Spiral duct waterproof??

[Rick Potter]

I just put my DC in an outside shed with 6' of 8" spiral duct between the two buildings. Future post on that. But for now, does anyone know if spiral duct is waterproof? Several feet of it is out in the weather.

If it is not, I will have to caulk the whole length. Yes I did avoid any fittings outside the buildings. I seem to remember seeing large spiral ductwork on the roof of commercial buildings.

[Mike Wilkins]

Don't know what type of pipe you have; but if it is the snap-lock pipe, you could orient the seam pointing down to lessen the chance of rain water getting in the pipe. However you may want to seal the seam anyway, since a running collector with the suction in the pipe could possibly suck water inside.
Or you could attach some brackets to the top of the pipe with rivets, and attach an umbrella-type cover over the pipe. Sounds like an interesting set-up. Please let us in on the system after you get it installed.

[peter gagliardi]

Yes, if it is good quality spiral pipe, you should be fine.

[Scott Brandstetter]

This is a quick brush on sealant that I used indoors but I can't imagine any water penetrating it. It is simple to use and creates a great bond.

WP_20151101_21_38_31_Pro.jpg

[Tom Wassack]

I just put my DC in an outside shed with 6' of 8" spiral duct between the two buildings. Future post on that. But for now, does anyone know if spiral duct is waterproof? Several feet of it is out in the weather.

If it is not, I will have to caulk the whole length. Yes I did avoid any fittings outside the buildings. I seem to remember seeing large spiral ductwork on the roof of commercial buildings.

Two things to add - here in NC, many of the (still operating) furniture plants have exterior exposed spiral duct work, so I think you're OK with exposed to the WX. Secondly, a quick check on the Spiral Manufacturing website (http://www.spiralmfg.com/spiralf.htm) shows additional options for spiral pipe - aluminum, stainless, aluminized steel, etc. I have used them many times for stock pipe and fittings, plus custom manifolds!

Regards,
Tom Wassack
Asheboro, NC

[Frank Pratt]

I used 26 ga spiral & it looks like the seams are either soldered, or more likely, heated so the zinc coating melts to seal the seem. So yes, it is waterproof.

[Rick Potter]

Thanks for the info. I should have been more complete. My spiral ducting comes from a HVAC wholesale store, and is 26GA galvanized. Looking at the inside of the pipe, it is certainly pressed together nice and solid, making a smooth wall. It is definitely not snap lock pipe, but it has one end pinched to fit in the next piece. As I said, there are no fittings outside the buildings at all.

Tom, that is a great website, and it includes a nice tutorial on dust collection systems.

(ANSWER TO QUESTION): I decided to call them, and asked for someone to answer a simple technical question. I was told that in a horizontal run between buildings, the pipe is waterproof, and not to worry about it. He did mention that if I had installed it in a vertical orientation, there would be a proper up side and down side. The spiral has a solid side, and a crimp side, so on vertical runs outside, the crimp should always be down, because water will follow the seam downward. Thanks for the lead, Tom.


Scott, That is the sealant I am using on the connections...great stuff.

The hardest part of this setup was reattaching the 8" main which now goes outside. I lost a whole lateral run, which I have to reattach somehow. I am rearranging the shop a bit also.