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

Okay guys, need some expert opinions. Here is what I am dealing with. I live in Wyoming so I have the need to water 6-7 months out of the year. Although most people think WY is cold (and it is in the winter), I live in the "high desert" so we regularly experience 90+ temps in the dead of summer. House (built 1989) sits on 13,000 sq ft lot, of which I would guess is 6-7,000 sq ft is turf (lots of landscaping and patios). House came with a 5-zone system installed (exclusively Rainbird) that covers all turfed areas. 3 of 5 zones are rotors and the other two are sprays. There is a substantial elevation change throughout zone 3. I water 3 times a day in the early morning (soak-and-cycle), 3 days a week - 15 mins for rotor zones, 10 minutes for sprays.

Okay, so at first I was excited it had sprinklers but quickly realized there were severe "design deficiencies" upon operating the system the first summer. Lots of dry spots, uneven growth, and sprinkler placements that make me go "huh?" on a regular basis. My first "solution" was to replace all the sprinklers with more modern technology. All rotor zones originally had Rainbird "TurfBirds" (R-50's, I think) installed which were replaced with Rainbird 5000 Plus Series with Low Angle nozzles installed due to the irregular shapes of all rotor zones.


The two spray zones had a grab bag of Toro, Orbit, and anything else handy in it. Replaced all with basic Rainbird 1804 (no SAM, no PRS) sprays with U-Series 15' nozzles.

After this, the system worked better but after operating for another whole summer, some problems are still showing up. Let's talk about the rotor zones first.

Because of the irregular shape, I often cannot achieve head-to-head coverage in the rotor zones without severe overspray onto hardscaping. Even if I bite the bullet and water some concrete, I wind up having to overwater 90% of the lawn to keep that last 10% alive. Simply put, there aren't enough heads. Great, I'll just add some heads to the existing zones.

Yeah, not quite that easy. I am already pushing flow. The current rotor zones have 6, 5, and 6 heads respectively. I am pushing between 11 and 13 GPM on the three zones. All this through a 3/4" copper house service line that quickly necks up to 1" PVC immediately after teeing into the water service line. 5/8" water meter, though it is a "mag meter" that I am told has minimal pressure drop. No back flow preventer (flame me now) and it does have a master valve. Here's something interesting - I have over 85 psig static, but the dynamic pressure ranges from 35-45 psig while the 5 zones are active. Dynamic pressure is measured shortly after the master valve so it doesn't account for the zone valve and associated lateral line piping out to heads. At this point I realized that adding heads is probably not going to help.

Now onto the sprays. Seems whomever "designed" the sprays zone didn't take Sprinkler 101. The two spray zones are watering a continuous 117' x 12' strip of turf using 6 heads per zone (12 heads total for both zones). And here's the kicker - they installed them in a SINGLE ROW!


Okay, now I need suggestions. I have pretty much relegated myself to the fact that I am going to have to redo this SOB and add a whole bunch of zones to what I have existing. I *THINK* i can reuse a lot of the already-buried 1" poly but I know that I have a ton of trenching in my future. My questions are more along the lines of what I should use for sprinkler heads. If I am digging trenches I am not going to care much if I am adding 10 or 15 more sprinkler heads to a particular area of the yard. The hard work is done at that point.

My first thought was to install rotary sprays (MP Rotators, etc) in ALL zones. I drew all my zones up in AutoCAD and realized I'd have to choke all these nozzles down to their minimum distance. Then I started looking at conventional sprays (namely, the Rainbird HE-VAN nozzles). This has worked out better on paper in terms of coverage but has increased my number of zones by a few because of their larger gallonage requirements. For example, I can do 2 zones in the front yard with rotary sprays, but I'd need 3 zones if I used HE-VAN nozzles. But, I don't really care about adding zones because, again, if I have to add 1 zone then adding 2 more isn't that much more work.

I can't stress enough the irregular shapes of these damn zones. Some parts of a zone are wide open and would lend themselves well to rotors but there is always at least one area of the zone that is small (like 11.5' x 10') and would be better off with sprays. I have toyed with the idea of "hybrid" zones that incorporate 5000 series rotors and Rainbird rotary nozzles. The product documentation indicates they have matched precip rates.

At this point I am leaning towards just going exclusively to sprays and add somewhere in the neighborhood of 30-40 heads across the 5 zones. It seems they have better uniformity than rotors in a compromised design. Like I said, I get really bad growth spots in some areas of certain zones while other areas of the zone are struggling to stay green. And if I don't mow every 4-5 days, I am taking (4) 30-gallon bags of clippings to the green waste dumpsters.

Anybody have any guidance???

If anybody is interested, I can probably upload the drawings of the zones from AutoCAD. I am pretty proud of them.

Also, in my "paper designs", I have been shooting for a max of 8 GPM per zone - sound reasonable?

Quoted from "Wet_Boots"

Install a proper backflow prevention assembly, and get back to us.

The house has a backflow preventer on it to prevent contaminating the city water supply. My sprinkler line just doesn't have a seperate device on it. So no worries, I'll only contaminate my own water.

Quoted from "Wet_Boots"

You do not have that right. Unless your state has no construction codes whatsoever, there are plumbing rules to follow, and backflow prevention is a part of those rules. A dual check device in place near a water meter is meant to be insurance to protect the city water supply from dipsh!t homeowners, but it is not rated as protection from lawn sprinkler systems.

Consider the practical matter of someday wanting to sell your home. The structure will be inspected. Unsafe plumbing gets flagged, and WILL be corrected to code official satisfaction, with fees and maybe fines piling up in the process.

If your sprinkler system is so marginal in performance right now, and you're willing to expend time and money to improve it, spend the effort wisely and install a PVB (if you are on flat ground) or an RPZ, and make the system work with the altered supply performance. There is absolutely no good reason not to do it.

By the way, if you did pull out working Rainbird R-50 heads, you can probably sell them on ebay.

Point taken, and I never said I WOULDN'T install a backflow preventer. But that wasn't my question. I don't have questions on whether or not a BFP is necessary, I asked for thoughts on improving my current design.

You're right, the amount of work I am going to undertake is phenomenal and installing a BFP would be a fraction of that total work. As such, I will install one. But forgive me, it seems a little like you are refusing to offer advice until I do so. If that is the case, then I feel like you are acting pretty immature about this whole situation.

And let's not forget, if I am doing all that work at one time, why wouldn't I do the BFP at the same time? To refuse to help until I do it is being impractical. If someone installing a brand new system came to you and asked you for advice, would you turn him down at first and reply "Install a proper backflow prevention assembly and get back with us"? There are known loss values for these devices so I am having trouble understanding how the design hinges on empirical data the is gathered AFTER the BFP installation...

Also, if you could please be understanding, I am not the original owner of this house and so I would ask that you please don't chastise ME for SOMEONE ELSE'S mistakes. I will make it right when I do the project. For now, I am trying to define what exactly that project is. BFP is at the top of the list, okay? Can we talk sprinklers now?

Lastly, and in hopes I don't hijack my own thread, I don't know what exactly they are looking at in an inspection, but it must be pretty small because there are about 4,000 things the previous owner did that I have serious doubts "meet code". And I'm not just talking plumbing. So your concern about inspection if I sell the home is noted, but I feel it is beyond the scope of the question asked.