Pueblo School District solves its water woes thanks to Watts OneFlow

Oct. 31, 2013
The environmentally friendly technology behind the OneFlow system was developed in Germany about 20 years ago. It was used throughout Europe for several years before coming to the U.S., and continues to be the dominant form of commercial and residential water treatment there. 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 bead surfaces through a batch-coating process.  

PUEBLO, COLO. — If you were to overlay an annual rainfall map of the U.S with that of a water hardness map, they’d be eerily similar.  The drier the area, the harder the water.  The only exceptions would be the Florida Peninsula and the states that border the Great Lakes – hardness levels there are notoriously bad.

But the worst states, Utah, Colorado and Wyoming, are in a class of their own when it comes to hard water scale issues.  Mechanical contractors in these states are all accustomed to dealing with the issue, as are sales representatives, wholesalers, commercial maintenance crews and just about anyone whose job brings them in contact with groundwater on a regular basis. 

At one of the OneFlow point-of-use systems, Custodian Jarrod Romero turns the water off at the end of the day. Before brass fitting were used, a water leak prompted the school to make overnight shutoff a standard procedure.

Water is considered moderately hard at four grains per gallon (GPG), and very hard at 10 and up.  Anything above 18 GPG is considered extremely hard.  While normal residential plumbing and domestic hot water systems can function properly – at least for a while – with very mild levels of water hardness, it gets out of hand quickly when the GPG rises.  More so if there’s specialized equipment involved.

Commercial “combi” ovens or steamers, those professional cooking appliances that combine the functionality of a convection oven and a steam cooker – when running in humidified hot air or atmospheric steam mode – are especially susceptible to scale buildup.  The familiar crusty white scale forms quickly when water is heated, and even faster when it evaporates, leaving the minerals (calcium carbonate) to adhere to the closest surface. 

Scale can quickly coat all heat exchange surfaces of these appliances, prolonging the amount of time it takes to heat food, and using more energy to do so.  It can also shorten equipment lifespan.

Nobody likes a late lunch

In Pueblo, Colorado, the school district wrestled with the scale problem for several years before finding a solution to the scale issue plaguing the 27 combi ovens in their kitchens.  Like many districts, Pueblo City Schools prepares food in their four high school production kitchens, then distributes the food to the 23 smaller schools, where it’s re-thermalized. 

“There was major scale buildup in the combi ovens in all the district’s kitchens,” said Jill Kidd, director of food services at Pueblo City Schools.  “The manufacturer of the first combi ovens we purchased insisted that we didn’t need filters or water treatment.  Those units lasted six months.”

Cook Loretta Lewis is able to safely prepare food for all the district’s schools without the concern of whether or not the combi ovens will operate properly.

After replacing the ovens, the school’s maintenance department was seeing only marginal success at staving off the scale problems.  Three different filtration and treatment systems were used, but each was either ineffective or used plastic fittings that broke shortly after installation.  After problems persisted, Kidd contacted Paul Gradishar, president of Grady’s Restaurant and Bar Supply in Pueblo.

“We work extensively with the school district, supplying the bulk of their kitchen equipment,” said Gradishar.  “The scale problem was so bad, and with the fittings constantly breaking, our list of options was exhausted.  I contacted Bob Reihmann, at The Redstone Group, to see if he had a trick up his sleeve.” 

The Redstone Group is a leading manufacturer’s sales agent for the commercial foodservice industry.  Operating out of Englewood, Co, the company has five locations throughout the West. 

“The call came just shortly after we acquired a new line of equipment, Dormont’s OneFlow template-assisted crystallization technology,” said Reihmann.  “We’d seen its effectiveness on a number of occasions, and this seemed like the perfect application for it.” 

Dormont is a Watts Water Technologies company that serves the foodservice industry.  While OneFlow systems are part of Dormont’s complete line of filtration systems and replacement filters for the foodservice industry – called HydroSafe - OneFlow technology is also offered to the plumbing industry by Watts.

OneFlow technology employs template-assisted crystallization (TAC) media within specially designed, reinforced cartridges or tanks. The media are specially manufactured beads the size of some powdered laundry detergents.

The systems are sized by flow rate, with applications as small as 1 GPM for point-of-use scale prevention, to multiple-tank applications for larger volume needs.  For example, in another OneFlow application, Fort Sill Army base, in Oklahoma, has a system capable of conditioning water at a rate of 900 GPM using 12 OneFlow TAC tanks.

Within a week of contacting Reihmann, Gradishar supplied one dozen point-of-use OneFlow tanks to the high school’s maintenance department, which installed the systems quickly to treat water for the combi ovens.

The science of it

“The environmentally friendly technology behind the OneFlow system was developed in Germany about 20 years ago,” explained Craig Schein, managing director of commercial food service at Dormont.  “It was used throughout Europe for several years before being brought to the US, and continues to be the dominant form of commercial and residential water treatment there.” 
Paul Gradishar, president of Grady’s Restaurant and Bar Supply, and Jill Kidd director of food services at Pueblo City Schools stand near a combi oven, one of many that was plagued by hard water scale issues.
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 bead surfaces through a batch-coating process.

The template initiates an interaction between hardness ions (calcium and magnesium) and their counter-ions (bicarbonates), so they combine to form inert nanometer-sized “seed crystals.”  This process, called nucleation, occurs when dissolved molecules or ions dispersed throughout a solution gather to create clusters in the sub-micron size range.

The crystals provide an enormous area for preferential growth of remaining hardness ions still in solution. “Low-energy heterogeneous transfer” then begins. The remaining dissolved ions reach their solubility shift, attach to the seed crystals and continue harmlessly downstream and out of the building.

TAC technology excludes the use of chemical additives and eliminates discharge and waste water that are byproducts of the brine cycle in a water softener.  It's a green solution that involves no use of electricity and results in zero pollution.  Plus, compared to water softening systems, installation and maintenance costs are minimal.

In a residential application, a OneFlow system looks like a water softener mineral tank but without a control valve and brine tank. A simple inlet/outlet connection is all that’s required; no pumps, meters, or valves are needed.

Another advantage of TAC systems over a traditional water softener is their ability to operate effectively at trickle flow rates.  TAC media are always used in upflow designs, so they are not subject to low-flow channeling or high-flow pressure drops.

In traditional water conditioning systems, hard water "bypass" occurs through channeling if the flow is considerably less than the design rate. That's because water finds the path of least resistance through the media, and comes in contact with minimal amounts of resin. TAC technology successfully prevents this.

Get it while it’s hot

Another problem solved in the Pueblo City School District through use of the OneFlow systems was that of plastic fittings breaking.  “Nobody is quite sure why the fittings on all the treatment systems kept breaking,” said Gradishar.  “The ovens don’t vibrate, and the fittings don’t get super hot.  It even happened on the OneFlow systems, but Dormont did something none of the other manufacturers offered to do.  They sent brass fittings that completely solved the problem.”

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

“Since we’ve installed the OneFlow systems, scale buildup hasn’t been an issue,” said Kidd. Today in Pueblo, there are no more bagged lunches or late deliveries from the high school.  Hot meals are now prepared and delivered on time, and maintenance staff that had been tasked with fixing scale issues are now free to handle other projects throughout the facility.

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