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While the standard multi-wire system still makes up the majority of most irrigation contractors’ installations, the use of two-wire is increasing – particularly for the right project.

Greg Winchel, owner of Winchel Irrigation in Grand Rapids, Mich., estimates that 30 percent of his commercial irrigation projects now employ a two-wire irrigation system. “I have three two-wire projects under construction,” Winchel says. “I still install multi-wire systems, particularly on small jobs within a confined property, where the costs work out in their favor. But my team would prefer to install two-wire anytime they can.”

Flexibility for expansion. The flexibility of two-wire systems pays off on long-term projects, says Walter Mugavin, managing partner of Aqua-Mist Irrigation in South Hackensack, N.J. “When we’re working on a five-year residential development, things change after two or three years and you can’t tear up driveways or buildings to accommodate that,” he says.

The systems, so-called because they use a single two-wire cable to connect all valves to the controller, allow for fast and easy add-ons to existing systems.

“We installed a two-wire system for a condominium property,” he says. “When the developer turned the property over to the condo association, they wanted additional landscaping at the entrance and requested additional sprinkling. It was much easier to splice in a new path for this leg, since we started with a two-wire system.”

Project size matters. Contractors do see limits for the application of two-wire irrigation systems. Rather than residential versus commercial, it’s the size and nature of the project that dictate when two-wire irrigation is preferred over the standard multi-wire system.

“We found that two-wire is not cost-effective until you get to 24 valves or more because of the cost of the decoders at each valve,” Roberts says. “Currently, we’re installing a 50-station project and earlier this year, we handled a 62-station system.”

The advantage for larger projects lies in the capacity of the two-wire controllers, Roberts says – they can handle up to 99 stations on one clock.

“There’s no reason not to use it in the residential environment. We have selected two-wire for homes on two to three acres and up to 30 acres. The smallest two-wire system we’ve installed used 20 zones,” Winchel says.

However, the application of simpler two-wire irrigation systems at lower price points is emerging. Donavin Baumgartner, Northeast divisional manager of Vanderwist of NE Ohio, installed a two-wire system with just 12 stations tied to well water using Hunter’s DUAL plug-in for the I-Core controller.

“Even though the project is small, it made sense because we know additions to the system are coming in the future,” he says.

New technology. Since their introduction, two-wire controllers have gotten easier to program. “Manufacturers have redesigned their controllers to make the interface more user-friendly,” Winchel says. “Now it’s easier to set run times, frequency, which stations run on which days and more.”

With the introduction of two-wire converters, contractors can transform standard multi-wire controllers to two-wire operation or hybrid two-wire/multi-wire systems. The converter offers a practical solution, enabling irrigation systems to use the host controller to run scheduled programs while the converter talks to the two-wire decoders.

“We can adjust for unexpected weather conditions or respond to requests from a property manager for a different watering pattern without having to travel to the site,” Winchel says.

Central control systems for site control are high on the project chart for Aqua-Mist. “The National Park Service horticulturist for Ellis and Liberty Island had to travel to each location to change irrigation programming. It took him up to three hours to make a change,” Mugavin says.

“We installed a new two-wire path on Liberty Island and tied it to a central control system. Now, he taps his computer keyboard and alters the timing without ever leaving his desk.”

The author is a freelance writer based in Shaker Heights, Ohio.

Photos courtesy of Aqua-Mist Irrigation and Underhill