Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts or go down after cleaning. This is because much of the dirt that may accumulate inside air ducts adheres to duct surfaces and does not necessarily enter the living space. It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoors and indoor activities such as cooking, cleaning, smoking, or just moving around can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to health.
It’s 11 years plus in the industry I have only had to sanitize two systems both were slab systems that were in concrete and could be cleaned with a different method than normal duct cleaning. We were able to use water to rinse out the disinfectant. Would you use a chemical on anything else you use to eat or drink with and not rinse it off? The ducts in your home should be thought of as your homes heart and lungs and breathe the same air that you do. And just like us we wouldn’t use bad chemicals in our lungs and heart.

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts or go down after cleaning. This is because much of the dirt that may accumulate inside air ducts adheres to duct surfaces and does not necessarily enter the living space. It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoors and indoor activities such as cooking, cleaning, smoking, or just moving around can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to health.
What about ringworm? If the fungus is as contagious as doctors warn, and the spores can live several months, doesn’t it make sense to spray some sort of fungus killer into the HVAC system to kill the spores that it has sucked in from the air? Duct cleaning would not be helpful at all here; these spores are microscopic and it could actually spread them further. But given how severely contagious ringworm is, body and especially scalp, does anyone make an aerosol product that will clean the system and kill the fungus? One the resident can use, not call an HVAC company; you can’t do that when you are in an apartment. I hear it’s not the same as mold, it is much more difficult. Truth?
There is a lot of good, general information in the article. As with anything, the homeowner should do their due diligence in getting enough information to make an educated decision. Should duct-work be cleaned? YES! Does it need to be cleaned annually or even every second or third year? Not necessarily. It all depends on a bunch of variables. You're right that a well designed and balanced system will deliver the right amount of air flow, but sometimes conditions outside the home/business, make it a necessity to get the ducts cleaned. As for mold? NO filter is going to address a mold issue. If you have mold, you have a moisture issue that needs to be addressed. Also, in my 38 years of experience in the HVAC and sheet metal industries, washable filters are one of the reasons ducts need to be cleaned. They are no where near efficient in cleaning/filtering the air to the level that they should.
Despite Bergendahl's experience, Vinick says NADCA's certification standards have improved the situation. "A lot of [service companies] weren't going about it the correct way," he says. “We have an anti-fraud task force, and we’ve gone after some fraudulent duct cleaners with the help of state attorneys general.” He suggests that in addition to NADCA membership, homeowners make sure their cleaners are an established business, have appropriate insurance and are registered to do business in their state and locality.
A house breathes just like you an I.For example every time your clothes dryer comes on it automatically creates a negative pressure inside the home.So if air goes out of the living area it has to be replaced.....now look above the ceiling fan ....you see the cover...underneath that is a hole straight to your attic....Now the stuff on your ceiling fan you call dust...call it insulation,rat fecies or anything else that is in your attic that could be pulled in your due to a negative pressure.
Duct cleaning generally refers to the cleaning of various heating and cooling system components of forced air systems, including the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils, condensate drain pans (drip pans), fan motor and fan housing, and the air handling unit housing (See diagram).
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