As long as the cleaning is done correctly, there is no evidence to suggest that such cleaning is harmful. The EPA does not recommend that air ducts be cleaned routinely, but only when necessary. If you or a member of 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, cleaning your ducts can appeal to you on an intuitive level.
After all, if your ducts are clean, all the air that comes out of your vents should also come out clean, right? Companies that clean ducts often advertise health benefits or suggest that duct cleaning will reduce their energy bills by improving system efficiency. 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 quantifiable benefit. In fact, the little independent research done on duct cleaning indicates that the process stirs up so much dust that it creates a bigger problem than it solves.
Although it intuitively makes sense to clean the ducts, after all, the rest of the house is dusted off and cleaned, the fact is that the dust that settles in the ventilation system usually stays where it is and is unlikely to be carried through the air unless disturbed. In most cases, dust is inert and harmless, and removing it with cleaning equipment actually creates major problems. Little research has been done on the effects of duct cleaning. Government studies from the United States and Canada and health professionals who have researched duct cleaning fail to recommend its use, but neither do they support it as a routine measure.
EPA
and CMHC researchers 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 methods used in a smaller number of homes. While the duct cleaning industry maintains that both studies are flawed, no other research has questioned the findings. And while the equipment and methods used by duct cleaning companies have changed since these studies were conducted, household air ducts have not.
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 need to be replaced every two to three months. Although they are not always part of their basic cleaning services, many duct cleaning companies also often clean heating and cooling equipment (heat exchangers, cooling coils, condensate drain vessels, fan motors, blades and fan housings). While much of the energy used to power heating and cooling equipment is wasted, that waste is due to equipment inefficiency, poor insulation, leaks around doors and windows, and unsealed ducts.
While cleaning and maintaining HVAC equipment has some benefits, that benefit is relatively small, and little energy waste can be attributed to dirty ductwork or equipment. CMHC researchers found that when duct cleaners also cleaned fan blades, there was a small reduction in airborne particles. Cleaning the fan could also slightly improve the energy efficiency of the system. The same goes for the evaporator coils inside your home's cooling system. Evaporator coils cause condensation and dehumidify air before it circulates through the house.
Condensed moisture can cause dust and other particles to adhere and accumulate in the coils. In addition, cleaning the drip tray (and the tray's drain nozzle) underneath the coils ensures that dirt doesn't accumulate or enter the system. It also prevents water from accumulating on and under the 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 any member of your family has specific health problems, such as allergies or asthma, see your doctor first.
It's important to identify the problem so your doctor can suggest alternatives to duct cleaning. Start by identifying if your ducts are part of the problem (they probably aren't) and if cleaning them will help (it probably won't). If you suspect there's a mold problem, either because of visible growth or a musty smell constantly coming from supply vents, cleaning the ducts won't do much good if you don't get rid of the mold. Mold starts with a moisture problem, and the ducts themselves are unlikely to be the source.
The most likely culprits are the cooling system's evaporator coils, which your heating and air conditioning contractor and most duct cleaning companies can inspect and maintain. Leaking return lines can also introduce moisture. Again, if you suspect a mold problem, consider having a service company inspect the duct system for leaks. Ordering only helps to a certain extent if you keep buying too much in the first place.
Be wary of companies that claim to have remarkable health benefits as research on cleaning air ducts and its impact on residents' health is still in its infancy. All air ducts accumulate dust and require cleaning although the amount of dust that justifies cleaning is subjective. A professional can help you identify specific cleaning needs for your home's air ducts and provide advice to help improve indoor air quality throughout the year. The vents can be cleaned as often as you want; many homeowners like to clean their vents every four to six months.
It's also a good idea to make sure your air filter is clean; if it's full of dust this is probably a good time to change it to a new one which will help prevent dust.
