Need help with front lawn sprinkler spacing

[llO0DQLE]

Due to my pie shaped lot, I'm finding it very challenging to space sprinklers head to head (left, right and front). Due to the fact that the width gets progressively wider as you run the length of the lawn, I either come up short or overshoot by several feet in certain directions.

See pic of diagram



I figured I'd start with the bottom right corner as I don't want to overspray into my neighbor's side as much as possible. A 6 foot diameter would come up too short along the arc and won't reach the next sprinkler up ahead on the length of the lawn on the left side. 8 feet is too much overspray so I figured 7 feet is the sweet spot. The problems get bigger after that because as I try to get head to head coverage side to side, coverage is several feet short across. If I increase the radius to get head to head across, then I over spray by several feet to the sides. I'm looking for the best possible coverage (best compromise) with the dimensions I have to work with. I don't mind over spraying to the right of my lawn as that's my garage pad and in front on the side walk. I just don't want to overspray my neighbor's lawn by more than a foot to avoid issues with my neighbor or potential future neighbors.

[Green]

Anyone replying will want to know if these are spray heads (or rotors).

Also, if you don't get sufficient feedback from someone here, there is Rainbird's design service.

[llO0DQLE]

It will be spray heads. I thought that it's pretty much a rule to use spray heads for distances less than 15 feet. It's a pretty narrow section. It's 6 feet in width at the very front, only widens to about 10 feet at the widest area in the middle. Sections in the back part behind the tree are between 5 - 7 feet in width due to the garden bed.

How good is Rainbird's design service? Irrigation tutorials warns against these free design services on the web... I guess it can't hurt to try and see what they come up with.

[Green]

I think this is an ideal case for matched precipitation rate nozzles. Maybe taking another look at the nozzle spec charts for Rainbird's U-series and other MPR nozzles will give you some ideas.

[llO0DQLE]

I was thinking of going with the Toro Precision Spray Nozzles. However, it's not so much the nozzles or the available arcs that I'm worried about. It's about how to space them in my front lawn to get head to head coverage in all directions. I'm redoing the sprinklers in the front - moving heads and splicing where needed to have sprinklers in the right spots. It seems you're thinking about my other thread(s) and thinking that I'm sticking with the current sprinkler head locations and changing the nozzles to get better coverage.

[Green]

My point was that because of the differing width, if you use nozzles with different radii, you're going to need to really keep a close eye on the charts for precipitation rates. Are you thinking about the Toros specifically because of their lower precipitation rate?

[Green]

Also, your spacing will likely be determined in part by which nozzles you choose, unfortunately.

I just think that the spec sheets of the various nozzles, as well as real-world testing of them, in conjunction with your measurements and diagrams, are going to be the most useful. Call it a holistic design approach.

[llO0DQLE]

Yes, lower precipitation rates, matched precipitation rates between different nozzles, ability to adjust radii down by 25% giving me ability to select radii from 3.75' all the way to 15' and ability to retrofit to Rainbird 1800 bodies which I currently have. The last feature may be a moot point because I'm thinking of replacing my current 4" tall risers to 6". Also, most contractors that I've contacted for quotes use Rainbird, with a couple that use Toro as well. Only one company in my city uses Hunter. Seems like irrigation companies here are stuck in the 80s for the most part. Probably have something to do with distribution and that lawn irrigation is not as commonplace here as in the US.

As an aside, I don't think I can do any testing as I can't buy the Toro nozzles locally or online. Canadian online irrigation companies don't carry them and Sprinkler Warehouse doesn't ship to Canada. Seems like I can only get them from contractors. Same goes for Hunter products. The ones that are readily available online are Rainbird VANs which I currently have.

[llO0DQLE]

Toro advertises that their precision spray nozzles are matched and have a 1" uniform spray with any radius and arc. That's all their tech sheet says. So my approach is just playing around with the spacing in my lawn and selecting radii to get as close to to head to head coverage.

[llO0DQLE]

Also, with lower precipitation/flow rates, I can fit more sprinklers in one zone. This is a big advantage in terms of cost savings since if I go with Rainbird VANs I would have to add another zone to get the same coverage. All the above reasons are also why I decided to go with Toro nozzles vs Hunter MP800SRs as well as the fact the Hunter says their MP Rotators perform best at 40 psi and to get radii below 8' I'd have to lower the pressure to 30 psi and I don't know what the uniformity will be like. At least Toro advertises that uniformity is kept even with 25% reduction and it's a simple screw to adjust radii after the sprinklers are in the ground.

[llO0DQLE]

Played around more with spacing and this is what I've come up with. Due to the trapezoidal shape, I can achieve head to head overlap side to side and across but not diagonally. Is this an issue? Only way to reach diagonally is increase the nozzle radius but keep them closer side to side which means over 2-3 feet of over spray side to side and across. Some sections already have a good amount of over spray especially at the front where the lawn is skinnier.

[ken-n-nancy]

Looks like a good plan to me. Getting head-to-head coverage from side-to-side and across should be excellent.

The full "hexagonal" head-to-head coverage is impractical to actually achieve unless watering a circular area.

[Green]

I think you're good, too.

Remember, most heads do tend to put out a bit more water right near the head, and it tends to fall off with distance. Also, when spray heads start up and shut down, they water a bit extra right near the head. So, even though it looks like your diagonals don't reach, I doubt it would be too much of an issue even if you were in a dry spell and had to rely 100% on irrigation instead of rainfall.

[Green]

Oh, and...

Who's stuck in the 80s now? H and R haven't matched Toro's lower precipitation spray heads yet. Joke's on them.

[llO0DQLE]

Oh ok.. so have I been needlessly agonizing about getting head to head coverage diagonally or is that still an ideal to strive for where possible? Because if all I should worry about is head to head overlap then maybe I should stretch the spacing a bit since I overlap quite a bit in certain areas. And yes, I'm aware that sprinklers put out water heavier near itself and gradually gets thinner as you go further out on the radius. And because of that I'm worries of too much overlap with side to side coverage. Lots of sections over spray 1 foot over from side to side.

[Green]

Here's a real-world example...but with rotors.

I have a 15-18 foot wide area that's a strip between the driveway and neighbor's boundary. My irrigation was designed with rotors mainly just on the driveway side most of the way...no square or triangular spacing in most parts. There is a tree line with a few mature trees on the border of the two yards.

Occasionally, the tree line area will dry out because it gets less water. But more often than not, it's fine since rainfall (and the neighbor's sprinklers help to fill in. I rarely have to hand water or set up a sprinkler on that area.

This is an extreme case...yours would have much better coverage...mine gets 1 inch on the side with the rotors, and 1/8-inch on the opposing side.

[llO0DQLE]

Yeah we get 2mm of rain most times it rains and my neighbor doesn't water. My lawn gets 80 - 90% of it's water through my sprinklers. So I have to get this right as much as possible.

Ok, thanks for all the help Green and KNN. I think I got the front figured out now. I'll be moving onto the narrow side yard and contemplating on whether I'll do a redesign or optimize the coverage with just nozzle swaps, maybe moving a couple heads or so only to minimize cost.

Contractors are expensive here. $4500 for a full install and my yard is only 1,800 sq feet. To redo the front and do some optimizing work in the back is $1000 to $1500.

[llO0DQLE]

So here's my final layout for my front lawn. Only question is if I can fit them all in one zone. If I understand correctly, you need to add the GPM for each sprinkler you're using at the PSI and radius you're using and see if that total GPM is within the GPM of your water supply?