Case Studies - January 2020

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Condensing boilers enable resort to operate more efficiently

Problem: At the JW Marriott in Tucson, Arizona, inefficient heating hot-water boilers were operating separately from the domestic hot-water system. Oversized storage tanks were contributing to additional energy losses. Both loops were operating year-round due to a requirement of hot-water reheat on the hydronic side of the system. The system was also failing to utilize current technological advancements effectively. The main goals of the project were to eliminate 6,000 gallons of stored hot water and ensure the new system could meet compliance with corporate initiatives for performance and Legionella mitigation.

Solution: During the replacement project, the contractor installed Harsco Industrial, Patterson-Kelley condensing boilers in three different zones. The boilers supply hot water to three different sets of P-K DURATION III, with the purpose of producing domestic hot water to all three domestic hot-water zones throughout the resort. With this new system installed, they were able to eliminate all the storage tanks. The condensing boilers installed include a SONIC SC4000, two MACH C1050s and two MACH C1500s. The P-K SONIC is a stainless steel condensing boiler that operates at 97% efficiency, while the P-K MACH is an aluminum condensing boiler with an alloy that resists corrosive condensate. Both units are equipped with the NURO Touch-Screen Control System that provides full cascading capabilities to ensure peak efficiency.

Result: The system achieved fuel savings of 50%. The instantaneous generation of domestic hot water will help the management team at the JW Marriott resort reduce its costs for Legionella mitigation. 877-728-5351; .

Collaborative planning enables tight radiant heating/cooling installation timeline at university

Problem: As they laid plans to build a new 800-student residence hall, Campus North Residential Commons, administrators at the University of Chicago set an aggressive energy-savings target and construction schedule. They mandated an annual energy usage intensity of 56.6 kBtu/ft2, a 41% reduction from the average Chicago residence hall. To meet this energy target while enhancing student comfort, the design-build partnership Studio Gang and Mortenson Construction specified a radiant heating and cooling system for the dorm rooms.

Solution: Installing 300,000 feet of REHAU 5/8-inch PEXa pipe within Mortenson’s schedule required ingenuity. Ryan Blackman, project manager at Mechanical Inc., says participation by his company and REHAU early in the planning stages helped them meet the tight deadlines. The team decided to preassemble each room’s radiant heating/cooling system on metal road mesh mats on the ground. A floor’s worth of mats were then stacked and lifted by crane on a custom-built platform for speedy installation.

Result: “The first couple of floors were a bit of a learning curve, but once we got into a groove of the entire fabrication process, we were able to meet Mortenson’s schedule and put in a quality product. It ended up going very well,” Blackman says. “A lot of times, when we don’t have this opportunity to participate early on in projects, things get drawn up that we as contractors can’t make work. Our front-end work along with the flexibility and innovative ideas of REHAU kept us from holding up construction on the job.” 703-777-5255;


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