When evaluating the purchase of most types of capital equipment, the obvious factor to consider is price/performance. Yet, an important factor that most people would agree should not be overlooked is value added, an amenity or service - such as warranty or engineering assistance - that substantially increases the worth of the product, or potential ROI.
When it comes to purchasing a cooling tower, an integral component of many HVAC and heat exchanger systems, value added often takes on more significance than usual. This is because factors such as warranty or engineering and installation assistance can be crucial to performance and extend the service life of the equipment. Hence, value added may significantly enhance the price/performance ratio.
This potential is realised by the latest in cooling tower technology, which features a shell composed of HDPE (high-density polyethylene) “engineered plastic,” and offers both exceptional performance and superior value-added.
One of the major problems that plague conventional cooling towers' performance is corrosion that is imposed by the environment (e.g., salt air, industrial pollutants) or cooling system waters and their required chemical water treatment. With a shell of galvanised sheet metal, the conventional models are maintenance intensive and destined to a relatively brief service life, often seven years or less. The maintenance factor is not only expensive in terms of downtime, but also laborious to clean or coat away corroded shell panels and weld or gasket patches. Plus, the amount of chemicals required to inhibit corrosion is also costly.
Conversely, HDPE engineered plastic cooling towers are impermeable to corrosion. Therefore, they require far less maintenance and downtime, and normally require relatively inexpensive chemicals used to retard biological growth.
Pioneered by Delta Cooling Towers and quickly gaining popularity, these advanced HDPE models are available in single and modular configurations from 10 to 2,400 cooling tons. They are in wide use for HVAC and heat exchanger applications throughout commercial, industrial and institutional facilities.
When Joe Matthews, VP of Construction at Vista Air Services (Houston, TX) was considering a self-contained, water-cooled HVAC system for a customer near Galveston Bay, he primarily had system efficiencies on his mind. However, since a cooling tower would be essential to the system, he was also concerned about the salt air and corrosive emissions from several surrounding chemical plants that would corrode a conventional, metal-clad cooling tower shell, making frequent maintenance and replacement necessary over the years.
Vista Air Services is a contractor that is involved in all aspects of HVAC systems. The application is a 66,000 sq. ft. industrial turbine repair station and training facility of Mitsubishi Power Systems, for its power generation turbines.
“B.R. Gonzales, a sales rep from AC Engineered Systems, one of our suppliers, suggested that we go with a Delta cooling tower because AC has had great success with those in Florida,” explains Matthews. “Considering the potential for salt-air corrosion, we felt that what was appropriate for Florida would also be suitable for a plant in the proximity of Galveston Bay.”
Matthews also figured that the HDPE cooling tower would be cheaper to maintain. He was quite impressed when he learned that the capital investment required would also result in a savings.
“Considering the potential operating savings, I was surprised to learn that the initial purchase price was also substantially lower than many conventional models,” he adds.
The water-cooled system that Vista sold to Mitsubishi was a space-saving design that would economise on plant space compared with an air-cooled system, which would entail massive package units.
“We installed four 40-ton air handlers mounted to the exterior walls, plus four 20-ton air handlers inside,” Matthews explains. “With a typical 40-ton air-cooled package you’ll have a 450 sq. ft. footprint. With our water-cooled system, we are only taking up less than 30 sq. ft.”
A deciding factor among most Delta cooling tower customers is the 20-year warranty on the shell, as opposed to one year for the metal-clad design. A 20-year warranty is obviously indicative that the HDPE towers provide a much longer service life than other models.
To ensure optimal operation and ease of installation, Delta also offers cooling system design and engineering assistance. When requested, the manufacturer even accommodates customers on cooling tower color.
In an HVAC application, engineered HDPE plastic cooling towers were recently installed at two Scott County Schools facilities in the Georgetown, Kentucky area.
Adam Berning, Sales Engineer with manufacturer's representative Blackmore & Glunt, explained that the county school board agreed to install HDPE cooling towers because of the economies offered in purchase price and imperviousness to the harsh chemicals required to treat the very hard water used in the system.
The Director of Maintenance stated that Georgetown, KY has the ‘worst water on the face of the Earth,’” Berning says. “He said they have to frequently clean their cooling towers, removing a salt-like residue that readily accumulates.”
Berning explains that the HDPE cooling tower will be virtually untouched by any corrosives was a major factor in the school board’s decision. But another important value-added factor was Delta’s ability to colourise the cooling tower installed on the roof at one location.
“The board wanted to have one of the cooling towers match the brick exterior of the school where it is installed.” Berning explains. “Ordinarily, getting a colourised cooling tower from the factory would be a challenge. The colour was to be a custom rust-brown that the architect specified. Custom colours are available from the factory. They simply inject the appropriate-coloured resin into the HDPE to make it exactly the colour you want. So, when the cooling tower arrived, it matched the building quite well.”
Berning says that the manufacturer also provided special water drainage outlets and a cooling tower platform.
He adds that the cooling system scheme at one of the schools called for the cooling tower to operate in two stages. Here again value was added through the inclusion of a variable-speed drive (VFD) compatible fan motor with the cooling tower package.
“The first stage of cooling is provided when water is pumped through the tower without the tower fan running,” Berning says. “As the system fluid temperature rises above a threshold as determined by the building automation system, the cooling tower fan is turned on to provide additional capacity. Once the fan is on, a VFD modulates the fan speed to provide the right amount of cooling. As a standard, the motor provided by Delta Cooling Towers is rated for operation through a VFD, and the VFD they provide easily communicates with the building automation system.”