# Dryer vent into 4" PVC



## jeffmattero76 (Jan 4, 2016)

Thinking out loud... How about a pvc 4x3 reducer and either connect to that reducer or add a small stub of 3"pvc pipe and connect to that. My only concern would be if that will give you enough exhaust flow. 

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## Windows on Wash (Aug 30, 2011)

Unless the code has changed, it should be made of metal.

http://www2.iccsafe.org/states/Florida3rdDraft2007/residential/PDFs/Chapter%2015_Exhaust%20Systems.pdf


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## Yodaman (Mar 9, 2015)

This is a electric dryer I hope. Definitely not safe if gas.

To attach the hose I'd probably just slit the hose longitudinally a couple inches, tape up using foil tape. Followed by a hose clamp.


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## clarenceboddick (Nov 30, 2016)

Slip a metal vent inside the PVC? If gas, I'd remove the PVC and go with a code approved metal vent.


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## ponch37300 (Nov 27, 2007)

It is an electric dryer. I think I will get a 4x3 adapter and see how the metal flex fits over that. Should be pretty close. Thanks for the tips.


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## Yodaman (Mar 9, 2015)

Reducing the line to 3" with a 4/3 adapter will reduce flow capacity by 40%. It will be like starting out with a clogged line, increasing dry times, create a bottle neck for more lint to clog, and increase risk for fire.

If needed, buy a short 4" alum duct pc. Put the crimped end into the PVC and the hose over the other end. Foil tape and clamps only, no screws


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## KPDMinc (Nov 7, 2016)

Yodaman said:


> Reducing the line to 3" with a 4/3 adapter will reduce flow capacity by 40%. It will be like starting out with a clogged line, increasing dry times, create a bottle neck for more lint to clog, and increase risk for fire.
> 
> If needed, buy a short 4" alum duct pc. Put the crimped end into the PVC and the hose over the other end. Foil tape and clamps only, no screws


wouldn't that essentially be the same as buying a reducer? a 4/3 reducer would be a much cleaner install...


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## Oso954 (Jun 23, 2012)

A reduction to 3-7/8 inches doesn't restrict airflow as much as a reduction to 3 inches.


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## Gary in WA (Mar 11, 2009)

I be surprised if there is not a 4" outlet on the dryer.... make sure no one slipped a reducer there already- that you can remove- check with her renters insurance for coverage of a fire-hazard/not meeting minimum safety code installation... who will pay for lost furnishings or loss of life...

Add footage for every bend, read your dryer manufacturers total footage, you may surpass it causing problems;* pp 7;http://www.codecheck.com/cc/ccimages/PDFs/CC6th_Sample.pdf

*Is this a US made dryer? Pushing that far, please don't add a reducer to make unsafe install worse. Check the termination hood, make sure no screen and has a back-draft flap.

Gary


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## indigo (Dec 14, 2009)

I'm quite certain the PVC is a no go due to static electricity build-up causing lint to cling inside the pipe. Would love to know if code changed on that.


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## rjniles (Feb 5, 2007)

I often see 4" PVC used underslab as a vent for a dryer on an inside wall. Metal would be gone in a year.


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## Yodaman (Mar 9, 2015)

"_wouldn't that essentially be the same as buying a reducer? a 4/3 reducer would be a much cleaner install"_


Yes, and it is a bad idea, irregardless of how clean it looks. The ID of the duct (or pipe in this case) should stay 4"


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## KPDMinc (Nov 7, 2016)

Yodaman said:


> "_wouldn't that essentially be the same as buying a reducer? a 4/3 reducer would be a much cleaner install"_
> 
> 
> Yes, and it is a bad idea, irregardless of how clean it looks. The ID of the duct (or pipe in this case) should stay 4"


and I agree. it was said to do the latter of his suggestion, which, IMO, would be the same as what he told him NOT to do...


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## Msradell (Sep 1, 2011)

Yodaman said:


> Reducing the line to 3" with a 4/3 adapter will reduce flow capacity by 40%. It will be like starting out with a clogged line, increasing dry times, create a bottle neck for more lint to clog, and increase risk for fire.


 Putting that reducer in the line if not going to reduce the flow by 40%. It will reduce the cross-sectional area by 40% for that small length of pipe but in reality it will just be acting like an orifice and will have minimal effect on the echo flow of the pipe (probably about 10% or less). You can't really calculate the flow loss unless you know the static pressure and expected flow rate.


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## Yodaman (Mar 9, 2015)

Msradell said:


> Putting that reducer in the line if not going to reduce the flow by 40%. It will reduce the cross-sectional area by 40% for that small length of pipe but in reality it will just be acting like an orifice and will have minimal effect on the echo flow of the pipe (probably about 10% or less). You can't really calculate the flow loss unless you know the static pressure and expected flow rate.



Perhaps you could put a 3" reduction into your own dryer set up. Do a long term study on the lost efficiency, increased dry times, and increased cost to run. Check with your local code enforcement to see if you have violated a fire code. And also the dryer mfg about the likely hood of voiding any warranty. :wink2:


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