Ever since the 1970s, irrigation experts have been debating the merits of the rotor sprinkler head vs. the spray head.
Of course, each job site presents its own challenges and requirements. But there are some general situations that make either spray heads or rotor heads the best choice.
According to Pete Diebolt, president of Diebolt Landscape in Mohnton, Pennsylvania, the type of head selected is dictated by the irrigation system design. “The heads are going to have all different lengths of throw and uniformity coefficient. The distribution pattern, wind, slope and other design factors would have a bearing on the size nozzle and how to program the zones to run,” Diebolt said.
The system design already takes into consideration a host of environmental factors: wind or shade, elevation changes, the square footage of the area to be watered, etc. After that, choosing between a spray head and a rotor head comes down to a few other factors.
Let’s explore the advantages and disadvantages of each.
More properly called “fixed spray heads” these heads are smaller and spray a fan-shaped pattern of water. Nozzles are typically interchangeable and determine the pattern and radius of the water throw (e.g., half circle, full circle, etc.) Specialty patterns are also available for long, narrow areas.
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Spray heads are usually spaced up to 18 feet apart. Water pressure must be between 20 and 30 PSI of for these heads to operate properly. Note: most spray heads start to create lots of mist at pressures above 45 PSI, resulting in poor sprinkler performance.
Spray Head Advantages
Designed for smaller areas, spray heads will disperse more water in a shorter period of time. So they’re a good choice for areas near patios or other hardscaping that is not intended to get wet.
While spray heads are less expensive than rotors, their installation requires more pipe, trenches and valves.
Justin Moseley is the irrigation manager for Nelson Landscaping in Edmond, Oklahoma. He believes spray heads definitely have their place.
“For flower beds, we use nothing but pop-up spray heads. If it’s a smaller area, from eight to 20 feet, we’re doing spray heads,” he said.
Spray Head Disadvantages
Spray heads are more prone to clogging then rotors, so they often require more maintenance, Moseley said. “In Oklahoma, we have hard water that causes calcium deposits to build up in the nozzles. About every five years, depending on water quality, you’ll have to replace the internal filter on that nozzle.”
Rotor heads utilize changeable nozzles that emit water as a single stream over an adjustable. Best example is the “impact” rotor sprinkler, which makes a distinctive ticking sound. But impact rotors are quickly being replaced by quieter, smaller, gear-driven rotors.
The rotor sprinkler head is much more flexible when it comes to spacing; they can be spaced from eight to 65 feet apart. Bear in mind that traditional rotors spaced more than 20 feet apart require much greater water pressure than spray heads — 45 psi, with an operating range of 25 to 65 psi.
Rotor Head Advantages
Rotor heads are usually the better choice for larger areas of turf. They have a low precipitation rate, so they will evenly cover more area over a longer period of time.
About Rotary Nozzles
While the terms “rotor” and “rotary” are often used interchangeably, they really are two different mechanisms.
“Rotor” is a general term that describes the various types of sprinklers that rotate streams of water back and forth or in circles over the landscape.
Rotor heads emit a single stream of water as they rotate.
“Rotary” heads produce multiple streams of water that rotate around the nozzle, resembling rotating spider legs. Depending on the mode, rotary heads have a general radius between 15 and 35 feet.
Compared to standard rotor heads, rotary heads are very small — the same size as the standard nozzle on a spray-type sprinkler. So they fit onto the smaller spray head pop-up bodies.
But these heads produce much less mist than standard spray heads, making them more efficient, and often promoted by water conservation agencies.
“Rotors are used in applications where large areas of turf need to be irrigated, and greater coverage distance is needed, such as on athletic fields,” said Kelsey Jacquard, product manager at Hunter Industries.
And because they allow more time for water absorption, they’re ideal for slopes. With a larger head than spray-type models, they easily provide more coverage, according to Diebolt. “The coverage might be three or four times the square footage. Labor savings is incredible,” he said.
Rotor Head Disadvantages
Rotors and rotary nozzles require less pipe and trenches, but the rotors themselves are more expensive than spray heads.
In addition, rotors may take longer to install than spray heads because their ultimate positioning is not immediately evident, according to Moseley.
“You have to set them and then recheck them after they’re installed. Whereas with pop-up sprays, once I flush them out, I can set a nozzle and know which way it’s going to spray. Be it a fixed or adjustable nozzle, I can set it where I don’t even have to have water running through it to be set. Rotors need a little more fine-tuning,” he said.
Rotor heads are also spaced further apart, so the material cost can be a little more than that of a spray head, Diebolt added.
Rotor or Rotary?
When determining whether to use a standard rotor or rotary nozzle (see sidebar), Jacquard offered this general rule of thumb: “Distances under 15 feet are best irrigated by rotary nozzles, and distances above 35 feet, by rotors. In between those distances, what type of sprinkler head to use is a matter of preference by the designer or contractor.”
For both rotors and spray heads there are plenty of product options. The challenge can be in educating the customer on their individual benefits.
“The cost difference between them is significant, so it’s important to educate the customer on why you are going with triple the amount for one head versus the other,” Moseley said.
The warmth of spring means it’s time to prepare your landscape sprinkler system for another season of watering.
Hiring a qualified irrigation professional to perform tasks like spring start-up is always best, but experienced do-it-yourselfers, can follow these tips:
Timing Is Everything
First of all, you need to make sure spring has indeed sprung. The soil beneath your landscaping is always the last to thaw, so use a shovel to confirm that the ground is frost-free 12 inches down. Starting your sprinkler system while the ground is still frozen can result in damaged pipes. Is the ground still hard as a rock? Wait another week and try again.
Then check the settings on your sprinkler to make sure they’re appropriate for your landscape’s watering needs. Replace the back-up battery in the timer/controller, if necessary.
Go with the Flow
Before turning on any water to the system, double-check that all manual drain valves are returned to the “closed” position. When you first turn the water back on, be sure to open the system main water valve SLOWLY to allow pipes to fill with water gradually. Opening the water valve to quickly can result in a high-pressure surge called “water hammer,” which often causes burst pipes and damaged valves.
Check for rocks, dirt, sand and other types of debris that could block your sprinkler heads. And keep an eye out for spray heads that may have become buried with debris over the course of the winter.
Nozzles and sprinkler heads are designed to withstand normal wear and tear of irrigation, but not errant lawn mowers or snowplows. So be sure to replace all cracked, chipped or worn components. A broken or leaky sprinkler can wreak havoc on both your landscaping and water bills.
Valves and Pressure Gauges
The valves in your irrigation system are the system’s heart. It’s important to visually inspect each valve to determine that it’s operating properly. You can do this by manually activating all zones from the controller.
Also, make sure the water pressure is at a safe operating range. Too much pressure will result in cracked pipes, busted valves, sprinkler head leaks and inefficient watering.
A water pressure gauge is often helpful. These devices typically connect to a hose faucet and give you a good idea of the pressure in your irrigation system. (Suggested operating range is typically 40 -65 PSI.) Hint: If water is “misting” out of your sprinkler heads, your pressure is too high and should be reduced.
Think It’ll Rain?
Most modern irrigation systems are equipped with a rain sensor. This device should also be checked prior to activating your system in the spring. Here’s how:
First, consult the systems operator’s manual to determine the proper setting for testing your unit. (For example, some systems must be set to the “manual all stations” setting to test them. If that is the case with your system, you cannot test it on the “manual single station” setting.)
After properly setting the irrigation system control, check the system to make sure it came on. (You may need a helper to assist you.)
Once you have confirmed that the sprinkler is running, depress the plunger located on the top of the rain sensor. The sprinkler system should stop irrigating within a few seconds.
If watering does not stop when you depress the plunger, you’ll have to troubleshoot the system. Confirm that all wiring connections on the sensor and on the sprinkler control unit are tight. Check to make certain that the jumper tab, also called a jumper wire, was removed when the rain sensor was hooked up to the control panel.
Also be aware that the disk inside a rain sensor can become clogged with dirt or insects, which can keep it from functioning properly. Consult your operator’s manual for the correct procedure to clean the disk.
A Word about Backflow
A backflow device has been installed on your irrigation system in accordance with Ohio state law. This device prevents a cross-connection from occurring between the drinkable and undrinkable water in your home.
Spring is a good time to have your backflow preventer tested, as annual testing of the device is required in the state of Ohio. This testing can only be done by individuals who have been certified by an approved testing school. Backflow testers must have at least 24 hours of training in the classroom and hands-on test lab.
To locate a certified backflow tester in your area, Click Here.
Leave It to the Pros
Again, it’s best to leave all spring start-up tasks to the professionals. A qualified service technician will go through your irrigation system zone by zone and check every irrigation spray pattern for optimum turf and plant coverage, as well as check each sprinkler head and valve for any leaks. He can also test and clean your rain or weather sensor to ensure top performance.
Lastly, the technician will program the controller for the proper irrigation schedule, based on your landscape and weather conditions, as well as neighborhood watering restrictions.