Air duct cleaning in commercial buildings, as opposed to homes, because of their larger size and various ductwork configurations, tends to be a more complex process. There are several different methods for cleaning commercial ductwork, but hands-down the most effective is the crawl-through method. This would be the preferred method when the ductwork is very large—big enough for a technician to fit into—in settings such as multi-floor office buildings, hospitals, community centers, etc
What is the crawl-through method?
Just as it sounds, this method involves the technician physically entering the ducts, typically through a 16-inch access point, and cleaning them from within, working his way slowly from one end to the other. Because of the high level of dust and debris inside, he wears personal protective equipment (PPE), including a Tyvek suit, a respirator, and gloves. Because of the technician's close physical proximity to the ductwork interior, as opposed to being outside of the ductwork feeding tools into it, he is able to exercise direct control over the movement of the tools rather than relying on air pressure to propel them, resulting in a much more thorough cleaning.
If a duct that is large enough to be crawled through were cleaned merely with tools, such as tentacled air whips or a brush system, without the tech physically entering the duct, the results would be inconsistent and unimpressive. The tool would simply not be able to cover all the surface area of the duct; it would likely bounce around in the center of the duct and hit a few surfaces but leave scattered clean and dirty areas. Additionally, the many off-runs would diminish the suction of the vacuum, whereas in the case of the crawl-through, the vacuum attachment (the brush head) is physically touching every surface.
What is the process?
Depending on the height of the ductwork, after creating the access point, the technician will use a 6- to 12-foot ladder (or a lift for higher systems) to enter the ductwork. He'll bring with him a length of hose appropriate for the amount of duct he'll crawl. The hose is attached to an industrial-strength HEPA-filtered vacuum. At the end of the vacuum hose that he holds are various attachments, including a 3-inch round brush head, a 14-inch brush head, and a foxtail brush (for cleaning turning vanes).
The technician begins the process on his back, starting with the top of the duct, working in arm's-length sections. He brushes methodically back and forth using the 14-inch brush head to dislodge and suction the bulk of the debris. Then he turns to his side and focuses his attention on the walls of the ducts, again methodically swiping from side to side. Finally, on his hands and knees to clean the floor of the duct, where some of the dislodged debris now sits, he switches to the 3-inch brush, which has greater suction than the 14-inch, to do a final, thorough clean of that section.
How are turning vanes cleaned?
The technician proceeds in this manner through the length of the duct, sweeping back and forth, until he reaches a turning vane. Turning vanes are located at 90-degree turns in ductwork and assist the air in changing direction with minimal loss of airflow. Because they are generally not removable, the technician must exit the duct at that point (through an access point created earlier). But before he does, he uses a foxtail brush to thoroughly clean the fins and walls of the turning vane before vacuuming it up with the powerful suction of the 3-inch brush head.
Back inside the duct on the other side of the turning vane, through another access point, the technician will use the same method to clean the other side of the turning vane, and then proceed in a similar fashion down the length of the ductwork until the job is complete and all runs have been thoroughly cleaned.
How much does it cost to clean commercial ducts with crawl-through?
Most commercial air duct cleaning companies will provide free estimates and consultations to companies considering having the work performed. The project estimator will have a look around the facility, consult with building supervisors, and study the facility's blueprints, if available, in the process of providing an estimate. Some of the factors that he'll take into consideration when determining price would be how many linear feet of ductwork are involved, how many AHUs (air handling units) are associated with the ductwork, whether there are any reheat coils or VAV boxes that need to be cleaned, and what style of supply diffusers and return grilles are present.
Technician experience and company reputation will also play a role in the final estimate price. Skilled, qualified commercial technicians rightly yield a higher labor cost, and companies who invest in consumer awareness and customer satisfaction generally have less need to slash prices in order to attract clients.
Wanna dig deeper? Our commercial air duct cleaning page contains detailed descriptions, before and after photos, and videos of our commercial duct cleaning processes.
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Many thanks to our commercial project manager Ben S for lending his expertise to this article.