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can provide the highest coolant pumping rate that will ever be needed to maintain the ice; however, a much lower coolant pumping rate will provide adequate cooling 75 to 95 percent of the time. Controls that provide multiple levels of pumping capacity greatly reduce the energy penalty from continuously operating large, high capacity coolant pumps at their maximum capacity. The cooling system pump control options available include: 1. using a variable speed drive to adjust the speed of the pump's motor 2. cycling single or multiple pumps on and off 3. using atwo-speed motor to power the pump The first two control options have been used successfully in Minnesota ice arenas. The third control option is commonly used in industrial applications and is also appropriate for ice arenas. Two-speed motors provide a lower cost alternative that is particularly cost-effective when a pump motor needs to be replaced. The approximate costs for these options range from $1,500 to $12,000 and the payback on investment is often attractive--even for short season ice arenas. The implementation of cooling system pump control should be considered in conjunction with improving ice temperature control and implementing automatic capacity control for compressors. In Minnesota, a number of newer packaged refrigeration systems have two different sized pumps that are automatically controlled. Contact information for two arenas that have variable speed drive control of the pump motor is listed below. Arena Litchfield Civic Arena Lily Lake (Stillwater) Improve Ice Temperature Control Contact Person Phone Steve Olson (320) 693-2679 Kevin Shields (612) 430-1234 Improvements to ice temperature controls can often provide better ice quality and reduce energy costs by consistently maintaining the ice surface at the highest acceptable temperature level. The ice sheet absorbs heat from the warmer air and building which surround it. As the temperature of the ice sheet increases, less heat is absorbed thus reducing the amount of energy needed for the refrigeration system. The reduced heat absorption into the ice sheet not only reduces the refrigeration system energy use, but also reduces the amount of energy needed to heat the arena. The ice surface temperature can often be increased by using two control technologies: 1. infrared ice temperature sensors 2. overnight setback of ice temperature Infrared sensors can be mounted above the ice sheet to measure the ice temperature by sensing the amount of infrared light radiated by the ice sheet. Although this promising technology has not yet been applied in Minnesota, it has been successfully used in a number of arenas in the United States and Canada. Overnight setback of ice temperature (e.g. from a normal setpoint of 20°F to 24°F) provides another opportunity to reduce refrigeration system energy use. This Page 8 Energy Improvements in Minnesota Public Ice Arenas Project Center for Energy & Environment