Greg Cunniff of Taco with Renaissance Providence Hotel Director of Engineering Steve Beretta.
In the hotel business the most common guest complaint is over room comfort, specifically air conditioning (TV problems are the next most common complaint). Described as being a "killer" in customer satisfaction indexes, this is exactly what happened when the Renaissance Providence Hotel, a Marriott property, opened its doors in the summer of 2007. Owned and operated by Sage Hospitality of Denver, the hotel's HVAC system, designed by Thomas A. Gilbertson Associates of Moraga, CA, called for a Taco LoadMatch®-IEC fan coil single pipe system in the hotel. With two Taco circulators per fan coil, there are some 600 installed LoadMatch circulators for the hotel's 300 rooms.
Affected rooms, normally cooled to 72ºF dry bulb and 58º F in summer, were stuck at 75ºF dry bulb and a humid 64º wet bulb, and guests, making their first stays in the renovated property, were not happy. In order to restore comfort for the guests, the hotel's Engineering Department faced the daunting task of cleaning and/or replacing a high number of system components.
Before and after view of system water.
The underlying problem was air in the piping system and, more specifically, the development of corrosive iron oxide created by the oxygen present. Draining system water in weekly cleanings, a high degree of sediment was found to be present. The big question then was how to get rid of the air and the associated gunk by purging the system, and how to do that without shutting down the hotel in the process. According to Steve Beretta, the hotel's director of engineering, it was an "ugly situation."
Having been called in on the problem, Taco LoadMatch experts, led by Greg Cunniff, P.E., Taco's Applications Engineering Manager, had a solution in mind. Greg felt that the common standard type air separators installed in both the cooling and heating mechanical rooms were inadequate for a problem of this magnitude. Initial tests on system water indicated that the gunk could be micro-biological induced corrosion (MIC) that was causing a galvanic corrosion process in the hotel's piping system. It was necessary to purge the system of the oxygen that the microbes were living off and creating the iron oxide corrosion problem.
View of hotel that was for decades an uncompleted building.
Draining the entire system and then flushing it with an acid solution would require shutting down the hotel for the duration of the work, a costly proposition and a potentially damaging one to the properties' reputation. Cunniff suggested a different approach: Taco would replace the hotel's two air separators in separate off-season actions, starting with the chilled side; that way there would be limited complications and the least amount of affect on guests. What was needed was a more powerful separator, one with air and dirt elimination capabilities Taco's 4900 Series, specifically the 4900-AD (Air & Dirt) model separator.
Introduced in 2005, the 4900 Series was designed for the complete elimination of air from closed loop systems. The key to the 4900 Series' effectiveness is its use of patented stainless steel PALL rings. Pall ring technology is widely used in the processing industry to mix or separate gases from liquids. Using PALL rings in hydronic air separation allows removal of microbubbles, sand, dirt and rust. Air bubbles are separated by the PALL rings through a process known as coalescence; dirt particles are caught and sifted to the bottom of the tank, where they can be removed through a blowdown valve.
Steve Beretta testing system water drained from Taco 4900 Series Air-Dirt Separator.
So convinced of their efficacy when it came to the Renaissance Providence Hotel problem, Taco donated two 4900-AD separators and helped install them in separate middle-of-the-night operations (again to minimize disruptions to hotel operations) in the spring of 2008 (for the chilled side) and then again in the fall for the heating side. Once operational, the system water, now being starved of oxygen, began to show improvement right away, according to Steve Beretta. In four months' time the problem was gone and system water had turned clear and sediment free.
Having been in hundreds of mechanical room over a 40-year career in the hydronics industry, Taco's Greg Cunniff has only encountered about a dozen MIC-type situations. "It's a bit more common in fire protection systems than hydronic systems," he says. How the biologic agent got into the piping loops in the first place is a question that goes back to the construction phase and also the water treatment tests that should have been done at the time of system commissioning. In any event, Taco's 4900 Series Air & Dirt Separator demonstrated that it's up to the toughest air and dirt problems.
Information submitted by Taco, Inc. www.taco-hvac.com
Sidebar on Renaissance Providence Hotel
The Renaissance Providence Hotel has a long and colorful history. But not as a hotel, however. Constructed as a Masonic Temple in the late 1920s and prominently situated on Smith Hill just across from Rhode Island's Stanford White designed state house, the uncompleted building became the victim of a building funds' theft followed by the Wall Street Crash. For the next 75 years the shell of the building stood as a symbol of the Roaring Twenties and the Great Depression that followed. In the last two decades there were various plans to finish the building as a hotel, all of which collapsed. Finally, in the middle of this decade, assisted by state backed historic-tax credits, the building façade, which was filled with graffiti and facing the wrecker's ball because of its structural dilapidation, was finally completed, ending a sorry tale and a very visible eyesore. With 300 rooms and stunning views of the state house and the city center, the Renaissance Providence Hotel, owned and operated by Sage Hospitality, is very much alive today, a bright new addition to the "Renaissance City." Opened in 2007 the hotel was named the 2008 Franchise Hotel of the Year by the Marriott Corporation.