Irrigation System Design

Irrigation systems, sprinklers & other watering topics
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dpainter68
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Irrigation System Design

Post by dpainter68 » Tue May 14, 2019 3:02 pm

Looking for advice on my design so far. Originally I had a 3/4" meter and the bucket test showed I had around 22-24 GPM and it was right around 80psi. I've since upgraded to a 1" meter (and tap) but haven't got to the point where I can test it yet.

The looped main will be 1 1/4" sch 40 PVC. I plan on using RainBird PGA valves with flow control. Laterals will be sized to keep the velocity around or less than 5ft/s. My plan is to use Rain Bird 5000 series heads for most of the yard. If you zoom in each valve is labeled with the nozzle type. They're a mixture of rain curtain and MPR. The front section between the house and driveway and the back yard that's fenced in I plan on using MP rotators. I haven't decided yet on which flow sensor I'm going with but it will either be the Rachio wireless or the CST. I'll have the Rachio gen 3 controller.

The flower beds will be drip. At least that's the current plan. I've never had a drip system before and don't know the best way to go about it. From what I've read I need to use pressure regulator and filter. There's a significant elevation difference from left to right (when looking at the front of the house) so I thought I would go with pressure compensating emitters. I don't know what brand/gph I need to use really. I know the gph are based on what the plants need so I'll have to do some research on that. Any suggestions on the type of valve, tubing, emitters, etc?

In zone 3 the reason I don't have heads spraying back towards the driveway is because it's a very steep hill. I shortened the distance between the heads and will be water part of the neighbors yard most likely. I can attach a pic of that helps.

Any thoughts or advice? The drawing itself is about as accurate as I can get it. The drawing program (Visio) has some quirks though so overlook watering of the driveway :D
Image
Last edited by dpainter68 on Tue May 14, 2019 4:17 pm, edited 2 times in total.

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Re: Irrigation System Design

Post by unclebucks06 » Tue May 14, 2019 8:52 pm

I didnt thoroughly go over it, but i would definitely try to split up that cluster of valves in the back. 3 or 4 in one area is enough imo.

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Re: Irrigation System Design

Post by g-man » Tue May 14, 2019 9:07 pm

I was going to comment about zone 3, but then I read your comment.

I don't have experience with drop systems, so I can't comment on it.

In the back, are those mature trees? Will you be able to place the heads there without cutting tree roots?

dpainter68
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Re: Irrigation System Design

Post by dpainter68 » Tue May 14, 2019 9:33 pm

g-man wrote:
Tue May 14, 2019 9:07 pm
I was going to comment about zone 3, but then I read your comment.

I don't have experience with drop systems, so I can't comment on it.

In the back, are those mature trees? Will you be able to place the heads there without cutting tree roots?
Yeah, I contemplated about trying to put them at the top edge of the slope but decided against it. I'll try and get a pic of it tomorrow.

They're fairly mature trees. My plan is to make a flower bed with pine straw just inside the canopy of the trees. I assume I'll be able to go straight in just enough to place a head at the edge of the bed with minimal root damage. Here's a pic of those trees. The only problem I see is the lone pine on zone 7 but I'm not sure if I have that tree placed correctly or not. I need to measure it.

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Re: Irrigation System Design

Post by Ecks from Tex » Wed May 15, 2019 12:19 pm

The flower beds will be drip. At least that's the current plan. I've never had a drip system before and don't know the best way to go about it. From what I've read I need to use pressure regulator and filter. There's a significant elevation difference from left to right (when looking at the front of the house) so I thought I would go with pressure compensating emitters. I don't know what brand/gph I need to use really. I know the gph are based on what the plants need so I'll have to do some research on that. Any suggestions on the type of valve, tubing, emitters, etc?
I use Rainbird drip system products although they are all about the same and you can order stuff on Amazon or Sprinkler Warehouse with similar results. I order simple stuff like tubing from SW or amazon. I order valves and things of that nature from Rainbird directly. SW does not sell all Rainbird products and I've found this to be especially true with drip.

You are correct that you need a pressure regulator and filter. Since you are doing it the right way and running drip off your irrigation system, what you need is to buy a pressure regulated valve built for drip systems for each of your drip zones rather than a regular valve. These regulated valves will put out the correct pressure and are much better than an in-line regulator. They will also usually have filters built in, but if not you can run an in-line filter directly leaving each valve.

The GPH are based on the plant, but you can always adjust this because you will essentially run a 1/4 lines to your target water area and can break off multiple 1/4 in drip leaders from that line. There is more pressure coming down the 1/4 in line than your drip emitters will allow (thus why you need pressure regulated valve).

Pressure compensating emitters - go for it. They aren't necessary for the most part but they are not unreasonably expensive either compared to regular gph emitters.

Treat a drip system like a whole new irrigation. You run 1/2 in poly tubing from your vale (this is your main) and you run laterals from the main by poking holes in the main and using unregulated 1/4 in drip valves to connect the laterals, which are 1/4 in vinyl or poly tubing. These go to either regulated gph emitters or various fancy spray emitters. If you have a huge bed full of flowers, maybe get a 1/2 poly tube with perforated tubing that will just spray everywhere similar to a soaker hose. This is not optimal efficiency but it is more efficient than sprays.

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Re: Irrigation System Design

Post by g-man » Wed May 15, 2019 1:47 pm

@dpainter68 I think you should not go above 11gpm on a 3/4in system. This is based on this page from https://www.irrigationtutorials.com/gpm ... er-source/

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Re: Irrigation System Design

Post by dpainter68 » Wed May 15, 2019 2:16 pm

g-man wrote:
Wed May 15, 2019 1:47 pm
@dpainter68 I think you should not go above 11gpm on a 3/4in system. This is based on this page from https://www.irrigationtutorials.com/gpm ... er-source/
I have a 1" supply line and meter now. The 3/4" reference was to when I did the bucket test. I should be able to do the bucket test on the current configuration (1") in the next couple of days. However, it states that 18gpm is the max for 1" and I realize I'm still over that some. The 1" is the supply line from the main to the meter. From the meter onward it's 1 1/4". So here's a question - the problem that could create is water hammer, correct? I could always do a test on this to see if I see/hear any issues with it when I do the bucket test. I don't believe I'll see any issues in the house plumbing - it's about 120' of pipe down stream from the point of connection and also has to pass through a regulator. That leaves me with where my 1 1/4" pipe connects to the 1" backflow preventer and/or 1" meter. Do you think any water hammer could pass through the backflow preventer? I've read a couple of places that say it's certainly reduced but I haven't seen any actual test data to confirm it.

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Re: Irrigation System Design

Post by g-man » Wed May 15, 2019 2:25 pm

Water hammer is just one of the issues. The webpage explains it:
Scrubbing is what happens when the high water velocity actually scrubs molecules loose from the inside of the pipe. Eventually it wears away enough that the pipe develops a leak. The higher the velocity, the more scrubbing you get. A little scrubbing may take 20-30 years to create a leak. With a higher velocity the problem becomes much worse. I have seen 7 year old homes need a total replacement of all the copper pipes due to scrubbing damage.
Will you need to have a zone at 20gpm?

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Re: Irrigation System Design

Post by dpainter68 » Wed May 15, 2019 2:28 pm

Ecks from Tex wrote:
Wed May 15, 2019 12:19 pm
The flower beds will be drip. At least that's the current plan. I've never had a drip system before and don't know the best way to go about it. From what I've read I need to use pressure regulator and filter. There's a significant elevation difference from left to right (when looking at the front of the house) so I thought I would go with pressure compensating emitters. I don't know what brand/gph I need to use really. I know the gph are based on what the plants need so I'll have to do some research on that. Any suggestions on the type of valve, tubing, emitters, etc?
I use Rainbird drip system products although they are all about the same and you can order stuff on Amazon or Sprinkler Warehouse with similar results. I order simple stuff like tubing from SW or amazon. I order valves and things of that nature from Rainbird directly. SW does not sell all Rainbird products and I've found this to be especially true with drip.

You are correct that you need a pressure regulator and filter. Since you are doing it the right way and running drip off your irrigation system, what you need is to buy a pressure regulated valve built for drip systems for each of your drip zones rather than a regular valve. These regulated valves will put out the correct pressure and are much better than an in-line regulator. They will also usually have filters built in, but if not you can run an in-line filter directly leaving each valve.

The GPH are based on the plant, but you can always adjust this because you will essentially run a 1/4 lines to your target water area and can break off multiple 1/4 in drip leaders from that line. There is more pressure coming down the 1/4 in line than your drip emitters will allow (thus why you need pressure regulated valve).

Pressure compensating emitters - go for it. They aren't necessary for the most part but they are not unreasonably expensive either compared to regular gph emitters.

Treat a drip system like a whole new irrigation. You run 1/2 in poly tubing from your vale (this is your main) and you run laterals from the main by poking holes in the main and using unregulated 1/4 in drip valves to connect the laterals, which are 1/4 in vinyl or poly tubing. These go to either regulated gph emitters or various fancy spray emitters. If you have a huge bed full of flowers, maybe get a 1/2 poly tube with perforated tubing that will just spray everywhere similar to a soaker hose. This is not optimal efficiency but it is more efficient than sprays.
Thanks for the info. What valve would you recommend? I'll probably get most of my stuff from the local SiteOne. They've given me pretty good prices on things so far and said they would price match also.

The reason I was going to go with pressure compensating emitters was due to what I read on the Irrigation Tutorials site. I don't remember exactly how it was worded but basically said if there was a big elevation difference to use them. On the front flower beds there's approx a 7-8' elevation change from one side of the house to the other. I wondered if I even needed to use an in-line pressure regulator at a couple of locations on the "main" 1/2" tubing.

I thought about the perforated tubing but also worried that it would get stopped up over time. Your thoughts on that?

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Re: Irrigation System Design

Post by dpainter68 » Wed May 15, 2019 2:34 pm

g-man wrote:
Wed May 15, 2019 2:25 pm
Water hammer is just one of the issues. The webpage explains it:
Scrubbing is what happens when the high water velocity actually scrubs molecules loose from the inside of the pipe. Eventually it wears away enough that the pipe develops a leak. The higher the velocity, the more scrubbing you get. A little scrubbing may take 20-30 years to create a leak. With a higher velocity the problem becomes much worse. I have seen 7 year old homes need a total replacement of all the copper pipes due to scrubbing damage.
Will you need to have a zone at 20gpm?
Oh yeah, I forgot about scrubbing. I guess I wasn't very worried about it because the only part that would be over the 5 ft/sec was the county's water supply side. I suppose I could add another zone and cut most of them down to 18 GPM, but if my math is correct I would still have one zone at 20 GPM. 16 zones is my max.

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Re: Irrigation System Design

Post by dpainter68 » Wed May 15, 2019 9:35 pm

Anyone have any suggestions on the valves I should use? I initially thought I'd go with RB PGA series, then landed on DVF-100's, then back to PGA series. After reading some more I'm thinking of going back to the DVF's... Im starting to sound like my wife trying to decide what color shirt she wants to wear :lol:

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