Most HVAC companies will promote duct cleaning as a solution to improve indoor air quality, but they fail to mention that this service can cause significant damage to duct systems that will require repairs in the future. Cleaning air ducts can cause significant damage that can be expensive to repair, as the ducts are made of various materials and you or an unqualified duct cleaner may not know the best way to clean them. You may want to consider cleaning your air ducts simply because it seems logical that the air ducts will get dirty over time and should be cleaned from time to time. The Environmental Protection Agency (EPA) does not recommend that air ducts be cleaned routinely, but only when necessary.
However, they do recommend that if you have a furnace, stove, or fireplace that burns fuel, they be inspected for proper functioning and maintained before each heating season to protect against carbon monoxide poisoning. If you or someone in your family has asthma or allergies, you may be considering cleaning your home's heating and cooling ducts. But even if you don't have special health problems, duct cleaning may appeal to you on an intuitive level. After all, if your ducts are clean, all the air coming out of the vents should also come out clean, right? While duct cleaning operations may insist that duct cleaning is essential to health, the evidence doesn't support their claims.
Companies that perform duct cleaning often advertise health benefits or suggest that duct cleaning will reduce your energy bills by improving the efficiency of your system. Some ads even use language such as: “Studies have shown”, but there is no data to support these claims. Even if your ducts are dirty, cleaning them probably won't provide any measurable benefit. In fact, the little independent research done on duct cleaning indicates that the process removes so much dust that it creates a bigger problem than it solves.
Although it intuitively makes sense to clean the ductwork, after all, the dust is removed and the rest of the house is cleaned, the fact is that the dust that settles in the ventilation system usually remains where it is and is unlikely to be carried through the air unless disturbed. Under most circumstances, dust is inert and harmless, and shaking it with cleaning equipment creates major problems. Little research has been done on the effects of duct cleaning. Government studies in the United States and Canada and health professionals who have researched duct cleaning fail to recommend it against it, but neither do they support it as a routine measure.
Researchers from the EPA and the Canada Mortgage and Housing Corporation (CMHC) used different methodologies. The CMHC study used several duct cleaning services. The companies were not informed that they were part of a study and the researchers did not control the time spent or the methods used. The EPA study prescribed and controlled the methods used in a smaller number of households. While the duct cleaning industry maintains that both studies are flawed, no other research has questioned their findings.
And while the equipment and methods used by duct cleaning companies have changed since these studies were conducted, household air ducts haven't. Changing air filters frequently is the best way to keep dust, allergens, and other particles out of your home. With a newly installed system or a system in a house you just moved to, check the filter once a month to determine how quickly it gets dirty at different times of the year. Most should be replaced every two to three months. Although not always part of their basic cleaning services, many duct cleaning companies often also clean heating and cooling equipment (heat exchangers, cooling coils, condensate drain containers, fan motors, fan blades, and fan housings).
While much of the energy used to power heating and cooling equipment is wasted due to inefficient equipment, poor insulation, leaks around doors and windows, and unsealed ducts; while cleaning and maintaining HVAC equipment has some benefits, those benefits are relatively small and energy waste can be attributed to dirty ducts or equipment. The CMHC researchers found that when duct cleaners also cleaned the fan blades there was a small reduction in airborne particles. Cleaning the fan could also slightly improve the system's energy efficiency. The same goes for evaporator coils inside your home cooling system; evaporator coils cause condensation which dehumidifies air before it circulates through your home. Condensed moisture can cause dust and other particles to adhere and collect on these coils. In addition, cleaning the collection tray (and tray drain nozzle) located below these coils ensures that dirt does not accumulate and enter into your system; it also prevents water from accumulating on and under these coils which can cause mold problems.
Also consider inspecting your duct system for leaks as leaking ducts reduce efficiency and introduce air quality problems. If someone in your household has specific health problems such as allergies or asthma consult your doctor first; it is important to identify the problem so that they can suggest alternatives to cleaning your air ducts. Start by identifying if your air ducts are part of this problem (probably aren't) and if cleaning them will help (probably isn't). If you suspect you have a mold problem either because of visible growth or because of a musty smell that constantly comes from supply grilles then cleaning your air ducts won't do much good if you don't get rid of this mold. Mold starts with a moisture problem and usually isn't caused by air ducts themselves; most likely culprits are cooling systems evaporator coils which your heating and air conditioning contractor as well as most professional duct cleaners can inspect and maintain; leaky return air ducts can also introduce moisture so again if you suspect there is a mold problem consider having a service company inspect your entire system for leaks. In conclusion, while there are some benefits associated with duct cleaning, such as improved energy efficiency or reduced allergens in certain cases; overall there is little evidence to suggest that routine duct cleaning, especially when done by an unqualified technician can cause more harm than good.
