No irrigation system is perfect, and this one has a couple of limitations which need to be accommodated.
First, as with all overhead irrigation, the sprinklers are very wind sensitive. We try to irrigate when the air is calm, usually first thing in the morning. Note in the above photos that we use 3 sprinklers at the center of the garden. Although the garden could be irrigated using just one sprinkler, we live in an area that is frequently breezy during summer, so irrigation must be done during brief calm periods early in the morning. Using 3 sprinklers allows the irrigation to be done in 1/3 the time required for a single sprinkler. In less windy areas, one sprinkler would work fine, it would just need to run longer.
Second, the sprinklers need to have steady water pressure in order to evenly irrigate a circle of a particular diameter. As water pressure drops, the diameter of the irrigated circle gets smaller and vice versa as pressure increases. If the sprinklers are connected to a municipal water supply, this doesn't present a problem. We irrigate from a well which, like most residential wells, incorporates a pressure tank and pressure switch. When the sprinkler is turned on, the water pressure drops steadily as the pressure tank discharges down to about 40 pounds per square inch (psi). At that point, the pressure switch turns on the well pump which pressurizes the tank back up to 60 psi, at which point the pump shuts off and the cycle starts over. As the water pressure continually varies between 40 and 60 psi, the irrigated circle fluctuates in size resulting in uneven application of water at the perimeter of the garden. This could be solved by by installing a pressure regulator to maintain steady pressure to the sprinklers. The problem is that most of the wear on a well pump occurs during startup. A pressure regulator would require the pump to cycle on and off during the entire irrigation period, causing unnecessary wear to an expensive pump.
I researched this and eventually solved the problem by installing a device that most plumbers have never heard of. It's called a "cycle stop" valve, and solves both problems. It is similar in principle to a pressure regulator, and is installed between the pump and the pressure switch. It insures that the pump delivers a constant water pressure to the sprinklers and also insures that the water pressure at the switch does not become high enough to turn the pump off, until the sprinklers are turned off, thus prolonging pump life. In the event that you might want to use such a system, I'd recommend reading the Cycle Stop Valve website at cyclestopvalves.com. (Note: I am not connected with this company and do not receive any compensation from it.)
Cycle stop valve is red and white fitting. Well head is on left.
The sprinkler heads we use are Rain Bird #5004 PC which are adjustable for irrigating any portion of the garden from one section (1/12th) up to the whole garden. They come with an assortment of nozzles depending on the area to be irrigated.
