PLUMBING | VARIABLE-SPEED CIRCULATION|


All photo credits: Kelly Gorham


is not unusual 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 principals involved. Sometimes a general contractor


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will poll his subs for “value- engineering” suggestions to help lower installation costs and stay within budget. Or perhaps the installing contractor 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


nce the bids are submitted and the contracts awarded on a commercial project, it


Airport carwash project saves maintenance costs and reduces power consumption


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 carwash facility with a three-building, washing and detailing complex for use by four rental car companies. The main unit, a 5,480 square-foot (sf) structure, would be devoted to vehicle washing, while the other two facilities — measuring 3,510 sf and 7,056 sf — would be used for vacuuming, windshield cleaning and other types of car-prep work. Among the salient features of the


radiant systems were built. “In the cold-weather months,”


McMullen said, “with all that water dripping off the washed cars, the slabs would ice over, making safe driving impossible inside or outside.


The mechanical area inside the car wash facility at the Gallatin Field Airport Car Wash., is shown here. Keeping the interior warm with radiant heat instead of forced air eliminates ice on the wet floors during winter months, while also keeping the heat at employees’ feet rather than the ceiling.


Pat McMullen (left) and Erik Chidester of PJ's Plumbing & Heating worked with the specifying engineer, Morrison-Maierle Inc., to reconfigure the project's pump and piping layout, reducing the number of circulators from 39 fixed-speed units to only 19, 11 of which are variable-speed.


his alternative approach, or at least not hindered. The engineer may not exactly


relish the experience of seeing his original designs and specifications


project, which was finished in early May 2010, were a radiant floor heating system inside the carwash facility and snowmelt systems on the exterior slabs, front and back, of all three buildings. Zurn PEX (crosslinked


polyethylene) tubing was 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 —Lochinvar Knight Heating Boilers with inputs from 210,000 Btu to 399,000 Btu — divided among the three buildings. Not surprisingly, given the rugged


Close-up of one of the Magna circulators: Six of these control circulation of warm water from the boilers to PEX loops in the snowmelt slabs outside the three buildings at the Gallatin Field Airport Car Wash.


Montana winters, the build team regarded all four of these heating systems, one radiant and three snowmelt, as absolutely essential for a year-round carwash operation of this magnitude. According to Pat McMullen, owner and president of PJ’s Plumbing & Heating (Belgrade, Mont.), the Gallatin facility handles up to 200 vehicles daily. PJ’s not only did the installation but also, as we will see shortly, spearheaded significant changes in the way the


With all the traffic in and out of the carwash 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 at the ceiling, creating a reasonably comfortable working environment, 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 separators and bathrooms, as well as the slab heating inside and outside. 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; specifically, the circulating pumps. Created by the Bozeman office of


Morrison-Maierle Inc., the original plans called for an injection-piping


phc january 2011 www.phcnews.com


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