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

Quoted from "Dan123"

Thanks in advance for looking over my questions, and any answers/advice would be greatly appreciated!!!
I already started purchasing parts, but have not started the install yet, and I want to make sure I do this right the first time.
I have a well that produces 15GPM+ and the PSI settings are 50 to 60, when the pump is running, and I'm using 15GPM its pretty steady at 58 PSI on the well tank, there is a 1.25" pipe ran from the well to my house plumbing and it T's off a 1" to all my house items, the other end of this T will be for the irrigation system.

Here is my plan so far, please let me know if anything is wrong, or you have better suggestions...
A) I want to install a 100-PESB for my mater valve, along with a Flow-Clik for added protection, these will be in the basement.
B) I plan on installing 2, in-ground valve boxes, one on each end of the house, each one will have a Febco 860 RPZ inside the box, along with 1" manifolds and 4x 1" HV valves.
C) I plan on using 1" poly for all underground sprinkler piping.
D) I plan on using R-van/P45 combos for all the sprinklers.

Now my questions:
1) Is it ok to install the RPZ's inside the in-ground boxes? Or would it be better in the basement? I heard they can spray water during normal operation?
2) Is it ok to run 1" pipe to my master valve? or should I run 1.25" (size supplied from well) and get a 1.5" master valve with reducers, is the master valve ok in the basement?
3) I have charts for the R-Van nozzles, and using the GPM at 45PSI what is the maximum GPM you recommend that I try and use?
4) Since I live in Wisconsin, I'd like to make this system self draining, how many drains should I put in each run? I also plan on blowing it out each season. What depth should I bury this at?
5) Since I have a well, there is some sand in the water, but right next to the well I installed a whole house 30 micron sediment filter, and I have never noticed any sand in my house water, but the filter definitely has a lot of sand in it when I replace it, do I need any additional filtering?

The only component that needs to be in the basement is a shut-off valve. From there, the plumbing proceeds through the foundation wall, above grade, as high as you can, up to four feet above grade. The next thing in the supply is the strainer, with a 100 mesh stainless steel screen. Then comes the RPZ. They have to be mounted above grade.

And note that the RPZ is used only if there is specific need for it. If the backflow assembly can be located a foot above the highest head in the system, then you employ a Pressure Vacuum Breaker. That saves you about 10 psi that you will need, so long as your pump pressure switch settings are as you described. It also saves you tremendous maintenance grief, as RPZs hate water with sand in it.

The size of the mainline does not have to match the size of the zone valves. 15 gpm is squarely in the operating range of one-inch valves. That flow is enough to lose pressure through any long run of one-inch pipe, so using inch-and-a-quarter will preserve pressure on long runs.

Forget self-draining completely. Buy an air compressor.

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No specific opinions on equipment choices, as I don't use what you chose. A flow meter is far less important than having zone valves with flow controls, along with a master valve.

About any sprinkler system items in basements - avoid them - anything that gets opened will dump water, so let it dump outside.

The strainer is one item you might do best to oversize, if you have sand concerns. In fact, some strainers get "doubled" with two in series with each other, with the first one of the series having a coarser screen, so that each strainer catches about half of the particles. Read the performance charts of the strainers. So, make that strainer a VFNT150-100SSP.

Pipe size. Nothing is known to us what the property dimensions are, so what pressure losses you have in one-inch pipe versus inch-and-a-quarter is equally unknown. Note that pipe size is just about pipe. Valves and backflow preventers and strainers are sized according to their own concerns. You do need to size pipe in order to avoid needless pressure losses.

PVBs and above-ground plumbing next to the house. Do you have central air conditioning? Think the outdoor part of that system is beautiful? It is not. Got a gas meter outside? Think it's beautiful? Got an electric meter? Face it, most modern homes come with necessary bits of ugliness next to them. It isn't too difficult to locate sprinkler system plumbing in the midst of that uglyville, without lowering real estate values. So a PVB that's four foot high? No biggie. In any event, the sand strainers need to be a few feet above grade, because the screen covers drop down from them for access.

Master valve. It gets located downstream of the backflow preventer, usually right next to the house.

System pressure is going to be a concern. Even with a PVB, you will lose at least 10 psi from the indoor pressure tank, before the water sees a sprinkler head. An RPZ could double that loss. And the strainers add their own pressure losses, as their screens trap particles. The simple way to accomodate to these pressure losses is to bump up the cut-off pressure. (the most popular Square-D pressure switch has a nut to tighten for raising the cut-off pressure, without changing the cut-in pressure)

In general, I would recommend considering standard rotors and sprays for a system fed from well water, because the sand tolerance of the modern rotating nozzles is a possible concern. Also, standard equipment needs less pressure, so you avoid tinkering with the pressure switch.

You may find that feeding a sprinkler system through a whole-house cartridge filter will get expensive. In any event, you'll keep an eye on the pressure gauge, so you'll know when to reload the filter.

Six-feet-plus is probably higher than any pro would set a PVB, but as long as you can maintain it, even with needing a stepstool to stand on, you can do it.