# Condensation accumulating in dryer vent.



## luckie_reubs (Dec 30, 2008)

Our W/D is on an interior wall of a single story house. The house is on concrete slab for foundation.

Recently we noticed that the dryer was taking longer to dry, and I discovered that there was a water build-up in the actual vent line. Ultimately, I had to run a plumber-snake from the outside vent to the inside starting point, duct-tape a towel to the end, and then pull the towel back through to absorb the water.

The dryer is now working better, but I fear that this was condensation and not rainwater (I assumed rainwater initially b/c one of the flaps on the dryer vent was missing and we've just experienced lots of rain). 

Does anyone have a solution to this problem, or am I stuck with the snake and towel method until we move to another house after we outgrow this one?


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## yuri (Nov 29, 2008)

Is it a gas dryer? They may give off more moisture than an electric. Try phoning some appliance repair companies in your area and see if other people have the same problem/ask them for advice. Don't know where you are but if it is very humid then that may contribute to the problem.

Good Luck


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## luckie_reubs (Dec 30, 2008)

We're in south Alabama, and no, it's an electric dryer. Thanks for the info; I was just curious if there was anything I could do myself, or if anyone had any suggestions.


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## hvaclover (Oct 2, 2008)

How is the dryer vent run?


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## luckie_reubs (Dec 30, 2008)

The dryer vent is run underneath the house through the slab (I assume). One thing I do know, though, is that the vent does not go directly outside. It goes about 30 feet from the point of origin to the point of exit. I just noticed about 20 minutes ago that I'll have to do the same procedure again in order to avoid running numerous dryer cycles. Thanks for any info!


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## hvaclover (Oct 2, 2008)

Your getting ground water seeping in.


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## Chemist1961 (Dec 13, 2008)

*Check for Blockage also*

Just puzzled here by your comments about loads still taking longer to dry. While I understand the issue with moisture in the pipe, I would approach that by replacing the existing vent with one with a weighted damper. 
However if your dryer is running longer cycles in AUTO mode, you may have a secondary issue beyond the moisture in the vent. My dryer senses humidity in Auto mode.
If you have a partial obstruction in the exhaust of the dryer, humiditiy could also be building in the pipe at the blower within the dryer from lack of air flow as well as in the within dryer drum delaying the normal cycle shut off time.
Several years ago I had this problem when one of my kids pulled the lint screen and dropped fabric softener sheets into the lint trap area. We didn`t see them and put the screen back at the bottom of the drier door area. The blower sucked them into the exhaust pipe in the base of the drier and the blockage caused the drier to run continually for several hours in auto mode due to humidity staying in the drier.
When we switched to manual timed cycles the issue continued. The drier built heat, but the loads still weren`t drying properly. I cleaned out half a box of fabric sheets in the pipe and a ton of lint as well and the drier was fine after that.


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## luckie_reubs (Dec 30, 2008)

Chemist: thanks for the response; hvaclover: I hope not; previously the water was clear, thus my assumption that it was condensation. I also checked the water meter, and there's no indication that there's a leaky pipe anywhere. Chemist: after clearing the water out on Sunday via siphoning and then a plumbing snake, the dryer ran beautifully. Tonight, I heard the sound of lapping water again, so I went back out with my hosepipe to start siphoning again. I don't think there's a blockage in the vent line b/c I ran a snake and a towel through on Sunday night with no problems. Tonight I shortened the vent connector (I don't know what it's called) that goes from the dryer exhaust to the vent line, and I pulled the dryer away form the wall. There is currently no binding at all in the vent connector, so air should be able to flow out easily and unimpeded from the dryer to the vent line. I'll keep an eye on out, and I'll post back. Thanks again for your help, and please let me know if there's any other info needed! BTW, Happy new year!


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## hvaclover (Oct 2, 2008)

Slabs hold water and if you have cold winters the heat from the dryer can melt FROZEN GROUND WATER. Ground water does not have to dirty.

I have serviced enough in-slab ducts systems that act exactly as you describe. Some times it was a high water table. Sometimes a leak before the water meter so it would NOT register on your water meter.

Also possible to be on your meter side if the leak is too small to register mass flow.

My thought are NEVER SAY NEVER just solve it.


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## luckie_reubs (Dec 30, 2008)

hvaclover said:


> Slabs hold water and if you have cold winters the heat from the dryer can melt FROZEN GROUND WATER. Ground water does not have to dirty.
> 
> I have serviced enough in-slab ducts systems that act exactly as you describe. Some times it was a high water table. Sometimes a leak before the water meter so it would NOT register on your water meter.
> 
> ...


 Thanks for the information. This is a 10 yr old house that we just purchased in Sept. 08. Is this something the inspector should have noticed or something that should have been pre-existing to this point? I know a few homebuilders in the area, and I'll chat with them about who to find in town to service this thing. Thanks again!


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## gregzoll (Dec 25, 2006)

Can you run it up, and place a Roof Dryer vent on the roof, and vent up, not down through the slab? That may be the better solution at this point.


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## 2G's (Mar 7, 2009)

*Same Problem*

luckie_reubs,

Would be interested if you discover a solution. I have exactly the same problem you describe. In fact, I live in a relatively new townhome community (3 years old) and approximately 6 of 22 units have the same problem. All townhome units are on concrete slab, and the dryer exhaust travels either through or below the slab some 15 to 35 feet depending on the unit. Several of us began noticing a musty smell coming from the lint vent in the dryer, and clothes taking too long to dry. After further inspection, we all had condensation build-up in the exhaust pipe; some with significant water build-up that was wet vac'd out. One of the affected owners bought a new dryer with increased blowing power. He claims the increased air-flow power keeps the condensation from building up. I have been looking into a "dryer fan booster" but am not sure where I could attach it because our exhaust system is inaccessible underground and the manufacturer says you should not attach it within 15 feet of the dryer; closer to the other end the better. Suppose I could try to attach it to the outside end; but still looking into it. If you discover a permanent solution, please post. Thanks.


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## kenmac (Feb 26, 2009)

Like the other poster said. ground water or condensation build up from that vent being under ground / slab... If possible , Re-rout the vent..I think that will solve your problem


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## diyme (May 30, 2009)

*Solution???*

luckie, 
I know this is an old post, but I found it while trying to fix this exact problem in my house. Did you ever discover a solution?


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## luckie_reubs (Dec 30, 2008)

I still haven't found a solution; sucking out the excess water with a hosepipe has been my solution so far! I'll keep you all posted with what I found out when I do find out something!


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## beenthere (Oct 11, 2008)

Is this a new high efficiency dryer.

Have you replaced the flap on the vent yet.

Is your furnace and or water heater using indoor or outdoor air for combustion.

Does your range hood put your home into a negative pressure when you use it.

Do you have a probe thermometer that you can measure the discarge temp at the dryer vent.


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## kenmac (Feb 26, 2009)

solution would be to find a way to re vent


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## Joe90989 (Jun 2, 2009)

*dryer moisture problem*

My daughter just had the same moisture problem buildup w/in her dryer exhaust and it caused a HIGH TEMPERATURE fuse to blow and that caused the heating element to fail to make heat. 

While buying the replacement part I saw an item on the parts supplier shelf that is a clothes dryer vent booster. It seems that whenever someone has a long span of exhaust duct the velocity might not carry through enough force for thorough enough drying. (That would allow lint and moisture to build up and cause deposits on the duct lining.) 

The parts man said that the reason the high temp fuse blew was because of too much moisture and back pressure. The fuse is there to protect the heating element from over heating and burning out as well as to protect the unit from catching on fire. That blower assist was by Deflecto and ran for about $200 here in S.C. (On line they are cheaper!)

The fuse and thermal switch cost about $40. Replace them as a pair at the same time. I didn't buy the blower assist yet but as soon and I install new duct I will.

Hope that helps, Joe:thumbup:


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## jogr (Jul 24, 2007)

Since the water builds back up right away then Hvaclover has to be right. If it was me I'd be looking for a shorter route out for the vent that wasn't underslab. Make sure it doesn't have any traps (low spots or dips) in it because eventually they will fill with condensation.


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## pelsmith (Sep 7, 2010)

*My solution*

I had the exact same problem: water was seeping into my dryer exhaust underneath my slab foundation home. I was also using a pipe snake with a towel taped to the end. It was getting old.

My solution:

Buy one of those gallons of weed-killer with the pull pump at the end of the nozzle, the kind where you don't have to constantly squeeze the trigger to spray the weed-killer. Go kill some weeds with it. Then, take the pump handle and its attached hose off. Tape a nail to the end of the hose for weight. Drop it into the dryer exhaust. Use it to pump the water out of the dryer exhaust.


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## seadub2 (May 17, 2012)

*Common problem with long UG vents*



hvaclover said:


> Your getting ground water seeping in.


I respectfully disagree. This is not a seepage problem. The problem is a simple matter of physics. I have this same problem and am currently working on a solution.

The problem is built in to the design of the vent system. You have a long tube buried in the slab, under the home, where the temperature remains cooler than ambient. Your dryer dries clothes by heating the fabric, causing the saturated water to evaporate and mix with the hot air blown into and out of the dryer chamber. That evaporated moisture has to go somewhere - it's pumped out of the drying chamber by the blower, out of the dryer through the dryer exhaust. 

This hot, moist air enters that long cool tube where, just like atmospheric humidity condensing on a cool glass of water, the moisture in the exhaust air condenses on the walls inside the tube. After time, the water builds up in the tube, eventually flooding it. Remember, a full load of wet clothes can contain a gallon or more of water! 

The symptoms of longer than normal drying times is due to the inability of the moisture to exit the dryer chamber. Not only is this aggravating, but it's also dangerous. Since the moisture has nowhere to go, it beings to accumulate in the dryer exhaust flex tube, flooding it, and possibly creating an electrical hazard. 

What to do about it? Well, re-working the vent is the best option. Since hot air wants to rise, the best option is to vent the dryer out though the ceiling and through the roof. 

I don't know yet what we'll do, but I do know what we won't do. We won't use a booster blower, 'cause there's no place in line to install it. Putting it at the dryer connection is akin to trying to get a good picture out of a bad negative. Garbage in, garbage out. There's still the issue of the moist air condensing in the tube. 

I will post as we work through the problem. 

Thanks....


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## hvaclover (Oct 2, 2008)

seadub2 said:


> I respectfully disagree. This is not a seepage problem. The problem is a simple matter of physics. I have this same problem and am currently working on a solution.
> 
> The problem is built in to the design of the vent system. You have a long tube buried in the slab, under the home, where the temperature remains cooler than ambient. Your dryer dries clothes by heating the fabric, causing the saturated water to evaporate and mix with the hot air blown into and out of the dryer chamber. That evaporated moisture has to go somewhere - it's pumped out of the drying chamber by the blower, out of the dryer through the dryer exhaust.
> 
> ...



After mulling it over I concur 100%. My head was in my back pocket due to health problems back then. So I agree with you whole heartedly.


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## Tom Struble (Dec 29, 2008)

how do you clean your dryer vent outlet on the roof:huh:,you will have lint sticking all over the shingles


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## seadub2 (May 17, 2012)

*Don't know*

Good question. Easy answer is I don't know! But that is something to consider when evaluating solutions. 

BTW I contacted a contractor about re-working the vent. I explained our issue and he stated the current vent in our house is not code-compliant in our county. Will investigate and post our findings.


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## luckie_reubs (Dec 30, 2008)

I thought I'd chime back in with my solution, which is that we're moving to a new house. :thumbsup:

Before we made that decision, though, we've just been using a bucket-head shopvac type deal from Home Depot. I think so much of the problem was having a cheap, low-end dryer in an interior room. We've got neighbors who have a newer dryer who aren't having the same problem, and other dryers I've looked at have boasted being able to blow hot air out for a good distance, allowing the dryer to be anywhere in the home.

Thanks for all the good suggestions, and I'm glad these problems will go away when we're able to vent the dryer straight outside in a few weeks.


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## slickshades99 (Dec 28, 2016)

Hello, 2014. This is an old post but it is relevant to me. I have the same problem at my house with the exhaust pipe of the dryer collecting water under the house in the slab. I went to Home Depot and got a small pump that fits on a drill to drain the pipe out. I have to do this at least once a month. I live southwest of Atlanta, GA and it probably has rained here 3 times during 2016. So, I know it is not rainwater coming in. I also live on a hill, don't think it is ground water. 

What I have been working on is making sure the air exiting the dryer has no restrictions. I am a car guy so those who know about turbos can relate to the airflow principles associated with that subject. Since my dryer is in a confined space, I am replacing the metal hose (from dryer to wall) with an aluminium periscope. I hope the smooth metal of the periscope will be more efficient at moving air through the system. The objective is moving the air out faster before it has time to condense. If that works, I am going to help the system out further by replacing the louvered cap at the end of the system with one that has a cage. It is open constantly but has a screen to keep undesirables out. If anyone is still listening to the thread, I hope to return with good news.


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## SeniorSitizen (Sep 10, 2012)

An interesting topic of how builders can be so ignorant. I read all the responses because it somewhat takes the place of the comic strips in my earlier days. No Surprise :surprise:
But it would be more interesting if I could see a pic of how the builder terminated the vent externally because I've retired from pigging pipe lines and maybe I can help with a solution if it was built in a specific way.


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## supers05 (May 23, 2015)

slickshades99 said:


> Hello, 2014. This is an old post but it is relevant to me. I have the same problem at my house with the exhaust pipe of the dryer collecting water under the house in the slab. I went to Home Depot and got a small pump that fits on a drill to drain the pipe out. I have to do this at least once a month. I live southwest of Atlanta, GA and it probably has rained here 3 times during 2016. So, I know it is not rainwater coming in. I also live on a hill, don't think it is ground water.
> 
> What I have been working on is making sure the air exiting the dryer has no restrictions. I am a car guy so those who know about turbos can relate to the airflow principles associated with that subject. Since my dryer is in a confined space, I am replacing the metal hose (from dryer to wall) with an aluminium periscope. I hope the smooth metal of the periscope will be more efficient at moving air through the system. The objective is moving the air out faster before it has time to condense. If that works, I am going to help the system out further by replacing the louvered cap at the end of the system with one that has a cage. It is open constantly but has a screen to keep undesirables out. If anyone is still listening to the thread, I hope to return with good news.


The pipe shouldn't have any dips or sags in it. Since it's in the slab, you probably have no choice about how it's now al oriented. 

2 choices:
- add new exhaust pipe above the slab so that it doesn't sag in spots. The warmer the space that it's in, the less likely it will condensate. 

- run the dryer for a short time sheet each cycle without a load. 10min or so. This will push dry air through the pipe, drying it back out. When done on each cycle, pooling won't be significant. 

Cheers!


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## SeniorSitizen (Sep 10, 2012)

The periscope solution has a couple of strikes against it when it was built. Air doesn't like to turn abrupt 90° corners. That's why turning vanes were developed several decades ago and turbochargers have neither abrupt 90° turns or turning vanes.

My old Maytag likes this setup .:biggrin2:


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