Help with sprinkler placement (and intro)

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sh3rlock
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Help with sprinkler placement (and intro)

Post by sh3rlock » July 18th, 2017, 3:58 pm

Hi everyone.

I just purchased a new (to me) house in NW Florida and want to get the yard in tip-top shape. The first order of business is the front yard. It is currently in very poor shape: sparse (unknown variety) grass, lots of sand, lots of ants and no irrigation.

My first action was to get the pest guy out here to treat the yard for ants and that seems to have helped for now. The next thing is to get a sprinkler system set up before I do a soil sample, reno, and seed with Zenith Zoysia in late August.

This is the layout of the front yard, sorry for the low quality scan. (Measurements are for green lines).

Image

I am following irrigationtutorials.com and have completed all the necessary measurements, but I am having trouble with sprinkler placement. I originally thought to break the area into 2-3 zones. The first would cover the 30x38' square area in the lawn closest the road with 4 rotors, 1 in each corner. But there are two issues with that layout: it would leave a small area that wasn't head-to-head spacing along the 38' length and it would directly spray at the underground electric box that sits on the property line. Is that ok? If not, how would you do it?

Next, I saw that the mailbox would potentially block one of the sprinklers and wondered if that would cause an issue. Should I supplement with a 360° rotor in the center of the lawn?

I'm at a loss on how to lay out sprinklers for the section near the fence and beds.

TL;DR I need help designing an efficient sprinkler layout, will you please help?

Any advice is greatly appreciated!

Thanks in advance.

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Re: Help with sprinkler placement (and intro)

Post by Riverpilot » July 18th, 2017, 6:26 pm

I just had irrigation installed this spring. A few comments.

1) Is this underground or dragging hoses around?
2) Make sure you know what kind of GPM you're going to be getting.
3) Just because a company like Hunter has a sprinkler head that states is can spray 40', doesn't mean it really does in real world conditions.
4) I have a similar front lawn size. I have 8 sprinkler heads covering that area.

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Re: Help with sprinkler placement (and intro)

Post by g-man » July 18th, 2017, 10:41 pm

This is a tough layout. The area called not irrigated, is it mulch and it could get wet?

So they only way I see doing this right is with 19ft spacing between the heads. This way you cover the width of the area. The problem is the 30ft depth. Since the heads are at 19, then you will end up watering the no irrigation area.

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 21st, 2017, 10:49 am

Thanks for taking the time to respond.
Riverpilot wrote:
July 18th, 2017, 6:26 pm
1) Is this underground or dragging hoses around?
2) Make sure you know what kind of GPM you're going to be getting.
3) Just because a company like Hunter has a sprinkler head that states is can spray 40', doesn't mean it really does in real world conditions.
4) I have a similar front lawn size. I have 8 sprinkler heads covering that area.
1) It will be underground.
2) I have a pex supply line. IrrigationTutorial.com suggests to use 7GPM as my flow rate. However, there is research that suggests the pex will be ok up to about 10 ft/sec which is around 11GPM. I will plan to use this 11GPM as my flow, and if i need to adjust down, I will.
3) I am cautiously optimistic in regard to sprinklers' radii. I will be following Stryker's rule with my spacing.
g-man wrote:
July 18th, 2017, 10:41 pm
This is a tough layout. The area called not irrigated, is it mulch and it could get wet?

So they only way I see doing this right is with 19ft spacing between the heads. This way you cover the width of the area. The problem is the 30ft depth. Since the heads are at 19, then you will end up watering the no irrigation area.
I can expand a little more about my drawing: The black "not irrigated" section will be mulched and can get wet. There is a small palm in that spot that I may be able to relocate and make that bed smaller. None of the beds are finalized at this point, I just bought the house and the hedges that are there will be removed once I get the lawn "up to snuff". The right side of the yard is the driveway (30') and the left is open to the neighbor's yard (roughly 50' of the 58') and fence (8' of the 58').

I am leaning towards a 19' rotor in each corner of the 30x38' (so 38x38' and watering some of the flower bed) section. Hopefully the 2' high electric transformer and the mailbox won't block too much of the spray and I can get even coverage.

For the north section of the yard I am leaning towards doing a couple of zones in sprays to try to get the coverage I need, but am still trying to finalize the exact layout.

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Re: Help with sprinkler placement (and intro)

Post by g-man » July 21st, 2017, 11:39 am

I have 3/4 pex to the meter and to the house. I read about the 10ft/s and tried it an open pipe with a ball valve. I did not like the hammer due to the speed. In further research I did, the Pex internal walls are smooth and wear should not be a concern with 10ft/s but the fittings are a different story. My house builder used expand pex (different clamp system) and plastic fittings. The fittings ID are even more reduced than the 3/4 pex ID. I did not like the risk of breaking a 90 degree fitting with the water hammer or just the turbulent flow above 10ft/s.

In the end I chose to limit my design to 5 gpm/zone. I went from 3/4 pex to 3/4 pvc valve manifold (short distance) and then 1in poly to all the heads. The 5gpm might be a conservative approach but I did not want to risk the hosue supply lines to maybe save in reducing by one valve or an hour extra of the system running. The system works really good and allows for the occasional use of sinks/house faucets in the am without impact to the spray gpm.


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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 21st, 2017, 1:14 pm

That's really good to know. I will definitely test before I finalize the number of zones I use. I may use the recommended 7GPM if necessary.

Quick question about the figures I am using for design via irrigationtutorial:

I took the reading of PSI using a gauge numerous times and consistently received around 80 PSI. I have a 3/4" pex supply pipe and a 5/8" water meter.

How do I find how much pressure to the sprinkler inlet I will be receiving to figure out how many 19' rotors I can put on a zone?

I am looking at this chart and see that I want 30-40PSI so it throws 21-22' with the 1.0 Dk. Green nozzle.
Image

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Re: Help with sprinkler placement (and intro)

Post by g-man » July 21st, 2017, 2:26 pm

You want to supply ~45 psi to each head. I think those are hunter rotors, so it would benefit from a regulated head at 40PSI (you could buy a 30 or 40 head). The heads (tries to) limits the pressure to avoid going above 40 PSI (Hunter PRS40). https://www.hunterindustries.com/irriga ... pray-prs40

You need to calculate all of your pressure losses thru all the pipes based on the flow of each pipe. Account for all obstructions (valves, filters, etc). Then subtract the worst case pressure loss to a head for that zone from the available pressure. The resulting pressure needs to be above 45psi (5psi as a safety factor). The worst thing is having a system installed that doesnt work because of pressure.

The price different 1in poly and 3/4 poly is not much, but there is pressure losses difference as a function of distance.

The max number of rotors for a given zone is mostly a function of gpm. For the one you selected it needs 1.5gpm. Based on your criteria of 7gpm, you could only place 4 rotors (1.5*4=6gpm). IF you are looking at hunter, I would recommend an MP2000 nozzle for the 19feet on a 40psi head.

Lastly, the house water pressure above 80PSI is not ideal. Most appliances will last longer at lower pressures due to the reduced flow (60psi). Here is some info from a water heater manufacturer http://www.bradfordwhite.com/pressure-d ... eaters-115 A pressure reducing valve (PRV) is normally used to reduce/control the city water pressure.

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 21st, 2017, 4:00 pm

Thanks a ton for the insight, g-man.

The house is only 7 years old. Is it typical for newer houses to have such a high water pressure? Is a PRV going to affect things like water pressure in the shower? My wife will hate that, haha.

I'll report back to this thread as progress is made, still waiting for the utility companies to come mark the lawn so I don't dig through anything. I do have a few questions regarding placement of sprinklers around or behind objects like the mailbox and electricity transformer if anyone has a suggestion for those areas.

Electrical box sits right on the lot line, shared with the neighbor. It is about 10 feet off of the corner of the lot. My water meter and shut off are immediately to the right of it. I should be able to put 3 rotors on this side. (I'll measure again when I get home from work).

Image

This is the mailbox location I keep talking about. It sits 2 feet off the corner and 2 feet in from the driveway. Do I put my corner rotor behind it? In front of it with a bubbler or something else to fill in the gap?

Image

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Re: Help with sprinkler placement (and intro)

Post by ken-n-nancy » July 21st, 2017, 11:50 pm

sh3rlock wrote:
July 21st, 2017, 10:49 am
...
3) I am cautiously optimistic in regard to sprinklers' radii. I will be following Stryker's rule with my spacing.
...
I am leaning towards a 19' rotor in each corner of the 30x38' (so 38x38' and watering some of the flower bed) section. Hopefully the 2' high electric transformer and the mailbox won't block too much of the spray and I can get even coverage.
Either I'm misunderstanding what you're suggesting above, or you're not planning for head-to-head coverage of your sprinkler heads.

You need to plan your sprinkler layout for head-to-head coverage or you will get dry spots. However, you don't need to take my word on this. It sounds like you've been getting good advice from the Irrigation Tutorials site, as you mention Stryker. Go to the page for Determining Landscape Sprinkler Locations and read the sentence right below "Important" and right before "READ THAT AGAIN!"

If you are planning to water a 38'x38' area with one rotor in each corner, then each rotor needs to throw 38', not 19'. If you only put one rotor in each corner of that lawn with a 19' throw in each, you will not be happy with your irrigation system.

Personally, to cover the area you have with head-to-head coverage, I'd suggest using a rotor with a nozzle that can comfortably throw a 20' radius, and then use the adjustment screw to reduce that to as little as 18' (or slightly less) for the places where that is needed.

When planning a layout, you want to follow the suggestions on the irrigation tutorials page linked above. Start by putting a head in each corner, which will dictate some throw limits (such as you're limited to an 18' throw in the little section farther from the street unless you want to water the fence or the house -- which is a bad idea).

Then, place heads around the perimeter, and if there is space left over in the center, put a head in the "dry spot" while gaining head-to-head coverage as much as possible.

I followed the above and came up with a straightforward layout which would require 11 heads. The maximum throw is 20' and the minimum throw is 15' which is well within the reasonable reduction achievable from a little use of the nozzle adjustment screw. All of the heads are on the perimeter except for one in the middle. That one will need a larger nozzle to make up for the fact that it is 360-degree coverage while the others are all 90-degree or 180-degree coverage heads.

You're probably thinking -- 11 heads, that's a lot! However, compared to the labor you'll spend digging the trenches (which has more to do with the distances to the far corners of the lawn than the number of heads placed along that distance), the cost of a few extra heads along the way is practically insignificant.

I've made a diagram below, free of charge. ;) To read the diagram, the blue dots are rotor placements. The blue number is the throw to which that head would be adjusted via the nozzle adjustment screw (max of 20').
The red lines and numbers are the distances between those heads, measured in a straight line across the ground. The occurrences of "equal" are to have the head that is there be equidistant from the two other heads to which the red lines are drawn. I didn't do the trigonometry to figure it out, but it will be approximately 20'. That head would be adjusted to give head-to-head coverage between those two sprinklers.

Image

Note that the sprinklers in the corners next to the driveway will actually both slightly overthrow the center head along the driveway. The increased head density in that area will give a little extra watering directly adjacent to the driveway, but that's actually a good thing -- the grass right along the driveway will tend to dry out more due to the heat absorbed in the pavement. Also, presuming that the overthrow isn't to an undesirable area, such as a building or pavement, it's better to overthrow a head then not quite reach it. (Again, don't just take my word for this; read that page on irrigation tutorials again to see that it says this, too!)

You don't need to worry about watering the underground electric utility box; it's built to survive torrential downpours without damaging the equipment within. You will want to use a nozzle that throws high enough to go over it, but using traditional rotor heads, that really shouldn't be a problem if you use a layout like the one below, given that the head placements in the layout below are more than 8' away from the box.

Figuring out which heads go one with which zone is a separate exercise -- the next step.

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Re: Help with sprinkler placement (and intro)

Post by ken-n-nancy » July 22nd, 2017, 12:02 am

Just realized I didn't mention the mailbox post. You really want to put the rotor in the corner of the driveway and road as close to that corner as you can.

Note, it's also important to connect the heads properly using a "swing joint riser" (see the page on Sprinkler Head Risers) as that will enable your sprinkler head to survive being driven over if installed properly. (I remembered this when suggesting putting that rotor right in the corner, which will increase the likelihood that it is driven over -- but, if properly installed, that shouldn't be a problem.)

You're in Florida, so you don't need to worry about the snowplow hitting the post. (That's a major concern for me in New Hampshire.)

I'd seriously consider moving the mailbox post closer to the curb (and maybe a little further from the driveway, while you're at it in order to lessen the likelihood of accidentally having a car hit it, especially if there will be any beginning drivers or elderly drivers in your household.) If you could get the post practically right up against the curb, you can offset the sprinkler head a little away from the curb in order to stop the throw from that corner rotor just before the mailbox post. (Note, to do this, you'll need to use a post that has the mailbox "on top" of the post, instead of offset to the front like the one you have.) The throw from the driveway center rotor and the roadside center rotor will also be able to help water the area near the mailbox, too, as long as you set up for head-to-head coverage as shown in the diagram above.

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 22nd, 2017, 12:17 am

Wow! Thank you so much for your in-depth response.

Sorry for the confusion about the spacing. Of course I am intending for head-to-head coverage. Thank you for kindly explaining the necessities. Others may just be learning and it was a great summary of the importance.

The diagram you provide is tremendously helpful. I was simply over thinking the entire process of the layout. Your proposed layout seems very straightforward and was the direction o was headed, slowly but surely.

Re: the mailbox. I wont be able to change the style per the HOA. I might be able to move it slightly, but only laterally away from the driveway.

Again, thank you very much for taking the time to respond in-depth to my questions. I sincerely appreciate it.

Hopefully I will have progress pictures soon.

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Re: Help with sprinkler placement (and intro)

Post by ken-n-nancy » July 22nd, 2017, 12:23 am

Also, from the nozzle chart you show above, it looks like you're considering the Hunter SRM. You may want to consider the I-20-SS. The I-20 has a useful feature of being able to turn on/off each head individually at the head. This makes it easy to make rotor adjustments without getting soaked, and also allows you to turn off specific heads if you're doing a renovation on a portion of your lawn and the area to be renovated doesn't exactly match your sprinkler head layout. The incremental difference in cost (about $11.50 for the SRM and $16.50 for the I-20-SS) isn't much. There is a short-range nozzle set available for the I-20 (like the SRM).

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 22nd, 2017, 12:56 am

Thanks for the tip, I was looking into the PRS bodies and MP heads because of my high water pressure, but I have seen the I-20-SS and they come with excellent reviews. I will look into them as I do my due diligence. It looks like I can get them with a pressure regulated body, too, but they are a bit more pricey. (25 vs 15 for MP sprays, so an extra $100 for the front yard).

Side topic: I'm planning zenith zoysia for grass, and with my current mower setup (rotary) I will have to keep it high-ish. Maybe 1.5-2 inches. Should I use the 4 or 6 inch rotor?

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Re: Help with sprinkler placement (and intro)

Post by ken-n-nancy » July 22nd, 2017, 9:47 am

sh3rlock wrote:
July 22nd, 2017, 12:56 am
Side topic: I'm planning zenith zoysia for grass, and with my current mower setup (rotary) I will have to keep it high-ish. Maybe 1.5-2 inches. Should I use the 4 or 6 inch rotor?
For a maintenance height of 2 inches, you'll be fine with 4 inch rotors. In my experience is that it's a height of about 4 inches that starts to show issues with the 4 inch rotors. (Of course, if you're cutting to a height of 3 inches, the grass is as tall as 4.5 inches before cutting.) So a cut height of 3" will show some bent over grass from irrigation rotors just before cutting.

I have no experience with Zoysia (or any warm season grass) though. Might be good to get the input from some warm season folks on that.

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Re: Help with sprinkler placement (and intro)

Post by HoosierLawnGnome » July 22nd, 2017, 10:42 am

Great sprinkler advice above. Have you thought about sodding or plugging the zoysia? Most of the successful renovations I've seen in our forum go that direction. Especially if you're going to try and seed in the late summer when zoysia may have not have as long to establish before growth slows down. But then, maybe growth never stops that far south?

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Re: Help with sprinkler placement (and intro)

Post by g-man » July 22nd, 2017, 10:47 am

I think ken-n-nancy did an excellent job in their layout. It matches what I had in mind when I recommend the 19ft spacing.

A few things to add. I would place the valve box in the top right side near the house. This keeps it out if the way. If you are really concentrate with the electrical box affecting the spray, you could use 12in risers to help the trajectory, just make sure it is leveled.

I would place the rotor just north of the mailbox post if you can't move it. Remember that the rotor is watering away from it and you don't want the post blocking the spray. The lawn around that rotor gets watered from the rotor to the north and west of it. Is this ideal? No, but it will be ok.

I keep heads at 4-6in from the driveway instead of touching the concrete. Again, does heads spray away from it and the angle adjustment allows another head to water the lawn near the driveway. This is explained in the irrigation tutorial website. The same applies to wood fences to avoid the water stains.

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 22nd, 2017, 11:00 am

I have considered it, but the wife nixed the expense this season. If going the seed route, should I wait until the spring? I haven't really gotten that far in my research about the renovation. I've never really done more than weed and feed my old Kentucky lawn.

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » July 30th, 2017, 10:16 pm

It's been a week, and wouldn't you it, my wife changed the plans. She is in the process of adding a bed around the utilities and extending the one near the house to include the fenceline. I will have two ovals of lawn kind of attached in the middle. As soon as she has finalized her design, I will post and get feedback. In the meantime, take a look at the results of 10 hours of ripping out hedges!
Image

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Re: Help with sprinkler placement (and intro)

Post by ken-n-nancy » July 31st, 2017, 12:05 am

sh3rlock wrote:
July 30th, 2017, 10:16 pm
It's been a week, and wouldn't you it, my wife changed the plans. She is in the process of adding a bed around the utilities and extending the one near the house to include the fenceline. I will have two ovals of lawn kind of attached in the middle. As soon as she has finalized her design, I will post and get feedback. In the meantime, take a look at the results of 10 hours of ripping out hedges!
Image
Bed around the utilities sounds like a good idea. Post a new diagram with your planned layout of sprinkler heads and folks here can help let you know if you have the coverage about right.

I'm guessing you'll be able to do the layout on your own by taking into account the approaches described above and the prior diagrams.

PS: I like that porch -- nice lighting, bench, and flowers!

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Re: Help with sprinkler placement (and intro)

Post by sh3rlock » August 1st, 2017, 12:11 pm

I think this is as finalized as I am going to get. I'm itching to order some parts.

Image

The green lines are modifications to the bed shapes. I will be shifting a couple heads around but I think that the general layout should still work for me.

Is there a preference for rotors over sprays? The MP2000 line with PRS bodies are quite comparable in radius and GPM to the I-20 line with the PRS bodies, and cheaper for the same number of heads. Any reason I should choose one over the other? Personal preference? How do I know when I should use the PRS bodies vs if I'm okay using regular bodies?

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