Redoing irrigation - Backflow Questions

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cleverchimp

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Hello all, I'm redoing my irrigation. It has 3/4" copper supply under the house that I'm planning to tie it to 1" as far as I can to the beginning of the water supply. Once the 1" copper goes outside, I will tie it to schedule 80 (thinking of doing the copper all the way to backflow but again, schedule 80 might fare better under the dirt, dont need to worry about corrosion) all the way to the backflow.

The current backflow is 3/4 inch and it is still good, I figure I will re-use it since the price of backflow seems to doubled recently. Will this cause any issue? Or should I just kept it all 3/4 inch all the way?
 

Breplum

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The larger diameter pipe over distance helps because it diminishes friction resistance which increases per ft.
When we run plastic pipe over long distance with turns, we run tracer wire to the far ends where pipe comes out of the ground to allow tracing of the line if problems arise in the future when nobody might remember where the pipe was
 

cleverchimp

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The larger diameter pipe over distance helps because it diminishes friction resistance which increases per ft.
When we run plastic pipe over long distance with turns, we run tracer wire to the far ends where pipe comes out of the ground to allow tracing of the line if problems arise in the future when nobody might remember where the pipe was
Thanks, I just know such product exist. I DIY this myself so I took a lot of pictures instead before placing the dirt back. Would it be a problem mixing 3/4 inch line with 1" line? And install 3/4" backflow before the sprinkle heads.
 

John Gayewski

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Thanks, I just know such product exist. I DIY this myself so I took a lot of pictures instead before placing the dirt back. Would it be a problem mixing 3/4 inch line with 1" line? And install 3/4" backflow before the sprinkle heads.
No
 

cleverchimp

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Brand and model number of bf and gpm needed
It is Zurn Wilkins Model 720A Bronze Fnpt 3/4-in Pressure Vacuum Breaker (Model #34-720A). I dont see any GPM rate on the spec but it is rated 150 psi and the supply is about 80 psi (after PRV).

 

Jeff H Young

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pretty basic question no math involved ... did it work befor ? if so why worry about continuing with a 3/4 valve? are all your sprinkler valves 1 inch and maxed out ?
Im not an Irrigation guy but many dont use a regulator Personally I think a system oughta be designed to work with 50 or 80 psi anyway as opposed to 100 or 130 see see often in my area
 

cleverchimp

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pretty basic question no math involved ... did it work befor ? if so why worry about continuing with a 3/4 valve? are all your sprinkler valves 1 inch and maxed out ?
Im not an Irrigation guy but many dont use a regulator Personally I think a system oughta be designed to work with 50 or 80 psi anyway as opposed to 100 or 130 see see often in my area
Yeah, the problem is that the 3/4 metal pipe (galvanized) leaking under the concrete. The pipes inside the crawlspace is fine but I have some pipe banging issue before with city supply at 120+psi (the main reason why it was put after the PRV - I ran my valves at 4-5AM).

I'm using 3/4 valves (ORBIT premade valves), 1" just the water supply to the valves (might as well upgrade to 1" while redoing this). The reason why I'm using a 3/4 backflow because it is still in good condition (I think it is 2 years old) and the new 1" PRV would cost $130-$140. When it fail, I'll get 1" to replace it with.
 

Jeff H Young

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I think a very good chance it will perform fine, Im with your plan . I been changing a lot of PRVs lately they are pricey and the backflow devices are way high too , I see a lot of the rpz like wikins 975xl and those are over 500 bucks I dont really know which type are appropriate sometimes and replace them on occasion with same or similar
 

cleverchimp

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I think a very good chance it will perform fine, Im with your plan . I been changing a lot of PRVs lately they are pricey and the backflow devices are way high too , I see a lot of the rpz like wikins 975xl and those are over 500 bucks I dont really know which type are appropriate sometimes and replace them on occasion with same or similar
Agreed. I recall these backflow were 50-60 bucks in 2022. 10% or so maybe ok but they doubled the price and I just refuse to pay the ransom money lol, hopefully they will go down to normal price again in the future.
 
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