by Thomas L. Tsaros
A creative heat recovery solution utilizing condenser water waste heat was implemented to offset electric hot water heating at Mount Wachusett Community College’s fitness center in Gardner, Mass. As part of a major HVAC infrastructure modernization project at the center designed by Fitzemeyer & Tocci Associates, chiller waste heat carried by the condenser water loop was piped for recovery and use by the facility’s pool water heating system.
The facility had already integrated its direct-expansion pool dehumidifier to capture the unit’s waste heat for pool water heating. However, temperature trend data collected through the building’s energy management system showed that the pool water heating system’s existing two, 36 kW electric water heaters were still operating to provide the remainder of the heating required. This presented an opportunity to further improve the existing heat recovery loop to reduce electric usage.
The center’s chiller, also being replaced as part of the HVAC modernization project, is located near the pool dehumidifier and associated heat recovery system piping. This allowed easy integration of the condenser water heat recovery system with the pool’s existing heat recovery loop. Heat from the 95 F condenser water is transferred to the pool water heating loop through a plate-and-frame heat exchanger, raising the pool water heating supply to 90 F. The heat exchanger was designed to meet the entire pool water heating load, thereby substantially reducing, or eliminating, operation of the existing electric pool water heaters during the cooling season.
In addition to the condenser water heat recovery system, a second heat exchange system was installed to use heat from the campus’ woody biomass building heating system to supplement the condenser water heat recovery system and for primary pool water heating during wintertime.
Operation of the new condenser water heat recovery system is anticipated to begin this spring. The college is also currently working with the local electric utility to secure a custom utility incentive for this project.
Thomas L. Tsaros is associate principal and energy & infrastructure service leader at Fitzemeyer & Tocci Associates.