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CarlF

New Member

Posts: 3

Location: USA

1

Friday, June 2nd 2006, 5:52am

Pipe & PVB size

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!

DOORZ

Advanced Member

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.


Tom

Supreme Member

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".

CarlF

New Member

Posts: 3

Location: USA

4

Friday, June 2nd 2006, 2:10pm

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

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

Thanks,
Carl

CarlF

New Member

Posts: 3

Location: USA

5

Friday, June 2nd 2006, 2:13pm

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Tom</i>
<br />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"></font 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"?)

Tom

Supreme Member

6

Saturday, June 3rd 2006, 5:35pm

1" copper male adaptors are expensive

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