I have two dryer ducts that go into a box which hangs from the roof inside the attic. This box is approx. one foot square ontop of which sets the roof vent with two flappers. I received a complaint about water in a dryer. Upon removing the roof vent cover I found the box was completely packed with link. Question, why the box and why did the contractor not take the dryer duct directly to the roof vent cover just behind the flapper? Getting onto a three story building and having to clean out these box's seems like a bad design. How do you determine if the design is flawed or legal?

actions · 2012-Sep-16 4:42 pm ·

pende_tim
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Selbyville, DE

1 recommendation

pende_tim

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2012-Sep-16 5:05 pm

Venting a dryer into an attic seems like a very bad idea for at least 2 reasons.

1. The moisture from the dryer will rot the rafters .
2. The lint is a fire hazard and needs to be removed often.

actions · 2012-Sep-16 5:05 pm ·

SparkChaser
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Downingtown, PA

SparkChaser

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2012-Sep-16 5:15 pm

said by pende_tim:

Venting a dryer into an attic seems like a very bad idea for at least 2 reasons.

1. The moisture from the dryer will rot the rafters .
2. The lint is a fire hazard and needs to be removed often.

+1

This is on of those, " what they hell were they thinking"

actions · 2012-Sep-16 5:15 pm ·

dcurrey
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2012-Sep-16 5:33 pm

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Description isn't clear to me. I was thinking two dry vents combine in attic in box then get piped out to roof vent.

Not that they just vent in the attic.

actions · 2012-Sep-16 5:33 pm ·

Bob4
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2012-Sep-16 6:03 pm

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quote:
roof vent with two flappers

actions · 2012-Sep-16 6:03 pm ·

pende_tim
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2012-Sep-16 6:43 pm

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I read it that the box was just hanging in the attic with the vents sitting in the rafters.

actions · 2012-Sep-16 6:43 pm ·

dcurrey
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dcurrey

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2012-Sep-16 7:05 pm

Guessing some pictures would help.

actions · 2012-Sep-16 7:05 pm ·

nunya
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2012-Sep-16 7:09 pm

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The required picture would clear things up immensely. Almost every cell phone has some sort of camera these days.

My *guess* is the "box" is actually a diverter of sorts to keep the dryers from backfeeding into the other unit.
Venting through the roof isn't ideal, but I see it in old buildings all the time. Usually because the walls are 3-4 layers of brick.

They probably used the diverter box to keep from having to make 2 roof penetrations.

actions · 2012-Sep-16 7:09 pm ·

GM
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Anon

2012-Sep-16 7:25 pm

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The box is attached to the ceiling of the attic and outside on the roof is the cover. When I remove the cover the box is full of lint because I assume the ducting for two dryers is not opening the flaps on the cover to let the lint out. Is this because the ducting is too far away from the (attached to the bottom of the box) flaps. The flaps are not stuck and work fine.

actions · 2012-Sep-16 7:25 pm ·

dunworkin
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dunworkin

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2012-Sep-16 7:39 pm

Have you thoroughly cleaned out all the lint and then fired up the dryers to see if the flaps are opening correctly? It may be that the system will need to be cleaned regularly to prevent future lint clogs. Rube Goldberg is laughing his head off.......

actions · 2012-Sep-16 7:39 pm ·

Msradell
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2012-Sep-16 7:41 pm

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The box creates a low pressure area so the lint settles out and sticks to any moisture present. Get rid of the box! Each dryer should directly vent to the outside with a flap that closes when not in operation. It's much better to go through a side wall instead of the roof!

actions · 2012-Sep-16 7:41 pm ·

Jack_in_VA
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Jack_in_VA

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2012-Sep-16 7:57 pm

said by Msradell:

I hate to tell you but I have a good smooth flexible duct sloped downward less than 5ft to outside louvered outlet. Yesterday I was outside and noticed the dryer was running but the louvers were barely open. I checked ant the inside of the louvers was completely clogged with lint. I cleaned it out and checked the inside of the vent pipe and it was as clean as a pin. Louvers working perfectly now. The outside louver with wet warm air that condenses on it is a lint trap.

actions · 2012-Sep-16 7:57 pm ·

pende_tim
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pende_tim

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2012-Sep-16 7:58 pm

I stand corrected.
Since it does vent to the outside that removes the rot issue from the moisture trapped in the attic.
Lint still needs to be removed periodically to reduce fire hazard.

actions · 2012-Sep-16 7:58 pm ·

GM
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Anon

2012-Sep-16 8:04 pm

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Here is the photo.

actions · 2012-Sep-16 8:04 pm ·

tp0d
yabbazooie
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tp0d

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2012-Sep-16 9:16 pm

Relatively easy fix..

Get some 4" galvanized flue pipe (assuming your existing pipes are indeed 4"), insert one in each dryer duct, and repipe them so they have a positive seal all the way to the flapper. Getting the lid back on, and have them seal as well may be interesting..

Also, those flappers look pretty heavy. Very possible the dryer pressure cant even open them.. May have to think of something lighter weight..

-j

actions · 2012-Sep-16 9:16 pm ·

Zorack
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2012-Sep-16 9:42 pm

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Wow.

actions · 2012-Sep-16 9:42 pm ·

robbin
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2012-Sep-16 9:52 pm

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It sounds like this is some type of multifamily rental property in Hawaii. Can you tell us more about the building.

actions · 2012-Sep-16 9:52 pm ·

AVD
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2012-Sep-17 10:13 am

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actually a nice set up. Just needs periodic maintenance.

actions · 2012-Sep-17 10:13 am ·

PSWired
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2012-Sep-17 10:26 am

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I see 3 problems here:

-There's no backflow prevention. If only one dryer is operating, the exhaust can enter through the other dryer.

-The transition from 4" dryer duct to the metal box causes the velocity of the exhaust air to decrease, and the lint falls out of suspension, collecting in the box.

-The flappers look pretty heavy and might not be well matched to the dryer output

I'd do what tp0d suggested and extend the dryer ducts so they exit as close to the flappers as possible.

actions · 2012-Sep-17 10:26 am ·

AVD
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2012-Sep-17 10:32 am

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said by pende_tim:

Venting a dryer into an attic seems like a very bad idea for at least 2 reasons.

1. The moisture from the dryer will rot the rafters .
2. The lint is a fire hazard and needs to be removed often.

3. GAS DRYERS VENT THEIR COMBUSTION EXHAUST THROUGH THE DRYER VENT. THERE IS A CARBON MONOXIDE HAZARD IN VENTING THIS INTERNALLY.

actions · 2012-Sep-17 10:32 am ·

PSWired
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2012-Sep-17 10:38 am

Read the thread...

actions · 2012-Sep-17 10:38 am ·

tp0d
yabbazooie
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2012-Sep-17 10:53 am

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Gonna guess that in hawaii, these dryers are probably electric. So, no CO issues, but still isn't good for either dryer.

I bet those lines are clogged with lint as well. If they're metal lines point to point, I'd blow em out with a leaf blower (electric of course)

-j

actions · 2012-Sep-17 10:53 am ·

AVD
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2012-Sep-17 1:11 pm

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said by PSWired:

Read the thread...

I think you are supposed to clean out dryer vent lines once every 5 years.

actions · 2012-Sep-17 1:11 pm ·

Corehhi
join:2002-01-28
Bluffton, SC

Corehhi

Member

2012-Sep-17 11:47 pm

said by AVD:

said by PSWired:

Read the thread...

I think you are supposed to clean out dryer vent lines once every 5 years.

I can tell you I lived in a 35 year old apt and the dryer took forever to dry things. Pulled the dryer out and checked the pipe straight out of the dryer, sure enough packed with lint. Checked the outside end where the flapper is and it was pretty much rusted shut. Short story, took the flapper off and there was a tube off lint about 4 foot long in the pipe, cleaned that out, ran the dryer and another few pounds of lint came out, new flapper and problem solved. To my knowledge all dryers require maintenance from time to time.

actions · 2012-Sep-17 11:47 pm ·

AVD
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AVD

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2012-Sep-18 7:30 am

said by Corehhi:To my knowledge all dryers require maintenance from time to time.
[/BQUOTE :

and a working lint screen

actions · 2012-Sep-18 7:30 am ·

Jack_in_VA
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Jack_in_VA

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2012-Sep-18 7:34 am

said by AVD:

and a working lint screen

The lint screen will not prevent lint build up in the vent pipe

We clean our screen every time we dry a load of clothes and the small fine lint will go right through it.

actions · 2012-Sep-18 7:34 am ·

AVD
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AVD

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2012-Sep-18 7:40 am

said by Jack_in_VA:

said by AVD:

and a working lint screen

The lint screen will not prevent lint build up in the vent pipe

We clean our screen every time we dry a load of clothes and the small fine lint will go right through it.

agreed, but absence of a lint screen will contribute to said build up. As i noted above, all dryer lines need periodic maintenance, cleaning of lint is a minimum.

actions · 2012-Sep-18 7:40 am ·

bemis
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2012-Sep-18 9:02 am

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I have one of those louvered vents with a "bird guard" on the end. I find that I have to clean it every 5 MONTHS. The lint screen is working fine and I clean it each time. it's just that moist lint has a tendency to stick and it doesn't just blow away once it dries out.

BTW I agree w/ your comment about the CO hazard. Someone said you should the read the thread because you were implying the dryer is vented internally (which it is not)... but I would counter by saying that IN THIS CASE the CO hazard is real because you have two dryers venting into a box with no backflow prevention. If the flappers do not open, where does the exhaust of the operating dryer go? Down the pipe to the non-operating dryer! So if they were gas/propane dryers the CO hazard would be an issue.

actions · 2012-Sep-18 9:02 am ·

sempergoofy
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2012-Sep-18 9:24 am

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This will help with an effective cleaning. I have one. Works good.
»www.amazon.com/Gardus-RL ··· 014CN8Y8

actions · 2012-Sep-18 9:24 am ·

Bamafan2277
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Jeffersonville, IN

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2012-Sep-18 9:42 am

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From what it sounds like your dryer vents are going more than 20' also. I would suggest adding one of these to each dryer. It will boost the output air pressure in the vent to carry the hot air to the vent and allow it to open the flaps better and exhaust all the gases and air.

»www.amazon.com/s?ie=UTF8 ··· 20Blower

I live in a apartment where our vent pipe goes up the the celing then 50' to the outside and my dryer took 1 1/2 hours to dry a load of clothes. With one of these installed it went down to 30 min. and saved me a ton on my electric bill.

actions · 2012-Sep-18 9:42 am ·

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