MECHANICAL CONTRACTING e Continued from p 64
said Chalstrom. Every inch of buried steam, glycol, or sewer line on base is wrapped in Owens Corning SSL II fiberglass pipe insulation. Even inside the building, the insulation doesn’t stop. In the mechanical room and through the walls of the home, all pipes are wrapped. The mechanical rooms for all the
multi-family units are identical, located at the end of the building nearest the substation for that area. From the substation, glycol enters the building in an insulated three inch main. “We used Taco’s new cast iron or
Slayden Superintendent Al Morlan (left) with Jason Chalstrom, civil and mechanical building jobsite supervisor. In the background is one of three large mechanical buildings where steam heat is exchanged with water, then pumped to the multiplexes.
68
off limits. Nonetheless, we learned that it’s a large, super clean, emission scrubbed, bituminous coal-fired, cogeneration plant. Waste steam from the power turbines is piped through deep, super-insulated underground pipes to all of the housing developments and also to new, radiantly heated aircraft hangars. The main steam plant and the
backup plant both receive coal from a rail line running through the base. Here, 420-degree steam is channeled toward three large mechanical buildings located throughout the base. These buildings identically match
the surrounding housing units, right down to the color of siding and placement of windows. Instead of carpet, couches and hi-def TVs, the front door opens to expose two stories of heavily-insulated heat exchangers and piping. The steam arrives at the
mechanical buildings at 80 psi and is there reduced to 15 psi, before running through Taco U Tube heat exchangers. All the mechanical buildings house three 24-inch diameter, cylindrical steam-to-water exchangers, totaling nine for the whole base. There’s one for each eight-inch loop. “The exchangers each handle 8,000 pounds of steam per hour,” said Jason Chalstrom, civil and mechanical building jobsite supervisor. “That’s nearly 650 tons of hydronic capacity per hour.” Crunching numbers, that’s well over seven and a half million Btu an hour, for each of the nine massive heat exchangers. All with waste steam. Keeping up with each heat
exchanger is a 32,000 lb./hour, steam driven condensation pump. To keep the system components clean and running smoothly, Taco 4900 series air and dirt separators serve each loop.
stainless steel 2400 pumps to draw glycol from the three inch pipe, supplying the multiplex mechanical rooms,” said Morlan. “As far as light commercial pumps go, they’re compact, yet with a range of up to 150 gpm and up to 52 feet of head. We can get a lot done with them, while easily fitting four in each small mechanical room.” A pair of Taco 008 circulators
draws water from the primary loop; one supplies the upstairs baseboard while the other feeds an indirect-
At one of Slayden's jobsite prefab assembly stations, Al Morlan (center) poses proudly with his two sons, Allen Jr. (left) and Joshua (right).
Chalstrom explained that a glycol
solution leaves the heat exchanger at 180 degrees and gets distributed to numerous substations. The substations, which look like large garden sheds, then circulate glycol to four multiplexes, each of which consists of four 1,800 sq. ft. single family apartments. Victaulic fittings and couplings were used on all the piping throughout the project, regardless of size. “The entire system puts 26 miles of ductile iron Utilidor piping to use,”
fired water heater. Because low temp water is needed for the radiant slab, Taco mixing valves are used to reduce the water’s temperature before it’s pumped throughout the slab.
Above and beyond the call of duty “At some point after the first 62
housing units were installed, military managers wisely decided to put hot
e Continued on p 70
phc may 2011
www.phcnews.com
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