# Dryer vent with 4" PVC pipe



## rjniles

I replaced a dryer vent that ran thru my crawl space for a distance of about 15 feet. The old vent was the plastic slinky with the wire coil. It was a mess, sagged and was full of lint. I replaced it with 4" PVC drainage pipe. The dryer works much better now and dries the clothes in much less time. My buddy says I have created a fire hazzard with the PVC pipe. I do not see how as the old slinky was plastic. Dryer is electric for reference. Any opinions or code issues?


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## Wildie

*Dryer vent*



rjniles said:


> I replaced a dryer vent that ran thru my crawl space for a distance of about 15 feet. The old vent was the plastic slinky with the wire coil. It was a mess, sagged and was full of lint. I replaced it with 4" PVC drainage pipe. The dryer works much better now and dries the clothes in much less time. My buddy says I have created a fire hazzard with the PVC pipe. I do not see how as the old slinky was plastic. Dryer is electric for reference. Any opinions or code issues?


 I just installed a new dryer and the manual says "Do not vent with flexible plastic material.Rigid or flexible metal duct is to be used. In Canada or the US, if metal foil, it must be of a specific type identified as to be suitable for use with clothes dryers. In the US it must comply to UL Standard 2158A"
I think that your friend is correct!


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## handy man88

t


rjniles said:


> I replaced a dryer vent that ran thru my crawl space for a distance of about 15 feet. The old vent was the plastic slinky with the wire coil. It was a mess, sagged and was full of lint. I replaced it with 4" PVC drainage pipe. The dryer works much better now and dries the clothes in much less time. My buddy says I have created a fire hazzard with the PVC pipe. I do not see how as the old slinky was plastic. Dryer is electric for reference. Any opinions or code issues?


I don't think PVC is meant to handle the heat coming from a dryer. Also, there's no insulation around the pvc pipe to prevent the hot moist air inside the PVC pipe from condensing during the winter before it leaves the outlet. This condensation can drain back to the dryer and pool.


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## Wildie

handy man88 said:


> I don't think PVC is meant to handle the heat coming from a dryer. Also, there's no insulation around the pvc pipe to prevent the ho moist air inside the PVC pipe from condensing during the winter before it leaves the outlet.


 Thats a good point, unless the pipe runs in a heated area!


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## handy man88

Wildie said:


> Thats a good point, unless the pipe runs in a heated area!


True, if the dryer is in a heated basement, then that may be ok especially if it's pitched down.

If it's going through an attic because the dryer is upstairs, then that may be an issue.


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## 1610 CUB

I don't know for sure, but I heard that static electric could/can be a big problem with pvc pipe.


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## Wildie

*Dryer vent*



1610 CUB said:


> I don't know for sure, but I heard that static electric could/can be a big problem with pvc pipe.


 I have a saw dust vacuum system in my shop that uses clear plastic tubing.
When installing this, I was instructed by the directions to run a bare copper wire inside the tube, that was grounded.
A spark in a dusty area can cause an explosion, so perhaps this would apply to PVC used as a dryer vent also!


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## Big Bob

Back to OP's Question. Any fire issues?

If we believe that appliances are made perfect and they will never malfunction... then we can duct with any reasonable combustible product we want.. RIGHT...

please let me know if I have not made my point....


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## handyman78

Replace it with 4" aluminum pipe for clothes dryers-


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## handyman78

Wildie said:


> I have a saw dust vacuum system in my shop that uses clear plastic tubing.
> When installing this, I was instructed by the directions to run a bare copper wire inside the tube, that was grounded.
> A spark in a dusty area can cause an explosion, so perhaps this would apply to PVC used as a dryer vent also!


True- but dryer output is more often damp and fuzzy than dry and dusty :wink:


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## Big Bob

Dryer fuzz will not stay damp for long..

Girl scouts collect this to make fire starters for their merit badges.

try to keep your new duct clean....and don't miss any payments on your HO insurance.


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## Termite

PVC isn't appropriate or safe for dryer vents. I'd remove it and run it in solid 4" round duct.


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## sendres

*Be with in code.*

I'm pretty sure the PVC just doesn't meet code. And practically speaking it would probably be fine and nothing would happen and likely it just hasn't been certified for that use. But if it something did happen, the HO insurance would likely not be worth the paper it is written on. They seem to frown on covering damage from code violations.


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## Big Bob

Actually, most HO & DP policies do cover " silly things that homeowners do". not permitted, or not to code efforts, improper installation etc..

The loss must meet the quick and sudden standards.

Getting money to fix the house...is little comfort if there is loss of life or limb.

Ever put that last load of wash in the dryer before you went to bed?

OP... change the PVC to smooth metal duct.. if not for your sake ... then the safety of the ones that live with you.


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## sendres

You may be right. The case my neighbor was involved was probably on the more extreme end. He used PVC to hook up his garage heater. As a"temporary solution". Let just say he's rebuilding it now, he almost has it done again. Fortunatly no one was around and it was detached. For some reason the insurance company didn't cover it.


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## Big Bob

The standards revolve around the legal interpretations of "what would a prudent man do".

In most claim situations this relates to " Homeowners duties after a loss:
1. contact the carrier in a timely manner 2. Mitigate the damage so additional damage does not occur. 3. Allow carrier to inspect damage ...etc..."

Your neighbors case...well lets just say it had nothing to do with what a prudent man might do.

Sounds more like a timer for a bomb.

For you and your neighborhood I hope this guy had some knowledgeable help for the restoration. ( Did you see a permit posted?)


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## wedge22

I am venting my dryer this weekend too into my attic and I was also wondering what to use for the ductwork, now I know thanks to this handy thread.


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## Big Bob

wedge22,

I hope you mean you are running metal duct through the attic and out the roof or soffit...right? You are not going to put all that hot humid air in your attic...right?


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## wedge22

I am going to run the ducting through the attic and out of the side of my house, I do not want to cut any holes in my roof.


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## Termite

wedge22 said:


> I am going to run the ducting through the attic and out of the side of my house, I do not want to cut any holes in my roof.


Good thinking. Big Bob was right in being concerned about venting into, and not just passing through, the attic. 

Just don't run too far with it. A maximum of 25' of pipe is a rule of thumb (and code), with 90* elbows counting as 5' deductions, and 45* elbows counting as 2-1/2' deductions. Many modern dryers will push farther, so if you need to go farther check your dryer's instructions. If you pipe it too far, you're begging for a fire, not to mention poor performance.


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## wedge22

Thanks for the info regarding the maximum length to run the dryer venting, I did not know this. I only require one bend so thats good. I believe the distance is approx 16 feet with one bend so its all good. I guess I can use exactly the same metal ducting as I used the other day for my bathroom extractor fans? Also the first piece of ducting into my attic will be flexi as its attaching to the dryer.


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## Termite

Yes, 4" metal (not flexible) duct is appropriate. I'd advocate using heat tape and a lot of force to hold it together, as screws will just catch lint and allow it to build up.

Flexible connectors are ok right behind the dryer, but use flexible aluminum ones...Not the plastic or foil springy type.


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## wedge22

I will be using non flexible metal duct all through the attic space and will only need around 3 feet of flexible pipe at the start of the ducting from the back of the dryer, it will be the good stuff too.As far as screws go I had not thought of this, that means I need to do a really good job of crimping, better buy myself a crimping tool then. What is heat tape?? I intend to strap down the ducting to some of the joists in the attic too so it will be secure.


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## Big Bob

thekctermite said:


> Yes, 4" metal (not flexible) duct is appropriate. I'd advocate using heat tape and a lot of force to hold it together, as screws will just catch lint and allow it to build up.
> 
> Flexible connectors are ok right behind the dryer, but use flexible aluminum ones...Not the plastic or foil springy type.


I usually agree 110% with Mr. KCTermite, and do so again.

Wedge 22, understand that the flex AL is at connection only ( elbows).

I agree screws are problematic ( lint catchers), HERE COMES THE , BUT

(and please correct me if I have missed a code change or addendum)

I believe mechanical codes require 3 screws at each round metal duct connection and I am not aware of exclusion for dryer vent ducting. (if exclusion does not exist, maybe it should ?)

Looking forward to the Mechanical contractors pipping in. (Pun intended)


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## evapman

PoP rivets work very well instead of screws. :yes:


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## Big Bob

evapman said:


> PoP rivets work very well instead of screws. :yes:


Yes they do!:yes: I have two guns... if I could only find them.. They hide until I buy a new one...:furious:


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## wedge22

So I have installed as much venting for my dryer as I can, I just need to get some ladders so I can reach the outside of the house and use my new sawzall to make a hole for the vent. I only had to use one piece of flexi and one 4" straight duct to reach the outside wall and I am coonecting everything with the clamp connectors so I have no screws in the ducting itself.


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## Big Bob

wedge22,

I'm glad this is going well and the end is insight for you.

I'm sure your connections will work fine for you. My take on the code requirement for all round metal duct having three mechanical fasteners is...to protect you and your duct from the cable guy.

someone in your attic might kick or dislodge the connection (thus separating the duct) a very easy thing to do in dark cramped quarters.
Of course anyone that did that would fix what they damaged or tell you about it...right.

Just in case (you get a shy not equipped to fix what they broke type) in your attic ... you might want to take a peek and be sure all is well.


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## Wildie

Just to be the devils advocate! I'm of the impression that dryer duct should be/is to cleaned annually.
Any time that I have cleaned mine, its easily taken care of by removing the screws and disassembling the sections.
Lint has always been coated all over the inside and screws were not a factor.
Fabric softeners are the culprit, to my mind!


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## Big Bob

My daughter had sent me this in an email months ago. 

http://www.snopes.com/inboxer/household/dryer.asp

wash them screens


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## handyman454

*Clothes dryer venting*

PVC piping, while used frequently in residential and commercial construction for venting forced air, gas furnace vapors (both hot and moist) is not an acceptable material for dryer vents due exclusively to its combustibility factor.

Accumulated lint in any piping system (metal, PVC, Vinyl etc) is a combustible material that can and does frequently catch fire.
A PVC pipe will burn and melt helping to spread the fire.
A metal pipe will not burn or melt until and unless the fire reaches extreme temperatures.

C.I.P.

Hardin County Planning and Development Commission
*Domestic Clothes Dryer Ducts*. *(IMC 504.6) “Exhaust ducts for domestic clothes dryers shall be constructed of metal and shall have a smooth interior finish. The exhaust duct shall be a minimal nominal size of 4 inches in diameter.*
*http://www.hcpdc.com/pdf/Dryer%20Vent%20Requirements.pdf*




Topical Fire Research Series
*Volume 7, Issue 1 / January 2007 *
*Clothes Dryer Fires in Residential Buildings*
The exhaust pipe should be as short as possible and have limited bends to allow for adequate airflow.
The American Household Appliance Manufacturers Association (AHAM) recommends the use of UL- listed rigid aluminum or steel duct or spiral-wound aluminum flex hose, NOT white vinyl hose.
*http://www.usfa.dhs.gov/downloads/pdf/tfrs/v7i1.pdf*


*The Association of Home Appliance Manufacturers* 
The installation and maintenance of clothes dryers are an important part of ensuring that the appliance performs as designed. The Association of Home Appliance Manufacturers (AHAM) has reviewed many of the building codes used across the U.S. to ensure that the installation of clothes dryers is in accordance with the manufacturer’s instructions.
AHAM, on behalf of its home laundry manufacturers, submitted comments to the 1999 edition of the National Fuel Gas Code (ANSI Z223.1/NFPA 54) to specify that exhaust and transition vents shall not be constructed of coiled-wire foil or plastic material and that vents be installed in accordance with the clothes dryer manufacturer’s installation instructions. AHAM recommends that clothes dryer vents be constructed of rigid sheet metal or corrugated semi-rigid sheet metal material.
http://www.aham.org/ht/a/GetDocumentAction/i/859


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