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New Supply Line to Sprinkler Manifold - Type of material, throughwall, backflow?

New Supply Line to Sprinkler Manifold - Type of material, throughwall, backflow?


  #1  
Old 07-07-13, 11:21 AM
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New Supply Line to Sprinkler Manifold - Type of material, throughwall, backflow?

Have a sprinkler system in the front yard. It was previously supplied by a 1" feed which fed both front and back systems. When I had a pool installed in the back, the back sprinklers were destroyed as was the feed to the front. The supply was cut off just past the ball valve in the basement.

I am reconnecting the front now. Have routed the water in the basement to the front wall of the house, but have a three questions to make it "the last mile". The feed is a 1" line.

1 - Material for the line. They used black poly before. However, I read that this isn't suitable (or perhaps even to code). I also tested this using 100 psi (my pressure is 60) and it burst. I have 160 psi now but haven't tested it. Burying to 18" may be problemmatic, and it's about 50' run to the manifold. What should I be using? Poly, Sch 40 PVC, or metals?

2 - Backflow preventer. Not sure that the valves are anti-siphon, so am planning on adding a backflow preventer. I was picturing a simple device in line in the basement similar to the check valve on my sump pump, but the only thing I am seeing is a complex Watts vacuum breaker L-shaped arrangement that would be outside. Would much prefer as much of the equipment in the basement due to winters. What recommendations for backflow in this case?

3 - Through-wall method. I will be taking this through the rim-joist/sheathing and then a brick veneer wall, then down to the ground. I read there needs to be a "sleeve 2 pipe sizes larger" in the brick. So this would be a 1.5 inch sleeve? Am getting blank stares at box store, so is there a special name for this sleeve, or do I just make it out of pipe myself?
 
  #2  
Old 07-07-13, 11:33 AM
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#1 where did it burst??? That pipe even though thin walled is good for certain psi... Were did you get the pipe? There is green and blue label at the home stores... Im at 60 psi too and never had an issue... Was there a kink or just pulled from a joint?

#2... Depends on the local code... Most are vacuum breaker types. Some towns allow check valves... Call the town or look it up...

#3... Use pvc. Yes sleeve it IMO.For 1" pipe you will not need 1 1/2 pipe I would think.... I believe 1" copper fits in 1" pvc..... May be wrong its been awhile...
 
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Old 07-07-13, 11:57 AM
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lawrosa - yeah, I was mystified too on the pipe bursting. I want to say it was "blue" and I went to "yellow" which was the highest psi, non-potable. The pipe would just rupture (nowhere near joints) in about 6" "slices" along the length of the pipe. It happened as the valve shut off, so am guessing maybe some surge pressure built up that was higher and hopefully the extra 60 psi will cover me. Otherwise I'm thinking sch 40 which is rated at 400 or so psi for that.

There is no real local code; tends to be whatever national standard is, and, in their words, "not always what you want to shoot for".

Will try 1" copper in the pvc. That would be a nice quick fix.
 
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Old 07-07-13, 12:49 PM
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If your pipe does not have an NSF (National Sanitation Foundation) mark signifying it as acceptable for potable water it should not be used ahead of the required backflow device.

A vacuum breaker MAY be acceptable for a sprinkler system but more and more the water utilities are requiring double check valve backflow preventers for sprinkler systems.

[ATTACH=CONFIG]14799[/ATTACH]
(Image courtesy of Clemson University.)

These must be mounted in an accessible location for testing and maintenance. They cost around $125 to $150 for a one inch size.

PVC is fine for the sleeve through the wall and you need to pack the space between the sleeve and the pipe with some material to prevent drafts and an entry for vermin. The pipe itself, where it can be hit by sunlight must be resistant to UV radiation, simplest is to use copper for any above ground piping but galvanized is acceptable.
 
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Old 07-07-13, 05:04 PM
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Furd - thanks. Will check with my building dept tomorrow on the requirements - is there any other benefits to using that contraption that would sway me to use it if it's over code? Also, the poly would definitely only be between the breaker and the manifold - so it would be ok to use it?
 
  #6  
Old 07-07-13, 06:48 PM
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Polyethylene piping downstream of the backflow preventer is acceptable.

The reason for the backflow preventer is to preclude the water in the sprinkler system from backing up into the potable water system in case of a loss of pressure. This loss of pressure could happen from several different causes, none of them real likely. Still, the model codes DO require some kind of backflow preventer on ALL underground sprinkler systems. If your area doesn't specifically require a double check valve device you can get by with a vacuum breaker as long as the mushroom top is installed high enough. High enough is generally defined as a minimum of 12 inches above the ground level OR 12 inches above a known high water level during a flood.
 
 

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