



One of the components of an irrigation system that has seen a major evolution in a very short period of time is the controller. What first started out as not much more than a clock with a timer has evolved into one of the fastest growing high-tech niches of the irrigation industry in the 21st century.

Where it all started

Prior to World War II, most controllers were built for large commercial landscapes, estates, and agriculture. These controllers used an electric clock and a system of hydraulics that sent water pressure through indexing pipes that would open and close the valves.

“The hydraulic system was the only type of irrigation controller available then, and it wasn’t designed for smaller residential properties,” said Glenn Bowlin of the Irrigation Association’s Irrigation Museum. “Then, in 1950, the Moody Sprinkler Company in Los Angeles, California, developed what is considered to be the first hydraulic irrigation controller for home use. It was simply a clock with metal stops inserted into holes in a dial. It wasn’t fancy, but it did the job.”

At first, these controllers were only installed on large estates, but with increasing demand and falling prices, it wasn’t long before a different type of controller came onto the scene using electricity, a clock and a set of wheels and dials.

This increased demand was precipitated by the end of World War II, when families began purchasing homes and moving to the suburbs, and planting flowers, trees and lawns, which needed to be watered. Above-ground sprinkler devices were replaced by more modern underground irrigation systems. These systems ended at the valve, and homeowners had to use a steel key to turn their sprinklers on and off manually.

An electro-mechanical timer replaced the hydraulic one, but the basic operation remained the same. A clock motor ran the timer and a series of dials and pins controlled the irrigation schedule. All the homeowner had to do was set the pins, move a dial and turn the switch to the auto, manual or off position.

As new electronic technologies began to develop, so did manufacturers’ interest in integrating them into their irrigation controllers. Solid-state circuitry emerged in the ’70s, and in the early 1980s, a new company called Irri-Trol introduced the first microprocessor controller to the market.

Microprocessors began to replace the electro-mechanical controllers. Unlike the knobs and dials found inside electro-mechanical boxes, these contained no moving parts, only circuits. Outside, the controller itself looked like a small computer. Dials were replaced with push buttons, and the watering cycle was programmed with a digital clock instead of a turning wheel.

In the early ’80s, we saw the beginnings of the personal computer age bringing new technologies, and it wasn’t long before computers were used to program central controllers. Instead of push buttons or dials, the watering schedule was programmed digitally. One company marketed a central controller that allowed the user to fill out a card and insert it into a slot on the faceplate of the controller. These controllers were revolutionary for their time, but their time was limited.

Programming these solid-state controllers took a little bit of a learning curve and many users of that era had not yet become comfortable with all the fancy bells and whistles of computer technology. In the days before GPS, DVRs and

HDTV, when it came to watering lawns, people simply wanted to “set it and forget it.”

“There was a bit of a backlash to the solid-state controllers, with all those confusing LED read-outs, keypads or the punch cards,” said Keith Shepersky, senior product marketing manager for Irritrol, Riverside, California. “But manufacturers didn’t want to totally abandon the technology. Instead they created a hybrid that used a circuit board on the back of the controller and user-friendly knobs and dials in the front,” he said.

For the next several years, users and installers of both residential and commercial controllers were pretty satisfied. Sprinklers went on and off like clockwork. Lawns were watered rain or shine—whether they needed it or not—and no one really paid much attention. However, the wheels of technology continued to turn and new products were being introduced into the market.

The first decade of the new century brought with it a greater awareness of water shortages and drought in many areas of the country. From Florida to California, a new battle cry was heard: conserve water! Water districts responded by putting stricter watering schedules in place, with heavy fines for violators.

Irrigation controllers that had started out as a convenience soon became a necessity. A simple on/off mechanism was no longer going to be able to meet the demands of a water-conscious society.

“It seemed like overnight every municipality and water district had different water scheduling regulations,” Shepersky said. “Where before you could program a typical three-day schedule—say, Monday, Thursday, Sunday, or every day of the week—now you had to figure out how to adjust for things like odd or even days, depending on your house number. With so many different calculations, one industry standard clock and calendar just didn’t hack it anymore,” he said.

At the same time, as tighter irrigation schedules were being mandated, a new eco-friendly movement was beginning to emerge. Phrases like “sustainable landscape” and partnership programs like the EPA’s

WaterSense were quickly moving into the foray of the irrigation industry. Water rates began to climb; rebate programs and building incentives were designed for those who installed water-conserving devices.

Controlling irrigation water use now wasn’t only the right thing to do for the environment; it was also the “smart” thing to do economically.

For an industry with a long history of being on the cutting-edge when it came to using new technology to meet customer’s needs, it didn’t take long before the word ‘smart’ began appearing alongside the word ‘controller’ on manufacturers’ packaging.

Whereas conventional controllers are simply programmed by hand, based on a specific manmade schedule, ‘smart’ controllers schedule the irrigation times based on scientific data received from evapotranspiration (ET), or meteorological (weather) conditions.

ET is the measurement of the amount of water that evaporates from the soil, (evapo) plus the amount of water that transpires through the leaves of the plants (transpiration). Soil sensors calculate the amount of water lost through ET and transmit the information to the controllers.

“One of the first soil sensors for irrigation controllers was manufactured back in 1978,” said Tom Penning, president of Irrometer Company, Riverside, California. “The sensor measures soil water tension. As the tension changes with water content, the resistance changes as well. The sensor contains a switching module that interfaces with the controller. At a certain moisture level, the sensor sends a signal to the controller telling it to turn off the water.”

Rick Capitanio of California Sensor Corporation (CALSENSE), Carlsbad, California, says early soil moisture sensors were built with a microprocessor and used a valve wire to transmit the moisture reading to the controller box that would automatically adjust the clock’s time. Today, calculations are determined by a combination of ET, water volume and a monthly water budget programmed by the user.

“Based on the square footage of a property, the controller automatically creates a monthly budget number, and the system will actually sound an alarm if the system goes over the budgeted amount,” said Capitanio. “In addition to the soil sensors, ET controllers with rain buckets attached monitor how much rain is falling at any given time.”

He adds, “Water use is based on the infiltration rate and holding capacity of the soil that adjusts the scheduled irrigation in real time, based on amount of rainfall throughout the day.”

When it first came on the scene, soil sensor technology for “smart” controllers seemed to be the final frontier. But with each new technological development, irrigation manufacturers find ways to incorporate the new with the old and create something that revolutionizes the entire industry.

Using technology that less than a decade ago was unheard of, irrigation controllers are now able to practically adjust themselves based on past, present and future weather conditions. What was once thought of as futuristic science fiction has become today’s reality.

One type of weather-based irrigation controller uses a wireless outside weather sensor that measures the temperature and rainfall to adjust the controller’s schedule.

“The installer slides a digital data card into the controller, which contains 10 years of weather information for that area,” said Shepersky. “It will be set for the hottest month, based on the location of the sensor, to get the maximum ET. Then, the controller takes over from there and will automatically adjust the entire irrigation system.”

Taking the weather-based controller even further, web-based controllers receive their information not from an outside sensor, but directly from a weather satellite and the Internet. The web-based weather controller can be monitored and adjusted online using a laptop computer, ‘smart’ phone or iPad from just about anywhere in the world.

“One of the advantages of mobile control is that you no longer have to sit in front of a controller or behind a computer to irrigate the way you want,” said Pat McIntyre, president of ETwater, Novato, California. “Even if you’re stranded in the airport during a blizzard in Dallas, you can check on and control your irrigation system on a property in California.”

Being ‘smart’ also means being economical. For many people, replacing their entire controller could be a costly and time-consuming process, especially if there are numerous zones and wires attached. To solve that problem, some manufacturers have designed a plug-and-play module that attaches to a standard controller and transforms the ordinary into the extraordinary.

“Our industry is driven toward innovation,” said McIntrye. “We continue to use technology to make our systems more powerful, reliable, and easy to operate. The more we can invent and create what was once perceived as difficult or even impossible, the better. From where we’ve been to where we are today, I’m confident that we’re definitely heading in the right direction for the irrigation industry of tomorrow.”