CO₂ System Integration Makes for “Flawless” Start-Up

Compared to other states, California is ahead of the curve in adopting low-GWP refrigerants. According to Don Cole, director of training and a journeyman refrigeration technician at Arctic Cooling Systems in Chino, California, CO₂ booster systems have quickly become the dominant architecture in new retail stores.

“Almost every grocery chain I can think of is installing CO₂ booster systems,” he said.

• Staging medium- (MT) and low-temperature (LT) compressors
• Ramping up to full speed and/or capacity
• Regulating system pressures in the gas cooler, flash tank, high-pressure valves (HPVs) and bypass gas valves (BGVs)
• Minimizing oil carry-over, especially during the supercritical mode of operation

As someone who has embraced the initial emergence of CO₂ refrigeration in California, Cole has worked with his share of CO₂ booster systems. For the past five years, he has helped to install, start up and commission CO₂ systems from various equipment and component manufacturers. He now leverages nearly three decades of refrigeration experience to educate associates of the Arctic Cooling System organization and is a certified trainer at the local United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry of the United States and Canada (UA) 250 HVACR branch.

“It’s a passion. I am a believer in CO₂ refrigeration,” he said. At a new installation in 2023, Cole led a contractor team through the start-up process, using a Zero Zone CO₂ booster system with a full-Copeland solution of compression, controls, valves and associated components. Despite his experience, Cole explained that every installation comes with potential snags.

“You have to understand that with a start-up, the system’s never run before; you have to test every aspect 100 percent, and there are always some hiccups,” he said.

Cole and his team quickly discovered that the Zero Zone CO₂ booster system powered by Copeland significantly reduced these hiccups.

“Everything just meshed and worked perfectly together,” he said, referring to how the coordination of each component contributed to a nearly stress-free installation.

Cole explained how this configuration played a key role in bringing the system into equilibrium during start-up.

“The CV4 high-pressure valve ran flawlessly,” he said, noting that communication with Copeland compressor electronics technology provided further assurance.

Copeland’s onboard compressor electronics technology gave Cole’s contractor team additional tools to monitor performance data. “There’s so much data that it makes troubleshooting easy,” he said, noting that his team had no issues with any of the compressors during this start-up.

Should any issues arise, the system features built-in safety measures to help protect compressors from harm or failure and preserve end users’ system investments.

When it came time to get compressor racks up and running, Cole recounted how the operation of Copeland compressors and VFDs surpassed anything he’d previously worked with — particularly in terms of quiet sound, low vibration levels and high performance.

“It was so quiet that I was physically a foot and a half away, and I couldn’t hear it,” he said.

His next course of action was to test the vibration levels as compressors ramped up to full speed using the EVH drive. He shared that this step typically requires his teams to skip hertz increments as they bring racks online and up to speed. Dealing with this issue can be a major source of frustration for technicians during system start-up and potentially put the system at risk of damage.

“I’m usually the one that has to make sure all compressors are rotating the correct way and figure out if we’re fighting opposing forces,” he said.

But with the Copeland compression and drive combination, Cole said these concerns were all but eliminated.

“Vibration levels were non-existent all the way from 25 to 60 Hz, which we had never seen before,” he said. “I was giggling like a kid in a candy store with a $20 bill.”

Because the installation took place in the warm Southern California climate, the CO₂ booster system was designed and expected to run in supercritical mode much of the time. Typically, this can cause a rise in oil carry-over rates that can lead to poor lubrication and an increased risk of compressor damage.

Cole explained that from his calculations, it appeared that the oil carry-over rate was very low in the all- Copeland system, saying, “There was nowhere near the oil we typically see moving through a system.”

As with any start-up process, Cole said his team needed some help familiarizing themselves with the new equipment. At one point during the installation, they needed assistance setting the discharge temperatures on the Copeland compressor electronics module. After a quick phone call to a Copeland solutions architect, Cole was directed to the correct application engineering bulletin and the exact page number with programming instructions.

“Copeland support has been absolutely unbelievable,” he said.

A model of CO₂ simplicity

After a successful start-up process, Cole said that the system has been running so well that he uses it as an example of an ideal CO₂ booster system. Those who have visited the installation have even called him to rave about the rack and system performance.

“It’s been running flawlessly and alarm-free. I tell my friends, ‘You need to come down here and see this.’ It’s something to behold,” Cole proudly exclaimed.

The installation and partnership with Zero Zone reflect Copeland’s longstanding commitment to developing user-friendly, robust and fully integrated CO₂ refrigeration technologies. As CO₂ installations like these become more commonplace throughout the country, we will continue to adapt and develop innovative solutions to meet the demands of our industry — while simplifying the adoption of CO₂ refrigeration technologies for all stakeholders.