HEAVE NO!
} by Kevin McCormack
Editor’s Note: As vice president of arena operations at Floyd Hall Arena in Little Falls, N.J., Kevin McCormack writes from experience regarding maintaining and inspecting your rink’s subfloor heating system.
A
S ARENA OWNERS, managers, operators, and personnel, we have many areas of responsibility. We often say we are jacks of all trades, and master of none. One
important area that we cannot afford to neglect is the “back of the house.” Te ice plant and its associated compressors, pumps, motors, dehumidifiers, condensers and other equipment is the lifeblood of any ice arena, big or small. Failure to monitor, inspect, maintain and invest in your refrigeration system can lead to failed equipment and cancellation of ice time.
One of the most overlooked areas of the ice plant is the
subfloor or underfloor heat system. Most year-round ice arenas that have been built in the last 25 years have a subfloor heating system. Several arenas have suffered through failures of their underfloor heating system recently. Without a subfloor heating system (or one functioning properly), a year-round ice surface will develop permafrost, a freezing of the subsoil layers under the ice surface. Te area under the ice can freeze farther and farther down creating a solid block of ice that can be inches and even feet thick. I have even heard of permafrost as much as 15 to 20-feet thick. Eventually the freezing can proceed far enough that it hits something solid like bedrock or dense soil. Once this big block of ice under a rink hits something solid below the rink, it can only do one thing: force up in the opposite direction and heave the ice surface, the slab or even the foundation of the arena. Tis can happen quite quickly, as it did at Floyd Hall Arena in Little Falls, N.J.
A refrigeration plant operates on the principle of heat
transfer. In simple terms, an ice arena refrigeration system removes heat (energy) from the water that is placed on the ice surface. Te removal of heat from the water causes the
10 SUMMER 2 017
water to change state and freeze. Te heat that is absorbed by the secondary refrigerant now must be moved somewhere to complete the refrigeration cycle. To increase efficiency in ice plants over the years, engineers have discovered some creative ways to reuse this waste heat for everything, from making hot water to space heat. Most ice arenas today have a waste heat loop that heats the snow melt pit and the subsoil below the ice surface. Tis last heat exchange is typically done through a shell and tube heat exchanger.
Heave Forms
In August, Floyd Hall Arena developed a leak in the underfloor heat exchanger. It had to be shut down for over 10 weeks while a new one was ordered, built and installed. During that time, the rink developed a heave at one end that raised the concrete slab more than seven inches above the surrounding concrete. Now the ice resurfacer must travel up this incline to access the ice, causing wear and tear on the vehicle. In addition, the ice resurfacer door is out of alignment and must be shimmed to close properly.
Te severity of this heave was caused by several factors,
including the length of time that the underfloor heat exchanger was not functioning and failure of the expansion joint around the concrete slab. Tis allowed water and moisture to infiltrate the underfloor subsoil as well as the spaces between the slab, insulation and vapor barrier. With the use of an endoscopic-type camera loaned to Floyd Hall by Tom Mattioli from the Rinx, we were able to inspect the layers and actually see the accumulation of ice between insulation and slab and in the subsoil.
The Importance of Maintaining Your Subfloor Heating System
Without a subfloor heating system (or one functioning properly), a year-round ice surface will develop permafrost, a freezing of the subsoil layers under the ice surface. The area under the ice can freeze farther and farther down creating a solid block of ice that can be inches and even feet thick.
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