Refrigeration Systems: Keeping Frosty 24/7

Posted on:

April 16, 2014

Like it or not, in the refrigeration business you have to be ready to take—and respond to—middle-of-the-night service calls.

“Most, but not all, air conditioning technicians go to work at 7 or 7:30 in the morning, and at 5 p.m. they wrap up their tools and go home,” points out Danny Halel, application engineering manager, Hussmann Corp., Bridgeton, MO. “When you are in the supermarket refrigeration industry, you could get a call at 3 a.m. and you have to get in your truck and go to the store. You won’t leave until it’s functioning. In a typical grocery store, we can have up to $1 million in retail food. If that system isn’t running, you may lose a portion of that food if the temperature goes above some federally mandated required temperature. For example, fresh meat must be at 41.5 degrees. If it goes above 41.5 degrees, the store manager pulls that meat and throws it in the trash.”

That’s one reason why Aire Rite Air Conditioning and Refrigeration in Huntington Beach, CA, operates on a 24-hour workday. “Our office is open seven days a week from 7 a.m. to 7 p.m.,” says Don Langston, president. “After that, the answering service screens the information and transfers it to the on-call supervisor. We have a dozen guys who are on standby emergency service every night.”

With 122 employees, the company requires technicians to be on call one weekend a month and one day during the week. Langston estimates the typical response time for refrigeration service to be about two hours, depending on the distance and traffic. The company, whose market niche is food service/hospitality/restaurant refrigeration, serves the southern portion of California and encompasses a radius of 150 to 200 miles.

“Everyone involved, from the person who answers the phone to the technician, understands the need for a rapid response,” he explains. “It’s a mindset. Guys who come up with a refrigeration background get it. They know they have to be able to respond and to work until the job’s done.”

The urgency of the service call usually depends on the problem, as well as the time of year. For example, if a single compressor goes out, other compressors in the parallel rack may be able to pick up the load until the defect is corrected, Halel explains. “If it’s July, your time frame is less than if it’s January, because your outside temperature determines to some degree, the capacity of your compressors and condensers,” he says. “If it’s cooler outside, you have more time to respond. If you get a refrigeration alarm, for instance, that’s something you have to address right away. If it’s a catastrophic failure, you better get there fast or you will lose the product in the cases.”

Advances in Energy Efficiency
During the 35 years he’s spent climbing the ladder of his second-generation family business, Langston has seen a number of changes in refrigeration techniques. Recently, he has noticed advances in defrost controls, primarily for walk-in coolers and freezers.

“We’re seeing increases there that help improve energy efficiency, more of what we call a smart defrost,” he says. “The new ones are using electronic controls that have memory and temperature sensors that start counting how long it takes a unit to go into the defrost cycle, remove all the frost, and then bring the mechanical refrigeration back online. That keeps the refrigeration system running more efficiently and keeps the defrost heaters, which draw thousands of watts of power, to a minimum. It also keeps the product colder and minimizes the temperature swings while in defrost.”

Depending on the application, walk-in freezers can defrost anywhere from two to six times a day, he explains, because they typically have large doors, product is frequently being moved in and out of them, and they are located in a warm kitchen with a lot of humidity in the air. “When a minus-5- to a plus-5-degree walk-in freezer comes in contact with the warm air in a kitchen, all that moisture gets drawn into the evaporator fan assembly.”

Langston also gives kudos to the advances being made in compressors. “The scroll compressors are much more efficient,” he says. “We’re seeing variable-speed compressors where they’re able to speed up and slow down and change their capacity depending on how much heat load is inside the box. They can match power consumption to the heat load in the box.”

Halel also sings the praises of the digital or variable-speed compressors, because they can more closely match the required load and waste less energy. He explains these compressors are primarily used in supermarkets, convenience stores, and large restaurants. “The upfront cost is a little higher, so you have to figure out the payback,” he says. “Many smaller restaurants and grocery stores don’t want to pay the upfront costs, even though they will pay for it later in energy.”

Another innovation, according to Halel, is the introduction of a micro channel condenser that uses significantly less refrigerant. “It also increases the capacity of the condenser and therefore may be smaller than a standard, air-cooled condenser. Instead of having eight fans, you might get by with six. Not only is your energy reduced, your refrigerant charge is reduced.”

Not Without Challenges
One of the challenges of the refrigeration business is finding and keeping good technicians, reports Bob Champe, president, Shearer Heating, Air Conditioning, and Refrigeration, Inc., Washington, PA. In his opinion, air conditioning technicians don’t necessarily make the best refrigeration specialists—and vice versa.

“We cross-train as much as we can, but basically we try to keep the refrigeration guys who are good at what they do on those types of projects and the residential guys on what they know best,” he says.

Halel emphasizes that refrigeration is a specialized field of expertise. “There are many more components, hundreds of evaporator coils, all hooked to the same refrigeration system, whether it’s a parallel rack or distributed system, all running at different temperatures. There are valves in the system these guys aren’t used to seeing.”

Champe, who started his first job almost 40 years as a supermarket refrigeration apprentice, indicates that eight out of ten times the refrigeration problem is electrical, perhaps a faulty component. His company, which specializes in restaurant refrigeration, handles national accounts such as Cracker Barrel, Longhorn, and Boston Market. “When we take over a store, we take over the HVAC and refrigeration,” he says. “All of our contracts are maintenance and service related.” For example, he negotiates a maintenance price to change filters, clean coils, and handle preventive maintenance, as well as an hourly rate.

To ensure he can obtain parts in an emergency, he obtains the afterhours phone numbers of his company’s vendors. “No matter what the problem is, we get them to open up their store,” he says. “If it’s 6 p.m. or 1 a.m. they will open up for us.”

Unfortunately, asking a vendor to get out of bed and get to the store in the wee hours of the morning takes time, which is in short supply when food in thawing in the coolers. “Logistically, an afterhours service call can take three times longer than a call during normal business hours,” Langston says. “We’re dealing with very complex mechanical equipment with a lot of moving parts.”

His advice for contractors considering a venture into refrigeration: “Understand you need a strong infrastructure to offer 24-hour service and deal with the faster response time,” he says. “It’s not something you can dabble in. You have to commit to it, build your infrastructure, and hire technicians who understand it.”