If not properly installed, maintained, and operated, heating and cooling system components may become contaminated with particles of dust, pollen or other debris. Today duct cleaning has become a major industry.
faced with the importance of indoor air quality, people are looking at air duct cleaning as a way to solve indoor air quality problems. Is air duct cleaning a solution?
Heating and cooling system components can become contaminated with pollen, dust, mold, and other debris if not properly installed and maintained. These contaminants may cause allergic reactions in some sensitive people.
What is duct cleaning?
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.
If not properly installed, maintained, and operated, these components may become contaminated with particles of dust, pollen or other debris. If moisture is present, the potential for microbiological growth (e.g., mold) is increased and spores from such growth may be released into the properties living space. Some of these contaminants may cause allergic reactions or other symptoms in people if they are exposed to them.
If the housekeepers decide to have heating and cooling system cleaned, it is important to make sure the cleaners should clean all components of the system and is qualified to do so. Failure to clean a component of a contaminated system can result in re-contamination of the entire system, thus negating any potential benefits. Methods of duct cleaning vary, although industry associations concerned have established standards with air duct cleaning.
Typically, a service provider will use specialised tools to dislodge dirt and other debris in ducts, then vacuum them out with a high-powered vacuum cleaner.
In addition, the service provider may propose applying chemical biocides, designed to kill microbiological contaminants, to the inside of the duct work and to other system components. Some service providers may also suggest applying chemical treatments (sealants or other encapsulants) to encapsulate or cover the inside surfaces of the air ducts and equipment housings because they believe it will control mold growth or prevent the release of dirt particles or fibers from ducts. These practices have yet to be fully researched and the housekeepers should be fully informed before deciding to permit the use of biocides or chemical treatments in the air ducts. They should only be applied, if at all, after the system has been properly cleaned of all visible dust or debris.
Why to clean
One may consider having the air ducts cleaned simply because it seems logical that air ducts will get dirty over time and should occasionally be cleaned. While the debate about the value of periodic duct cleaning continues, no evidence suggests that such cleaning would be detrimental, provided that it is done properly.
On the other hand, if a cleaner fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt, and other contaminants than if one had left the ducts alone. A careless or inadequately trained service provider can damage the ducts or heating and cooling system, possibly increasing the heating and air conditioning costs or forcing to undertake difficult and costly repairs or replacements.
How ducts should be cleaned?
There are various duct cleaning procedures available. Reputable duct cleaners will be familiar with different techniques and their effectiveness. Duct cleaners affiliated with heating and air conditioning firms may be able to provide a more thorough system tune-up. They should also be able to offer references from satisfied customers. Some duct cleaners visually inspect the ducts after their work, either through duct access panels that they cut into the sheet metal or by in-duct cameras. This allows some proof of the effectiveness of the cleaning.
Do not accept offers from duct cleaners to spray or fog the ducts upon completion of the work, ostensibly to get rid of residual bacteria or mold. Registered products, if they existed, would have been tested for effectiveness and human safety. A proper duct cleaning job does not require the use of a biocide to clean up missed areas. Based on current research, broadcast spraying of biocides through hoses is considered inappropriate if you wish to maintain good indoor air quality.
The housekeepers and others should consider having the air ducts in their property cleaned if:
• There is substantial visible mold growth inside 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 heating and cooling systems:
• Many sections of heating and cooling system may not be accessible for a visible inspection, so one should ask the service provider to show any mold they say exists.
• One should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by an expert and may require laboratory analysis for final confirmation. For about Rs. 2500, some microbiology laboratories can tell whether a sample sent to them on a clear strip of sticky household tape is mold or simply a substance that resembles it.
• If one has insulated air ducts and the insulation gets wet or moldy it cannot be effectively cleaned and should be removed and replaced.
• If the conditions causing the mold growth in the first place are not corrected, mold growth will recur.
• 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 premises from supply registers.
Researches suggest that cleaning dirty cooling coils, fans and heat exchangers can improve the efficiency of heating and cooling systems. However, little evidence exists to indicate that simply cleaning the duct system will increase your system’s efficiency.
What Does Duct Cleaning Entail?
Duct cleaning entails cleaning the various heating and cooling system components of forced air systems. These components include 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.
Cleaning heating ducts
A hot air furnace heats and distributes air through its ducting system. The ducts are usually made of sheet metal and are most obvious in basement of the property, where they hang from the floor joists. The return, or cold air, ducts bring air to the furnace, usually collecting it centrally in the premises. The return air trunk duct is the big rectangular duct along the basement ceiling that enters the bottom of the furnace.
The supply, or warm air, ducting usually exits from the top of the furnace. It starts with a trunk duct on the basement ceiling. The individual supply ducts, in round or smaller rectangular sheet metal, branch off the trunk duct and go to each room, where they terminate in a floor or wall register. Over time, dust and debris will collect in these ducts, particularly in the return air ducts. One may be wondering whether it would be worthwhile to have these ducts cleaned.
Some cleaners may apply a chemical biocide to the inside of ducts to kill bacteria (germs), and fungi (mold) and prevent future biological growth. Some service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.
Among the possible problems with biocide and ozone application in air ducts:
Little research has been conducted to demonstrate the effectiveness of most biocides and ozone when used inside ducts. Simply spraying or otherwise introducing these materials into the operating duct system may cause much of the material to be transported through the system and released into other areas of your premises.
Some people may react negatively to the biocide or ozone, causing adverse health reactions.
Use of sealants
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. As with biocides, a sealant is often applied by spraying it into the operating duct system. Laboratory tests indicate that materials introduced in this manner tend not to completely coat the duct surface.