Apr 01, 2015

Open to Options

Commercial applications opt for TAC technology to treat hardness

template-assisted crystallization water hardness
template-assisted crystallization water hardness

Occasionally, it is those new inventions that surprise skeptical, change-resistant Americans. 

My first experience with a drone happened while watching a real estate agent pick up the pieces of his flying machine after it crash-landed. I had already seen news of the military using multimillion-dollar military drones in the Middle East; little did I know drones also could have everyday uses here in the U.S. 

A once-obscure bottled drink was invented as an alternative to morphine addiction and to treat headaches. Its inventor, a Confederate veteran of the Civil War who suffered from morphine addiction, first invented a sweet, alcoholic drink infused with coca leaves for an extra kick. Twenty years later, the drink recipe was honed, sweetened and carbonated. Today we know that drink as Coca-Cola. 

The water treatment business is no different—it can take some time for new technologies to become widely accepted and implemented. One newer technology that is quickly showing its value in the industry is template-assisted crystallization (TAC). These systems come in a range of sizes (0.5 to 450 gal per minute [gpm]) and have broad applicability for the residential and commercial markets. They have become an alternative to salt-based water softening for control of hardness and scale.  

TAC systems have several positive features:

  • No backwashing required, with zero discharge;
  • No electricity required;
  • No chemicals or salt required; and
  • Long-lasting media (three-year lifespan) that needs no regeneration.

Physical Water Treatment 

TAC falls into a category of water treatment often referred to as physical water treatment (PWT). The driving force for PWT in the marketplace is to offer a more environmentally friendly technology. 

TAC media starts out as polymeric beads (resin) in the 20- to 40-mesh size range. Catalytically active sites or templates are “imprinted” or coated on the bead surface through a batch-coating process. The exact recipe, procedure and precision with which this is done are critical to manufacturing processes, ensuring optimized media performance.

TAC is technology that influences the water solution at localized sites on the media surface such that hardness ions and their counter-ions (bicarbonate) combine to form inert nanometer-size “seed crystals.” Called nucleation, this is when dissolved molecules or ions dispersed throughout a solution start to gather to create clusters in the sub-micron size range. 

The volume of seed crystals provides an enormous area for growth of the remaining hardness ions in the solution. When the remaining dissolved ions reach their solubility shift, they attach to the seed crystals and continue harmlessly downstream, eventually to be consumed or simply slip down the drain. 

A Universal Dilemma

Building owners, property managers, chief engineers and facility maintenance personnel all face the same challenges in battling the ill effects of hard water. Protecting a commercial plumbing system from damaging lime deposits, called scale buildup, can bring considerable expense, both up front and ongoing.

TAC can be used in point-of-entry (POE) applications to protect whole buildings on the hot and cold sides. Selecting the appropriate size TAC system can be easily accomplished—peak flow rate is all that is required to size a commercial system. 

TAC media is always used in an upflow design, which prevents it from being subject to low-flow channeling or high-flow pressure drops. The pressure drop as measured at peak flow rate is less than 4 psi. Like other resins, the media is subject to water chemistry limitations, such as chlorine, iron, manganese, copper, tannins and pH.

Point-of-use systems also are offered to protect specific pieces of equipment that may be more prone to scale from water hardness, such as a boiler with a domestic water heat exchanger or instantaneous water heaters.

Case Study: Fort Sill

Over the past few years, facility managers at Fort Sill in Oklahoma have tackled a vexing problem within its several, uniquely star-shaped “starship barracks.” The facilities acquired the nickname because they are completely self-contained, with living quarters, classrooms, mess halls and latrines all under one star-shaped roof. Many of the starship barracks, designed to house up to 500 troops, are being renovated, chiefly to reduce energy consumption.

Hard water has plagued maintenance crews at Fort Sill for years. Unfortunately, southern Oklahoma has some of the nation’s most challenging water quality. 

With 500 troops mobilizing together, high-quantity water use is inevitable. And at Fort Sill, dealing with persistent scale was a costly problem to solve, compounded by the inevitable spikes in water use. At the start of each day, soldiers have a set routine. An early wake-up call leads to a quick shuffle to the showers, where a combined 632-gpm surge of water moves through the pipe.       

A daunting challenge for the mechanical contractor was how to provide scale protection for domestic water systems at a rate of 632 gpm with a water quality defined as very hard—27 grains per gal (gpg) of hardness.     

“One [POE] plan was to use a commercial, salt-based water softener,” said O.G. Mills, vice president of Tulsa, Okla.-based OK Sales. “But the four tanks needed wouldn’t fit through the mechanical room door, and once inside, would’ve taken up far too much space. Also, the sheer amount of salt used to regenerate the water softeners would have required additional storage.”

Ultimately, the Army Corps of Engineers chose Watts’ OneFlow TAC anti-scale central treatment systems for the buildings at Fort Sill.  

“Another huge advantage the TAC system has over a traditional water softener is the ability to operate effectively at trickle flow rates,” said Jim Suomi, national sales manager, RV and OEM, for Watts Water Technologies. “TAC media is not subject to low-flow channeling or high-flow pressure drops.”  

The first phase of the Fort Sill project called for 12 OneFlow tanks, each capable of handling 75 gpm. Linked in parallel, the tanks treat up to 900 gpm. This system also affords the base the flexibility to isolate tanks if the barracks are not at full capacity, and to perform media change-outs one tank at a time.

“For the Army Corps of Engineers to review and ultimately select TAC technology over a traditional softener, it meant that we had to meet a very strict performance standard to protect their plumbing systems,” Suomi said. “We have thousands of installations, some in areas where water is even harder than at Fort Sill, so I was certain the technology was best suited for their use there. They’re very happy with the zero water discharge and no expense for salt.”  

Case Study: Miami University 

Another application of TAC technology for POE water treatment involves the installation of OneFlow tanks at many of the buildings on the campus of Miami University in Oxford, Ohio.  

Students walking along the flagstone paths of the large, mature campus, with its stately stone and brick structures and old-growth oak trees, would never think of the challenge that has plagued maintenance teams there for years. Yet, when water comes from the ground at 24 gpg, a solution is needed. 

POE water softeners serving each of the buildings on campus required large amounts of salt and maintenance through the years. In fact, until recently, the school’s many “salt bunkers” were visited frequently by large trucks delivering salt by the ton.   

So far, more than a dozen campus buildings have been converted to OneFlow systems, with more conversions in progress. The systems serve all domestic water needs.  

“The systems are installed immediately downstream of the backflow and pressure-reducing valve,” said Brett Mullins, outside sales for Disney McLane & Associates, a manufacturer’s representative firm based in Cincinnati. “The work is in full swing now, and from what I’ve heard from the school’s maintenance crews, they’re very pleased with the new technology.” 

Case Study: Pueblo City School District

Another example of the suitability of TAC technology for POE applications is seen at the Pueblo City Schools kitchens in Pueblo, Colo. Scale buildup in the combi ovens in all the kitchens was so bad that at times lunch was served late. After replacing the ovens several times and trying a variety of treatment systems, the school’s maintenance department was seeing little to no improvement in the scale buildup.

Jill Kidd, director of food services for Pueblo City Schools, contacted Paul Gradishar, president of Grady’s Restaurant & Bar Supply in Pueblo to ask for help. Within a week, Gradishar supplied one dozen OneFlow tanks to the high school’s maintenance department, which installed the systems to treat water for the combi ovens. 

“Since we’ve installed the OneFlow systems, scale buildup hasn’t been an issue,” Kidd said. Hot meals are now prepared and delivered on time, and maintenance staff that had been tasked with fixing scale issues now are free to handle other projects throughout the facility.

According to Kidd, the school’s maintenance department had no trouble installing the units. One thing was certain: They were happy not to deal with scale problems on a daily basis. 

So the next time you head to the vending machine for a cold cola, or look up to see a drone hovering above, consider the emergence of new technology in your own field.

About the author

John Vastyan, owner of Common Ground, is a journalist whose work focuses on the plumbing and mechanical, HVAC, geothermal and radiant heat industries. Vastyan can be reached at [email protected] or 717.664.0535.

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