Sprays vs. rotors

Sprays vs. rotors

We take them head-to-head to find the best irrigation solutions.

November 2, 2018

While each job site will present its own unique challenges, there are some universal qualities that make either spray heads or rotor heads the advantageous choice in certain locations and conditions.  

“The fundamentals and the principles behind the design are still the same as they were when I took design classes years ago. The products are addressing all of that. Most of the changes over the years have been with the control systems and some of the heads,” says Pete Diebolt, president of Diebolt Landscape in Mohnton, Pennsylvania.

The system design accounts for environmental conditions like wind or shade, elevation changes, the square footage of the area to be watered, and more. From there, choosing between a rotor head and a spray head comes down to a few other factors.

“The type of head that you use is dictated by the design because 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 says.

Rotor heads:

The pros. Generally, rotor heads are 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. This is ideal for sloped areas because it allows more time for water absorption. The head itself will also be larger and provide more coverage than a spray head, Diebolt says.

“The coverage might be three or four times the square footage. Labor savings is incredible,” he says.

Rotor heads also tend to require less maintenance than spray heads. Most rotors nowadays will pass the majority of debris found in reclaimed water sources without clogging, Diebolt says.

The cons. However, rotor installation may take a little longer than spray heads because their ultimate positioning is not immediately evident, says Justin Moseley, irrigation manager for Nelson Landscaping [JM1] [BH2] in Edmond, Oklahoma.

“You have to set them and then recheck them after they are 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 whereas rotors need a little more fine-tuning,”  Moseley says.

Rotors can also be a little more expensive to install. They are spaced further apart, so the material cost can be a little more than what a spray head would be, Diebolt says.

“Your primary decision is based on area of coverage and water supply. If I have 12 gallons a minute, I can only put a few rotors on a zone. Then, you have added labor and material cost in terms of a controller that can support more valves and you have more valves because you will have more zones,” he says. “That gets expensive, as opposed to if you have a better volume of water available, you can put larger zones out there and get your watering time shortened up.”


Spray Heads:

The pros. Spray heads are designed for smaller areas and disperse more water in a shorter amount of time. This makes them a good choice for areas close to buildings, patios or other hardscaping on site that is not intended to get wet.

“For flower beds, we use nothing but pop-up spray heads. If it’s a smaller area, from 8-20 feet, we are doing spray heads,” Moseley says.

The Cons. Spray heads typically require more maintenance than rotors because they are more prone to clogging, Moseley says.

“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. Rotors don’t have that filter, so they are flushing all of that hard water buildup out,” he says.

Compromises. With either type of sprinkler head, there are plenty product options available to split the difference between them. For instance, Moseley uses a lot of matched precipitation nozzles to accommodate a large area with a small nook within a rotor zone.

Rotary nozzles used on a spray head also provide a versatile solution for mid-size areas. The nozzle Diebolt prefers is made in both male and female for use on any spray head.

“Instead of a thick spray that just sits there static when the head pops up, (the) product actually has a gear-driven rotor inside the nozzle body that acts like a mini rotor. They have a pretty good uniform distribution pattern that goes down to 12 feet and up to 28 feet,” Diebolt says.

The biggest challenge in taking advantage of all the bells and whistles can be educating the customer on their benefits, Moseley says.

“The cost difference between them is significant, so it is important to educate the customer on why you are going with triple the amount for one head versus the other,” he says. “In the consultation, we explain how a 4-inch popup is going to be blocked by all of the shrubs here, so that’s why we want to have the 6-inch and the 12-inch so we get overlapping coverage for the flower beds.”

Contractors should also prioritize creating efficient system designs and getting the proper training to achieve it. All sprinkler heads are adjustable to a certain extent without affecting the spray pattern, but above all, the design is about distribution uniformity. Systems should be as operable in the driest, hottest time of the year as they are in wet periods, Diebolt says.

“Some of the heads are helping with that because they are forgiving and cover up the sins of the lesser-trained folks out there in the industry,” Diebolt says. “But a lot of times, vendors don’t have your best interest at heart. You are the last resort as far as the customer goes to put in the right product that is going to give them the right coverage and the right system for what they are paying for.”

The author is a freelance writer based in Kentucky.