This article describes that technology and engineering combine to keep rinks flush, below freezing, and efficient enough to turn a profit in even the balmiest climes. An expert specifies that to prevent the latex paints from running, additional layers are carefully sprayed over the decorations, sealing them. A warm-sand underfloor keeps the rink frost line away from the ground, preventing any heaving of the slab. Among the many elements that Commercial Refrigeration incorporates into its rinks, finned pipes improve the rate of heat transfer. Exceptional care is used in positioning each pipe precisely within the concrete slab, Martin said, as a way of bettering heat transfer and rink efficiency. Eight-inch-diameter headers distribute coolant to the floor pipes. Smaller headers beneath circulate warm brine to the pipe. Low-emissivity ceilings can reduce heat loads by 20 percent. The new machine requires less maintenance than those that rely on internal combustion engines.
Robb olexin has spent the better part of his life making ice. Although he’s now the general manager for Ice America Inc., his passion for building rinks actually began in Canada, where he grew up. This same passion eventually led him to Plano, Texas, a Dallas suburb that is Ice America’s hometown.
Texas? Sure, Olexin said. Texas boasts more professional hockey teams than any other U.S. state. Southern rinks often stay open all year, he said, a business boon to arena operators. Northerners don’t skate much in the summer, it seems. They prefer spending their skimpy allotment of short-sleeve days in the sun.
Yet, professional hockey teams and their arenas still seem to be oblique additions to the Sunbelt’s landscape. Has technology played a factor? “In the sense that it has become affordable to operate these facilities there—yes Olexin said. “If you couldn’t make the technology energy efficient, the owners of hockey teams wouldn’t look south because operational costs would be so high.”
A big difference between snow-country rinks and their southern counterparts is the spacing between pipes in the rink itself, Olexin said. In the northern United States, there are approximately 13 miles of pipe in the average floor, spaced 4 inches on center, he said. “In the south, pipes are spaced 3 inches on center just to have the better heat transfer.”
The most important consideration for any rink, though, is the refrigeration system.
“We prefer ammonia as the primary refrigerant,” Olexin said, “and brine, or calcium chloride and water, as the secondary, because less horsepower is needed to move ammonia compared with freon.” Sizing the refrigeration system is important, too, he said. Ice America sizes its plant compressors to run about half the time. “That’s one thing we like to do—not necessarily overdesign—just design them properly so they aren’t running to where they never shut off,” Olexin said. “You’ve got costs later on, obviously. Maintenance is less. Overhauling your compressors will have to be quicker if your plant’s going to run 24 hours a day,” he said.
Keeping the ice surface at the right temperature is one path to energy efficiency. Keeping the ice at an optimum thickness is another, Olexin explained. The sweet zone lies between 1 and IV2 inches, he said. A rule of thumb says that for every eighth of an inch the ice deepens, 10 percent more load piles onto the compressors. “It’s easy to add an eighth-inch to a 1½-inch slab,” he said.
Putting in the Ice
Freezing the water for a 17,000-square-foot rink is no trivial undertaking, Olexin said. By the time a rink bed is chilled, its ice sprayed on layer by layer, and its red line, blue lines, and white base painted, two or three days have gone by. “It’s a big process,” he said.
In Texas, it is still a safe bet that rodeo ranks higher than hockey in popularity, making multipurpose rinks a near-necessity. “I was in Abilene two years ago, and we did our ice seven or eight times in seven months,” Olexin said, describing the process necessary in switching between the two events.
Yet, taking out the ice isn’t as big an endeavor as putting it in, he said. After workers turn off the refrigeration, the bond between the base of the ice and the concrete floor loosens. Then a front-end loader comes in and shovels the slab away. “You don’t wait for the ice to melt,” he said. In Canada, that would take weeks, he added.
Making ice is fussier. First, the compressors start and chill the concrete slab—or, in the case of some year-round, single-purpose rinks, the sand bed—to 16-18°F. Then, using a 10-foot-long spray boom with 15 nozzles, the ice maker coats the entire surface with a fine spray. “It might take 10 minutes to do the spray and five minutes for it to freeze,” Olexin said. By repeating the spray and freeze pattern many times, the ice maker eventually builds up a layer of ice a quarter-inch thick. It may take seven to 10 sprays to do so, he said.
With a thin layer of ice covering the floor, three or four coats of white ice paint go down. Without the paint, the clear ice would look like concrete, Olexin said. Then a few layers of water go over the paint to seal it, he said.
Lines, markings, and logos go on next, Olexin said. Lines are painted or applied with tissue paper frozen into the ice. Logos are painted on most of the time, although printed paper can be used for them as well, he said.
“Every time you make the ice you go through this. It's a big, time-consuming, back-breaking process,” Olexin said. “Lines and logos take 24 hours for a pro team: two 12-hour days,” he said.
To prevent the latex paints from running, additional layers are carefully sprayed over the decorations, sealing them. When an additional 1/4-inch of ice is down, the ice maker brings out the Are hose and floods the rink, taking the ice thickness a total of 3/4-inch above the markings. “You can’t just dump 10,000 gallons out there, let it find its own level, and then let it freeze,” Olexin cautioned. “Too much water will burn through the layers protecting your lines and logos.
“After you’ve built up the ideal thickness of ice, you bring out your resurfacer,” Olexin said. Up to this point, the entire ice building process has used cold water. The resurfacer uses hot water, Olexin explained. “With the blade, you shave high and fill low. That’s how you get a nice, level sheet of ice,” he said. Ice makers smile when they can keep the final surface flat to within a quarter or an eighth of an inch over the entire rink, he added.
“A pond would probably freeze closer to zero because you’re talking a level surface,” Olexin said. “I used to do a lot of curling ice. Those rinks are 114 feet long by 15 feet wide and divided. Curling is finicky. The ice has to be perfectly level. Because of their size, I would fill them up with water and they would find their own level,” he said.
Cast in Concrete
“The rink floor is the most difficult part of the system to change or improve later,” said Darryl Martin, P.E., general manager for Commercial Refrigeration Inc., an Edmonton, Alberta, company that has specialized in ice rink refrigeration for 35 years. “The floor—so humble— is the part that everybody misses because you don’t see it after it’s done,” Martin said. “Yet it is the most important decision because it is the one irrevocable decision that the design engineers must make. All the other stuff—you can see it running, and you can tweak it and change it and optimize it later. But you can’t change the floor.
“The floor is made out of materials not normally associated with the heat-transfer business,” Martin said. “We’re using pipe and we’re using concrete to make a large heat exchanger.” Polyethylene and concrete aren’t exactly known for their conductivity he added. The materials are inexpensive and strong, though. And strength is important, he said, “because it’s going to be walked on.”
Among the many elements that Commercial Refrigeration incorporates into its rinks, finned pipes improve the rate of heat transfer. Special care is used in positioning each pipe precisely within the concrete slab, Martin said, as a way of bettering heat transfer and rink efficiency.
Air in the pipes is another source of inefficiency, Martin said. “Air, allowed to accumulate, restricts coolant flow and acts as a barrier to heat transfer,” he said. The finned pipe design helps expel this air, as do several proprietary piping schemes.
The typical rink begins with nearly a foot of compacted sand. Through it run underfloor heating pipes on 12-inch centers. Atop the sand go two layers of polystyrene insulation, followed by the 5-inch slab, which embeds the reinforcing wire mesh, the pipe chairs, and the pipes in concrete starting an inch below the finished surface.
’’During construction, you’re using materials and people that are not commonly employed in this manner,” Martin said. “Civil engineers and concrete contractors normally don’t know much about it.”
As an example, Martin said that most concrete pours add air to the mix to increase insulating value. That’s exactly what is not wanted in a rink, where heat transmission is so important. But entrained air also helps concrete endure another phenomenon, the freeze-thaw cycle. Leaving out the air casts that particular benefit aside, he said. Of rink design, basically “the whole thing gets turned on its head,” he said. “It’s a unique specialty.
“It has to perform a lot, this little floor,” Martin said. When the circus comes to town, for instance, the floor has to already have built into its surface the points for attaching all those turnbuckles. That’s a lot of inserts, he added.
There are other considerations in building a rink, Martin said. “Environmental issues-—which refrigerants and secondary heat transfer fluids you’re going to use. Ozone issues. CPCs. All of them put a wrinkle in it,” he said.
With computer-controlled rinks and remote monitoring, “One guy can run six rinks from a laptop,” Martin said. But, he cautioned, it’s easy for rink buyers to get caught up in the latest trimmings, and fail to invest in the plant and the floor, where the real efficiencies happen. “There have been some cases where owners have scrimped on the basic system to free up money for computer control—not a good choice,” he explained.
Humidity is another consideration in the trend for more efficient (read: tighter) ice arenas. “There aren’t many rooms that have water on the floor all the time,” Martin said. Increasingly, rink makers are adding dehumidifiers, better airflow management, and control of radiant heat sources to their designs, he said.
Low-emissivity ceilings can reduce heat loads by 20 percent, Martin said. These ceilings started showing up in rinks about 10 years ago, he said. They haven’t caught on yet, he added, “because not many people understand the Stefan-Boltzmann law.
“A low-emissivity ceiling is reflective, so laymen think what it does is reflect cold back,” Martin said. That’s wrong. “You can’t reflect cold,” he said. Low emissivity has nothing to do with a reflective surface. “A reflective surface just happens to be closely aligned with low emissivity,” he said.
Martin provided a brief refresher on black body radiation. “A black body has an emissivity of 1,” he said. “It’s fully emissive.” A low-emissivity material, with a rating of 0.02, say, can get very hot without giving off much infrared radiation.
“Everything that’s low in emissivity also happens to be shiny,” Martin continued. “Any ordinary material behaves like a black body and radiates heat in proportion to its temperature.” Sun shining on a rink roof can add to it a considerable amount of heat. For ordinary materials, that heat radiates down at the ice as it follows the heat transfer path from hot to cold. “We supply a low-emissivity membrane that can get as hot as it wants without emitting heat,” he said.
With all that’s happening beneath the ice, it’s no surprise to find that there’s nearly as much technology in use at the surface. Toronto-based Cimco’s ice temperature control system, for example, uses infrared sensors to monitor the temperature at the ice surface, as well as within and beneath the slab. The system monitors outdoor temperatures, too, and is programmed to call for more or less refrigeration as heat loads vary.
Perhaps the most visible technology—certainly the one dearest to hockey fans—is the ice resurfacer. Developed in the 1940s by Los Angeles-based Frank Zamboni & Co. as a way to replace hand scraping, ice resurfacers today rely less on internal combustion engines and more on electric motors for powering main drives and auxiliaries. Concern over emissions is the main factor behind this trend, explained Andy Schlupp, president of Resurfice Corp. in Elmira, Ontario, which made its first resurfacer in 1967. Economics plays a role also, he said.
Recently, Resurfice added a nickel-cadmium battery-based machine to its line of gas engine and plug-in models. Though the initial cost of a nicad unit is about $18,000 more than an electric machine using lead-acid batteries—which is already double the price of a gas machine—it is in cost per use, or flood, where the electric vehicle pays off. A propane system costs about $2 a flood, Schlupp explained. A nicad machine operates for about 12 cents a flood, he said.
With a machine operating on natural gas or propane—or the now-prohibited gasoline—every use requires a complete exchange of building air. “We don’t know what that cost in energy is because it depends on the outside temperature whether you have to heat or cool the building,” Schlupp said. “Building size also changes from site to site,” he said. But the savings, though difficult to pinpoint, are substantial with electric machines, he said.
In looking to develop an electric machine that didn’t require a cord, Resurfice contacted Solectria Corp. of Wilmington, Mass. According to Solectria’s lead engineer for the project, Ricardo Espinosa, Resurfice wanted to match the weight of a fossil fuel machine as closely as possible. The company wanted a machine sufficiently lithe that it could roll onto any rink without endangering the ice. “Some of the lead-acid machines get so heavy that they break the ice,” Espinosa said, “Some rinks need special reinforcement to support that weight,” he added.
After initial discussions produced several proposals, Resurfice shipped a frame intact with components to the Solectria plant. “We did it as an in-house engineering project,” Espinosa said, a typical approach to a vehicle integration job. Solectria picked components to meet the specification, then tested the machine for two weeks. “It took a little while to refine the machine, adjusting the many motors and pumps,” he said.
Eventually, Solectria began shipping kits of entire drive systems—batteries and motors—to Resurfice, while training the company’s employees in installation and diagnostics. “They are at the point now where they are doing it all on their own,” said Espinosa, “We’re just shipping them kits.”
The only hydraulic systems remaining on the nicad resurfacer operate power steering, a snow bin lift, and a small brush along the side of the machine. “We could have taken the machine 100 percent electric,” Espinosa said, “but for some practical reasons, like timing and getting the machine on the market, we went probably 70 percent.” Solectria chose Saft nicad batteries to meet a capability requirement of 20 floods without charging. Twenty-four hour-a-day availability was another requirement, so the machine had to be fully rechargeable between uses.
The new machine requires less maintenance than those that rely on internal combustion engines, Espinosa said. Its charging system needs only a 50-amp, 200-volt outlet. “A rink has power available for other machinery, so that’s absolutely nothing in terms of charging infrastructure,” Espinosa said. “The machine is very light, relatively speaking—only about 2,000 pounds heavier than an IC machine.
“It can roll into any ice rink in the world,” he added.