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Originally published in the March 2017 issue of Sweeping Magazine

Question: There can be quite a few! In no particular order, let's take a look at some of the common ones.

by Mike Segerstrom 


Long vent runs- Longer runs may have worked for older clothes dryers, but the new dryers are high-tech and can be very sensitive. Some of the new dryers will even specify in their manual, what the maximum length is, and the maximum number of elbows or turns. When you get the call from a homeowner that says their new dryer won't work, this is something to definitely look at. We may have to advise the homeowner that more frequent service is needed, or that it may be necessary to reroute the vent.

Inaccessible bird/animal guards- And that means inaccessible to the homeowner. If their dryer vent terminates through a second or third floor exterior wall, or through the roof, and is equipped with a screen, that screen will likely clog with lint quickly. At ground level or through a first-floor wall, the homeowner can usually remove the lint from the screen on a regular basis. A clogged screen could result in longer trying times, moisture leakage out of the vent into the home, and even hazardous dryer operation conditions.

When a dryer vent terminates through the roof, birds typically are not attracted to it because the pipe is positioned vertical. As long as the termination is equipped with a flap that closes when the dryer is not in use, bird entry is usually not an issue. Usually.  But when the vent exits a sidewall of the home, this can be very attractive to birds, as the horizontal pipe creates a great nesting place. Even if the termination has a self-closing flap, sometimes they will get stuck open. Or as lint builds up in the vent and the airflow diminishes, birds can move in. With problematic sidewall vents, there are a few approaches to consider. We can install a screen with a larger mesh, we can install a screen that is larger than the vent termination, or consider a reroute to a lower floor or through the roof.

Bird's nests- It can be quite common for birds to make their nests in dryer vents near the exterior termination. Sometimes the nests are small, but sometimes they may be found in several feet of the dryer vent. There are specialized nest removal attachments for most dryer vent servicing rod systems. These are effective, but may be time-consuming as we want to make sure we don't damage the vent while we are removing the nest. Also, if live birds are present, especially young ones that don't fly yet, we have to check with local and state requirements for removing and handling birds. In addition to removing the nest, we may have to call an animal control to remove live birds.

Disconnected dryer vents in concealed areas- This is something that can be common in older condo and townhome developments. The piping for these dryer vent systems is often put together with vinyl duct tape. Over the years, this tape will fail. On its own, or during servicing of the vent. We may suspect a disconnection because of no airflow at the termination, or moisture stains in ceilings or walls. Unfortunately, sometimes we discover a disconnection because our rods get stuck!

If we don't have an obvious water stain on the ceiling, specialized camera equipment can make it very easy to locate the disconnection. If we don't have this type of camera, there are other methods. If the vent passes through an attic, we may be able to disconnect it and look into it from there. In some cases, we may be able to feed our dryer vent rod, without spinning it, into the vent without a brush, and determine the location of the disconnection based on how the rod moves through. Without a camera though, there will be times that we will have to make educated guesses to make openings in ceilings or walls to locate and repair the disconnection.

Transition duct problems- The transition duct is the piping that connects the dryer exhaust outlet to the vent. The transition duct is also often completely located behind the dryer. We will see in the field that these consist of flexible foil, flexible aluminum, rigid round pipe, and sometimes close clearance boxes. When servicing dryer vents, we should always also service the transition duct. It's not uncommon to see the corrugated transition ducts full of lint, or the transition duct crushed, torn or even disconnected behind the dryer. The transition duct should be as short as possible while still allowing movement of the dryer for service, and rigid or smooth pipe is the best. The transition duct should also be securely connected to the dryer exhaust outlet and the vent. A damaged, improperly installed or disconnected transition duct can result in a variety of problems including lint and moisture in the home, and dryer venting hazards.

These are just a few of the more common issues we may see. Other problems include old vinyl ducting as transition duct or as the vent concealed in the wall, improperly sized dryer vents (3" instead of 4"), screws used to connect the piping and protruding into the vent, and sometimes we will even find that the exterior termination was completely removed when the siding or roof was replaced.

These are just a few of the things we may encounter. The CSIA has a dryer exhaust technician training program, and also offers certification ( The proper training and certification will help us provide a high quality service to our dryer vent customers.

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