Commercial exhaust systems serve to vent odors, moisture, and smoke from indoor spaces such as locker rooms, commercial kitchens, and bathrooms to the outdoors by way of a fan—similar to the way a home's kitchen or bathroom exhaust functions but on a much larger scale. These systems are continuously pulling bad air (dirtied with foul odors, moisture, smoke, cooking smells and oils, etc) from a large and crowded space. For this reason they tend to become quite dirty with filth and grime. When this product of exhaust builds up too much inside the ducts, proper venting to the outside is restricted, resulting in odors and moisture lingering in the occupied space. This has the effect of making the room in question "stuffy" and malodorous, and generally exhibiting poor air quality and circulation.
The above set of before and after images was taken inside a stretch of flexible ductwork belonging to the exhaust system of a municipal community center's locker room. The building itself was constructed in 1998, and the exhaust system had never been cleaned. The resulting accumulation of filth and fluff is visibly evident.
Because the area of the room being exhausted (in this case a locker room) is heavy with moisture and warmth from frequently running water, hot showers, hand and hair dryers, etc, the debris exhausted tends to stick quite readily to other particles and to the venting itself, causing a cumulative, clumpy buildup that's as stubborn as it is unsightly.
The flex duct above was cleaned using the Viper Clean Sweep System, a multi-tentacled whip attached to an air hose. When engaged, the plastic tentacles thrash vigorously to and fro, loosening debris from every crevice for the vacuum to swallow up.
Once the length of flexible duct leading from the locker room had been air whipped, it was time to tackle a larger run of rectangular metal ductwork that followed from it. Because this duct was large enough to accommodate a person, the crawl-through method was used to clean it. During this process, the technician dons personal protective equipment (PPE) and crawls through the duct on his hands and knees, armed with an industrial vacuum with brush attachments, physically brushing the debris from the walls of the ducts and into the vacuum.
In this case, the technician moved through the length of the duct until reaching a large turbine fan, which was also caked with locker-room grime.
To clean the fan, the technician water-blasts it with a pressure washer, washing decades of dust and debris from the surface of the fan and blades. The water is cleaned up with a wet vacuum, and the fan blades and other components are wiped down with a dry cloth. Once one side of the fan is clean, the technician exits the duct through an access hole created earlier, then enters the duct on the other side to finish cleaning the other side of the fan.
Having thoroughly cleaned the fan, the technician then turns his attention to the 15-foot section of rectangular duct remaining before the outside grille. This section is also cleaned with the crawl-through method, with the debris manually brushed off the walls of the ducts going straight into the industrial vacuum, which sits below. (The technician enters the duct with enough hose to accommodate the length of the duct.)
The final step is to clean the outside grille that sits like a window on the exterior of the building. The same manner of dust and grime found inside the flex duct and rectangular duct clogs the tiny holes on the screen of the exterior grille. To clean this, from the inside, the tech washes it thoroughly with a pressure-washer. While most of the excess water from this process runs down the side of the building, whatever is left inside the duct is sucked up with a wet-vac.
The ultimate result of this days-long job is a community center whose occupied spaces boast a visibly cleaner venting system, improved indoor air quality, fewer odors, and a generally improved atmosphere.
Wanna learn more about the process of commercial air duct cleaning, the various components cleaned, and the tools employed?
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Many thanks to our commercial project manager Ben S for contributing photos and wisdom for this article.