KNOW THE FACTS ABOUT RESIDENTIAL FLEX DUCT CLEANING.

Posted on 2013-02-06 14:31:35

Myth associated with residential flex duct cleaning.

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes or other structures increase because of dirty air ducts. This is because much of the dirt in 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 your health.

You should consider having the air ducts in your home replaced if:

There is substantial visible mold growth present in hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system. There are several important points to understand concerning mold detection in duct systems:

Many sections of your heating and cooling system may not be accessible for a visible inspection, so ask the service provider to show you any mold they say exists. Remember mold like growth does not indicate harmful mold. Some mold growth may be caused by persistent moisture exposed to friendly temperature where humidity is at a certain level.

You should be aware that although a substance may look like mold, a positive determination of whether it is mold can be made only by an expert and may require laboratory analysis for final confirmation. For about $50, some microbiology laboratories can tell you whether a substance sent to them on a clear strip of sticky household tape is mold or just something that resembles it.

If you have insulated air ducts and the insulation gets wet or moldy it should be removed and replaced as it cannot be effectively cleaned. Wet flex duct should always be replaced. If the conditions causing the mold growth in the first place are not corrected, mold growth will recur.

If ducts are infested with vermin (e.g. rodents or insects); or ducts are clogged with excessive amounts of dust and debris and/or particles are actually released into the home from your supply registers the duct section should be replaced.

If any of the conditions identified above exists, it usually suggests one or more underlying causes. Prior to any retrofitting, or replacing of your ducts, the cause or causes must be corrected or else the problem will likely recur.

Some research suggests that cleaning heating and cooling system components (e.g., cooling coils, fans and heat exchangers) may improve the efficiency of your system, resulting in a longer operating life, as well as some energy and maintenance cost savings. However, little evidence exists that cleaning only the ducts will improve the efficiency of the system. You may consider having your air ducts cleaned simply because it seems logical that air ducts will get dirty over time and should be occasionally cleaned. Provided that the cleaning can be done in the first place, no evidence suggests that such cleaning would be detrimental. Industry does not recommend that the air ducts be cleaned routinely, but only as needed. Industry does, however, recommend that if you have a fuel burning furnace, stove or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning. If you decide to have your air ducts cleaned, take the same consumer precautions you normally would in assessing the service provider’s competence and reliability.

Air duct cleaning service providers may tell you that they need to apply a 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 applications 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 system. Whether on not you decide to have the air ducts in your home cleaned, preventing water and dirt from entering the system is the most effective way to prevent contamination.

Rigid flex duct use in residential applications is constructed using an interior lining made out of very thin plastic material. A metal coil is wound over the plastic for strength. Insulation fiber glass covers the plastic and metal assembly. A sheaving material of aluminum foil type material completes the external material of the duct.

The duct is connected to the plenums of the system and forms the air delivery system. The black plastic material seen in the photo is extremely thin and very easily damaged. That any company would advertise flex duct cleaning as being either practical or necessary is beyond common sense. Just peep into your attic witness how the duct is installed with twists and turns, into boxes and wyes and other connections and you would appreciate how ridiculous it is to try cleaning installed flex ducts.


Flex duct showing basic construction.

Any one offering to spray chemicals into your HVAC system is putting the life of your family and yourself at risk. I have not found any chemical writeup on the market specifically designed for cleaning air ducts. I am not comfortable with 805 of persons involved with repairing HVAC units on the basis of trade knowledge. I am literally frightened of persons without knowledge of chemical dangers using chemicals to clean ducts.