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Airport Car Wash Project


Uses Variable-speed ECM Circulators to Save Maintenance Costs and Reduce Power Consumption


Mechanical contractor works with engineer


and general contractor to shift spec from 39 fixed-speed pumps to 19 ECM variable-speed models at Gallatin Field Airport Car Wash, cut- ting power consumption without undercutting longevity and performance


O


nce the bids are submitted and the contracts awarded on a commercial project, it is not unusu- al for many of the specifications and perhaps even


the mechanical-system designs themselves to undergo varying degrees of revision by one or more of the princi- pals involved. Sometimes a general contractor will poll his subs for “value-engineering” suggestions to help lower installation costs to stay within budget. Or perhaps the installing con- tractor has what he believes to be “a better way of doing things” and will convince the owner, the general, even the specifying engineer that building performance and longevity will be enhanced by his alternative approach — or at least not hindered. The engineer may not exactly relish the experience of


seeing his original designs and specifications tweaked, let alone given a radical makeover. Then again, if the client- owner is happy and his project well served by the changes, he may not be inclined to argue. All of the above scenarios came into play on a recent,


successfully concluded project at the Gallatin Field Airport in Bozeman, Montana. The property owner and manager, the Gallatin Airport Authority (GAA), sought to replace an existing, five-building car-wash facility with a three-building, washing and detailing complex for use by four rental-car companies. The main unit, a 5,480-square- foot (sq. ft.) structure, would be devoted to vehicle wash- ing, while the other two facilities — measuring 3,510 sq. ft. and 7,056 sq. ft. — would be used for vacuuming, windshield cleaning and other types of car-prep work. Among the salient features of the project, which was


finished in early May 2010: • a radiant floor heating system inside the car wash


facility; and • snowmelt systems on the exterior slabs, front and


back, of all three buildings. • Zurn PEX (crosslinked polyethylene) tubing was


Page 54/Plumbing Engineer


used in all the radiant and snowmelt systems, while the manifolds and other components were furnished by Watts Radiant — all through local wholesaler-distributor MDM Supply Company and its Bozeman branch. The heat sources were eight high-efficiency, condensing boilers divided among the three buildings: Lochinvar Knight Heating Boilers with inputs from 210,000 BTU to 399,000 BTU. Not surprisingly, given the rugged Montana winters, the


build team regarded all four of these heating systems — one radiant and three snowmelt — as absolutely essential for a year-round car-wash operation of this magnitude. The Gallatin facility handles up to 200 vehicles daily, according to Pat McMullen, owner and president of PJ’s Plumbing & Heating (Belgrade, Mont.). PJ’s not only did the installa- tion, but also — as we will see shortly — spearheaded sig- nificant changes in the way the radiant systems were built. “In the cold-weather months,” McMullen continues,


“with all that water dripping off the washed cars, the slabs would ice over, making safe driving impossible inside or outside. And with all the traffic in and out of the car-wash facility, the doors open and close constantly, too.” Both of these factors made radiant the optimum choice


for this application. Keeping the floors exterior pads warm would eliminate the hazardous ice for driving. Radiant would also keep the heat at employees’ feet rather than the ceiling, creating a reasonably comfortable working envi- ronment even on bitter-cold days with the facility doors wide open much of the time to accommodate vehicle movement. Change in circulator strategy: PJ’s bid on — and won


— the entire plumbing and mechanical portion of the Gallatin Car Wash job: trench drains, sand and oil separa- tors, and bathrooms, as well as the slab heating inside and outside. But when general contractor Martel Construction approached its mechanical sub for ways to cut costs to bring the project more in line with budget projections, McMullen zeroed in on the radiant part of the job; specif- ically, the circulating pumps. Created by the Bozeman office of Morrison-Maierle Continued on page 56


January 2011


All photo credits: Kelly Gorham


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