FirstMerit Tower gets an efficient closed-loop cooling system to reduce water waste.
After a skyscraper has been around for a few years, it can begin to fade into the skyline. After a few decades, when buildings begin to wear around the edges, we may barely notice some of the once-majestic structures. It can be easy to forget that some of these institutions aren’t simply boring office buildings—they are perfect examples of influential architecture.
The centerpiece of downtown Akron, OH, the 27-story FirstMerit Tower, was completed in 1931, when Art Deco was at the height of its popularity in the United States. After undergoing a facelift and restoration, the tower is listed on the National Register of Historic Places. As part of continuing interior updates, the building needed a larger-capacity cooling tower,
energy-efficient variable-frequency-drive (VFD) pump assemblies, and associated piping for its HVAC system.
Originally, an open-loop piping system, consisting solely of supply lines, was used to cool the lower floors—floors 12 and below. On floors above 12, city water was being run once through an air-conditioning unit, and then dumped down a drain. Now, after the recent renovation, the open-loop system continues to feed cooling-tower water to the lower floors, while a new closed-loop system recirculates cooling-tower water for the upper floors using supply and return lines.
The old system was, “highly inefficient and wasteful,” said Kevin Kindbom, vice president and co-owner of consulting engineering firm Bandwen Williams Kindbom, Akron. “The building was dumping about 500 gpm of water down the drain on the hottest day of the year.”
Automatically controlled, the new closed-loop system saves approximately $150,000 each year in utility costs.
Contractor Harner Plumbing, Mantua, OH, chose for the project a 200-ton Marley cooling tower to accompany the two existing cooling towers, four Armstrong pump assemblies with Danfoss VFDs, three additional Danfoss VFDs for the cooling-tower fans, Armstrong triple-duty balance valves, a heat exchanger, and an Armstrong air separator. The contractor also had to choose a piping solution that could match the efficiency of the closed-loop system’s design. Although the project originally was specified with Schedule 40 grooved steel, Harner Plumbing installers had been working and having success with a type of polypropylene-random (PP-R) pressure piping called Aquatherm. Because installers had used Lindon, UT-based Aquatherm systems for more than three years on a variety of projects, they were able to select the PP-R piping again with confidence. By switching from steel to PP-R piping systems, the project saved $18,000.
Additionally, there was a problem with a 150-ft. run of 8-in. Schedule 40 pipe during the project. The piping system was shut down while the new PP-R piping was installed. “When the Schedule 40 piping system was reenergized, the whole system basically blew up. Even though the system was rated for the little bit of extra pressure we added, it had rusted out enough that even just a small bit of extra pressure caused the whole seam to break,” Kindbom said. “That was a nice little emergency at the end of the job.”
The SDR 17.6 Aquatherm Blue Pipe used on the project is extremely lightweight; just 2.93 lb./linear ft. of 6-in. pipe. Comparatively, Schedule 40 steel weighs close to 19 lb./ft. “On the labor, Aquatherm gave us a big advantage,” said Harner Plumbing owner Ray Harner. “The labor savings really helped; the Aquatherm was easy to lift and move.”
Heat-fusing the piping systems required less labor than trying to groove the steel pipe. Easy to handle and put in place, the PP-R piping saved the project another $20,000 or more in labor.
To construct the closed-loop system, Harner Plumbing used 500 ft. of 1-in., 500 ft. of 1 1/4-in., 300 ft. of 1 1/2-in., almost 1,000 ft. of 6-in., and 300 ft. of 8-in.-dia.Aquatherm Blue Pipe. Fully recyclable, the piping was developed for hydronic heating, chilled water, geothermal, and industrial applications. The PP-R piping systems offer exceptional chemical purity and a flexible physical strength that differs from other piping systems. They are non-corroding, so they won’t break down, weaken, or scale like metallic piping systems. A uniquely stable material, Aquatherm PP-R won’t react with water, is highly resistant to most chemicals, and doesn’t require chemical maintenance.
The piping systems’ 10-yr. warranty and third-party-certified environmental product declaration (EPD) means all Aquatherm PP-R piping systems can directly contribute to LEED v4 credits. The piping systems use reliable heat fusion to form connections. Heat fusion bonds both sides of a joint into a single, homogeneous material without the use of chemicals, adhesives, or mechanical connections, which eliminates systematic weaknesses and potential fail points in the pipe. The seamless heat-fusion connections, combined with the piping’s resistance to corrosion and abrasion, help ease leakage concerns.
Although “the project originally was specified to be welded, we couldn’t do that in this kind of bank environment,” Harner said. The perfect solution for a sensitive project, heat fusion eliminates toxic materials, glues, and resins as well as fumes and gases and open flames from the piping installation process.
Because of their light weight and sturdy connections, in addition to all of heat fusion’s benefits, the PP-R piping systems lend themselves well to off- and on-site fabrication.
For this project, the company’s Design & Fabrication Services team fabricated some segmented fittings at Aquatherm’s Utah headquarters, but the contractor fabricated even more of the closed-loop piping system at the jobsite.
Workers fit 600 ft. of 6-in. pipe in 9-ft. lengths onto an elevator and carried the pipe down a narrow hallway on the 12th floor to position for installation. Doing so with steel would have been impossible. The installers extended a mechanical chase, running the 6-in. supply and return risers in a vertical shaft from the 12th floor to the 26th.
Schedule 40 steel often has to be rigged. On this project, the PP-R piping’s light weight was again a bonus inside the tight mechanical chase. The installers were able to stay on one floor and lower the piping in 60- to 80-ft. sections without having to move. The PP-R piping’s lighter weight and flat edges reduced the risk of injury.
“The owner was very impressed with the Aquatherm,” Kindbom said. “They could see the joints were good just by looking at them.” The installers followed all of the company’s testing procedures, and the piping project experienced zero leaks. Out of all of the various pipe branches and heat-fusion welds, not one drop of water was seen.
“This project changed the way I think about Aquatherm,” Kindbom said. “In the past, we’ve used Aquatherm when we’ve had a hydronic piping project underground, and we never tried using it on a large scale, inside the building as a hydronic system before.
We saw some of the intangibles: the less impact Aquatherm makes on a building structure because it’s lighter, which also makes it easier to lift or monkey into small existing spaces; no welding; no odors—all of these things make Aquatherm a great application that we hadn’t thought about in the past but certainly will in the future.” CA