# Srpinkler Placement Question -- Does this make sense?



## tmmabey (Jan 10, 2020)

Hey TLFers!

I am doing a total landscape redesign including a new irrigation system in my front yard. I've been doing a lot of research and using Jess Stryker's tutorials as my guide. I am at the point of head placement, and I could really use the help of an experienced eye to help me move forward.

I have a lawn area that is rectangular, 17.5 x 33.75 feet, with a small adjoining rectangle of 5 x 9 feet on one end. You'll see from the pictures what I am talking about. I am considering two designs: (1) Using standard MPR Rainbird spray nozzles. or (2) Using MP Rotators from Hunter (or Rainbird equivalent).

I like the MP Rotators because it cuts down the number of heads and the trenching. I don't care much whether it comes out costing a little more or a little less. Quite frankly, I just like the way they look when they are operating, and nobody else on the street is using them.

I think the size of my lawn works nicely with either approach, but covering the little 5x9 patch is the challenge. Using standard spray nozzles, I have a design that seems to work, I think. It is shown in the first layout picture. The real challenge I am having is figuring out what to do with the small area for the MP Rotator approach. The main large rectangle is covered very nicely with 6 MP Rotators. Is it practical to also cover the 5x9 section with MP rotators as well? In theory, some MP Rotators work down to 5 or 6 feet, so those could be used to cover this area (that is kind of what I have shown on the sketch), but it just seems excessive to have 4 or 6 heads for just that small rectangle. Plus some sources say they don't work great for smaller radiuses Up to now, I am kind of treating the two rectangles as two independent areas, and that may be the wrong thing to do. I could also just use conventional MPR spray nozzles for the small 5x9 area and put it on the same circuit as the outlawn area (two 5.4 x about 12 feet areas shown on the bottom of the diagram) that probably needs to have conventional spray heads anyway, right?

Would appreciate any suggestions or critiques, bring it on!

I hope the sketches are easy to interpret. The "ladder" on the right is for scale. Those are 1 foot squares.

Thanks!


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## g-man (Jun 15, 2017)

Welcome to TLF.

You did your homework and your drawing looks really good. I see your dilemma with the 9 x 5 section. Consider making it a landscape area if possible.

I like the second layout better. For the 9 x 5 area I think you should use MP Strips Left (or right) at two corners. The MP should be on a 30psi Hunter body so you can dial it down. You will overwater by 3-4feet. This will need to be in a separate zone so you can control the duration independent from the rest.

The other option is the MP800SR. These are short radius one. Set them at 5ft in a rectangular pattern (6heads). Again, you want this in a separate zone. You will over water by 1 feet.


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## corneliani (Apr 2, 2019)

I much prefer the Rotators over the spray heads and went that route myself while designing my own system. What I liked about them is the low-flow GPM that allowed for more heads per zone, and the low precipitation rates that do not saturate the ground as quickly -- especially useful when designing efficient head to head coverages as you have. You're looking at +/- 1.2 in/hr with the sprays vs +/- 0.8 in/hr with the Rotators.

Also worth mentioning is the difference in spray patterns: the sprays waste more water by misting whereas the rotating streams of the rotators are a bit more defined & controlled (at least in the distances you have to deal with).

The only thing I'd change on the head placement is that 5x9 section. Look at the specs of the MP800 series (may require PRS heads for 9' radius) .. you may be able to get away with only 2 heads in the far corners (the overspray into your 'large' section should not be a concern because water distribution tends to taper off at the edges).

Awesome drafting work btw!

NOTE: I see @g-man chimed in before I finalized this post :thumbup:

EDIT: Attaching a sketch of the corner MP800 that should give you similar precipitation rates.



Heres the distribution uniformity of the MP2000 (can't find one for the 800 series) but it shows what I mean by tapering off at the edges:


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## tmmabey (Jan 10, 2020)

Thank you g-man and Corneliani for your excellent comments. You are confirming what I suspected. I was hoping to avoid lots of added complexity to handle the 9x5 area (extra zone, maybe even 6 heads!), but I understand that sometimes that may be the only way to solve the problem. Actually, your first suggestion of avoiding the problem by making it a landscape area is something I had already been considering, and now I think I will revisit that option.


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## tmmabey (Jan 10, 2020)

Corneliani, with your suggested version using to MP800s in the corner, do you think it is possible to operate them on the same zone as the others? I haven't studied the MP Rotator data closely at this point, but I assumed "MP" means matched precipitation so that perhaps the PR is about the same for the MP800s as the larger radius version.

Also, does Rainbird have a similar product to Hunters MP Rotators? Any preference of one over the other?


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## corneliani (Apr 2, 2019)

tmmabey said:


> Corneliani, with your suggested version using to MP800s in the corner, do you think it is possible to operate them on the same zone as the others? I haven't studied the MP Rotator data closely at this point, but I assumed "MP" means matched precipitation so that perhaps the PR is about the same for the MP800s as the larger radius version.


Technically the PR specs of the 800s is twice that of the other MPs, so be aware of that. But that doesn't mean you can't operate them together, it just means that the 'art' of the design has now expanded (design is just as much art as science, imo). The way I sketched it those 800's will give you approx 0.5 -0.6 in/hr, albeit not in as thoroughly linear fashion as installing 4 equidistant heads would, but that's the tradeoff. I know it sounds like i'm compromising but it's no different than your sketch above where I see you counted the number of heads hitting certain parts of the yard. As you noticed not every inch of yard gets the exact same coverage, so if you feel like this area can handle a bit more water and does not require the 'perfect' distribution that add'l heads would give you, then go for it. Honestly there's no 'perfect' solution for you so it's essentially choosing the best option available given all the variables.

Here's the math for the PR i used: 
each MP800-90 @ 40psi throws out 0.23gpm over 10'. 
Two heads total gpm= 0.46
0.46x96.25 / 100 sqft = 0.44 in/hr


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