PVC Pipe Through 3/8" Ply: Caulking Or.... ?

viz: http://tinyurl.com/mb4jqph http://tinyurl.com/k2zbnoq http://tinyurl.com/lk87r54
It's Schedule 40 PVC pipe and I figure I'll just put a bead of white silicone caulk around on each side and sort of knead it in so if fills the clearance gap.
Exhaust heat is not an issue: I left the device running for an hour with no hole in the door and the muffler 2" from the wood and the wood was barely warm. I can hold my bare hand up to the exhaust no problem.
Main function of the caulk is to keep the PVC from falling out and maybe take the occasional bump - but nothing more.
Since the caulk I have won't go off until temps are in the sixties I've got plenty time and figured Greater Minds Than Mine might know of something more appropriate.
--
Pete Cresswell

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On Monday, March 10, 2014 3:44:17 PM UTC-4, (PeteCresswell) wrote:

That's what I would use.
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Hi Pete,

Is that a shop vac, a generator, or something else? If the exhaust port of the device is plastic, you're probably fine using PVC. If the exhaust port is metal, you may want to use metal pipe instead of PVC.
I'm also curious why you reduced the full size port down to a smaller size? That would reduce air flow, which could be a bigger issue than the caulk. I would try to keep the same size pipe all the way out, especially considering the short distance you traveling.
Assuming the PVC pipe is appropriate for your situation, I see no reason why you couldn't use caulk to seal between the plywood and PVC. If the gap is larger than 1/8 inch or so, you might want to fill the gap with "foam backer rod" before applying the caulk. You can find that in various sizes in the home centers where weatherstripping is sold. It minimizes the amount of caulk you need to pump into the hole, but more importantly it allows the caulk to flex more than a big thick chunk of caulk. A thinner application will cure quicker too.
If you want to get fancy, they sell PVC trim rings to fit around PVC pipe. They're normally used where drain pipes penetrate sheetrock. Dab a little caulk underneath and slide the trim ring on. The trim rings are usually stocked in the plumbing area near the traps and valves.
I don't know what your application is, but you should probably install an elbow facing down on the exterior of your structure. This will prevent rainwater from blowing in and draining back to your appliance.
Good luck,
Anthony Watson www.mountainsoftware.com www.watsondiy.com
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On 3/10/2014 3:44 PM, (PeteCresswell) wrote:

Dear (PeteCresswell), When I did heating and AC, we used Diversigum http://www.diversitech.com/Product-Sub-Category?id 4C000000JpCtjIAF
item # 6-202-1 in the box. Roll it like Play-doh snake, push some around the outside much like caulk. Lasts nearly forever, and pretty much non hardening.
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(Christopher A. Young)
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Some sizes of PVC pipe telescope within one another. So slide the next size up on either end and caulk the connection point.
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Per bob haller:

That's what I spent a half hour rummaging though Home Depot's pipe section trying to find. Seemed like it would add a little bump resistance too.
Now that I know it's possible, I'll go back and look some more.
--
Pete Cresswell

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On 3/10/2014 3:44 PM, (PeteCresswell) wrote:

What is the budget?
Option 1 Machine a ring from 316 stainless steel exterior would have grooves to hold a Buna-N O ring on either side of the wall. Interior would have a silicone sleeve to hold the PVC in place and absorb vibration.
Estimated cost $176.50
Option 2 Silicone caulk
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