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Geary

New Member

1

Sunday, November 22nd 2015, 6:52pm

Sprinkler head location design help request



Hi everyone,

Firstly, thank you for the information which you have made available on here, it has already been a great help. This is my first attempt at an irrigation design and I feel like I've already put way too many hours into it trying to over engineer it before I buy all the bits. My lawn is couch and I'm about 400m from the beach so quite sandy soil. The purple areas are plants/hedge that aren't covered by drip system and I was going to see if these could be captured by the lawn sprinklers though I understand that the water requirements are a bit different - is that being too lazy?
I have split the system into 3 zones and this is based on hose run to be honest. To be clear - the north side (top of pic) at the front of the house is put in Zone 2 to allow use of the poly line run out the back as I can continue it down the fence line and avoid going under the driveway. I did do some calculations on flow a while back and found that it was ok but haven't rechecked.

I would appreciate if anyone could provide some feedback on the head layout and coverage to see if I have this right. Particularly with the back area I was unsure if I should go with more smaller range sprinklers but thought it might be unnecessary (and I'm trying to be frugal I guess).

My plan was to buy all the kit and have it all laid out above ground with stakes and test run/tune it before trenching. Unfortunately I don't have any good irrigation stores near me so will be mail ordering all the parts. Quotes I have had so far - pro supply and install $6.5k!!! Pro supply and design - $2.5k My design and supply through internet $1.1k

Back yard (left side of pic) was going to be Blue (MP3000) for all except top left which was black (MP2000).
Front north (top right of pic) was going to be maroon (MP1000) for all.
Front south is black (MP2000) for all except the two off 270deg units which are green (MP2000)


Hunter MP design guide is here

FWIW here is my layout for the control point also. Note that zone 2 is left out for clarity.


Thanks in advance

This post has been edited 2 times, last edit by "Geary" (Nov 22nd 2015, 7:14pm)


Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

2

Monday, November 23rd 2015, 7:24am

Where is your location? The metric BSP indications puts you outside of the States. The zone 2 area next to the drive might do better on its own, even though the flow is small. This is because there is a 'hidden' number in system design that has to account for extra water flow during the time that the heads pop up. The longer the pipe run, the more of a problem you can have with heads not popping up properly.

Also, no backflow preventer is shown for the plumbing. Recommended is either a PVB to feed the sprinkler valves, or the use of anti-syphon zone valves, with their built-in backflow prevention. (it is assumed your property is nearly flat, so the elevation requirements for these devices can be met)

There is no reason you shouldn't bury some additional line during installation so that you can add drip to the front areas you are not going to cover for now.

Geary

New Member

3

Monday, November 23rd 2015, 2:38pm

Hi Wet Boots, thank you for the feedback and well done on spotting that I'm not a local. I'm on the east coast of Australia in Newcastle so pretty much the same climate as Sydney. There is a backflow preventer at the tap with the item title "domestic backflow connection kit"

So with the zone 2 at the front are you saying that because there is a distance between these and the back units the back units would pop up and cause a drop in line pressure before the flow reached the front and this drop would prevent the front heads from rising fully? If that is the case I will need to run an additional 50m of poly @$55. Not a killer given I'm already spending $1100 and doing all that trenching of course especially if that means that the system will run better. I consider this route preferable over water jetting a line under the driveway as I'm concerned that jetting could create a cavity under the driveway and flowing enough cement in there to fill the void would be more trouble and cost than the alternative.

Can I take "no comment" on the head placement as "that's fine"???

Thanks again.

Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

4

Tuesday, November 24th 2015, 12:32pm

The "domestic backflow connection kit" should be replaced with a genuine backflow preventer with a "toxic backflow" rating. No great expense, and that ups the protection to as good as you can get. (the pictured device was intended for installation next to water meters, as a "just-in-case" backup, and not as primary task-specific protection)

Your diagram kind of supplies its own critique by way of color intensity. Some areas have single coverage, others are triple covered, or even more. Not optimal.

Another possible issue will be the sprinkler choice. Fast draining sandy soil might be better watered by conventional sprays, even if that choice might mean more heads and/or zones. Better to drench that sandy soil quickly, maybe even in multiple cycles.

Geary

New Member

5

Friday, November 27th 2015, 5:09am

Thanks for the advice.

Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

6

Friday, November 27th 2015, 1:51pm

If you choose anti-syphon valves, you should look for Irritrol 2711/2713 APR as a good choice. Rainbird and Hunter also make one, but the Irritrol is most likely to be trouble free from the start.

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