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PVB and blowout & PVC vs. Copper

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daronson

Senior Member

Posts: 19

Location: USA

1

Tuesday, March 26th 2002, 6:35am

PVB and blowout & PVC vs. Copper

I have a rather large yard, and am installing 10 zones. To avoid running 5 lines around the deck to the other side of the house, I am installing 2 manifold boxes, one on either end of the house. The plan is to tee off in the basement (after the sprinkler shutoff valve and a boiler drain valve) with PVC and run the 50’ of PVC in the basement to the other end of the house for manifold box # 2. Upon exiting house, each line will be attached to a PVB, then into the ground to the manifold. Is there a special connection I should use (union?) to attach PVC to the PVB so that I can remove PVB if necessary without having to cut the PVC? Should the blowout be BEFORE or AFTER the PVB?
Is a simple threaded PVC tee with a cap ok for a blowout, or should I use some type of quick-connect fitting?
Is it ok to run PVC in the basement? Other option was to run copper, and switch over after exiting the house, but a few local installers say they would (and do) use PVC and NO COPPER.


RVLI

Supreme Member

Posts: 462

Location: USA

2

Tuesday, March 26th 2002, 12:40pm

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When you run the mainline out, bring it to the wall closest to both manifolds, using the least amount of pipe. Then once the pipe is after the PVB, tee it off to the two separate directions of the manifolds.

Use a union when connecting the PVC to the PVB. It makes it easier to take it off in the winter rather to cut the PVC as you mentioned.

Connect the blowout AFTER the PVB. When we install our systems, we slip a tee after the PVB with a cap that has a the blowout attachment connected to it. A threaded tee with a cap on it also works.

It is Ok to run PVC in the basement to the PVB, then the manifold. It is also Ok to use copper to the PVB, then to the manifold too.



daronson

Senior Member

Posts: 19

Location: USA

3

Wednesday, March 27th 2002, 3:22am

The reason I was putting the tee in the basement and running out to 2 PVB's is b/c my deck is 30' wide, and the location midway between the 2 valve boxes is smack underneath the deck!! Boy, If I had only installed the sprinklers BEFORE the deck!!! I would rather run most of the pvc INSIDE instead of OUTSIDE anyway.

Do you use one union, on the outlet side of the PVB, which would allow you to spin the PVB off of the inlet side once the union is removed?? Or do you use a union on each side? Also wasn't planning on removing PVB every winter, was just going to winterize (blow out)the PVB along with the rest of the system.

This capped tee with a blowout fitting you are referring to, can you be more specific? Is this something I would need to assemble myself, or can I go to a supply store and buy the tee with the fitting attached? pipes are 1", is a 1/2" blowout fitting sufficient, or should it be 3/4"?

RVLI

Supreme Member

Posts: 462

Location: USA

4

Thursday, March 28th 2002, 2:26pm

Use one union as you said, but this is usually how we install the blowout if there is both one on the inlet and outlet side:

When you want to blow out the sprinklers and the mainline, use the blowout hookup on the outlet side of the PVB. Then when you want to blowout from the PVB and back to the line in the house, use the hookup on the inlet side. When you blowout, the air should never go through the PVB, as usually the valves connecting it to the PVB itself have the blowout hookup attached to it. This means if you want to blowout the mainline from the inlet hookup to the beggining of the mainline in the basement, that you have a ballvalve teed on the mainline so that one end is free with nothing attached to the end, this way when you blowout the mainline in the basment, that the water has someplace to escape.

THE BLOWOUT HOOK-UP
This was for a customer that didn't want any backflow for some reason, so I came up that they're going to somehow need a blowout hookup. So, I took an air hook-up from a tire ( I forget what they are called), drilled a hole through a cap, just big enough for the tip to fit through, and insert it through the hole until the black stop and sealer stopped it. then take the nut and thread it on the opposite side of the the sealer and stopper (the sealer and stopper will both be on the underside of the cap) and tighted it until it is hand tight with a crescent wrench. The sealer will stand the pressure at all times. then, take a small piece of pipe, slip it on to a slip x slip x slip tee, then slip the cap with the air hookup to the small piece of pipe on the tee. Then, slip it on the mainline pipe in the basement right after the shut-off valve. This may sound kind of complicated, so if you want a picture I will try to illustrate it on paint on my computer if you want to see it. e-mail me at akooima17@hotmail.com if you want to see the picture I drew for it. But, I don't reccomend using this if you have a PVB or any other backflow device, as it should be used only when you don't use a backflow device.

This website is also really good with the blowouts and the whole installation of a sprinkler system. If you need more info on blowouts and winterization, try this site: www.jessstryker.com

Hope this helps and if you need more info, e-mail me at
akooima17@hotmail.com

As for the blowout fitting, use the 3/4 inch size.

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