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Earlier this year, the Environmental Investigation Agency (EIA) released a report stating that several major U.S. supermarket chains were leaking significant amounts of HFC refrigerants into the atmosphere. According to the report, EIA investigated dozens of supermarkets in the greater Washington, D.C. area and, using infrared cameras, found that over half of the stores investigated were leaking refrigerant into refrigerated aisles.

This may not be surprising to some, given that the Environmental Protection Agency’s (EPA’s) GreenChill program has long reported that supermarkets have high rates of refrigerant leaks. Indeed, GreenChill has repeatedly noted that the typical supermarket has an annual leak rate of about 25%, which equates to about 1,000 pounds of leaked refrigerant every year. But leak rates do not need to be so high, as evidenced by participants in the voluntary GreenChill program, whose stores emit at least 65% less refrigerant than the average supermarket.

By following a few best practices, contractors can help their food retailer customers reduce the amount of refrigerant leaking from their refrigeration equipment.

Fundamental Challenges

Refrigerant leaks can be a fundamental challenge for many supermarket operators in the U.S. and around the world, said Katrina Krites, market and business development manager, food retail, refrigeration for Emerson’s Commercial & Residential Solutions business.

“Large, field-erected systems are typically more prone to leaks, due to the numerous field-installed components and joints needed to connect equipment,” she said. “However, even though some parts of the refrigeration system may be more leak-prone than others, the more robust the installation process and more thorough the preventive maintenance program, the greater the probability of operating a near leak-free system.”

Regular maintenance becomes of even greater importance as a system ages because over time, systems inevitably drift from their commissioned performance baseline.

“When a refrigeration system is first installed and commissioned, it operates at peak performance — in part because the system is not leaking refrigerant,” said Krites. “But over time, systems inevitably drift from their commissioned performance baseline, contractors perform repairs to keep systems running, and the potential for leaks starts to rise if a system is not properly maintained and managed.”

LEAK CHECK: At Climate Pros, HVACR specialists such as Mike Bolkunowicz perform a leak check on every service call. (Courtesy of Climate Pros)

While refrigerant leaks can be a problem in supermarkets, Todd Ernest, founder and CEO of Climate Pros, which is a fully comprehensive commercial refrigeration and HVAC firm with offices located in more than 40 states, is not convinced that it’s happening as often as cited in the previously mentioned report.

“Given the importance of this for the environment, for food safety, and for cost, every time a technician from Climate Pros goes into a store, it is standard protocol that they perform a leak check — no matter the purpose for the actual service call,” he said. “During this process, sometimes we will find leaks and sometimes we don’t. However, I can absolutely tell you that half of the stores that we service are not leaking.”

That said, leaks can occur, as refrigeration systems are complex with many connection points, welds, and threaded fittings that are all tied together with thousands of feet of pipe running throughout the store, said Ernest.

“These can be located underground or overhead and exposed to varying conditions, and this dynamic presents tremendous amount of opportunities for leaks to occur,” he said. “Factor in vibration, harmonics, excessive temperature swings from cold to hot, and also pressure swings throughout the systems (from as much as 0 psig all the way to 500 psig), and it only heightens the risk of leaks.”

Leak Prevention

Leaks can occur in just about any part of a refrigeration system, but Climate Pros wanted to find out the leading causes behind most leaks. To that end, the company recently performed an in-house study with over 2,000 stores all across the country, and what they found is that leaks are often dependent on the type of system as well as where it is installed.

“Systems with hot gas defrost seem to leak the most, as a result of the expansion and contraction of the piping when a system goes into defrost multiple times throughout the day,” said Ernest. “Aside from that, it all depends on the manufacturer of the equipment and the quality of the installing contractor.”

One of the biggest problems Climate Pros encounters is that many stores across the country are still using the same copper lines and systems that were installed 20-plus years ago. While copper lasts a very long time, it is not intended to last forever, and the insulation and mounting hardware are not as durable.

“So many things change over the years in these stores, including the cases on the floor, but the piping systems and mechanical systems that run those cases rarely get replaced,” said Ernest. “Then over time, the leak occurrences go up dramatically, simply because the systems are exceeding their life expectancy. This is also the most expensive part of the system to replace and provides little upfront value to the retailer because the customer can’t see it, unlike the new merchandising cases that may change two or three times over the life of the store.”

Keeping refrigeration racks and the mechanical room as clean as possible is also essential for preventing refrigerant leaks, said Krites.

“Compressor racks, air-cooled condensers, remote headers, walk-in evaporator coils, and other components should be kept free of oil and dirt, which can make it more difficult for technicians to spot leaks,” she said. “Corroded steel components should be removed and/or painted with a rust-inhibiting paint to help prevent future corrosion.”

Leak Check

Depending on the system size or type, service technicians should conduct refrigerant leak checks at regular intervals. For large, centralized systems, for example, leak inspections should be completed every 30 to 60 days, said Krites.

“This involves checking refrigerant levels and comparing them to data from previous visits, as well as performing a walk-through of a facility with a portable leak detection device,” she said. “Contractors should also recommend the installation of a refrigerant leak monitoring, notification, and alarm system to ensure the detection of any leaks between regular leak inspections.”

There are three key elements to implementing an effective leak detection program, said Krites, and they include: 1) accurate detection methods, 2) reliable notifications, and 3) continuous monitoring for system leaks. Detection devices should also be installed in the locations most likely to produce refrigerant leaks — particularly on refrigeration racks and display cases — to monitor the concentration of refrigerants in the air.

“When integrated into facility management systems — such as Emerson’s Lumity™ supervisory control platform — these devices also send notifications to designated store staff and/or service technicians to alert them when a leak may have occurred,” said Krites. “These systems enable continuous monitoring of refrigeration data to help retailers correlate the leaks with respect to different sections of the system or specific maintenance events.”

Ernest agrees that every refrigeration system should have a leak detection system, noting that today’s systems are much better and more accurate than ever before. However, he adds that in order for this to be effective, regular maintenance is critical — as long as it’s performed by the right contractor.

“I see two types of contractors: one who treats their customers like gold and does a great job for them, and the other — the more common one — who takes advantage of their customers any way they can. This ultimately creates a poor marketplace for the rest of us,” said Ernest. “Another problem is that retailers are attempting to turn our specialized trade of commercial refrigeration into a commodity that they want to buy at the lowest possible price. When you do that, you usually get what you pay for, and that results in poor installations and poor maintenance programs, which leads to leaks for years to come.”

Climate Pros prides itself on offering the highest standard of service and installation practices, which is why every system they install is nitrogen purged and pressure tested to ensure that there are no leaks present. They also use the highest quality materials and time-tested techniques to ensure that the projects will last the lifetime of the site. For example, using the proper securing mechanisms for piping and the proper piping techniques is critical to a successful installation.

“On the service side, our standard operating procedure is to leak check every service call we run,” said Ernest. “Our technicians are trained that their leak detector should be in their hand every time they walk into a store. This technique has proven to catch leaks early and reduce the overall exposure our customers have with refrigerant leaks. On top of all of that, our custom-built refrigerant tracking system helps us identify when leak rates are approaching a critical point for our customer, and this allows us to make recommendations to our customer before things get worse.”

Leak Repair

Today’s leak detection devices make it easier to pinpoint leak sources, said Krites, but it’s important to remember that in many cases, the first refrigerant leak found in a system may not be the only one — or even the largest one.

“Contractors need to compare the quantity of refrigerant charge lost and the leak rate at a specific location,” she said. “If the leak found is too small to leak the quantity of refrigerant lost, the technician should assume there is another leak in the system and continue the search. When all leaks have been repaired, technicians should confirm that refrigerant receiver levels have stabilized and are not indicating the presence of additional leaks elsewhere in the system.”

If a leak is detected, the most important thing a contractor or facility operator can do is respond as quickly as possible, said Krites. That’s because large quantities of refrigerant can leak out of a system relatively quickly, so a fast response is essential for mitigating negative impacts to system performance and minimizing associated economic costs. For this reason, supermarkets should establish proper leak detection response protocols and institute proactive measures to quickly address any leaks.

“If persistent leaks continue even at lower leak rates of 20%, supermarkets could lose approximately 700 pounds of R-404A annually; at $7 per pound, that equates to an expense of nearly $5,000, in addition to any potential costs associated with compliance or environmental consequences,” she said. “Once the leak sources have been repaired and the entire system has been verified as leak-free, contractors can then add refrigerant back into the system to restore that which was lost during the leak.”

Climate Pros maintains the systems of many large national food retail chains, and according to Ernest, most are very diligent about finding and repairing leaks. They also properly track and record all leaks that happen in their sites.

“The smaller, independent retailers may represent an opportunity here,” he said. “Often in this segment of the market, they have fewer resources and may lack the time and capacity to be as diligent as they could be. We do our best to protect even those customers by utilizing our refrigerant tracking system that we built for this purpose. It helps to ensure our customers stay compliant and have the proper records in the event they are ever audited.”

While finding and repairing leaks in a refrigeration system is not typically an exhaustive process, especially with the latest handheld leak detectors available, preventing leaks from happening in the first place may be a greater challenge. That’s because refrigeration systems are highly complicated and complex, with miles of piping connecting hundreds of pieces of equipment that contain multiple valves, fittings, and components, making these systems prone to leaks, said Ernest.

“But we can all do better,” he said. “First, we need retailers to replace the infrastructure more often in their stores instead of only investing in cases on the retail floor. Second, refrigeration contractors should hold themselves accountable for providing quality installations that are designed to last. We are often called in to fix the problems left by substandard contractors who are hired for their low price. Retailers never realize that this poor decision costs them many dollars down the line — they simply are not considering the total cost of ownership. If more contractors would invest the time and money in their workforce — like we do with our own Climate Pros University — then we all can build stores today that last for many years to come.”