Case Study: Choked Apartment Dryer Vent

While many multi-family properties are on a regular (usually yearly) dryer vent cleaning schedule, it sometimes happens that we’re called to a property not for scheduled maintenance but for an urgent cleaning. This typically happens because the dryers have lost so much efficiency that residents complain to property management, who then determine that the vent lines are in need of cleaning. This was the case recently for an apartment complex in St Paul.

Apartment dryer vents
A shared laundry in an apartment building in St Paul, MN. Dryer vents were 4 inches going into a 10-inch horizontal vent line.

Complications from a dryer vent clog

This commercial dryer vent cleaning project was for a shared laundry room in the basement of the apartment. The laundry room had 4 clothes dryers for about 175 units, so the machines saw very heavy usage. Additionally, they had never been cleaned. The 4 dryers had 4-inch individual vent lines that fed into a shared 10-inch horizontal line. During the course of the cleaning, a massive clog was observed in this 10-inch line, heavily restricting air flow.

Because the air that a clothes dryer exhausts is not only hot but moist, when air flow is restricted and a clog begins to form, the clog can become quite heavy with moisture. As this moisture-laden clog grows, its weight can cause the dryer vent line to become disconnected. An additional concern with heavy clogs is that the moisture buildup that accompanies them can promote mold growth, damaging sheet rock, insulation, etc. The restricted air flow caused by a dryer vent clog also has the potential to burn out the dryer’s heating element, requiring a costly repair.

A clogged dryer vent line in an apartment laundry room.
A massive clog in the 10-inch dryer vent was greatly reducing air flow and caused a disconnect in the vent line.

In the case of this project, there was a disconnect behind one of the dryers, which was promptly repaired. To remove the clog in the 10-inch vent line, this section was disassembled and thoroughly cleaned with an industrial vacuum and attachments, then reassembled.

How the dryer vent line was cleared

The configuration of this particular dryer vent line was unconventional in that the 10-inch horizontal vent line went through the wall and into an old clay-flue-tile-lined chimney stack that vented onto the roof. A powerful mushroom fan at the top of the chimney, specifically for dryer vent lines, assisted in drawing the moist air up and out. Of course, the massive clogs throughout the system hindered this process. Even in the otherwise large cavity of the vertical chimney, the blockage was more than 60%. The individual components of the mushroom fan were also clogged with lint.

To clean the vertical run up the chimney, an industrial vacuum was hooked up to the bottom of the chimney and air whips were used from the top down. The mushroom fan was removed for proper cleaning and then reinstalled.

A clay flue tile chimney liner serving as a dryer vent line, choked with lint.
BEFORE: This chimney lined with clay flue serving as a dryer vent line is severely choked with lint, reducing the diameter of the opening.
A chimney serving as a dryer vent line that has been cleaned of dryer lint.
AFTER: The chimney/vent line has been thoroughly cleaned of lint, drastically improving air flow and thus the efficiency of the dryers.

Staying ahead of the game

Because of the many problems that can follow from a clogged dryer vent—disconnects, breakdowns, moisture, mold, etc—not to mention frustrated residents, it really pays to stay ahead of the dryer vent cleaning game and schedule regular cleaning. Most property management companies are on an annual cleaning schedule with their HVAC cleaning company, so that clogs don’t have long enough time to form in the first place, leaving dryers running smoothly all year long.

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