A dryer exhaust is being vented up through the ceiling, attic, and roof.
Apparently, local code requires that this vent be rigid (as opposed to flexible). However, making the final connection to the dryer is proving to be fairly difficult given the space constraints of the laundry area.
My question is: does code demand that the ENTIRE LENGTH of the exhaust line be rigid, or is it OK to use flex line within the finished area of the laundry room and just use rigid through the attic space?
I know that it all comes down to what the inspector says, but I was wondering if anybody had any direct experience with this.
Thanks in advance.
Replies
Personally I have almost always found it necessary to use flex right at the dryer.
Once I know I didn't I had a custom made boot made for a stacked unit.
Leaving the flex entirely exposed seems as if it should fly.
You can get an adjustable sliding metal connection.
http://repair2000.com/ventkit.html#peri
But with my one experience with them you still need to be able to access the dryer from the side to keep it aligned when pushing it back.
And I suspect that the tight turns would reduce the air flow.
Personally I think that a SHORT piece of expanding METAL duct is better.
Speically if you use a dryer box.
http://dryersolutions.com/
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I just put in rigid for a long run outside that might get some abuse. I used 4" pvc drain pipe. Behind the dryer I used alu flex. The inspector should be fine with flex behind the dryer.
i've been told pvc is a no no. it can build static elec. and start a fire with the lint.just something to check on. larryif a man speaks in the forest,and there's not a woman to hear him,is he still wrong?
I can see how that would come up but I don't buy it. I installed a duct system for my shop with pvc. They recommend having a ground wire wrapping the outside of the PVC and connecting to each machine and the dust/chip collector. I did that for the shop system but for the clothes dryer?
If it builds up static when it is drying clothes can I walk up to it and get a zap? I should be able to. Or is the static build up just inside the PVC tube? I just don't buy it. Maybe I'm wrong.
I have seen static build up on high speed conveyer systems. We were running plastic wrapped CDs, cassettes, and videos down the conveyer. The plastic on the packages ( the kind that are real hard to open ) was the culprit. One conveyer went up an incline and then another was level. Right where the transition happened the boxes were doing wheelies. We had to set up a high speed camera to see it.
All we did was attach ground wires from the frame to the floor. The static was gone.
Edited 12/2/2007 9:52 pm ET by popawheelie
With a dryer the air is way to moist to allow any static buildup.The real problem is that if you have a fire from the dryer the plastic will generator too much smoke and contribute to the fire..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Code here is, gas must be metal. I've seen some use that aluminum foil like coiled stuff. I doubt that is going to help much in a dryer vent fire.
Run ridged as much as you can, you can buy 5 ft sections. Use foil tape on the joints. In unheated spaces wrap it with insulation. Keep the run as shot and straight as possible and make it so it can occasionally be cleaned.
Don't use plastic!
What always passes here is all I can comment on.
Dryer venting - must be full sized defined as "whatever size comes out of the dryer" - can oversize if you want.
Rigid metal piping inside of walls, aluminum or galvanized - no screws - metallic tape on all joints. Can get a little tricky supporting a vertical run to the roof deck - external clamps to brackets to framing.
Metal flex is fine for less than 5' provided it is exposed and can be serviced - like from the wall to the dryer or in an attic. The funny plastic wrapped wire "pipe" is frowned upon for electric, not permitted for gas.
They will also permit a short 3' or 4' length of metal flex below the roof jack to allow easy cleaning of the vent screen.
Insulation around the pipe through the attic is a nice idea but not required.
Same rules / requirements for gas or electric dryers.
Jim
Thanks to everyone for their responses -- it's helped a lot.
Since I forgot to mention it in the initial post, it's an electric dryer.