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head pressure needed for proper system operation whenever it is possible. Most ice rink refrigeration equipment can operate with lower head pressures during mild and cool weather because the condensers can more easily dump heat to the outside air. However, typical condenser fan and pump controls are not capable of tight, consistent head pressure control so they are set to operate the equipment well above the lower head pressure limits. Retrofitting existing equipment with a variable speed drive on the condenser fan motor is often the best way to continually keep the head pressure near its minimum operating limit. Maximizing the cost-effectiveness of a condenser fan variable speed drive retrofit usually requires some changes to the condenser control strategy. Therefore, a new control unit for both the condenser fan and pump (for evaporative condensers) is often needed. The new control strategies used with variable speed drives virtually eliminate the short-term on and off cycling of condenser fan and pump motors and the associated head pressure fluctuations. Although installed costs for recently completed retrofits have averaged $7,000, there has been a wide variation in cost from project to project. Typical energy cost savings are $1,200 annually. Contact information for a number of arenas that have installed a condenser fan variable speed drive control is listed in the table below. Arena Contact Person Phone West St. Paul Arena Dave Malay (612) 552-4155 Litchfield Civic Arena Steve Olson (320) 693-2679 Farmington Civic Arena Jim Bell (612) 463-1851 Hutchinson Civic Arena Marv Haugen (320) 234-4227 Cottage Grove Arena Dean Mulso (612) 458-2846 Victory (Minneapolis) Virgil Oldre (612) 627-2953 Reclaiming Waste Heat from the Refrigeration System Waste heat generated by the ice sheet refrigeration system can often be cost-effectively captured and used to supplement an arena's heating needs, thereby reducing heating fuel use. The ice sheet refrigeration system normally takes all of the heat that the ice sheet absorbs (plus some extra heat added by the refrigeration system itself) and then dumps that heat to the outside air through an outdoor condenser. However, much of the heat that the refrigeration systems normally rejects to the outside air can instead be reclaimed to provide useful heat. The reclaimed heat can be used to heat air or water up to a temperature of 90°F or more. Typical uses of reclaimed heat include: heating the air in the arena, heating service hot water, and/or melting the snow scraped off by the resurfacer. More than half of the ice arenas in Minnesota use well- established heat reclaim technology to provide heat for one or more of these uses. Adding heat reclaim equipment costs at least several thousand dollars, but in some cases the investment will pay for itself in just a few years. Cooling System Pump Control More closely matching the ice sheet coolant pumping rate to the exact amount of cooling that is needed saves energy. The pump that circulates coolant under the ice sheet is chosen so that it Energy Improvements in Minnesota Public Ice Arenas Project Page 7 Center for Energy & Environment