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issue: August 2004 APPLIANCE Magazine

Controls & Sensors
Freezing Out the Competition

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by Tina Grady Barbaccia, Managing Editor

When commercial foodservice equipment manufacturer Master-Bilt’s competitor developed a new controller system that was threatening to take away business, the New Albany, MS, U.S.-based company knew it had to take action.

“We were getting locked out because we couldn’t just supply an equivalent control,” says Kenny Owen, engineering manager, Master-Bilt. “We had customers, and this other competitor came in and sold them on the benefit of electronic control and solid-state circuitry.”

Master-Bilt had used these types of controls before, but on a limited basis. That is when Master-Bilt engineers realized that no one else had developed this kind of control for walk-in freezers, so they decided to develop one. From this decision was born the company’s new Mater Controller Demand System with Reverse Cycle Technology, which was patent-pending at press time. The new control system was officially unveiled at this year’s National Restaurant Association Show, held in May at McCormick Place in Chicago, IL, U.S. The Master Controller itself has been on the market for nearly a year and a half, but the reverse version of the control was released on Master-Bilt appliances in June, Mr. Owen reveals.

Master-Bilt has just launched its patent-pending Reverse Cycle technology for its commercial, walk-in freezers and coolers. The technology, which is used in conjunction with its Master Controller system, involves a reverse-cycle valve that is added to the condensing unit. The valve’s primary function is to reverse the direction of refrigerant flow during defrost, reportedly reducing defrost energy usage by 80 percent.

Defrosting a New Idea

The company’s new reverse-cycle defrosting involves a reverse-cycle valve that is added to the condensing unit. The valve reverses the direction of refrigerant flow during defrosts, which is automatically activated by the Master Controller. The reverse-cycle valve is activated when the Master Controller demand system determines that defrosting is necessary, and high-temperature refrigerant flow is reversed through a multi-step process. Once the process is triggered, refrigerant flows backward through the evaporator coil, heating it along its entire length, which eliminates the buildup of frost.

To develop the new control and ensure it was different from competitive offerings, Master-Bilt engineers analyzed the new solid-state electronic control that its competitor had developed and decided to simplify it. “It had a lot of drawbacks,” Mr. Owen says. “Just like most electronics, the first generation doesn’t go nearly where you want it to.” Master-Bilt saw this as an opportunity and decided to take advantage of it. “We took theirs, we looked at it, and looked at all the benefits,” he said. “We took out a lot of the unnecessary parts, kept the good parts, and added a whole lot of other things to it.”

Typically, a walk-in freezer or cooler is supplied with several components that are installed and wired in the field. In the new solution, an electric expansion valve and an integrated circuit board have been put in place and all of the wiring is done at the factory. “The electric expansion valve and integrated circuit board do the work of the separate components,” Mr. Owen says. “We added more reliability, but the biggest benefit we added was simplicity.”

However, the research and development of the controller did not come without obstacles. Although the controller was simplified in terms of components—which left less of a chance for something to go wrong—the technology was more advanced. A typical reverse-control system has been mechanically controlled and uses more expansion valves, Mr. Owen explains. “This means more parts, so there are more problems,” he says. “The beauty of our system is that the plumbing is identical. Our electric expansion valve works the same way in defrost and in cooling—it modulates the flow of the system. It’s very simple; it’s all pre-wired. There are no check valves. And it’s something no one else has done.”

But it did take some time to perfect, Mr. Owen admits. Master-Bilt did all of the program debugging and has gone through hundreds of iterations of programs in doing so, he says. “It took us about a year to get it working the way we wanted and then about a year of field testing before we started selling it,” Mr. Owen says. “We have been selling the control on our freezer for about a year now, but the Reverse Cycle part of it we’re just starting to sell on our appliances.”

The decision for Master-Bilt to be its own supplier—to design its own control—was based on myriad reasons. A key factor is that no other company will have this technology integrated into its controller. “It could be used on other walk-in coolers or freezers, but we’re not gong to sell it to others,” he discloses.

And the results look promising. With the new design, the reverse cycle in the controller also results in an 80-percent reduction in defrost energy usage because defrost time has been lessened, and there are no defrost heaters, he says. This will prove to be beneficial, he says. “People are looking for energy efficiency,” Mr. Owen contends. “Now, I hope our challenge becomes how to build enough units to keep everyone up and running.” But that, he says, still remains to be seen.


More from our August 2004 Report
Controls and Sensors

Silicon: Smart and Strategic

The Right Touch

Freezing Out the Competition

Perfect Timing



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