SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Quoted from "HooKooDooKu"

2. Ensures the pressure isn't too great. If you need to adjust the throw of an MPRotator towards the lower end of the listed range, you have to have a working pressure no greater than 30psi, otherwise it will be impossible to dial the rotator down as low as is theoretically possible. Additionally, with all irrigation, if the pressure is too great, the head will spray too fine a mist, causing more water to blow away in the wind that the system was designed for. Now all this can be taken care of using a valve with flow control... but then again that is just one more thing to adjust

That is a GOOD thing. You should want more things to adj a system. I have installed some without flow control and it sucks. Having the extra option comes in handy on job, area too wet/dry. Last job to get an extra 4 feet was great. I would rather have that then need to go back to take out nozzles, added a head (another BS tee) etc. For the extra $1.50 per valve, WELL worth it.

I have my own puller and for me trencher are too slow and cause more grass issues then they are worth. But that is me.

Problem I see is no one is taking PD (pressure drop) into the case. Mp3000 are nice but run time is very long to get precep you need.

Installing these is not complex if you do somehomework or have been doing it for sometime. Both are the same but latter does not need to run the rumbers on paper. Been there..

First of all, the 160' of pipe quote is just the pipe needed to circle the yard and get one pipe to the center of the yard. It did NOT include pipe needed to get from your water main to the manifold/valves and then to the yard. But as I see it, the most simplistic pipe layout is to simple encircle the entire yard (two 50' length, two 40' lengths, one 20' to get from the edge of the yard to the center). But to do that, you basically send two pipes to the edge of your 50'x40' area, then have one pipe turn right, the other turn left, and they each go around the perimiter of the yard in opposite directions. It doesn't matter where you start the perimiter, you can always route pipe such that each one feeds two corners, one 50' center, and one 40' center. From there, you just tack on running an additional pipe for 20' from one of the 50' center heads to the center of the yard (or if for some reason you want to keep the two zones balanced, place two 180 degree heads in the center of the yard and have 20' of pipe coming from both 50' center heads to the 180 degree heads at the center of the yard, taking the total pipe length to 180'... still excluding pipe to get to the yard perimiter.

As for the pressure regulated sprinkler bodies... are they REQUIRED? No. But using them does two things for you.
1. Ensures equal working pressure at each sprinkler head. Without them, the working pressure at each head will be different. Will the difference be enough to matter... perhaps not, and if it does, you can balance the system adjusting the throw of each head. But if you start with all of them at equal pressure, that's fewer things that have to be tinkered with.
2. Ensures the pressure isn't too great. If you need to adjust the throw of an MPRotator towards the lower end of the listed range, you have to have a working pressure no greater than 30psi, otherwise it will be impossible to dial the rotator down as low as is theoretically possible. Additionally, with all irrigation, if the pressure is too great, the head will spray too fine a mist, causing more water to blow away in the wind that the system was designed for. Now all this can be taken care of using a valve with flow control... but then again that is just one more thing to adjust.

I personally found it easier to just leave everything wide open and allow the presure regulators even everything out for me. And at $30, that sounds pretty cheap compared to the cost of everything else. After all, just renting a trencher to open up all that trench is going to run you well over $100 to rent one for a weekend.

Once again, thanks for the help. I started mapping the pipe layout last night. Amazingly enough I came up with about 290 feet. I do not see how to get 160 feet but I will try and re route it to come up with some shorter distances. I would still like to have that middle sprinkler though. Another question I had was do I really need the pressure regulated sprinkler bodies? Just curious because they are about three dollars more expensive. I may be sounding cheap but I just want to know if I really need these. Thanks once again everyone for their input.

Quoted from "Candance"

My advice was going off of over 15 years installing systems professionally and not a DIY website for homeowners.
What you propose will work but with added cost and work.

What is the added cost?

After reviewing the two basic suggestions, I really see only three primary differences:
1. MPRotators vs. "TRUE" Rotators (and the requried GPM difference)
2. Addition of one extra head in the center of the lawn.

IMHO, the KEY difference to picking one over the other is the difference in GPM requirements. IMHO, it would be foolish for a DIY to attempt to build their 1st system designed to require 92% of the maximum flow they could produce from a bucket test. There's just hardly any room for error... and if there is indeed error, the result will be rotors that can't throw enough water far enough with no possible solution.

But using MPRotators requires only about 50% of the maximum flow from the bucket test. That leaves plenty of extra to work with when things are not quite right. After all, not only .. and the MPRotators can also throw 25 to 30 feet.



OK, hold the phone!!!

I do see the one thing that wil seriously add to the lastest plan for MPRotators layout... Pipes and trenches. Obviously adding a head in the center of the yard requires at least an extra trench from the edge to the center. But the other thing is to place the corner heads on one circuit and the center heads on another requires potentially twice as much pipe. Not including the pipe to get to the yard, one plan requires about 160' of pipe, while the other requires about 290' of pipe.

So before you decide how to setup your circuits Andrew, pull out a piece of paper and map how you plan to lay the pipe.

My advice was going off of over 15 years installing systems professionally and not a DIY website for homeowners.
What you propose will work but with added cost and work.

That sounds like a pretty good idea. Thanks for your help.

Quoted from "Andrew77"

Would it also be feasible to put in some more sprinklers in the middle of the 40 ft lengths? I could add some 180 degree MP2000's on the top and bottom to get better head to head coverage. This would only add about 1 to 1.5 GPM.

If you want more rotors, then I would suggest removing the two MP2000's from the center and replace them with one MP2000 180 degree rotor at the center of each 40' edge and one MP2000 360 degree rotor in the very center of the yard. To divide the rotors into two circuits, I would place the four corner rotors and the center rotor on one circuit, then the four rotors on the center of each edge on a second circuit.

Here's an interesting thought. If you set the circuits up this way, each circuit covers the whole yard. So rather than running both circuits say once every four days, alternate circuits every other day.

Quoted from "HooKooDooKu"

Quoted from "Candance"

...
Most rotors will shoot 25 to 30 foot or better at 90 PSI so you should have plenty of head to head coverage.
And you would be able to do the front yard in two zones with 11 GPM on each zone.

Let's keep in mind by the OPs own admition that the figure of 90 PSI and 12GPM is from a bucket test. And as he well should know from reading the irrigation tutorials that that does NOT mean he has 12GPM @ 90PSI.

I would also recomend AGAINST a new DIYer in irrigation to try to design a system that close to the limits (i.e. Do NOT design for a system to run at 11GPM when a bucket test indicates 12GPM max). Speaking as a DIY and being the "engineer" type, I would suggest to the OP that he design for a system with no more than about 8GPM MAX. Even then you can't be sure unless you've run the correct test to determine at running pressures what GPM you can produce.

Now if the issue is simply a matter of enough throw, then the MPRotators do have the 3000 series. In theory, these should shot about 30 feet. But from a practical stand point, you should design for a throw of 27 feet.

My general suggestion would be to go with MPRotators and use something like the RainBird PRS series of bodies (i.e. their regular bodies with pressure regulators built into them). It will make things much more consistant at each sprinkler head.

As for spacing, how about this...
Use 6 MPRotators 3000 series, one at each corner and one at the center of each 50' edge. This will give excelent head to head coverage along those edges. Of course that doesn't provide head to head coverage along the 40' lengths, so fill in the center of the yard with 2 306 degree MPRotators 2000 series using triangular spacing. Basically place them about 14 feet apart from each other and dial down the distance so these in the center are only throwing 14 feet rather than the 18 to 20 feet they would normally throw.

Would it also be feasible to put in some more sprinklers in the middle of the 40 ft lengths? I could add some 180 degree MP2000's on the top and bottom to get better head to head coverage. This would only add about 1 to 1.5 GPM.

Quoted from "HooKooDooKu"

Quoted from "Candance"

...
Most rotors will shoot 25 to 30 foot or better at 90 PSI so you should have plenty of head to head coverage.
And you would be able to do the front yard in two zones with 11 GPM on each zone.

Let's keep in mind by the OPs own admition that the figure of 90 PSI and 12GPM is from a bucket test. And as he well should know from reading the irrigation tutorials that that does NOT mean he has 12GPM @ 90PSI.

I would also recomend AGAINST a new DIYer in irrigation to try to design a system that close to the limits (i.e. Do NOT design for a system to run at 11GPM when a bucket test indicates 12GPM max). Speaking as a DIY and being the "engineer" type, I would suggest to the OP that he design for a system with no more than about 8GPM MAX. Even then you can't be sure unless you've run the correct test to determine at running pressures what GPM you can produce.

Now if the issue is simply a matter of enough throw, then the MPRotators do have the 3000 series. In theory, these should shot about 30 feet. But from a practical stand point, you should design for a throw of 27 feet.

My general suggestion would be to go with MPRotators and use something like the RainBird PRS series of bodies (i.e. their regular bodies with pressure regulators built into them). It will make things much more consistant at each sprinkler head.

As for spacing, how about this...
Use 6 MPRotators 3000 series, one at each corner and one at the center of each 50' edge. This will give excelent head to head coverage along those edges. Of course that doesn't provide head to head coverage along the 40' lengths, so fill in the center of the yard with 2 306 degree MPRotators 2000 series using triangular spacing. Basically place them about 14 feet apart from each other and dial down the distance so these in the center are only throwing 14 feet rather than the 18 to 20 feet they would normally throw.

Thank you for the help everyone. As you stated, I do know that 11 or 12
gpm is a pretty unrealistic number. I'll be keeping each zone to around
5 or 6 gpm. The mainline coming in from the street is old galvanized
steel, about 50 feet of it. I made the connection in the basement with
a backflow preventer and ran it outside. I will also be using 1 inch
poly in the yard. The plan you laid out sounds great. I started coming
up with something like this last night but was too tired to think about
it.