Dryer Venting

[Tbonedog]

Hey all. Simple question here. Is a 90 degree upturn in a dryer vent safe? Dryer is on the other side of the wall.

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[ItsNemo]

Yes, you can 90 out the back and head straight up...but the seal (or lack there of) into the house there doesn't look safe.

 

[Fishplate]

Any bend adds restriction to flow, and gives a place for lint to accumulate.

I'd straighten it out as much as possible. I can't even figure why it can't go straight...

 

[pmiranda]

If the parts we can't see are straight it should be fine, but of course you'd be better off with no joints or two 45's, and of course smooth pipe instead of the bendy stuff. How far does the bendy part go?

 

[gnpenning]

Take out the 2 90's and straighten it out.

For what can be seen it's not worth a fire hazard.

 

[MrBalll]

If anything take it off and make you an airtight access door so you can clean it out every once and awhile.

 

[csp]

Better yet, get rid of the two 90s and the flex pipe. Go with rigid vent pipe.

 

[UpNorther]

Any bend adds restriction to flow, and gives a place for lint to accumulate.

I'd straighten it out as much as possible. I can't even figure why it can't go straight...

^ This

 

[DeliveryGuy]

In the manual to my dryer, one 90 bend is an equivalent restriction to 10 feet of straight pipe. Whirlpool gives you a maximum linear footage of vent pipe, reducing that number by 10 feet for every 90.

 

[readhead]

I presume it is going through the wall into the garage. Not a good idea.

 

[LS6 Tommy]

A long run like that would be rigid at my house....

Tommy

 

[MFolks]

Gas or electric dryer? If gas,think of carbon monoxide buildup,and possible life threatening leaks.

 

[Moose97]

Where a clothes dryer exhaust duct penetrates a wall or ceiling membrane, the annular space shall be sealed with noncombustible material, approved fire caulking or a non-combustible dryer exhaust duct wall receptacle. - IMC 2012 504.2

Exhaust ducts shall have a smooth interior finish and shall be constructed of a metal a minimum 0.016 inch thick. The exhaust duct size shall be 4 inches nominal in diameter. IMC 2012 - 504.6.1

Exhaust ducts shall be supported at 4 foot intervals and secured in place. IMC 2012 -0 504.6.2

Transition ducts used to connect the dryer to the exhaust duct system shall be a single length that is listed and labeled . Transition ducts shall be a maximum of 8 feet in length and shall not be concealed with construction. - IMC 2012 - 504.6.3

The maximum length of the exhaust duct shall be 35 feet from the connection to the transition duct from the dryer to the outlet terminal. Where fittings are used, the maximum length of the exhaust duct will be reduced in accordance with Table 504.6.4.1 - IMC 2012 - 504.6.4.1

4" 45 degree elbow - 2'6"
4" 90 " " - 5'
6" 45 " " - 1'
6" 90 " " - 1' 9"
8" 45 " " - 1"
8" 90 " " - 1' 7"
10" 45 " " - 9"
10" 90 " " - 1"6"

 

[BD1]

I would remove the two elbows and install a sheet metal box with lid for cleanout. The vent from dryer would go into the back of box and the front of box would be the outlet . Remove lid for cleanout.

 

[four.cycle]

In a perfect world, all dryer vent hoses would be nice and straight and short.
In my house, the dryer vent hose makes a full 360 turn before exiting out the exterior wall; only way to hook the damn thing up because of space limitations.
I replace it every couple years and take it off every once in a while and blow it out with the leaf blower.
Crazy, yeah... but I've managed so far to not burn down the house.


The condo my mother lived in over in Gig Harbor vented the dryer (with a 90-degree connection at the back of the dryer) over about 3 feet into the wall, where it made another 90-degree turn and went all the way up through the roof.
Worked okay until the little piece of screen blew off the top and a couple birds figured it would make a good nesting site. Finally discovered the reason everything in the laundry room was always coated with a layer of lint was because of the petrified dead bird stuck in the vent pipe up near the roof.

 

[Jackfre]

Many residential dryer vents systems do not dry as folks would like due to the excessive length or poor choice of materials/installation of the vents. Some systems require a booster. Here is one of them I had good luck with.

http://www.tjernlund.com/dryer_booster.htm

 

[Tbonedog]

Wow everyone! Thanks for the feedback. I didn't expect so much info. So the vent runs through that wall turn up 90, runs about 8' along that wall then turns 90 left to a vent to the exterior. Sounds like I should insulate that pass through on the interior wall. Is it better to have that 90 upturn (or 2 45s?) closer to the machine for greater velocity or by the exterior vent where the temps are cooler? It's an electric dryer. Thanks again everyone.


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[NUTTSGT]

In a perfect world, all dryer vent hoses would be nice and straight and short.

That's exactly correct. Sometimes you do what you have to do to get the dryer vented. If it's questionable, make sure to keep it clean and lint free.

Atleast the OP has flexible aluminum duct rather than the cheap, cheap, cheap plastic flexible duct. I'm truly surprised that stuff is still made and sold.

 

[junkyardwarrior]

This is a subject I need help with as well. Bought my first house a couple years ago. The laundry room is right smack in the middle of the house. The dryer vent runs out of the dryer, then into the wall, straight up and dumps into the attic. Upstairs there is a LOT of lint built up on the rafters and insulation. I KNOW there has to be a better way of doing this. Additionally, my dryer takes forever to dry clothes and usually I stop the cycle after about 30 minutes and clean out the lint screen-which is usually pretty close to being plugged at that point. Electric (not gas).

Directly behind the wall of the laundry room is a bath tub and bathroom, so it can't go straight out. On the other wall is the other bathroom and tub. And on the third wall is the master bedroom. It has to run up the wall-there is no other way unfortunately. It's been like this since 1987 when the place was built.

I clean the ductwork about once a year, usually in the early spring when the weather is somewhat warm, attic temps in the 80's by then (65 outside) so it's not such a nasty sweaty job. But it doesn't change the fact that it's a pain to do and it don't help the clothes to dry, not to mention the possibility of mold, mildew, and of course all the dern lint in the attic space.

What do y'all suggest? The closest exterior wall is about 15 feet from where the duct enters the attic. Run a 90 at the end of the duct, then into a booster, then out the side of the house? Those boosters look expensive but may be my only option.

 

[csp]

junkyard can the vent go down, then out?

 

[junkyardwarrior]

No, concrete slab underneath. I thought of that too.

 

[csp]

I wondered if it might be slab on grade. Bummer

 

[pmiranda]

Junkyard, I'd definitely look for a way to vent that outside. It's a huge no-no to vent a dryer or bath into the attic. The whole point of a vent is to get that humidity out of the house!
If you're only going up 10 feet, over 15, and out to the wall, you can definitely have a couple 90 degree bends and not need a booster.
In my house I have a 90 coming out the side of the dryer (since there's no room behind it), a 90 in the wall, and another in the ceiling, then it goes straight across about 12 feet to an outside wall. All smooth duct, no bendy stuff, and the dryer works fine. (electric)

 

[four.cycle]

Good grief! Vented into the attic?
Bad news for your house - humidity will play havoc with the structure.
As noted, replace with rigid duct and get it plumbed outside.

I've been in apartments and motel rooms where ducting from dryers/bathroom fans was plumbed 15-25 feet through rigid ducting to an outdoor vent - always thought it was completely crazy, but I guess they do what they have to do.

NUTTS: Last piece of duct I bought (about two months ago) - I inquired about the plastic stuff and the guy said "We don't sell it any more." Oddly the place right across the street still sells the old-time plastic (flimsy as hell) duct hose.

 

[flat tire]

my dryer is in the garage and vents 4"above a bucket of water

 

[LS6 Tommy]

The dryer vent runs out of the dryer, then into the wall, straight up and dumps into the attic. Upstairs there is a LOT of lint built up on the rafters and insulation. I KNOW there has to be a better way of doing this.

That is illegal. How did the house get through inspection?

Tommy

 

[junkyardwarrior]

That is illegal. How did the house get through inspection?

Tommy

It may not have been against code in 1987 when the house was built? I don't know. Seen a bunch of houses in this area like that though. It gets so hot in the attics that I wonder if mold can even survive up there. Summertime, we're temps upstairs in the 155-165 degree range, in the hottest sunniest days. That's WITH the whirlybirds installed. Without them in my old place it was even hotter.

I have work to do. Bi think I can go straight up and out the roof just as easily as over to the side. I'm thinking maybe only about 6 foot straight up. I'll have a look-see before I go any further.

 

[pmiranda]

In the winter condensation would be an issue... it could drip down into the house and stain your ceiling or even worse, unseen inside a wall and form nasty mold.
If you get Real Winter it could even form ice!

 

[redmondjp]

If anything, I'd extend the horizontal pipe straight up through the roof to a roof vent. With that line, I'd only use rigid pipe if it isn't already - the corrugated pipe causes so much more internal resistance to the flow.

 

[LS6 Tommy]

It may not have been against code in 1987 when the house was built? I don't know. Seen a bunch of houses in this area like that though. It gets so hot in the attics that I wonder if mold can even survive up there. Summertime, we're temps upstairs in the 155-165 degree range, in the hottest sunniest days. That's WITH the whirlybirds installed. Without them in my old place it was even hotter.

I have work to do. Bi think I can go straight up and out the roof just as easily as over to the side. I'm thinking maybe only about 6 foot straight up. I'll have a look-see before I go any further.

IDK when the code was put into effect, but it was WAAAAAY before 1987...

Tommy

 

[redmondjp]

In the winter condensation would be an issue... it could drip down into the house and stain your ceiling or even worse, unseen inside a wall and form nasty mold.
If you get Real Winter it could even form ice!

Yes, which is why the dryer vent pipe should be insulated (as much as possible) when it passes through unheated spaces - you don't want the moisture-laden air to cool off and have condensation form inside the pipe.