# Exterior Dryer Vent Question



## jibe (Feb 24, 2009)

Currently my dryer is vented out a basement window. I want to replace the window and vent the dryer through the rim joist to the exterior. It seems like a simple job, but I am wondering if all exterior vents are created equal? Any point in spending more money on a better vent?


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## fossil (Feb 24, 2009)

Going out through the rim joist with a dryer vent is very common.  I wouldn't think you need anything special, just something with a check valve flap and a critter screen.  Off the shelf pretty cheap.  Plastic housing and a length of aluminum vent pipe.  Housing can be painted with any paint suitable for plastic, if you want to change the color of it.  Rick


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## John_M (Feb 25, 2009)

I second what Fossil said. However, while at my local lumber yard/hardware store purchasing materials for the new hearth, I noticed a heavier duty version of the standard 4" dryer vent. It also seemed to have a larger hooded opening to allow more air to pass. It cost about twice what the typical plastic hooded dryer vent cost but I thought it was worth the difference so I purchased it. 

Am happy I did so.  John_M


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## TreePapa (Feb 25, 2009)

I went with a louvered vent similar to this one

http://www.lowes.com/lowes/lkn?action=productDetail&productId=294823-131-1424W&lpage=none

'cuz the vent come out my garage wall near a walkway and I didn't want the sharp pointy hood sticking out for folks to bump themselves on. Since it exits an unfinshed garage wall (i.e., no plaster, drywall, etc. inside), the install was easy. Can you route the vent through the basement wall? Or is that masonry?

In my case, the dryer used to vent into the garage. What a mess.

Peace,
- Sequoia


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## DBoon (Feb 26, 2009)

I would get one with a built-in bird screen - you don't want a nest in a hot dryer vent pipe.  Also, use rigid metal pipe - no plastic and no flexible pipe.  Plastic accumulates lint due to static charge and is not allowed by most codes.  Sure, the flexible pipe is easier to install, but it also reduces airflow quite a bit compared to the rigid pipe.  Avoid 90 degree bends - use two 45 degree bends instead.   The only 90 degree bend in your setup should be the one coming out of the dryer and running to the vertical pipe behind your dryer.  Don't use flexiible pipe for that either - a 90 degree rigid bend is at most $6-7 - well worth the cost. 

One last tip - when you cut the hole you are going to need a 4" hole saw and a 1/2" drill to have enough torque to get through the rim joist.  However, you can not imagine the torque that a 1/2" drill generates until a 4" hole saw catches in the rim joist and stops.  If you are standing on a ladder when that happens, you will likely be tossed off the ladder.  I speak from experience , so be careful.


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## John_M (Feb 26, 2009)

Follow-up to Dboons comments. 

1) Last week I asked a younger and stronger friend to drill a 4 1/8" hole through two layers of 3/4" Advantec on top of my elevated hearth. I provided a 4 1/8" Lennox hole saw and a 1/2" Milwaukee right angle drill w/extensions for him to use. He smartly decided to use a very slow cutting speed. After about 5  seconds the hole saw grabbed with all teeth and created incredible resistance. The torque of the drill almost threw him off the 12" hearth. We ended up using a Makita 18 volt cordless drill. It had less torque and took a little longer to drill the hole but the work was more controllable and much safer. 

2) I would recommend using a hole saw slightly larger than 4" if you have one. It is much easier to get 4" aluminum dryer vent through a 4 1/16" or 4 1/8" hole than through a 4" hole. 

3) I believe his comments about the various kinds of pipe are significant to achieve the least restrictive air flow. I am not certain the flow of air through corrugated pipe is quite the same as the flow of water through corrugated hose. If the two are similar, here is something to consider: In choosing hose for bilge pump use in boats corrugated hose can reduce the flow of water by as much as 30% compared to hose with a smooth inner wall. If the same applies to the flow of air, the 4" flexible corrugated vent pipe is really allowing a much smaller amount of air to get to the stove. Is the area of a circle A=pi x r squared? Do the math.

4) Use the very available tin foil kind of tape to seal all pipe joints. This tape is made just for that application. It lasts a very long time and is not easily removed. 

John_M


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## jebatty (Feb 27, 2009)

Leave at least 2" of solid wood at the top and bottom of the joist, that is, cut the hole in the middle of the joist.


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## Redox (Feb 27, 2009)

Skip the bird screen: it will just clog up with lint.  A backdraft damper will keep the critters outdoors.  Do not use screws to hold the ductwork together; they also form little lint catchers.  Solid pipe is hard for lint to stick to.

Chris


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## velvetfoot (Mar 5, 2009)

I drilled a hole through the siding in 2006 and replaced a 15' hose that went down to the basement and out through the rim joist with a 1' piece of pipe (the dryer is on an outside wall and I got the kit for the dryer to vent on the side).  I put some fiberglass insulation around the pipe and got a good outlet vent (not the louvers) - one that had a cap that positively covers the vent.  It's been quite warm.  Even opening the door when the dryer has been off it's not cold.  The clothes dry quickly too.


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