IRRIGATION: Rotor Roles

Sprayheads and rotors may look similar, but they play very different roles in proper irrigation. With water conservation one of the top issues in the industry, it is imperative irrigation contractors are well versed on the proper use and placement of various components. “There is a real awareness to ‘go green’ to the point where the average person can make a difference,” says Don Fisher, product and marketing manager with The Toro Co.’s irrigation division, Riverside, Calif. “A lot of thought is going into making irrigation systems do what they’re supposed to do without wasting precious resources.”
 
While identifying the basic differences between rotors and sprayheads is the first step, contractors need to recognize the emerging trends and advancements that aim to take efficiency one step further. And to get the most out of an irrigation system, contractors must first know the size and type of property they’re irrigating to decide whether a sprayhead or rotor would be the best option. “Each type of sprinkler is intended for different applications,” says Martin Thomas, owner of Hydroscapes, West Carrollton, Ohio. “But virtually all projects will require both types.”

WHAT’S THE DIFFERENCE? The difference comes down to distance. Rotors are ideal for areas 15 feet and larger, while sprayheads are best for areas 15 feet and smaller, says Gene Smith, sprayhead product manager for Hunter Industries, San Diego. Rotors can be classified even further as short-range, made for areas 15 to 30 feet, mid-range, for areas 25 to 40 feet and long-range, for areas 40 to 100 feet.
 
A sprayhead’s emission is static, while a rotor, well, rotates. Rotors move in full and partial circular patterns. Sprayheads are often used to water ornamental beds and small areas, like patches of grass between walkways, Thomas says, adding a rotor’s spray strength will knock the blooms off annuals and perennials. Sprayheads usually run at 30 psi, while rotors run from 45 to 55 psi, with precipitation rates of 1.5 inches per hour and 0.5 inches per hour, respectively. As a result, rotors are intended to water large patches of turf.
 
Because of their tendency to put down too much water too quickly, sprayheads have gained the reputation of being the more inefficient way to irrigate. Manufacturers agree a sprayhead can only run for a short amount of time before run-off occurs, particularly in nonabsorbent areas with thick, clay-like soil. Rotors are known to have a lower precipitation rate, and can be 25 percent more efficient than sprayheads by using less water in the same amount of time with higher uniformity, Smith says.
 
It’s common to put down too much water too fast with a sprayhead, says Heather Kraus, product manager for commercial rotors, Rain Bird, Glendora, Calif. Rotors give turf a chance to absorb the water that would instead form a puddle, she says.
 
While rotors are more efficient, the popularity of the two products varies not only based on the size of the area being irrigated, but also according to the region, Smith says. Rotors are more popular in the North and Northeast where lawns are larger, while sprayheads are more common in the South and Southwest where lawns tend to be smaller, he says.
 
Thomas has a 3-to-1 ratio of rotors vs. sprayheads for installations. “The majority of our jobs here in Ohio are on half-acre lots or larger, which is probably a much bigger area than the lawns you’d find in the South,” he says. “If we would try to complete our jobs with sprayheads instead of rotors, we’d have to use four times as many parts.”

EXTRA OPTIONS. Size and type of job determine if a rotor or sprayhead is the best choice. Whether contractors use sprayheads or rotors, Fisher says many tend to choose one product and use it for all of their jobs, regardless of differences in landscapes.
 
This stick-with-what-works mentality is influenced by past experiences or by a manufacturer’s low prices. “Contractors have a tendency to choose one product, stick with it and use it for all of their jobs,” Fisher says. “They should look at the vast array of product offerings that could allow them to differentiate themselves from other contractors.” Contractors who use various sprinkler advancements can use that as a marketing tool and outbid the competition. 
 
For example, a rotor and a sprayhead hybrid, technically known as a multi-stream, multi-trajectory rotating sprinkler, or a “sprotor” for short, offers the flexibility of watering 4- to 30-foot areas, which can’t be achieved by a rotor or a sprayhead. “A hybrid takes on the benefits of rotors and sprayheads and combines them into one product line,” Smith says.
 
Pressure regulation is a relatively new rotor advancement, although this feature has been available in sprayheads for some time, Kraus says. A pressure regulator, a small valve located in the pop-up stem, prevents misting and fogging by allowing a rotor to run at an optimal 45 psi, rather than typical city water pressure of 50 to 60 psi. “The water pressure may be too high coming in, but a pressure regulator breaks up the stream into a nice, even distribution,” Kraus says.
 
Another advancement in the rotor market is the shift toward taller pop-up heights, a response to taller turf heights, Kraus says. Rotors made 10 years ago reached heights of 3 to 4 inches, while today’s standard is 5 to 6 inches. This height is tall enough to spray over turf and shrubs.
 
Sprayheads come in heights of 2 to 12 inches, Smith says, adding shorter pop-up heights are used in the Southwest where shorter mow heights and less workable soils are prevalent. “The variety of heights allows the sprinklers to pop over shrubs that would otherwise be in the way,” he says. “Pop-up sprinklers help manufacturers provide equipment that is as transparent in the landscape as possible.” 
 
Check valves also contribute to water savings by preventing excess water from draining out of a system’s lateral lines once a system shuts off. This not only saves water, but it also avoids a consistently wet, muddy area in a client’s lawn. Some cities require check valves, so most sprinklers either come with this feature or provide the option as an upgrade. However, check valves are not necessary on every zone, Thomas says, adding he only installs them in elevated or hilly areas. “Most of the sprinklers we install have check valves, but not 100 percent of them,” he says. “There’s really no need to install them on flat, level areas.”
 
Check valves can extend the life of a rotor by a few years by preventing excessive air hammer when the system starts, Smith says. When the system starts back up, it has to extract that air, which weakens a sprinkler’s parts over time. “Most rotors will last 10 years or more,” he says. “But eliminating unnecessary start-up impact by using check valves and running the system at the appropriate psi can extend that life to 12 or 15 years.”
 
Flow stop is growing in popularity, particularly when it comes to maintenance needs, Fisher says. This feature enables contractors to turn off one sprinkler while others are still running, allowing them to work on the system without getting wet or interrupt a lawn’s watering schedule.

Some rotors come with a trajectory feature that allows contractors to change the angle of a spray. Most standard nozzles emit water at 24- and 28-degree angles, Fisher says, which can create problems in high-wind. Angles ranging from 7 to 13 degrees more effectively fight wind, he says. “If you’re in a windy situation, spraying at too high an angle will result in a lot of blow back and lost water,” Fisher says. “A weaker radius will fight strong winds more effectively.”
 
The extra efficiency of a rotor does come with a price. Rotors cost five to six times more than sprayheads, Fisher says, but with various discounts and manufacturer relationships, contractors may only pay three to four times more. A single-stream rotor costs $15 to $20, Smith says, while sprayheads usually go for $3 or $4. Pop-up sprinklers cost $3 to $10 depending on height, and “sprotors” cost from $4 to $8. Check valves can add $2 to $3 to both sprayheads and rotors, he adds. “Most rotors have their pros and cons,” Smith says. “Which one a contractor chooses will largely depend on price, features and manufacturer relationships.”
 
Contractors should choose sprinklers based on factors other than price. Fisher suggests making a broad comparison of different products side by side before deciding on one. “By utilizing the advancements available or trying something new, a contractor could really start to make a name for himself in the industry,” he says.

FUTURE FEATURES. Rotors have drastically improved over the years, particularly in durability. “They’re easier to work with and they are even more durable now than before,” Thomas says.
 
A durable rotor is important, particularly in commercial settings. Rotors can fall victim to vandalism or simple wear and tear from being in a public place, Kraus says. “A durable rotor will continue to operate even if disturbed,” she says.
 
Nozzle performance to apply water as uniformly as possible is another area manufacturers are striving to improve, Smith says.
 
With the recent focus on water conservation, contractors seek improved matched precipitation rates in both rotors and sprayheads, Kraus says. “Matched precipitation rates are getting better all the time,” Thomas says. “But options that help avoid overwatering could be improved.”

Lastly, contractors want rotors that work well and come at a great value, Smith says. “Most irrigation sprinklers are designed to be easy to install and work with,” he says. “For the most part, if they’re used within a manufacturer’s guidelines, they should remain durable and perform as expected.”