Clothes dryer vent opinion

[Mark P]

What is your opinion of a clothes dryer that has a section of vent that runs straight up into the attic? The house I did yesterday was set up as follows. Dryer is located in 2nd floor closet. The vent runs straight up (around 4’) into the attic and then turns and runs at a downward slope (around 12-15’) to the exterior wall and outside. There are 2 90 degree turns not counting the transition. I know what the IRC says and I understand the numbers. I’m just wondering what others think about the vertical section and what you would say in the report if anything. I think I’m going to place something as follows in the report.

“Your clothes dryer vents runs up into the attic where it turns and runs above the master bedroom ceiling and outside by the chimney. There are 2 90 degree turns in the vent. This set up may allow for lint to build up which creates a fire hazard and increases dry time. My recommendation is as soon as you move in use a leaf blower to blow out the vent, from the inside, and do this every 6 months. I also recommend you contact the manufacture of your dryer to obtain their venting instructions.

General practice is that the max the maximum length of a clothes dryer exhaust duct shall not exceed 25 feet from the dryer location to the wall or roof termination. This length is reduced 2.5 feet for each 45-degree bend and 5 feet for each 90-degree bend. This does not include the transition duct. The exception to the practice is when dryer manufacturer’s installation instructions permit something different.â€

[Darren]

From your last picture, it looks like the vent system is or was leaking (see all the lint).

I wouldn't recommend how it gets cleaned, just that it does get cleaned.

Darren

www.aboutthehouseinspections.com

[SonOfSwamp]

Any reason to think a leaf blower will clean out a dryer vent? My unscientific guess is that it wouldn't work at all. Or, if, say a nuke-powered leaf blower moved enough air to blow out lint, it might move enough air to blow out the taped joints and make a giant mess.

Anyhow, when our dryer vent needs cleaning, we take it apart and clean it by hand, kinda like a chimney sweep might clean a flue. If we're feeling a little lazy, we call the appliance shop and have them send over a guy to do it. Costs about $200.00.

Maybe it's just me, but I don't think an HI should be telling a customer to take a leaf blower to his dryer vent. Sounds a little folklorey to me.

I say tell the customers to call an appliance tech to fix the vent, per the dryer manufacturer's specs. That way, the customer has the proper instruction, which no sentient being could misunderstand.

WJ

[Ken Meyer]

Why not just run it out through the roof at the first elbow in photo #2?

[Mark P]

Okay Walter, Good advice and I agree w/ you 100% and to boot you did not even annoy me this time. Thanks. [^]

[Neal Lewis]

My dryer installation instructions state that a smooth wall 4" vent can be used up to a length of 65 feet.

Some townhouse complexes require annual dryer vent cleaning. The method of choice for the company hired to do the cleaning? Leafblower. Heard this several times.

[dbyers]

This site has a list of vent lenghts for various manufacturers:

http://www.appliance411.com/faq/dryer-vent-length.shtml

I'd recommend upgrading by insulating the vent in the pictures.

Dave

[Mark P]

Originally posted by dbyers

This site has a list of vent lenghts for various manufacturers:

http://www.appliance411.com/faq/dryer-vent-length.shtml

I'd recommend upgrading by insulating the vent in the pictures.

Dave

Thank you, that looks like a useful site.

[jon_ran]

My understanding is the following:

25' is the max length.

You subtract 5' for every 90 and 2.5 feet for every 45.

Transition at the dryer does not count as a 90.

25 feet - 15 (horizontal run) - 4 (verticle rise) = 6 feet

6 - 10 (2 90's) = -4 (or 4 feet too long)

If the horizontal run is 12', you are still 1' too long.

I would call it out for improvement, but I don't think that the extra length is siginifigant and wouldn't make a huge deal over it.

However, it will accumulate lint more quickly due to it being in an unconditioned attic. Condensate will form on the inside of the pipe and attract the lint. It shouldn't plug as quick as the white flex vent in the 2nd picture, but it will need regular cleaning.

I would recommend replacement of the foil vent (from the dryer to the pipe) with a flexible aluminum pipe.

[Mike Lamb]

You could try this but its too many words.

"The set-up for the clothes dryer venting is horrible. The proper venting of water, lint and other gases will be nearly impossible. This is a moisture, mold. fire and CO hazard. Plus it may take forever for your clothes to dry. Consult anyone but an architect (who decided the laundry room should be in the middle of the house) or a clothes dryer installation professional (who, if they could read directions, would be teachers)."

[John Dirks Jr]

Originally posted by Ken Meyer

Why not just run it out through the roof at the first elbow in photo #2?

Roof vents of any kind are among the more common points for leaks to develop. Whenever possible, it's best to avoid punching holes in the roof.

[hausdok]

Originally posted by AHI

Roof vents of any kind are among the more common points for leaks to develop.

Really?

That hasn't been my experience.

OT - OF!!!

M.

[Mike Lamb]

Going straight up through the roof is probably the best that can be done here short of moving the laundry to an outside wall. There are roof vents designed for this bad idea.

Leafblower? There's a whip tool with a brush at the end that can be hooked up to a drill.

http://www.woodlanddirect.com/Chimney/D ... rce=nextag

[chrisprickett]

I use a shop vac. My ducting goes up 9' thru an interior wall and over 15' thru a first floor ceiling. Theres no way to get to it. I carefully feed the 12' vac hose (no attachements) from both ends. Works like a charm.

[hausdok]

Hi,

A few years ago, I took a cheap pipe snake and attached a 4 inch bench grinder brush to the end and used it to clean a vent by pushing the snake through the vent first and then pulling the brush through the vent. It was a snug fit and it practically polished the sides of that vent. The trick was getting the snake through the duct in order to get ahold of it. Getting around the corners required some twisting and jiggling back and forth.

I see dryer vents straight up through attics around here a lot. they seem to work just fine when the installers are clear headed enough to use smooth-walled ducting and don't install an outlet with screen over it. However, there seem to be a fair number of installers out there who don't realize that installing an outlet with a screen on it isn't very smart and I often find those clogged solid at the terminus.

OT - OF!!!

M.

[dbyers]

Originally posted by hausdok

I see dryer vents straight up through attics around here a lot. they seem to work just fine when the installers are clear headed enough to use smooth-walled ducting and don't install an outlet with screen over it. However, there seem to be a fair number of installers out there who don't realize that installing an outlet with a screen on it isn't very smart and I often find those clogged solid at the terminus.

OT - OF!!!

M.

Yes, dito on this. The sad thing is that dryer roof jack exhaust hoods are made and sold with screens installed. Also, most of these have smaller mouth, 12 sq inches or less. There are large mouthed dampered mouths available for roof dryer vent terminations. Now wouldn't it make sense for sidewall terminations to use larger hooded or plastic dampers (lint collectors), even if a 4-6" vent reducer would have to be fitted, given the safety nature here.

[mark40511]

My laundry room is in the center of the house (single story) and vents through the room. Straight up about ten feet, then 45 degree turn then another ten feet and a slight turn as it goes out the roof. The roof cap did have a screen and it did get clogged. I climbed on the house (steep pitch) scary and took the screen off. I have great success with an electric leaf blower. My clothes are dry anywhere from 38 to 45 min's. Perhaps slightly longer for heavy full loads like jeans but not much longer.

[mikes334]

Sounds like a normal dryer.