The chillers used to cool mid-sized and larger buildings are expensive pieces of energy-hungry equipment that require a lot of attention to keep them running right.
The good news is that manufacturers offer an array of products, tools, and tips to help lower operating costs, optimize maintenance, and extend a chiller’s life.
Today’s chillers are markedly different from the behemoths of not too many years ago. They have smaller footprints, digital controls, wireless connectivity and sensors that allow for remote monitoring and predictive maintenance, and, many times, variable-speed drives (VSDs) that save on electricity.
Manufacturers are looking to the future — a future of increasing energy-efficiency standards and lower-GWP refrigerants — in product development, but also are able to retrofit some older chillers with the technology, like VSDs and remote-monitoring capability, that will give chillers new life and lower their carbon footprint.
NEW MODEL: The latest iteration of the York YVAA air-cooled screw chiller. The chiller uses a variable-speed drive to improve efficiency and operates with lower-GWP refrigerants. Its capacity ranges from 150 to 575 tons of refrigeration. (Courtesy of Johnson Controls)
“We are in a continuous state of advancement of compressors, heat exchangers, and control technologies. We can extend the usable life of many chillers through incremental upgrades,” said Todd Grabowski, vice president and general manager of the chillers and air-handling systems division of Johnson Controls, which builds the York brand of chillers.
A large chiller typically has a rated life expectancy of 20 or more years, depending on the usage and operating conditions, the weather in the region in which it’s located, the type of building being cooled, and other factors. Manufacturers have advice for maintaining chillers for an optimum lifespan, minimum down time, and peak energy efficiency.
“We’ve got chillers that have been in use more than 25 years — some more than 50,” said Meredith Emmerich, vice president of commercial HVAC, North America, at Carrier. “If you properly maintain it, if you take care of it, you’re going to get the most out of that piece of equipment.”
Regional sales manager, Daikin Applied Americas
• Keep it clean, keep it cool. Condenser tubes should be brushed-cleaned at least annually, as contaminants increase thermal resistance, which hinders overall performance. Maintaining treated water at the proper chemistry, and inspecting water loops at least yearly, are also essential.
Reducing the temperature of the water entering the condenser, if possible, is also beneficial and cuts energy costs too.
ORDER OF MAGNITUDE: A Daikin Magnitude WME-C centrifugal chiller, which uses lower-GWP R134a refrigerant and, the company says, is up to 40% more efficient than standard centrifugal chillers. Magnitude chillers are available in capacities from 75 to 1,600 tons of refrigeration. (Courtesy of Daikin Applied)
“Maintaining clean heat transfer surfaces and low approach temperatures is key to achieving an optimum lifespan,” said Thomas Mayhew, regional sales manager at Daikin Applied Americas.
• Keep it charged. Maintain specified refrigerant levels, and inspect systems daily for refrigerant leaks and signs that air or moisture have been introduced into the refrigerant system.
“A low refrigerant charge will cause the compressor to work hard for less cooling effect,” said Grabowski.
• Test the tubes. Grabowski recommends eddy-current tube testing, which can find defects in tubing before they would be apparent during a visual inspection, to head off unexpected tube failure and costly, unplanned repairs.
ON DISPLAY: Carrier’s AquaEdge 19MV water-cooled centrifugal chiller was introduced in December and on display at this year’s AHR Expo in Las Vegas. The model fits through typical double doors without disassembly, uses either R-513A or R-134a refrigerant, and is available in capacities from 300 to 700 tons of refrigeration. (Courtesy of Carrier)
• Upgrade and retrofit. A chiller motor typically demands more electricity than any other single building component. Installing variable-speed drives on an older, constant-speed centrifugal chiller, said Grabowski, can result in energy savings averaging about 30%.
Retrofitting chillers with system-monitoring and data-collection technology, when possible, can also pay off, by keeping a record of operating conditions and helping identify problems early. Grabowski recommends keeping a daily chiller operating log, a task made easier with data-collection technology.
• Check those sensors. Sensors that are faulty or out of whack can affect energy use, and while sensor failure is usually easy to spot, said Grabowski, a sensor that is not in proper calibration can result in increased energy usage.
“For example, a sensor that is reporting a higher chiller supply water temperature than the actual temperature will require the chiller to use more energy than necessary to achieve the required cooling needs,” he said.
• Good vibes only. Machinery vibration patterns, and changes in those patterns, can reveal a lot about a compressor. Emmerich said such readings should be analyzed as a way of diagnosing equipment problems and problems-to-be.
“Vibration can be an indicator of something starting to fail,” she said. “We look at a machine and say every machine has a unique acoustic footprint.”
Repair Versus Replace
A new chiller is a major capital investment, so a building manager should think carefully about long-term goals, the building’s cooling needs, the cost of repairing and maintaining an older chiller, and relevant regulatory factors, such as changing energy efficiency standards or new refrigerant requirements, before deciding whether to spring for a new chiller.
“There’re a lot of things that will impact on whether it’s time for a replacement chiller,” said Emmerich. “That’s a big decision.”
Repairs and retrofits can make sense, experts said, but in certain circumstances — such as the failure of a costly major component, a need for more chiller capacity in the building, or a chance to reap long-term energy savings or meet sustainability goals — a replacement may be the best path.
“When you’re doing a repair, you’re doing nothing to improve the overall equipment reliability,” said Emmerich.
“In some cases, the technology leap forward is too far for an upgrade and replacement with a new chiller product is the right choice,” said Grabowski.
Carrier, Daikin Applied, and Johnson Controls all have systems for remote chiller monitoring and troubleshooting.
“We can have the same capability (remotely) as if we were in front of the equipment,” said Satoru Akatsu, a Daikin Applied product manager.
“A connected chiller allows us to monitor, predict, and diagnose many maintenance and/or repair needs without having to dispatch a service vehicle,” said Grabowski. “When support services require an on-site visit, we are better prepared with the correct parts and resources.”
The coronavirus pandemic, which is now into its third year, hastened the need for more remote monitoring and “virtual inspection” technology, experts said.
“To mitigate risk of bringing the virus into the building, remote inspection is a key measure customers would request,” said Akatsu.
The pandemic, and the attendant focus on IAQ, may also change the equation when it comes to chiller capacity, experts said, as greater volumes of outdoor air being brought into a building could require additional capacity.