Pipe & PVB size

New Member

Location: USA

Friday, June 2nd 2006, 5:52am

If I understand correctly, installing mainline pipe of larger diameter is better.

I have a 3/4" supply line.
I plan to lay about 35 feet of 1-1/4 PVC (Sch40) from the PVB to the manifold where the zone valves will be. Then I plan to run 1" poly pipe after the valves.
Hopefully this is a good plan (?).

My questions are about the PVB/pipe size.

I intend to install a Febco 765 at the beginning of the main line.
Is there a benefit to using a 1" PVB rather than a 3/4"? (Less pressure drop?) The 1" is actually cheaper at Sprinklerwarehouse.com!
I would then use a short piece (~ 2-3 feet) of either 3/4" or 1" from the PVB down into the ground to join my 1-1/4" line. Should I use copper or sch200 PVC pipe for this short above-ground connection? 3/4" or 1"? (a length of 1" copper can be very expensive!)

What is best?

Thanks!

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DOORZ

Advanced Member

Posts: 54

2

Friday, June 2nd 2006, 10:23am

My supply line to the house was 1", and I ended up using 1-1/2 pipe for my mainline. Why 1-1/2 do you ask, well becuase I had 400' of mainline to get all the way to the back of my house. I used the larger pipe for 2 reasons, the pressure loss in 1-1/2 pipe was less than 1-1/4, and it also turned out that the 1-1/2 pipe was cheaper.

I ended up having to use a RPZ valve (1"), which I installed right near my 1" supply line, and then stepped up my mainline to 1-1/2 right after the backflow.

I would at least use SCH40 for your above ground connection, as the cl200 pipe would be too thin walled. You could always check with the inspector to see what's required.

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Tom

Supreme Member

Posts: 306

3

Friday, June 2nd 2006, 1:52pm

with a 3/4" supply, I'm guessing your designing for about 10gpm. I'd use 1" sch 40 pvc to your manifold, and copper pipe above ground to connect your PVB. This section of copper could be 3/4" or 1".

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CarlF

New Member

Posts: 3

Location: USA

4

Friday, June 2nd 2006, 2:10pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DOORZ
I would at least use SCH40 for your above ground connection,
<hr height="1" noshade id="quote"></blockquote id="quote">

I believe that Sch 40 PVC pipe should be used above ground, as it degrades in daylight.

Thanks,
Carl

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CarlF

New Member

Posts: 3

Location: USA

5

Friday, June 2nd 2006, 2:13pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Tom
 with a 3/4" supply, I'm guessing your designing for about 10gpm. I'd use 1" sch 40 pvc to your manifold, and copper pipe above ground to connect your PVB. This section of copper could be 3/4" or 1".
<hr height="1" noshade id="quote"></blockquote id="quote">

Thanks, but what do you think about a 1" PVB? (since there is no cost penalty for the bigger unit, is there any other reason not to use 1"?)

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Tom

Supreme Member

Posts: 306

6

Saturday, June 3rd 2006, 5:35pm

1" copper male adaptors are expensive

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