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New Member


Tuesday, March 19th 2002, 4:39pm

questions about backflow/sprinklersystem

I"m putting a sprinkler system in, and I have just ran a 1/2 inch copper pipe off a cold water 1/2 copper pipe that is used for the washing machine...I did'nt want to tear up my basement to run off of the main line....

they only sell 3/4 inch backflow is it ok to go into the 3/4 backflow with 1/2 copper? and come out of it with 1/2 copper??

also,I bought 1 inch flex pipe
for the lines in the that ok? or would 3/4 be better???

(I have a small yard and I am only running 3 sprinklers max on each valve,so I should have plenty pressure)

and just 1 more question...I have seen pre assembled valve manafolds on line, but haven't found them in any stores...are they worth ordering?

Edited by - redwine on Mar 19 2002 10:44:53 PM


Supreme Member

Posts: 456

Location: USA


Wednesday, March 20th 2002, 12:06pm

My first suggestion is that you should really go from the basement waterline. It is worth doing more work to get water from your mainline so you can have more pressure, therfore, having more sprinklers on a zone. If you still wish to come from the washer line, use 1/2 copper from the pipe to the washer, to the backflow device, then come out of the device with 3/4" PVC to your valve manifold.
Then, use the 1" Flex pipe (I am assuming poly pipe) from the valve to your sprinklers. It is ok to use the 1" pipe that you bought.
It is also worth using the valve manifolds that you can order. They are alot stronger than manifolds that you make. My suggestion is to use the ordered manifolds.

Hope this helps!!!


Supreme Member


Friday, March 22nd 2002, 9:58am

I probably wouldn't recommend using a 1 inch mainline when you are supplying it with 1/2 inch copper! You will have trouble, unless the three heads per line you are running are all low volume lawn heads Hopefully they aren't I-20's with huge nozzles!

Remember, the 1/2 inch copper can only run about 6 gallons of water through it. You can only push that much water. YOu can only push as much as your SMALLEST pipe! To prevent any chance of water hammer or high velocity through the 1" mainline I would probably take it back and use 3/4".

Just my opinion.

As for the pre-assembleds...I never use them but that doesn't mean anything. We always build ours as needed.

Sprinkler Solutions, Inc.
Arizona and Colorado

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