In order to meet local building codes, ice arenas need to introduce large quantities of outdoor air. This is like leaving the door open to your freezer all day.

“The trick is trying to introduce the proper quantity of outdoor air and still maintain humidity control,” said Lahah.

The newest Polar Ice facility is built at the end of a mall in Grapevine, TX. It has two enclosed NHL-sized rinks connected by some locker rooms and a pro shop. The ice arena has approximately 32,600 sq ft of total ice surface. It is well insulated and of tight construction. The arena uses eight 25-hp refrigeration compressors for the two ice surfaces.

However, the humidity in the arena would run as high as 95% rh if not conditioned, and the refrigeration equipment would have to work overtime to maintain the ice. It is estimated that 15% of the total load on the ice surface is a function of the humidity level. Therefore, high humidity periods would cause energy costs to rise and reduce the quality of the ice.

As would be expected, high humidity levels cause a number of problems. These include fog, condensation, mold and mildew, and even customer discomfort. The only way to combat these issues is to provide the proper amount of dehumidification and make-up air without sacrificing energy consumption.

Taking control

To tackle these problems, the rink operator attended a local trade show where he heard about “Make-up Aire,” a gas-fired desiccant-type energy recovery dehumidifier from Munters DryCool (Selma, TX). This system is a way to introduce make-up air and dehumidify the arena while simultaneously reducing the facility’s energy consumption.

According to the manufacturer, the major advantage of this type of dehumidifier is its ability to go to very low dewpoints. These lower dewpoints are necessary due to the low ambient temperatures experienced in ice rinks, particularly during summer operation.

The system is designed to achieve lower dewpoints because the desiccant removes water in the vapor phase and is not limited by temperature. It is designed to remove moisture continuously without requiring a defrost cycle.

In the end, the owner installed a single, 15,000-cfm, gas-fired Make-up Aire system. The unit utilizes a 92% efficient direct-fired natural gas burner to dry out the desiccant wheel. An energy study projected the rink would save approximately $12,000 a year. The system was sized to handle the outside air and internal latent loads in both rinks to maintain 40% to 50% rh year round.

Testing it out

Before the dehumidifier was turned on it was 43° and 96% rh inside the ice rinks.

“Six hours after the desiccant dehumidifier was turned on, the temperature had risen to 55° and the humidity was lowered to 50% rh,” said Lahah, noting that the dryer had removed 800 to 1,000 lbs of water from the air.

This solved the humidity problems in the building and provided a more comfortable environment while improving the ice quality.

“The internal environment is really comfortable now. Skaters rave about the excellent ice surface. The air quality has improved and even asthma suffers have seen a difference,” said Lahah. Also by lowering the humidity levels in the arena, the rink owner was able to increase refrigeration capacity for ice making.