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Dolwick Drive: Taco LoadMatch® System suits new office building just fine
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PDF of the case study.
A former single-story warehouse across the Ohio River just south of Cincinnati has been reborn as a new two-story Class A office building. The Dolwick Business Center, 1360 Dolwick Drive, is a 230,000 sq. ft. office building located in Erlanger, Kentucky. The renovated building is within three minutes’ drive on I-275 to the Cincinnati/Northern Kentucky International Airport, making it an ideal location for new office space. After a total gutting of the structure’s interior, and the addition of a second floor, renovation work was completed in two stages – April 1st for the initial tenant move-in and June 1st for the remainder of the building. For indoor comfort, the new building utilizes an innovative Taco LoadMatch® system providing hydronic heat and cooling.
Commercial HVAC (www.commhvac.com) of Cincinnati, Ohio was the design-build contractor for the project. One of the major considerations in the selection of the building’s HVAC system was the fact that the new structure would have a central interior courtyard with a roof atrium above it to allow for natural light during the day. With the addition of the second floor, deck to deck heights were very low, as the existing roof structure was not raised to accommodate the added floor. The low roof, modified by addition of the atrium, raised concerns that the existing warehouse metal roof was not capable of accommodating roof mounted HVAC equipment. The low ceiling height made installation of an all-air system with large trunk ducts problematic. An HVAC system using smaller hydronic piping was deemed a better solution, although it might come with a higher first cost for the developer, Corporex (www.corporex.com), a multi-disciplined investment builder headquartered in Covington, Kentucky.
Several HVAC systems were explored including DX/VAV, chilled water and water-source heat pumps. Based on the developer’s desire to maintain flexibility in the layout to accommodate future tenant changes and provide the best zoning possible, the water-source heat pump system approach was chosen.
Corporex signed its first tenant – the retailer GAP – just as the design team began work on the construction documents. GAP wanted 50,000 sq. ft. of the building but wanted occupancy within 12 weeks’ time. This meant that the design and construction schedule had to be severely compressed, and the entire hydronic system – piping, boilers, cooling towers and controls along with the make-up air systems - needed to be fully functional to accommodate the first tenants. Because design of a water-source heat pump system doesn’t allow much in the way of shortcuts, as compared to other systems, a creative solution was needed.
Commercial HVAC was introduced to the LoadMatch single pipe system just prior to the start of the Dolwick Business Center project. Able to design the HVAC system very quickly using the Hydronic System Software (HSS) program that supports LoadMatch, Commercial HVAC discovered that LoadMatch fit the building’s needs better than any other systems. Three reasons led to the use of the LoadMatch system: first, less pipe was needed than conventional two-pipe systems, which meant less first-cost; second, the roof structure of the building couldn’t handle the weight of the extra piping mains required in a two pipe system without major modifications, and third, the LoadMatch system energy use projection offered significant energy savings over the life of the building. With LoadMatch, Commercial HVAC was able to eliminate almost half of the piping and reduced the imposed weight to the structure by approximately 50%, which made the project’s structural engineer “very comfortable,” according to Bob Stiens, Commercial HVAC’s president.
Taco’s LoadMatch system is a self-balancing single pipe system. It replaces all control valves and most balancing valves with small, low KW circulators. The circulators help deliver water to where it needs to go as opposed to forcing the water to go where it doesn’t want to. All loads in a LoadMatch system operate separately from one another, and the secondary flow that circulates through each terminal is independent of the system’s primary distribution pumps.
Because LoadMatch requires less materials to install than a traditional two pipe system, installation was accomplished much faster, meeting the now compressed construction schedule. In addition, because the system is self-balancing, start-up time was reduced and callbacks to “tweak” balance valves were eliminated. The system also proved to be more efficient: with the elimination of balance and control valves, coupled with the fact that LoadMatch is a direct return system, a lower pump head and lower installed horsepower were achieved. With circulators operating to match the load and flow in the secondary circuits being variable volume, electrical consumption for pumping was less than a conventional two pipe system.
Dolwick’s LoadMatch system consists of 150 Taco LoadMatch-configured circulators linked to heat pumps. The building’s mechanical room contains two Parker boilers plus Taco KS vertical in-line pumps and a heat exchanger. The indirect-fired WH Series Parker boilers virtually eliminate any problems with rust and corrosion, as well as scaling, because the colder heat pump loop water doesn’t come into contact with the high temperature furnace or with flue gas. The primary side of the boiler remains at a steady temperature, which results in high combustion efficiency and lower fuel consumption, and also provides excellent system temperature control, preventing nuisance cold water lock-outs of the heat pump units.
System start-up went smoothly with no problems and the GAP employees moved into their new offices on time on April 1, 2005. There have been no complaints regarding heating, cooling or indoor comfort variations during the building’s initial operating season. Commercial HVAC submitted the Dolwick Business Center project to the Ohio Valley Chapter of ABC – Associated Builders and Contractors, Inc. – for its Contractors Excellence in Construction Award and received an “award of merit” last year.
Commercial HVAC president Bob Stiens reports that LoadMatch brings two major advantages to today’s cost-conscious building projects – the simple system is cost effective in terms of materials needed and installation savings, and energy efficient in operation. Since the completion of the Dolwick Business Center, one of the largest spec Class A office buildings in the Greater Cincinnati Tri-State area, his firm has completed two additional office buildings in the Greater Cincinnati area, and both are LoadMatch installations.
Click here to read a profile of the project in the May 2007 issue of Commercial Building Products.
Information provided by Taco, Inc., Cranston, RI.