Adjusting Sprinkler Systems
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Adjusting your sprinkler system is an often overlooked part of the installation process, and you should be alert to keep the system adjusted over the years to maximize its efficiency, conserve water and save you money!
The key to an efficient sprinkler system is to control the pressure at the nozzles within the optimum pressure range. Too much pressure is BAD! It will cause the spray pattern to break up too early, form small droplets, and REDUCE the radius of the spray pattern! You know for sure you have too much pressure when you see mist (looks like smoke) rising from the sprinklers, and they are making a hissing sound. (Remember- hissssssss is bad.) Properly adjusted sprinklers are quiet, and produce very little mist.
Likewise, if you install an oversized nozzle on your rotors, the flow rate in the pipe will be higher, increasing the friction loss in the pipe, This results in less pressure at the nozzle. Too little pressure means large drops, and you will not get enough water in the area near the sprinkler. The nozzles are carefully designed to provide just the right water distribution at the optimum pressure, so if you try to get "smart" and "improve" things by using the wrong nozzle, you'll screw up the water distribution and waste a bunch of money.
The ideal operating pressure for most spray sprinklers is around 30 to 40 psi. Rotors operate best at 50 to 70 psi. Rotors need to operate at higher pressure because the orifices in rotor nozzles are larger than in spray nozzles. To break up the large stream a higher pressure is required. You probably won't be able to measure the pressure in the nozzles while they are operating, but you can observe the spray pattern and determine if the pressure is close to the right value.
There are several ways to control pressure delivered to the sprinkler nozzle-
If you have a mixture of spray stations and rotor stations, you should adjust the pressure at the rotor stations first. If you have only one kind of sprinkler (rotors or spray stations, but not both), follow first two steps. If you have a combination of rotor and spray stations, follow the first three steps.
Step 1- Turn on the largest station (if you have both rotor and spray stations, select the largest rotor station) and adjust the master valve flow control until the flow control is either closed as far as it will go (usually clockwise) or the spray stream begins to droop. Then open the flow control back up (usually counterclockwise) slightly until the pattern reaches its full throw radius, then a little more for margin in case your supply pressure drops a few psi in the future.
Step 2- If throttling down the flow control on the master valve doesn't accomplish enough pressure reduction, or the valve makes an undue amount of noise due to turbulence, make additional adjustments to the flow control at the station valves. Follow the same procedure that you used for adjusting the master valve in the preceding step, paying attention to the sound and appearance of the spray pattern. If you have a mixture of rotor and spray stations, adjust all of the rotor station valves at this time to optimize the pressure to all rotor stations. If you have all the same type of sprinklers (either rotors or sprays) adjust all of the remaining stations to optimize pressure.
Step 3- If you have both rotor and spray stations, and you adjusted the rotor stations in the preceding steps, adjust the remaining spray stations now. Since rotors require higher pressure to operate well, adjustments made up to this point will deliver too much pressure to the spray stations. Adjust each of the spray station valve flow controls by watching the spray pattern droop slightly while closing the flow control, then open it slightly to reach full radius.
Step 4- If you have adjusted the flow controls as much as you feel comfortable and you still have misting, consider adjusting the radius screw on the top of each sprinkler by turning it clockwise to reduce the flow. This will introduce a friction loss in the nozzle itself, reducing the flow of water. If the pressure was too high to start with, this will reduce misting. If the pressure was OK to start with, this adjustment can reduce the radius.
Want to know a powerful way to squeeze every drop out of your water use by making the system super efficient?
Most yards have very small areas that are shady or have good soil, or for whatever reason- the grass is greener. If this area is entirely within one station, just water it slightly less than the poorer areas, and you'll save water, while giving that area an adequate amount. If the lush area is only surrounding a few sprinklers, try adjusting the radius screw to reduce the water flowing from those sprinklers, or replace the rotor nozzle with a smaller size. Since you will probably be watering when the worst looking area needs it (when the lush areas still look fine) you can save a little water every time you water your lawn.
This can easily add up to thousands of gallons of water each year!
Go around the yard while the sprinklers are operating at least a couple of times each year and observe every sprinkler. If debris becomes caught in the screen or nozzle, remove the nozzle and screen and flush that sprinkler. This is especially important for sprinklers where significant adjustments have been made to the radius screw in the nozzle. By doing this, you'll get the most benefit out of every drop of water you put on your lawn!