[laxdad]

i have a contiuous clogging problem with 4 inch dryer vent. 10 feet vertical and 20 feet horizonal to the wall cap with most of this in the attic. someone recommended i increase the pipe to 5 inch, use 2 45degree elbows in place of a 90 and insulate the pipe with foil faced duct wrap. is this a good idea? will it be of any benefit?

 

[Red Squirrel]

Do you have some kind of booster fan on that? 10 feet seems long. It may be clogging as the air is not moving at a high enough pressure to push any lint away. Also this is solid pipe I hope?

 

[laxdad]

yes soild 28 gauge pipe, no booster fan. i cannot find any info on running this pipe in an attic good or bad.

 

[Ironlight]

Where does the clog form, how long does it take to build up, and what have you been doing to unclog it to date?

All three of those changes will help. If you live in a cold area then insulating the duct will definitely help. Right now, as the warm humid air goes along the duct in the cold attic moisture is condensing along the inside surface of the vent and catching lint. Bigger diameter and gentler bends will be less restrictive.

 

[laxdad]

I am an a/c tech with 24 years. I understand the condensation issue. this problem is in my friends house. a Sears appliance guy told her it was too far of a run. i have found the heaviest lint clogging about half way down the pipe. i wanted to use a r-8 foil faced wrap on 5" pipe to insure minimum condensing. there is no other place to sidewall ventcap other than through the attic. the laundry room is next to the front door leading out to the garage. thanks for you time! - Bowie, Maryland

 

[Red Squirrel]

Oh definitely need insulation on that pipe. I just assumed it would be insulated. That may or may not solve the clog issue, but it will solve potential issues that you may not even be aware are happening, such as condensation and water dripping. Maybe not enough to damage anything but over time it will.

And yeah I'd add a booster. Look at one that is designed to withstand decent heat. I find the centrifugal inline fans you see for bathrooms are very powerful, though not sure how good they would be in a heat application. I have one with a duct run that is a good 12 feet with bends all over and it makes the shower curtain move when I close the door as it's sucking air from the furnace vent as makup air. Very powerful units.

 

[Jacques]

So you have 40' of venting. but since most of it is a straight run only 2 90's. i think your problem, as was said, is due to moisture. is the hood closing? no screws connecting vent sections? attic ventilated properly?

 

[Marty S.]

All ducting in unconditioned spaces has to be insulated. Residential driers have a max vent length of 25' including elbows so you're looking at installing a booster fan.