# dryer vent



## tazmanian (Jul 22, 2010)

anyone been called to look at a dryer vent that leaked into the ceiling?
How does water get into the dryer vent and how to fix it.........?
I am perplexed but have some basic answers to myself and want to see if they are good?!?!?!?!?!?


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## rselectric1 (Sep 20, 2009)

Metal vent?

If so the warm moist air inside coupled with potentially cold air on the outside can cause this.

There are other things, but I've found this to be the most common and has always been solved by insulating the vent completely.


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## ohiohomedoctor (Dec 26, 2010)

Rselectric is 100% right on. It is one one the most overlooked items in track home building. In my area almost every newer house has small water stains in 6' increments because of poor rim joist insulation and 0 vent pipe insulation. Tape and insulate all pipes every time. It's more than worth it and is an easy up sell that separates you from the guys who don't even understand the concept.


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## Seven-Delta-FortyOne (Mar 5, 2011)

There is also the (slim) possibility that wind-blown rain is entering through the vent cap, especially if it is missing. I went into an attic the other day because a bath fan was not operating properly, and I poured 4 gallons of water out of the duct.

Then I raised the duct work up so it sloped to the exterior.


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## ohiohomedoctor (Dec 26, 2010)

A.T.C. said:


> There is also the (slim) possibility that wind-blown rain is entering through the vent cap, especially if it is missing. I went into an attic the other day because a bath fan was not operating properly, and I poured 4 gallons of water out of the duct.
> 
> Then I raised the duct work up so it sloped to the exterior.


Was that flex pipe, or was it the most waterproof silver tape job ever? Was it the vinyl shutter type wall vent cover that is sold in the $17 all in one kit? I have always been wary of those..


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## Seven-Delta-FortyOne (Mar 5, 2011)

It was actually rigid pvc, with a piece of flex to connect it to the fan. But, yeah, it was that cheapo vinyl shutter thing on the outside. I like to install those hoods.


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## Tom M (Jan 3, 2007)

IMO I think something like what ATC said about exterior water getting in and the pipe being pitched backwards.

If there were condensation it would only be very brief and any dampness it created would not likely build up enough stain.


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## tazmanian (Jul 22, 2010)

thank you one and all i see i have to do what all of you have said to get this under control
i do not think it is a big deal but will take it on with gusto and make it work.........................
thank you again and thank you for all being here when i turn here in need


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## robert c1 (Mar 11, 2007)

How long is the run? 

If the vent has a long run and a low point in the middle you can guarantee it will fill up with water (or leak out). 

A dryer load of clothes can easily send a gallon of water through that vent. It's pretty simple from there: If it's able to cool down it will return to a liquid state and flow downhill!


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## Cmpletehomeserv (Jan 12, 2010)

How about a bird's nest? haha! Yep... actually did a repair for this!

The Owner noticed a wet spot forming on the great room ceiling... We took out a small section of drywall and discovered the dryer vent (cheap plastic of all things) had a hole in it, and there was a birds nest in there.

We replaced the vent with metal, and installed an inexpensive "vent cover" cage thingy on the exterior. 

Repaired drywall, and painted the ceiling. 

Turned out to be a fairly expensive "pest problem"! 

Bob


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## Tower (Nov 3, 2011)

I've actually seen a properly installed, insulated flexible duct leak as well, the screen was plugged at the vent. This in turn didn't allow any airflow to escape and it ended up coming back down in liquid form to the low point, luckily in that situation it came out on the garage sheathing and not finished drywall.


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## TNTRenovate (Aug 19, 2010)

Tom M said:


> IMO I think something like what ATC said about exterior water getting in and the pipe being pitched backwards.
> 
> If there were condensation it would only be very brief and any dampness it created would not likely build up enough stain.


Condensation is not brief and can build up in great amounts.

I had an exhaust fan vented directly above the AC condenser. Hot air was forcing the dampener open and warm moist air into the vent pipe. It was flexible metal pipe. With the AC running all the time the hose and metal fan housing were very cold causing a huge amount of condensation. Water was dripping out of the fan and when I pulled it down there was at least a quart of water in the housing alone.

I just had an attic fan that was poorly installed and went up into the attic a few feet and then back down the to a soffit vent. The soffit vent was forcing the bathroom vent air back into the attic. The attic had visible water on the rafters, there were several around the area that were stained and black mold every where.

And finally we had one a few weeks back that was blocked by a birds nest and was causing the moist air to build up condensation in the poorly insulated chase.


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## mrmike (Dec 9, 2008)

robert c1 said:


> How long is the run?
> 
> If the vent has a long run and a low point in the middle you can guarantee it will fill up with water (or leak out).
> 
> A dryer load of clothes can easily send a gallon of water through that vent. It's pretty simple from there: If it's able to cool down it will return to a liquid state and flow downhill!


This is right on. The builder installed a "cheap" 50 cfm fan & run the vent 40 to 60 ft to vent it out. And what happens is like said above !!
I have had to change the fan to a higher cfm or re-route the vent.


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## Tom M (Jan 3, 2007)

I never see vents longer than 12-15 ft and I rarely encounter ones traveling through adjacent. Unless there is a booster. I thought the max used to be 25 ft with deductions for 45's or 90's. 
Certainly have seen a few birds nests though. Unless its a bad location like TNT said I bet the pipe is disconnected in the ceiling somewhere and the there is a lint build up.
Hopefully he will follow up for us.


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## mrmike (Dec 9, 2008)

Tom M said:


> I never see vents longer than 12-15 ft and I rarely encounter ones traveling through adjacent. Unless there is a booster. I thought the max used to be 25 ft with deductions for 45's or 90's.
> Certainly have seen a few birds nests though. Unless its a bad location like TNT said I bet the pipe is disconnected in the ceiling somewhere and the there is a lint build up.
> Hopefully he will follow up for us.


I just used 40 to 60' as an example, but I have encountered them up in a condo up here in the north, where anything goes:laughing: 
But This is the problem I see the most for water coming back in, because of the "cheap" fan & a long run & the fan does not sufficiently do its job..............


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## Gary H (Dec 10, 2008)

We have many houses in my area that the fans are vented in the soffit. But instead of putting 3 to 4' of solid either way of the vent , all eves are all vented soffit. Which thens blows or gets sucked into the attic. And then rots out the eves and soaks up in the blown cellose.


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