Commercial dryer vent cleaning refers to the cleaning of dryer vents in businesses or multi-unit dwellings (condos, apartments, etc) as opposed to single-family homes. What's referred to as the dryer vent (or more appropriately, the dryer duct or vent line) runs from the back of the clothes dryer itself to the outside, exhausting the warm, moist air produced by your dryer. In the process, small bits of lint that slough off your laundry are also exhausted. Lint is extremely combustible and cannot be permitted to build up inside the dryer duct, as it is an extreme fire hazard. The process of dryer vent cleaning removes the lint buildup from the entirety of this duct and renders the machine more efficient and, more importantly, it eliminates the associated fire hazard.
The above photo was taken at an apartment building in Chaska before the dryer vent was cleaned. It can be assumed that when lint is hanging off of the outside vent (and had to travel a good distance to get there) that there is a buildup of lint inside the vent line and cleaning is needed. Of course, a dirty dryer vent line will not always result in lint hanging from or stuck to the outside vent, so it should never be assumed that if lint is not visible on the outside, it is not present on the inside.
What is the difference between residential and commercial dryer vent cleaning?
Typically, in a commercial setting—that is, in multi-unit dwellings--the dryer is located more toward the interior of the building and not as close to a wall, through which the vent will finally exhaust. This means that in most cases, the run is longer—sometimes 35 to 50 feet in length--than in a single-family home, and it also contains more twists and turns than those that vent in a straight shot through the wall to the outside. In many cases, dryers in multi-unit dwellings vent onto the roof. All of this means that the process for cleaning the vent line is more complex and the need more frequent than in a residential setting.
How are commercial dryer vents cleaned?
In apartment buildings and condominiums, it is rare that any dryer vent lines are shared; typically each unit has its own dryer and dryer vent line, which exhausts somewhere out the side or roof of the building. In some cases, the first and subsequent floors vent out the side of the building, and the top floor vents to the roof. In other cases all dryers vent to the roof.
Regardless, the process for cleaning them is similar. The technician positions himself where the dryer exhausts (using a lift to reach the higher floors). He inserts a cleaning tool attached to a high-pressured air line into the vent and feeds it down the vent line, as far as it goes, until it reaches the back of the machine itself. When the tool (a reverse-blowing spinning air ball") is engaged, it spins around and spits out air through tiny holes in the metal ball. As the technician slowly extracts the tool, the lint is blown out with it (quite forcefully; most technicians wear face masks). The technician repeats the process if necessary until he has confirmed good air flow from the vent. Importantly, the technician will also remove any screening that is in place over the dryer vent, as this is a violation of code and additionally a fire hazard.
How often should commercial dryer vents be cleaned?
Typically dryer vents in multi-unit dwellings such as apartments and condominiums should be cleaned yearly. Most properties of this nature have an ongoing yearly contract for service with an HVAC cleaning company.
Estimates can be provided for the cost to clean all vents in a building in a single service, and prices vary depending on how many units to be cleaned, how many stories in the building, how long the dryer vent lines run, and where the dryers exhaust. Obviously, the more units, the higher the total price (though the cost per unit tends to decline as the number of units increases). Higher floors would necessitate the rental of a lift, which would also contribute to the estimate total.
Reputable commercial dryer vent cleaners are equipped and experienced to handle properties of all sizes and configurations, and yearly contracts establish consistency and predictability with the project, making planning easier on property management companies—and dryers safer and more efficient for tenants.
Wanna dig deeper? Our commercial dryer vent cleaning page contains detailed descriptions, before and after photos, and videos of our commercial dryer vent cleaning processes.
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Many thanks to our commercial project manager Ben S for lending his expertise to this article.
The air handling unit (AHU), or rooftop unit (RTU) if it's located on the roof, is the heart of a commercial HVAC system. Most commercial cleaning jobs include cleaning both the AHUs/RTUs and their associated ductwork. When estimating these jobs, the commercial project estimator will consider the unit's location and how difficult it is to access (e.g., a hanging AHU), its size, the labor involved in removing the access panels, and of course, how dirty the unit is.
Preparation for AHU/RTU cleaning
Before cleaning can take place, lockout/tagout procedures must be implemented in order to ensure a safe work environment. If there are smoke sensors in the ducts, the system should be put into test mode for the duration of the work. All access panels to the unit are opened, and air filters removed. In order to protect electrical components and the supply and return drops, 2- or 4-mil polyethylene sheeting is placed.
The cleaning process
Cleaning of the unit begins with a HEPA-filtered dry vacuum. All interior-insulated surfaces are vacuumed in order to remove larger debris. The commercial technician will then apply degreaser to the fan and other metal components inside the unit to remove grease that's been previously applied and has built up over time. A pressure-washer is then taken to the unit, and, if necessary, a scrubbing pad for hard-to-remove debris.
To clean the unit's heating and cooling coils, a coil cleaner is applied with a sprayer and allowed to sit a few minutes until foaming. Once the foam has worked its magic, the technician uses a pressure-washer to rinse it off at a downward angle, toward the drain pan. The drain pan itself is then cleaned with a pressure washer and wet-vacuum.
One of the final steps in the process is to ensure that the drain line is properly draining, as overflow from the drain line would fill the drain pan and enter the supply duct line, potentially contributing to mold growth on the insulation.
When the cleaning is complete, all excess water is wet-vacuumed and dry rags are used to wipe metal surfaces if needed. The unit is then reassembled and all access panels replaced.
The benefits of air handling unit cleaning
Your building's occupants and your HVAC system will thank you. Cleaning of the air handling unit and its associated ductwork means the minimization of contaminants entering the indoor air, Increased efficiency of the overall HVAC system due to improved air flow, increased ability of the unit to heat and cool occupied spaces, and prolonging the life of the unit.
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.
Commercial air ducts, as in an office setting, are often lined with interior insulation for the purpose of noise attenuation and the reduction of heat transfer. Ducts with this insulation on the inside (as opposed to exterior-insulated, or having no insulation at all) are often referred to as "lined ducts." Interior insulation reduces the amount of fan and other system noises heard moving through the ducts, and additionally allows air that is heated or cooled to maintain its temperature while making its way through the ductwork. The twofold benefit is a quieter system for building occupants, and greater overall system efficiency, reducing energy costs.
How lined ducts differ from unlined in terms of cleaning
Because the surface of interior-insulated ducts is more porous and less smooth than uninsulated, they tend to collect more debris and need specialized or more frequent cleaning. Interior insulation is often pin-welded, and at the location of the pin, or where the seams meet, particulates—often fiberglass particles--tend to slough off and spread throughout the ductwork over time, dirtying the ducts alongside more run-of-the mill dust and debris. Below is an image before cleaning of lined ducts in a 10-story commercial office setting in Minneapolis.
How to clean interior-insulated ductwork
The two primary methods of commercial cleaning of lined ducts are crawl-through and air whipping. The first method is just as it sounds. If the ducts are large enough, a technician dons personal protective equipment and crawls through the ductwork (variously on his stomach, back, and sides) with a 3-inch dust-brush head attached to a 100-ft hose, which connects to a HEPA-filter vacuum on the ground below. If the ductwork is big enough to stand in, he may use a 14-inch long dust-brush head. Below is the same ductwork after having been cleaned with the crawl-through method.
If the size of the ductwork is prohibitive, the alternative is to use air whips, along with compressed air and forward and reverse skipper balls. The process begins with the insertion of an industrial vacuum hose to create appropriate negative pressure. The technician will then cut 8-, 10-, 12-, 14-, or 16-inch access holes (depending on the size of the ductwork) down the line. He'll use this access to insert a multi-tentacled air whip (such as the Viper Clean Sweep or the Octopus Predator) starting from the furthest point upstream, slowly reinserting the whip and moving progressively downstream toward the vacuum.
Some commercial technicians will use bristled brushes rather than rubber-tentacled whips for this process. In this case it is vital that the bristles not be too stiff or left in place for too long lest they damage the insulation.
Finishing up with antimicrobial coating
After cleaning, an assessment will be made regarding the integrity of the insulation and whether an antimicrobial coating is necessary. Some of the various products applied are Foster 40-20, IAQ 8000, or Sentinel 24-7. These coatings are applied using an airless paint sprayer for even application.
When complete, the coating provides a smooth and durable surface that inhibits odors as well as the growth of mold and bacteria. (In the case of a previous fire event in the building, interior insulation tends to hold the smell of smoke, which then circulates throughout the building until it's been cleaned and coated.) These products have the additional effect of sealing the surface of the insulation to inhibit the sloughing off of fiberglass particles into the airstream.
Below is the same ductwork as in the previous two images, after an antimicrobial coating has been applied.