.
They arrived within the time range I was given, and they even called about 20-30 minutes before arrival, so that was appreciated. They arrived and started bringing some equipment - A shop vac (yea, like you can buy at any hardware store), a handheld vacuum cleaner, and large vacuum that came in on wheels. After showing them the locations of all of the vents in the home and cold air returns, the technician (Simon) started going over a few things with me about their plan for cleaning and showing me the dust & dog hair build up in one of the vents. After showing me that, he started to try to up-sell me on additional services. That additional service was to insert a 'brush' that would agitate the dust/pet hair and allow for the vacuum to get everything out of the vents.
If you think duct cleaning might be a good idea for your home, but you are not sure, talk to a professional. The company that services your heating and cooling system may be a good source of advice. You may also want to contact professional duct cleaning service providers and ask them about the services they provide. Remember, they are trying to sell you a service, so ask questions and insist on complete and knowledgeable answers.
Air duct cleaning service providers may tell you that they need to apply chemical biocide to the inside of your ducts as a means to kill bacteria (germs) and fungi (mold) and prevent future biological growth. They may also propose the application of a "sealant" to prevent dust and dirt particles from being released into the air or to seal air leaks. You should fully understand the pros and cons of permitting application of chemical biocides or sealants. While the targeted use of chemical biocides and sealants may be appropriate under specific circumstances, research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by EPA for use in internally-insulated air duct systems (see Should chemical biocides be applied to the inside of air ducts?).