Circulator technology Continued from page 57


only had to save the project money, but also to make sure it performed to the level that the engineer, the general con- tractor and the owner all expected.” Mark Maierle of Morrison-Maierle characterizes the


mechanical aspects of the Gallatin job as unusual, if only because “it’s not that often that our firm will redesign a pro- ject at the installer’s request.” On the other hand, Maierle is savvy enough to acknowledge the downside of compelling experienced professional installers like McMullen and his team in a direction they don’t really want to go. “There are many different ways to skin a cat, so we


Close-up of one of the Magna circulators: Six of these con- trol 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.


were responsive to Pat’s comments and suggestions,” Maierle continues. “We believed — and still believe — our original primary-secondary loop system would have served the airport authority well for many years. But the airport now has a system that will work equally well, and, in the end, that’s the most important consideration.” Morrison-Maierle’s Weiel has serious reservations about


the projected energy savings from the 11 variable-speed cir- culators, at least when comparing them to the pumps they replaced from the original piping design. He comments: “We chose the injection piping scheme for several rea-


sons, including greater boiler redundancy — so the system could function close to its intended capacity with one boil- er completely out of service — and to handle multiple water temperatures on the same system. Each loop had two circulators, which is why the reconfigured system was able to reduce the number of pumps by half. But in our injection-piping scheme, only one circulator would’ve run the majority of the time, because the injection pump oper- ates only when the system demands additional heating.” Weiel does not doubt the ability of AUTOADAPT to


cut power costs from the injection-piping scenario: “But by 50% or more? That does not seem feasible to me, given the thorough consideration we gave to energy conserva- tion with the original design. “In addition, the original pumps were not greatly over-


sized,” Weiel continues. “In fact, they were closely tai- lored to the head losses calculated for the loops they served. That is why a wide number of different model number circulators were originally specified.” Nonetheless, Maierle and Weiel could readily see —


Pat and Erik have become huge fans of variable-speed cir- culator technology. Says McMullen: "I have never come across a circulator that works so easily and efficiently with so little power” as the Alpha and Magna models made by Grundfos.


so little power.” What’s best for the client? Which brings our story back


to the specifying engineering firm that developed the orig- inal plans and specifications. As McMullen graciously notes, “Morrison-Maierle was very progressive and very open to our alternative ideas. We understood that we not


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and appreciate — the strong convictions that McMullen and this crew had for their alternative, variable-speed pumping solution. Weiel notes that Morrison-Maierle came to regard this alternative and the design changes it necessitated as net positives for the project. “When the contractor is more familiar with the design


— as was the case here with PJ’s and the variable-speed circulators they recommended — he is usually more com- fortable doing the installation as well as any servicing that may follow the commissioning,” he comments. “A con- tractor taking ownership for what he is installing becomes a win-win situation for everyone — most especially the owner. As long as the alternative approach does not com- promise the quality, performance or longevity of the pro- ject, we are willing to work with the contractor on pursu- ing that alternative. “In the end, we’re all here to help our clients achieve the best possible finished product.” n


January 2011


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