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The do’s and don’ts for winterizing irrigation systems

September 28, 2022 -  By
Experts say to avoid auto- draining irrigation systems during winterization. (Photo: Site One Landscape Supply)

Experts say to avoid auto-draining irrigation systems during winterization. (Photo: Site One Landscape Supply)

Fall is a busy time of year for irrigation professionals across the country. Falling temperatures bring irrigation system shutoffs and winterization. Experts say irrigation professionals should ensure proper air compression and move away from auto-draining when performing irrigation system blowouts and winterization.

Balance your air compression

Don Davis, assistant training manager for irrigation with SiteOne Landscape Supply, recommends manual drainage with an air compressor. However, he stresses that too much compression power can be a first-class ticket to major system trouble.

“Don’t blow out an irrigation system with more than 80 pounds per square inch (PSI),” he says. “Most compressors can charge up to 120 PSI or more. Excessive pressure can damage components in the irrigation system.”

He recommends not exceeding the maximum pressure specification for the lowest pressure-rated component in the irrigation system. He also warns contractors not to exceed 80 PSI for PVC or 50 PSI for polyurethane pipes.

Other general project tips from Davis include turning off the master valve and tagging it for future reference, starting work in areas with the highest elevation and leaving ball valves or drains on backflow preventers at a 45-degree angle to prevent condensation buildup over the winter.

“Once the pressure has bled from the system, and the water has drained down a little, it’s time to hook up the compressor to the winterization port,” Davis says. “A minimum compressor rating of 20-25 cubic feet per minute (CFM) is recommended for winterization services; compressors with ratings of 50-100 PSI are common for larger sites.”

Err on the side of caution

Mark Eads, sales and operations manager for Franco Irrigation Systems in Lexington, Ky., says the volatile nature of Kentucky winters can open the door to an array of hazards for irrigation professionals and property owners.

Franco Irrigation Systems offers irrigation services for a 70 percent residential and 30 percent commercial client base. He says his team starts winterization services in October, but each fall is a little different.

“Each customer can be different too. Some want water all the way up to December, and others are done right at the start of October,” he says. “You can have a day that jumps to 80 degrees in October, and someone asks, ‘Why’d you shut off my irrigation system?’”

Eads strongly recommends opening system valves manually during the blowout process.

“By doing it manually, you make sure there is an exit point for that compressed air,” he says. “If you have a malfunction with a remote or controller, you’re also not sitting there constantly needing to charge the line. The air is constantly escaping.”

Avoid the hammer

Aaron Katerberg, CEO of Grapids Irrigation in Grand Rapids, Mich., recommends not auto-draining irrigation systems during winterization because it could lead to system damage or freezing if water isn’t removed from the line.

“When we start an irrigation system each year we are always careful to turn the water on very slowly,” Katerberg says. “This makes it so the empty lines don’t get hit by water hammer. When you turn on water it rushes down the line slamming into each fitting with a force equal to the water pressure.”

In addition to irrigation services, Grapids Irrigation provides drainage and landscape lighting services to a predominantly residential customer base.

Water conservation measures built into modern irrigation equipment promote systems’ incompatibility with auto-draining, says Katerberg.

“All the manufacturers’ top-quality heads now include check valves so that the head won’t drain when the system is off,” he says. “These also keep water from getting out of the heads and to the auto-drains.”

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