project HVAC
M
uscatine, IA is home to a Beaux-Arts-style courthouse constructed in 1907 and listed on the National Register of Historic Places in 1981. According to county budget director Sherry Seright, there were growing signs that the building’s more than 30-year-old cooling and heating system needed to be replaced. “We found water in the basement from the old boilers, and the pipes were starting to leak. The indoor units were loud, moldy, and fuzzy, and everyone disliked the huge, ugly condenser unit sitting prominently on the roof of our handsome … building, spoiling the view,” she said.
The Beaux Arts-style courthouse in Muscatine, IA, uses a VRF/geothermal integrated HVAC system from Mitsubishi Electric Cooling & Heating.
Searching for green
Judged To Be Efficient Integrated VRF and geothermal systems save energy for an historical courthouse. 34
COMMERCIAL BUILDING PRODUCTS
JUL/AUG 2013
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The County Board of Supervisors wanted to learn more about going green and knew it was time to replace the courthouse’s failing, outdated HVAC system. A proposal from Vic Amoroso, a 40-year HVAC design engineer and president of A&J Associates PC, North Liberty, IA, caught their attention. Amoroso explained the basics of a closed-loop geothermal system and how smoothly it would work in tandem with a variable-refrigerant-flow (VRF) zoning system from Mitsubishi Electric Cooling & Heating, Suwanee, GA. Bruce Senti, an independent sales representative from Mitsubishi Electric, explained to Amoroso how the VRF zoning water-source system would interface with a geothermal field. “Our new W-series modular units perfectly combine the energy effectiveness of geothermal systems with the excellent efficiencies of our VRF zoning technology,” said Senti. “These new units are 30% smaller than previous models and can be easily transported down the stairs into the basement of the courthouse. By connecting to the geothermal loop, backup heat would not be needed as it might with air-source units.” The system, which uses water instead of air as a heat-exchange medium, is superior to air-cooled systems, especially in Iowa, where it is not uncommon for winter temperatures to dip below –10 F. The system’s dry mode is effective for the months of July and August, which can make Iowa feel like a greenhouse. Because of the hot, humid Iowa summers, Senti recommended another key VRF zoning product, a Mitsubishi Electric City Multi dedicated outdoor air system (DOAS). The DOAS would supply outdoor ventilation air to the courthouse, delivering the proper amount of fresh air to each room, and also provide ample dehumidification without excessive reheat. The DOAS would also increase the VRF zoning system’s energy efficiency because it pre-conditions outside air for introduction into the downstream HVAC units, reducing the load on the HVAC system. The fact that the DOAS and the VRF zoning system were designed to work together was appealing to Senti. “The DOAS from Mitsubishi Electric was very convenient for us,” he said.
