This seems to be a topic skipped in most design books.
Because of length limits I need to run the vent through the slab, but the codes only “seem” to permit a metal duct.
The slab is built up so it would be about 12″ above the ground.
Could I use PVC?
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Replies
That would probably warrant a phone call to the permit dept. Down here pvc is allowed in-slab for jenn-aire cooktop vents, so I would vote yes.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
The craftsman formerly known as elCid
I am googling as we speak and most of the material is vinyl, so I don't see where PVC would not be as good.
Hot Dog! I sound this. Thanks for your help.
Section G2437 (Clothes Dryer Exhaust) is amended by adding section G2437.5.3 to read as follows:
"G2437.5.3 Under slab installation. Exhaust ducts for domestic clothes dryers shall be permitted to be constructed of schedule 40 PVC pipe provided that the installation complies with all of the following:
1. The duct shall be installed under a concrete slab poured on grade.
2. The underfloor trench in which the duct is installed shall be completely backfilled with sand or gravel.
3. The PVC duct shall extend not greater than one (1) inch above the interior concrete floor surface.
4. The joints of the PVC duct shall be solvent cemented."
Hot Dog! I sound this. I sink I unnerstand which you are staying, but of not I'm sore you'll fell me in latter.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
The craftsman formerly known as elCid
Sorry apparently I got to excited :-). It sounded good when I typed it.
Maybe I won't drink as much communion wine next sunday.
P.S. I love your signature text. T. Roosevelt has always been a hero of mine.
Edited 3/14/2004 9:23 pm ET by Kyle
One inch above the concrete? I guess you just run the vinyl flooring up and over it.
There was a thread somewhere about an underslab duct. The owner was having trouble with it filling with water from the exhaust point, even though he had installed some sort of baffle there. I think if you go underslab you want to make sure it's easily cleaned, and maybe pitched somehow so it can drain any condensation that happens.
I believe that inch above is refering to the vertical stand leg, not the horizontal run. They are specifying that for the connections above the slab, you need metal
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You're probably right, but the way it's written immediately led me to think what I did.
filling with water from the exhaust point, The original post said the slab was elevated 12", but you raise a good point.Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
The craftsman formerly known as elCid
I've seen it said that, for some reason, lint collects in PVC worse than in metal. At the very least, if you route through the slab, you'll need to make provision for cleaning via an access pit or some such.
"lint collects in PVC worse than in metal"
PVC, as an insulator, develops a static charges and lint does too. Since those charges are different, they attract. Like that film of fine dust that builds on your monitor screen, but on a larger scale. Metallic paint (grounded to metal duct) on the inside of the PVC would fixed that, but I've only seen that done in more technological and safety conscious areas (wave guides, aviation, fuel tank farms, etc)David Thomas Overlooking Cook Inlet in Kenai, Alaska
Instead of metallic paint, do what some shops do for dust collection...run a bare copper wire inside the duct, grounded at one or both ends.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
The craftsman formerly known as elCid
I do not think that a PVC pipe buried under a slab would be a static electricity problem. While not a super ground in the usual electrical sense you would think it would be enough.
For Ed Hilton:I certainly would not run a wire inside, wrap outside if you feel it necessary. Inside is a recipe for a clog. Remember you are trying to bleed off or prevent rather than clear a fault.
I was one of the ones talking about water in such a pipe. I still have not dug down and checked out my daughter's problem. I believe that they probably just stuck the pieces together or did not worry about get a good solvent weld since it was not carrying water.
I think that if I was doing this I would attempt to use the absolute minimum pieces possible and be sure to reach in (or somehow wipe) and clean each joint on the inside. I would then do a little extra solvent on the outside to make sure it was water tight. I think her problem will be taken care of when she gets the drainage issues along side of the house corrected.
Edited 3/15/2004 11:04 am ET by RASCONC
"I do not think that a PVC pipe buried under a slab would be a static electricity problem. While not a super ground in the usual electrical sense you would think it would be enough. "
Ah, but the PVC insulates, right? So to ground the outside (and I agree that concrete is a good enough ground for static build-up) won't effect the inside, unless you connect the two with a conductor.
Insulating duct won't have a problem where the duct has cooled and gotten more humid. But closer to the dryer where it is hot and therefore dry, static might develop, depending on moisture load and air flow.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Ive posted this site before, hartshearth.com. They have all sorts of dryer ventpipes and things for cleaning them out. Ive ordered from them and was pleased with the products and service. We use pvc under slabs here with no problems.