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Everything You Need to Know About Clothes Dryer Transition Hoses

Wisconsin Homeowners Trust the Dryer Vent Wizards!

What is a Transition Hose?

Twisted and crushed dryer transition hoseThe transition hose, also known as the transition duct, is the short length of dryer vent connecting your dryer to the vent line that runs through your wall to the outside of your house. It may be a small part of the entire dryer vent line, but it's one of the most critical parts and can cause many problems if a substandard product is used or improperly installed.

What Are the Building Code Requirements for Transition Hoses?

The International Residential Code (IRC) Section M1502 Clothes Dryer Exhaust guidelines state:

"Transition ducts shall not be concealed within construction. Flexible transition ducts used to connect the dryer to the exhaust duct system shall be limited to single lengths not to exceed 8 feet (2438 mm), and shall be listed and labeled in accordance with UL 2158A."

Unfortunately, what’s missing from this guideline is any mention of the material the transition duct is made from. Too many homeowners use the cheapest transition hose they can find, which is usually made of a flammable Mylar foil stretched over metal spiral rings.

The Problem(s) With Most Flexible Transition Hoses

1. They’re Highly Flammable. The biggest problem with many transition hoses is their flammability. The shiny, flexible hoses that resemble a Slinky with a thin foil-like covering over them are the worst. Not only does lint accumulate in the nooks and crannies created by the metal spirals of these hoses, but if a lint clog ignites the entire hose will go up in flames in about one minute. Another common variety is the white vinyl covered transition hose—which is also highly flammable.These have been off the market for some time, but many homes still have them.
2. They’re Easily Crushed. While a flexible transition hose makes installation easier, it also makes it highly likely the hose will be crushed at some point. All it takes is for someone to push the dryer a little too far toward the wall, or for the dryer to vibrate backwards over time and start crushing the hose.  Once the hose is pinched, it obstructs the flow of exhaust from your dryer. When the flow of exhaust is impeded, heat builds up inside the hose. Add some lint trapped in the hose to the equation and you have a recipe for a fire.
3. They’re Lint Traps. The undulations created by wrapping foil over spiral rings results in multiple places for dryer lint that got past the lint trap to accumulate inside the transition hose. Yes, small pieces of lint inevitably get past your lint trap, even if you clean it every time you do a load of laundry.


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What is the Safest Clothes Dryer Transition Hose?

Depending on the distance between your dryer and where the transition hose will connect to the main exhaust vent line, there are two options: Semi-rigid aluminum duct and a flame-resistant aluminum ribbon transition vent made by DryerFlex.

The semi-rigid hose works well in those rare installations where there’s a fairly straight run from the dryer to the main vent line, but can be easily crushed if a dryer is pushed against it and can come off the exhaust port of your dryer if it’s subjected to too many bends. 

The aluminum ribbon transition hose looks like the shiny, Mylar-coated foil hoses that go up in flames within seconds, but is UL rated as a fire resistant product. It offers the flexibility of foil hoses, so it’s easy to install, and it has the air flow efficiency of a semi-rigid duct. On top of all this, it resists crushing.

Here are the results of flame test DryerFlex conducted on their transition hose and on some other transition hoses (none of which were the highly flammable Mylar or vinyl covered hoses, incidentally). This should explain why Dryer Vent Wizard only installs DryerFlex transition hoses:

DryerFlex transition hose flame test

Don’t All Transition Hoses Sold Today Have to be Fire Resistant?

Dryer manufacturers and building codes specify a UL2158A rated transition duct, but there are two classes: Class 1 and Class 0. A Class 1 rated duct is generally considered safe, but it will develop smoke and flame spread at lower temperatures. A Class 0 rating ensures the hose can withstand fire exposure to 482 degrees (the Surface Burning test) without smoking or igniting on fire. Only semi-rigid transition. UL rated ducts and the DryerFlex transition duct have a Class 0 rating.

Before You Do Another Load of Laundry, Check on Your Transition Hose

Right now, before you put another load of clothes in your dryer, get a flashlight and go take a look behind your dryer. Start by gently pulling your dryer away from the wall enough so you can peek behind it. You want to make sure your transition hose is actually connected to your dryer and the vent line in your wall, and also make sure it’s not crushed by your dryer pushing against it.

If you have a shiny, foil-wrapped transition hose, or one of those white, vinyl covered hoses, you need to replace it…as soon as possible.

Does Dryer Vent Wizard of Wisconsin Install Transition Hoses?

Yes, we can install a transition hose for you. However, we can’t schedule a service call for such a small job. What we recommend is scheduling a dryer vent cleaning, at which time we can replace your transition hose if necessary.

While we’re at your home, we’ll also inspect your washer hoses—the lines that carry water into and out of your washing machine. The rubber washer hoses commonly put in by installers are only reliable for about 5 years of service, after which there is a very real risk of them rupturing and flooding your home. If yours are over 5 years old, or are showing signs they may fail, we can also replace these for you.

Lastly, you may want to consider having the interior of your dryer cleaned. Over time, lint particles accumulate inside your dryer, forming a layer of highly flammable lint.  Because they’re in such close proximity to the heat source, there’s a very real risk of fire. You can learn more about dryer deep cleaning in this article.

Lint clogged dryer vent lines are a fire hazard.Now is a Good Time to Have Your Dryer Vent Line Cleaned

If you can’t remember the last time you had your dryer vent line cleaned, it’s probably due for a cleaning. Because lint can build up inside a vent line over time, it’s recommended to have your dryer vent cleaned every year. Families who do more than 5 loads per week, or regularly launder pet blankets with hairs on them, should have their dryer vents cleaned every 6 months.

Contact the Dryer Vent Wizard of Wisconsin Nearest You:

Northeast Wisconsin: Fond du lac, Sheboygan, Manitowoc, Kewaunee and the Fox Valley Counties. 920-644-3797

North Milwaukee: All locations north of Highway 94 in Dane County, Waukesha, Milwaukee, Ozaukee, Washington and Dodge counties. 262-757-8368

Southeast Wisconsin: All locations south of Highway 94 in Dane County, Waukesha, Milwaukee, Walworth, Racine and Kenosha counties.  262-312-1991. For property managers and condo associations, call 262-501-5240.

Contact Dryer Vent Wizard of Wisconsin now to schedule a dryer vent cleaning.
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