Appliance Repair Wisdom for the Ages

Wednesday, October 15, 2003

Appliance Tip of the Day: The Ultimate Dryer Venting Guide

I reckon dryers are trickier than I thought for most folks. People seem to have a hard time understanding that the dryer vent is absotootly, posilootly critical to the safe and efficient operation of your dryer! Period. Folks, if your dryer vent sux, then your dryer's performance and safety will suck, too. It's just that simple. The idea with a dryer vent is to have as little back pressure as possible. Back pressure retards the flow of moist air outta the dryer and also collects lint in the dryer and vent system creating a fire hazard. And, hear this, poor venting will cause dryers to overheat, too! Another great cause of dryer fires.

The number one thing you should do to make your dryer safer to operate and dry clothes more efficiently is to follow the do's and don'ts in this chart. Look at this figure carefully. I didn't put the link there just to look purdy. Examine it, study it, memorize it, print it out and sleep with it under your pillow...well, maybe not. But you get the idea.

In addition to the basic do's and don'ts above, you shall obey these dryer vent length criteria. You like your overly-long dryer vent just the way it is? Ok, Slick, here's your future.

Note that white vinyl vent hoses are not UL-Approved and are a great way to start fires in your house. The American Household Appliance Manufacturers Association (AHAM) recommends the use of either rigid aluminum or steel duct or spiral-wound aluminum flex hose--NOT the white vinyl hose. For any dryer, but especially gas dryers, white vinyl vent hose should never be used. If yours has this installed on it, replace it ASAP with UL-approved materials. Examples of UL-approved dryer venting materials are shown here. If you need to upgrade your vent using UL-Approved materials, some recommended items are listed below. Hint: these are links, you can click 'em to see pictures of 'em.

• Basic Dryer Vent Kit - To vent a gas or electric dryer up to 8 feet from the dryer outlet. 4-inch diameter flexible semi-rigid venting up to 8 feet in length. Includes two protector style connectors and foam seal. Instructions included.
• Side/Base Exhaust Kit, Maytag - Kit for exhausting a Maytag dryer either through the side or through the base. Includes exhaust opening plate, exhaust duct with bracket, exhaust duct, elbow and instruction sheet.
• Side/Base Exhaust Kit, Amana - Kit for exhausting an Amana dryer either through the side or through the base. Includes two self drilling screws, exhaust duct, exhaust opening plate.
• Loop Vent Kit - 4-1/2-inch wall clearance. Snap fittings and rotating collars make installation easy. Additional vent can be snapped on for longer runs. Kit includes two close elbows, one 6-foot flexible vent and two 4-inch adjustable steel clamps.
• Flexible Dryer Vent Duct, 6 foot - Flexible 4-inch diameter dryer vent expands to 6 feet. Male to female connections.
• 8-foot flexible dryer venting - Vent expands from 8 inches to 8 feet. Fits most common home installation requirements. Clamps are designed for quick and easy installation. 4 inches in diameter.
• Flexible Dryer Vent Duct, 5 foot - Flexible 4-inch diameter dryer vent expands to 5 feet. Male to female connectors.
• 8-foot Semi-Rigid Dryer Venting - Semi-rigid metal construction is flexible and easy to install. Vent expands from 23 inches to 8 feet and fits most common home installation requirements. 4 inches in diameter.
• Periscope Vent - Use when vent outlets overlap or are offset. Provides 2-1/2-inch clearance between dryer and wall. Extends to 18 inches.
• Elongated 90 degree, Close Wall Elbow (Wall Vent) - Snap-lock, rotating collar. Elbow turns 90 degrees within 4-1/2-inches of wall. Clamp required. Male to female connections (use on wall vent outlet).
• 90 degree Close Wall Elbow - Standard, 90-degree, short radius elbow. Use for 90-degree turns within 4-1/2-inches of wall.
• Elongated 90 degree, Close Wall Elbow (Dryer Outlet) - Use where outlet vent on dryer is projecting outward. Snap-lock, rotating collar. Elbow turns 90 degrees within 4-1/2-inches of wall. Clamp required. Female to male connections (use on dryer outlet).
• Dryer Vent Pipe - Deflecto 4-inch by 24-inch aluminum dryer vent pipe.
• Dryer Vent Hood - Through-the-wall gas or electric dryer tube and vent hood with a removable bird and rodent guard. Louvered self-closing internal damper keeps out drafts and provides efficient dryer airflow.
• Dryer Vent Periscope, 0-inch to 5-inch - Includes uniquely designed periscope to allow close placement of the dryer to the wall. Vent adjusts from 0 inches to 5 inches and pivots 180 degrees. Metal clamps make installation easy with common household tools
• 90 Degree Close Dryer Vent Elbow - Uniquely designed elbow to allow close placement of dryer to the wall. Energy efficient metal construction for safe operation. Simple instructions for easy installation with common household tools.
• 4 inch Clamp - Two 4-inch clamps for use with dryer venting duct. Phillips/hex head screws.

One of the ways that dryers can start household fires is by igniting the excess lint that accumulates around the motor, burner shroud (for gas dryers) and cabinet interior. Y'see, Slick, lint is composed of very small, dry clothing particles which includes cotton and polyesters--both very good fire starters. Polyesters are particularly pernicious fire starters and are very difficult to extinguish once they ignite. Polyesters, vinyl in particular, pose another fire hazard when used as vent hoses, which we'll talk more about later in this article.

One of the biggest causes of vent hose fires is when this accumulated lint inside the vent hose ignites. Lint gets caught in the folds and creases and sticks there because of the humidity. Over time, the lint builds up to such a degree that the dryer cannot exhaust properly. This results in increased drying times initially and, ultimately, in a fire. Once a fire starts in a vinyl vent hose, the hose itself ignites and burns vigorously creating a fire that is very difficult to extinguish.

Another reason for using rigid, smooth-walled aluminum ducting for your dryer vent is that you can easily clean it out using a vent brush. You need to do this annually to keep your dryer running at optimum efficiency and to ensure that you won't get any lint fires started inside the dryer vent. Oh yeah, it can still happen even with aluminum duct but the results will be far less catastrophic than a white vinyl vent fire.

Folks, I don't make this stuff up. I couldn't make this stuff up even if I wanted to. If you're having dryer problems like long dry times and overheating, you need to check out your venting in accordance with foregoing pearls of wisdom.

I can't even tell you how many time I hear Grasshoppers tell me, "My dryer is (circle one) [overheating, runs too long, fires the heaters only briefly, smells hot, blah blah blah] and I checked the vent and it's OK." Checked the vent and it's OK? Checked the vent and it's OK? Well, just what in the hell does "OK" mean? What criteria are you using to check the vent? Do you even know what to look for? (Hint: the answer to all the above is "I didn't know but now I do after reading your inspiring and illuminating Appliantology article on the subject, oh wise Samurai.")

Ok then.

Samurai Appliance Repair Man cast these pearls at 02:51 ET.  [permalink]

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10 Comments:

i was wondering why does the steam that comes out of the vent all like steamy adn it smells really good

By  Anonymous, at March 30, 2005 6:36 PM  

I was wondering how much of the "steam" you'd been whiffing before you posted your comment.

By  Samurai Appliance Repair Man, at April 01, 2005 4:50 AM  

My wife and I just bought our first home. The home inspector told me he did not like to see that there was white plastic venting. Took me two weeks to get around to changing it, but when I got into the crawl space I found the old piece of tubing that was replaced with the one I just tore out. This told me that someone recently took the time to replace the venting, but still put in the white tubing... GRRR! Anyways - just for "fun" I emptied to 68 inch line and filled a Safeway bag with the lint and hair that was trapped inside... No wonder it took 3 runs to dry towels.
Anyways, thanks for the tips!
PS - I replaced my venting with a rigid line. 2 90's - one that goes down into the floor from the back of the dryer, and one that turns that line towards the exit wall.

By  Rick, at July 16, 2005 9:22 PM  

If you have trouble getting your dryer to vent check to see if there are any rat nests inside of it. Especially if its been sitting ina garage for yrs. I found this out the hard way

By  Anonymous, at August 17, 2005 8:43 PM  

A year after installing a pricy washer and dryer in our new house, it is taking long, long time to dry. Checked the vent hose and had to remove a little wet lint. Then I went outside and was amazed to find that a grill on the new vent hood was 1/2 inch thick with lint, effectively stopping airflow either way! The grill is history. Small animals and birds are welcome to enter the dryer!

Thanks for the advise.

By  Anonymous, at April 14, 2006 7:49 PM  

Fabulous! Hope you've been enjoying the roasted sparrow! Clean the grill and put it back or go buy a different type of vent.

By  Chris, at September 04, 2006 10:13 AM  

My husband recently replaced our flexable dryer vent hose with a PVC pipe that he had left over after plumbingthe basement. It is mainly one long piece with 2 90's in it. Do you forsee any problems with using a PVC pipe oh wise Appliance Samurai??

By  Anonymous, at December 28, 2006 1:10 PM  

The good news is that after buying a new house, thanks to your website, I am now able to fully disassemble and reassemble a Hotpoint electric dryer.

The bad news is that the only thing wrong with the stupid thing is that someone stuffed a handtowel in the outside vent opening causing no ventilation, overheating, taking too long to dry, and water in the inside ventwork.

Thanks for the learning experience (yes, the dryer works fine after I put it all back together - go me!)
I hope someone learns a valuable lesson from my idiocy.

Sincerely,
Super Blonde!

By  Wendy & Billy, at February 12, 2007 10:17 PM  

Hi, thanks for your info.
I'm just moved but this is an old house. The only option i see to run the duct is through the crawlspace. From the laundry area to the outdoor will be a 18 ft long with 2 joints (90). Is that ok?

By  Jose, at January 15, 2008 6:38 PM  

I also have a long vent however have installed a fantech dryer booster to help the kenmore elite dryer. The dryer gets plenty of venting. Any pros or cons? Can you have too much venting?

By  taylordr61, at January 22, 2008 9:21 PM  

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