Installed inside the Acacia Court Building is a McQuay frictionless chiller, with magnetic bearings, oil-free compressors, and digital electronic controls.
STOCKTON, Calif. - The expansive Acacia Court Building, originally a state hospital built in the 1920s, has been given a new life. An extensive renovation has converted this 100-yard-long concrete building into a showplace of University Park, located in Stockton's historic Magnolia District. The Stockton Midtown neighborhood is being redesigned as a "live, learn, work, walk" redevelopment, and Acacia Court is home to the satellite campus of California State University, Stanislaus-Stockton.

Students and staff occupy part of the first floor of the sprawling building; with future plans to include expansion into other sections as well. The renovation draws on unique technology, including an HVAC system designed around a new frictionless, magnetic bearing centrifugal chiller, with impressive results. The chiller consumes far less power, costs less to operate, and generates much less noise than conventional chillers.

Four years ago, the Grupe Commercial Co., a California developer, was awarded the University Park contract to develop the area into educational, office, retail, and residential facilities, as well as a community center. Over 32 buildings have been razed; 19 will be renovated. Part of the goal is to keep floor plan changes to a minimum, primarily as a renovate-to-suit project.

Working with chiller manufacturer McQuay and its representative, Norman Wright Mechanical Equipment Corp., Grupe Commercial Co. determined that the HVAC system was high on the list of systems to be updated at Acacia Court. The existing system included two chiller units dating from the 1950s, and some of the piping for them had collapsed.

"The efficiency of the old system was really poor," said Chris Rasmussen of Grupe's facility management department. "We explained to the university that the building needed a new chiller, along with new piping and a cooling tower."


The McQuay frictionless chiller features magnetic bearing compressor technology that is oil-free. This design is to significantly reduce sound levels, because the magnetic bearings eliminate the metal-to-metal contact noise of conventional bearings. According to the manufacturer, sound pressure ratings are as low as 77 dBA per ARI Standard 575.

Energy performance is also considered revolutionary. The company's frictionless centrifugal chiller is designed to operate as low as 0.375 kW/ton IPLV. Full-load performance is supposed to be as low as 0.62 kW/ton - about 32 percent more efficient than screw compressor chillers, said Daryl Showalter, director of marketing, McQuay chiller products.

"The magnetic bearing technology of the McQuay frictionless centrifugal chiller provides superior energy efficiency by eliminating the high friction losses of conventional centrifugal compressors," said Showalter.

"Variable-frequency drives unload the chiller to 10 percent of full load. The chiller requires less than five amps to start, compared to 500 to 600 amps for a traditional screw compressor chiller. And, because magnetic bearings require no lubrication, there is no need for oil heaters, oil coolers, oil pumps, or oil piping."

The expansive Acacia Court Building was originally a state hospital built in the 1920s.


Despite the completely new technology and design, installation went smoothly.

"We had a really good experience," said Rasmussen. "We completed 90 percent of the installation work with our own maintenance staff, which really helped reduce the cost. And since the system went online, there has been zero unscheduled downtime because of problems, only scheduled downtime for a couple of software upgrades."

The two compressors of the frictionless chiller operate on a common refrigerant circuit, designed to improve system reliability. In the event of a mechanical or electrical problem, one of the two compressors is designed to continue to operate until repairs can be made.

"If there is a problem with one compressor, we can still run with a 60-percent load on the other one," said Rasmussen.

The MicroTech II™ digital unit controller on the chiller is designed to effectively run and monitor the chiller operation. The chiller is currently run based on a time clock input because there are not as many maintenance issues with the magnetic bearing compressors. When the budget allows, the staff can integrate the MicroTech II chiller using BACnet®, LonTalk®, or Modbus® protocol, thanks to the Protocol Selectability™ feature of the unit controller.


"As far as cost saving goes, it's just incredible," said Rasmussen.

"The old chiller required 1,000 amps per leg at start-up. By contrast, when the new chiller starts up, each compressor takes only seven to 10 amps. Also, it ramps up more slowly, so we don't require a big surge of electricity in the beginning, which would be quite costly for the state."

Maintenance is equally worry-free. With the magnetic bearings compressors, the oil handling equipment of the chiller is eliminated. According to the manufacturer, there is no need for oil pumps, oil reservoirs, and/or oil coolers - and their associated maintenance costs - that are needed to maintain oil quality. The only requirement is to "punch tubes," or clean the pipes with a rotary brush, and blow out dust from the controls.

"That's our PM [planned maintenance] for the chiller," said Rasmussen. "One other task we avoided is having to replace the refrigerant type in the near future."

The McQuay frictionless chiller uses HFC-134a refrigerant, which has no phaseout date.


Noise is the other big plus with the frictionless chiller - or rather, lack thereof, since noise is virtually absent.

"We have an air compressor in the basement, and when the air compressor is running, we can't tell if the chiller is also running," said Rasmussen.

"We actually have to walk up to the unit to see if it's still going. We also have a couple of screw chillers at the university, and you can hear them all the way up from the basement to the first floor. They're totally different from the McQuay chiller."

For the university, the quiet new chiller makes the old building more useable, as well as more efficient. While only a portion of the building is currently occupied, development plans include moving other university departments, as well as a computer lab, to Acacia Court.

Students and staff who use the building now and in the future will benefit not only from the renovated building and its technologically advanced chiller, but also the entire livable concept of the Magnolia District.

For more information, see "Frictionless Compressor Chiller" at For the name of a local McQuay representative, call 800-432-1342 or visit

Publication date: 01/23/2006