Circulator technology Continued from page 54


Inc., the original plans called for an injection-piping strat- egy in each building. Multiple boilers and a series of smaller circulators in a secondary loop would transfer warm fluid from a primary loop to the individual system loops: 1) low-temperature water for the radiant heating and snowmelt systems; 2) high-temperature water for the


“We recommended a relatively new type of circulator


that automatically adjusts its speed according to current demand, instead of maxing out every time it came on. We figured this variable-speed technology could cut power consumption by up to 70%.” Alpha and Magna: The circulators that PJ’s ultimately recommended were the 115-volt Alpha and the 230-volt Magna, made by Grundfos Pumps USA and supplied by MDM. Both feature a permanent magnet motor design to cut power consumption dramatically. And both are equipped with proprietary logic circuitry — trade-named AUTOADAPT™ — that automatically varies circulator speed to match system demand. The Magna is the larger of the two circulators, with a


flow range of up to 170 gallons per minute (GPM) and a head range up to 42 feet. Six of these units were ultimate- ly installed to control the movement of warm water from the boilers to PEX loops in the snowmelt slabs outside the three buildings. Five of the smaller ALPHA circulators (22 GPM, 19


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.


hot-water unit heaters warming the two “vacuum build- ings,” and for an indirect water heater supplying the car- washing equipment. (The indirect unit was subsequently eliminated as unnecessary.) The number of circulators in all of these loops totaled 39, all fixed-speed models. Even while bidding the project, McMullen pondered an alternative approach to the pumping. Upon winning the contract, he met with MDM sales representative Todd Sisson to revisit the pump strategy. The team thought they could shrink the circulator total to 19 by changing the pip- ing layouts from primary-secondary to a direct supply- and-return. The new pumps would be somewhat larger and with more horsepower, but reducing the number of pumps from 39 to 19 and eliminating of all those electri- cal connections would cut costs substantially. (The final savings turned out to $12,368.) Reducing the number of circulators by 20 would inevitably have lessened ongoing maintenance hours and costs, of course. But PJ’s believed their new approach could also shrink the airport authority’s monthly electric bills by a substantial percentage. “Just looking at the total wattage of the 20 circulators we were eliminating, we thought we could cut power consumption by half at least,” says McMullen. “At least” is the key phrase here: PJ’s wanted not only


to halve the number of pumps, but also to introduce a new, power-saving technology into the mix: ECM (electrically commutated motor) variable-speed circulators. As already noted, all the pumps in the original design for the car wash were constant-power — that is, “fully on no matter how much power is actually required,” explains Erik Chidester, a PJ’s field supervisor who oversaw the installation.


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feet of max head) were subsequently used for the radiant slab heating system inside car wash facility: one for each of five zones, each with a different load. Rounding out the pump package at Gallatin are four


Grundfos UP26-99 circulators (115-volt) and four Grundfos UPS26-150 circulators — all used at fixed speeds to manage boiler-loop circulation. “Thanks to AUTOADAPT, we were able to use the


same Alpha circulator in all five zones in the car wash building, despite their differing loads,” says Chidester. “Variable speed pumps like the ones used on the


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.


Gallatin project eliminate the margin of error for friction calculations traditionally used to size pumps,” adds David Weiel, P.E. (pronounced “wheel”), the mechanical design- er on the project. “Reputable engineers use the best tools and techniques


available to them to calculate friction losses. But not every situation is ideal, and piping layouts often change in the course of construction. As a result, projected head losses


January 2011


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