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Dryer vent condensation

Posted by psyblade (My Page) on
Sun, Aug 11, 13 at 11:36

OK. Water is building up in my dryer vent. I did not install this. The dryer is in an interior space in the finished basement which is the coolest part of the house. Metal flex comes out of the driver and bends 90d, runs on the floor for 3 ft, bends 90d and goes up a wall 3 ft, bends 90d and goes into a wall. I can�t see from here for 5-8 ft, but it must bend 90d and go up a wall to the ceiling for 4 ft and somewhere in here it changes to white plastic flex. Then it bends 90d and runs across the ceiling for 14 ft with another 90d bend in the middle where it crosses an I beam. Then it bends 90d and heads to the outside wall vent for 11 ft. The total is about 35 ft and seven 90d bends. I figure about 10 ft metal flex and 25 ft plastic. The metal and plastic flex tubing is 4 in in diameter.

About the 26 ft mark, where the plast runs across the ceiling along an I beam where our hot water heater is, there is a plastic T that I can access and loosen the clamps and check the plastic tubing. From this T, it rises slightly (about 3-4 in over about a 2.5 ft length) before making the 90d bend towads the outside wall. Water is condensing between this T and the 90d bend. I just noticed this the last couple of weeks, but suspect it has been an issue longer than that because the clothes have been harder to dry the longer we are in our weekend washing/drying process. When I first noticed the water, the tubing was sagging and may have been virtually full of water because a lot poured out. Since then I have been trying to drain it once a week or so at the T. I notice no lint clogs anywhere and water only between the T and the 90d bend heading to the outside wall. There might be 1/16th or 1/8th of lint along the plastic flex tube.

Is there anything I can do to stop the condensation short of tearing out the entire venting and redoing it with fewer 90d bends? Would even that fix the problem


Follow-Up Postings:

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RE: Dryer vent condensation

I don't know what part of the world you are in but condensation usually comes from a large variation of temperature inside vs outside of the pipe. Is there any area like that where the pipe goes through?

I would probably replace the line because where you used to have water usually turns into moldy surfaces. I would check the entire line for mold.

Does the exit for the exhaust pipe on the exterior of the house have a flap on it? That could prevent cold air from getting into the exhaust.


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RE: Dryer vent condensation

How old is the dryer and have you ever popped the cover to clean all the lint out of it? How long has this water thing been going on for?


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RE: Dryer vent condensation

Dryer is about 10 years old. We have cleaned it within the last couple of years, but I see not blockages or problems at the dryer. The exterior flap is a louver system and some air comes out the end, but not tons, the louvers are not fluttering out horizontal at all. As for how long this has been going on, we just noticed the actual water issue the last couple of months, but I suspect it is the reason for our off and on dryer problems over the years. The basement is pretty constant in temperature I think. I think the hot air just naturally cools over the length of the duct.


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RE: Dryer vent condensation

Is 35' really the shortest possible route to outside access? If not, revise the entire configuration to an alternate path.


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RE: Dryer vent condensation

Duct should be ridged ducting. I have a pdf file that I saved and it is from "Hardin County Planning and Development" who ever they are. any way I will pull several quotes from that artical:

1) 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. The entire exhaust system shall be supported and secured in place. The male end of the duct at overlapped duct joints shall extend in the direction of airflow. Clothes dryer transition ducts used to connect the appliance to the exhaust duct system shall be limited to single lengths not to exceed 8 feet and shall be listed and labeled for the application. Transition ducts shall not be concealed within construction.” [Note: Once they pass through a wall, floor or ceiling the code determines the duct is concealed and must be an “exhaust duct” and not a “transition duct”.]

2) Transition Duct Connectors. (IMC 504.6) specifically addresses transition duct connectors. “Within the context of this section, a transition duct is a flexible connector used as a transition between the dryer outlet and the connection point to the exhaust duct system. Transition duct connectors must be listed and labeled as transition ducts for clothes dryer applications. Transition ducts are currently listed to comply with UL 2158A… Transition ducts are metalized (foil) fabric supported on a spiral wire frame. They are more fire resistant than the typical plastic spiral duct. Transition duct connectors are limited to 8 feet in length and must be installed in compliance with their listing and the manufacturer’s instructions. “These duct connectors must not be concealed by any portion of the structure’s permanent finish materials such as drywall, plaster paneling, [e.g. flooring, ceiling, wall], built-in furniture or cabinets or any other similar permanently affixed building component; they must remain entirely within the room in which the appliance is installed (Section G2439.5, International Fuel Gas Code, Chapter 24, 2006 IRC).”

3) Maximum Length. (IMC 504.6.1) “The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet from the dryer location (the point in the room containing the clothes dryer, where the exhaust duct starts at the wall, floor or ceiling opening) to the outlet terminal (the point at the immediate exterior of the house where the dryer exhausts ends with a backdraft damper to the outside). The maximum length of the duct shall be reduced 2 ½ feet for each 45 degree bend and 5 feet for each 90 degrees bend. The maximum length of the exhaust duct does not include the transition duct.”


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RE: Dryer vent condensation

SInce you said "some air" comes out the exterior end of the vent I'm willing to say that you may have a partial blockage in the vent line. This would result in the hot moist air being stuck in the vent and when it cools it produces moisture or water.

I agree with Enduring. See if you can find a shorter route to the outside.


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