Dryer Booster Fan- A Solution To A Long Dryer Vent

Have your clothes taken too long inside your dryer? That’s more than just an inconvenience, it’s a drain on money and a potential fire hazard. This can come from any number of possible causes, but a major one is that your dryer’s vent duct may be too long!

Dryer exhaust vents typically run around 25 feet long, which a typical residential dryer can handle, but not all houses or apartments are so lucky to get 25 feet or shorter. To make matters worse, a long exhaust vent can cause a lot of problems for both your dryer performance and the building itself.

This is where a dryer booster fan comes in. With just a little bit of DIY work, you can get rid of this problem. In this article, we’re going to take you through what a dryer booster fan is, what it does, and why we recommend installing one in case you have a very long dryer exhaust vent.

How Dryer Booster Fans Work?

All the hot air and lint from a dryer’s operation has to go somewhere, which is why most dryer models need a vent duct to carry them away. Generally speaking, an airflow of 100 cubic feet per minute (CFM) is needed to kick lint and exhaust out of a typical dryer vent. Your typical residential dryer outputs 160 CFM of airflow, so in most cases, there’s enough force coming from the dryer itself for lint and exhaust to clear the entire run.

The problem comes if you have an exhaust vent longer than 25 meters, or one with a lot of bends in its path. An exhaust run that’s too long or with too many bends will reduce airflow, especially as it gets further away from the dryer. This means lint won’t exit the vent but instead build up inside. Lint buildup within your dryer vent will create a blockage that reduces airflow, leading to reduced performance, longer drying times, greater usage of electricity, and a potential fire hazard.

A dryer booster fan solves this problem by increasing the airflow in the duct, thus carrying away lint through the entire length of the duct. The booster fan is mounted onto the duct, sometimes in-line, sometimes offset. It’s also equipped with a sensor that turns it on when the dryer is running, saving you the trouble of having to manually turn it on before you start your dryer cycle.

The specific model of dryer booster fan you’re getting will also determine how much extra distance of vent run it can handle, so before you get one, make sure to measure just how long your vent run is, and compare that to your chosen dryer booster fan’s manual to see if it can handle the length of your vent.

How Dryer Booster Fan Work? -Homedepot

Residential And Commercial Dryer Booster Fans

Of course, not all dryer booster fans are made equal. You might have only one or two dryers at home, but a laundromat has a lot more, and sometimes they’re not placed conveniently enough for a duct to carry away all the lint and exhaust without a booster fan. Or the building may have a vent run that serves multiple laundry rooms across multiple floors. There are two general types of dryer booster fans, and to compare the two types, we’ll look at a representative example from each.

Residential: FanTech DBF 110


The FanTech DBF 110 is a residential dryer booster fan. It fits in-line into a section of 4” duct and provides airflow of up to 188 CFM. This much extra airflow lets it handle duct lengths out to 120 feet (36.57 meters) or equivalent. It’s an excellent choice for ju st about any laundry room and is capable of handling most typical dryers. It weighs 9 pounds.

Commercial: Tjernlund CDB8


The Tjernlund CDB8 is a commercial dryer booster fan. It fits into a section of 8” duct, either as a 90-degree elbow or in-line with an added kit from the manufacturer. It can accommodate up to four laundromat-capacity dryers with a combined airflow of 1,000 CFM. The unit weighs 25.5 pounds.

As we can see from the two products, the major technical differences are airflow and capacity. A residential dryer fan generally doesn’t need to vent more than one or two dryers, those dryers aren’t usually very large, and vent runs are usually much shorter. Thus, a residential dryer vent fan only needs to supply a small amount of extra airflow to cope with a long exhaust vent. A residential dryer vent fan is small and cheap, and it’s easy to install and maintain.

Commercial dryer vent fans have to deal with larger, multi-story buildings or multiple dryer units, which may themselves output more lint and exhaust than your typical residential dryer. A commercial dryer vent fan supplies more power and more airflow, thus permitting proper venting of a laundromat or large building. Also, since larger dryers produce more exhaust, a laundromat tends to have a larger duct diameter, and commercial fans are made for those wider ducts.

To Summarize, Here’s a Table Comparing The Two Types

AirflowGenerally less than 200 CFMCombined airflow of 400 CFM or more
CapacityCan vent 1 or 2 dryersCan vent multiple dryers
Duct DiameterStandard 4” ductLarger duct widths, 6” or wider
Size and WeightGenerally under 9 lbsHeavier than 10 lbs

Installing A Dryer Booster Fan

First off, tools. You’ll need a screwdriver, a power drill, tin shears, foil tape, and your dryer booster fan.

Installation is simple enough. There are two main challenges before you can get to putting in the fan itself. The first is in accessing your dryer vent run. How difficult this is will depend on your house’s setup and how your duct is installed. Try and get to as much of the duct as you can reach so that you have room for options.

That first challenge affects the second, which is how far down your vent should you install your dryer booster fan. There’s no real correct answer here beyond ‘not too close’. Refer to your specific dryer booster fan’s installation manual to check what the manufacturer recommends for their model.

Once you have access to your dryer exhaust duct, installing your dryer booster fan is simple enough. First, check just how much space your booster fan occupies. Cut out an appropriate section of your dryer exhaust duct. Attach your dryer booster fan into the duct, and tape around both ends of the fan to ensure no air escapes. Secure the booster fan to a nearby wall or column if the manual calls for it or if you feel it necessary, then plug it in.

And that’s it. It’s a bit of hard work, depending on just how difficult it is to get to your exhaust duct, but there’s nothing complicated. The booster fan itself doesn’t need any fiddling after it’s plugged in, because it’s already set up for you.

Of course, there are a few other concerns. The biggest one is that you may need to run a power line and an outlet near the booster fan, because that plug needs somewhere to go and your existing sockets may be out of reach. That’s simple enough, though it’s a bit of added work. Also, consider how you’ll access the booster fan for maintenance purposes.

Do I Need A Lint Trap?

A larger concern worthy of its own section is whether or not you’ll need a lint trap. It may be inconvenient to install your dryer booster fan some distance down the vent run, and it may be that the best place to install it is close to your dryer. This is not a problem as long as you also install a lint trap.

Lint is still wet when it exits the dryer but usually dries out enough by the time it’s traveled down the dryer vent. If your dryer booster fan is far enough from the back of the dryer, then the lint will be dry enough that it won’t stick to the booster fan and cause a problem. But if you have to install your booster fan closer, then the lint will still be wet enough to stick and thus clog up your fan. Generally speaking, a dryer booster fan that’s closer than 15 feet (4.57 meters), not counting bends, is too close and needs a lint trap. Some models may also specify how close you should install them to your dryer based on whether or not you have a lint trap, so check the manual to be sure.


FAQ- Frequently Asked Questions

Some questions come up a lot when we start talking about dryer vents and booster fans, so we’ve compiled them here for easy reference.

  1. How do I enhance airflow in dryer vents?

    With a dryer booster fan! There isn’t really another way to do it. Regular cleaning of your vent to remove any built-up lint will keep your dryer vent’s airflow optimal, but it doesn’t enhance airflow the way a fan does. The only other solution is to make a shorter vent run, which isn’t always possible.

  2. Do dryer vent booster fans work?

    Provided that they’re installed correctly, yes. Always pay attention to the instructions, check that your model has enough airflow for the length of your exhaust vent, make sure that you’ve supplied enough power, and check the duct distance between the fan and the dryer’s vent end. Remember, at 15 feet or shorter, you need a lint trap.

  3. Where should a dryer booster fan be installed?

    There’s only one place to install them, and that’s as part of your dryer exhaust duct. Consult your model’s installation manual to see exactly where on your vent duct it should be placed, as the manufacturer usually has a recommendation on how far down to place the booster fan. Also, don’t place it too close to your dryer. Ideally, your dryer booster fan should be 15 feet (4.57 meters) or further away on the vent from your dryer, so that it doesn’t get clogged up by lint. If you do have to place it closer than 15 feet, you’ll need to install a lint trap.

  4. Can I vacuum my dryer vent?

    Kind of. First off, note that regular cleaning of your dryer vent is important to maintain dryer performance, keep drying times to a minimum, and reduce electricity use, so you should make an effort to get into the vent run and clean it out. Twice a year will be fine.

    As for using a vacuum, you can, but a vacuum alone won’t be enough. Even with an attachment that lets it fit inside your vent duct, a vacuum won’t dislodge the lint that’s clinging to the vent walls. You’ll need a dedicated dryer vent cleaning kit. These have a specialized brush that can fit inside your dryer vent, and that will loosen the lint from the walls and pull it out of the vent. Once it’s out, you can then vacuum it up.

    You should also go in with the vacuum after giving your vent a good brushing, just in case you missed anything that’s already been loosened up.

    If you did install a lint trap along with your dryer booster fan, you’ll need to clean a bit more often. This will depend on how often you use your dryer, but generally, somewhere between once a week and once every two weeks will do fine.

  5. How far can I run a dryer vent?

    Ideally, your dryer vent should be as short as physically possible. This makes cleaning easier and reduces any risk of fire. Your typical residential dryer can adequately vent at up to 25 feet (7.62 meters) or equivalent. That ‘or equivalent’ is necessary, because bends in the duct reduce airflow. A 45-degree bend is a reduction equal to 2.5 feet (0.76 meters), while a 90-degree bend is equivalent to 5 feet (1.52 meters). Thus, a 20-foot duct run with a 90-degree elbow is already at the 25-foot limit.

    Note that your local building code may differ, so check how it is where you live in case it calls for a different length. Either way, though, going over 25 feet can affect your dryer’s performance. Check how long a typical drying cycle takes and compare it with how long other people with the same model of dryer take to see if performance is affected. If you’ve got a long vent run and you’ve noticed you’re taking longer than your friend with the same dryer, it’s time to buy a dryer booster fan.


Even if you have to run your dryer vent duct a bit further than necessary, there’s still a solution to that. Lint buildup and longer drying cycles won’t be a problem with the right dryer booster fan installed. All you need to do is run a power line and do some work with tin shears and a screwdriver, and your lint and inefficiency troubles will be a thing of the past.

Maintenance is a lot easier, and the fire hazard of lint buildup will be gone when you install a dryer booster fan. If you’ve got an 80-foot dryer vent out of your apartment’s laundry room, the FanTech DBF 110 will serve you well. If you need to vent the laundromat you’ve just set up, then the Tjernlund CDB8 has the airflow you need. That long dryer vent run isn’t such a big problem when you’ve got your fan in place.

I am a cleaning enthusiast and a writer for renowned cleaners guide sites. I am the Chief Executive Officer for All-City Janitorial and All-City Duct Cleaning. This is where I write about my exploits in detail to share my experience with everyone.

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