Hospitals contain some of the most diverse and demanding environments, requiring consistent, dependable performance from their HVAC systems. Operating rooms, critical-care facilities, data centers, imaging centers — plus worker productivity — are, to some extent, dependent on the reliable operation of the HVAC system, particularly in warm weather.
When cooling towers are sluggish or out of service for maintenance, added stress is placed on chillers, and in turn the HVAC system performance is often downgraded.
Such was the case with Davis Memorial Hospital in Elkins, W.Va., a subsidiary of Davis Health System. The 160,000-square-foot hospital was founded in 1904, fully renovated in 1994, and is now undergoing a 72,000-square-foot expansion. The modern hospital includes a 90-bed medical facility with nine intensive care and 36 telemetry (monitored) beds. Services range from emergency treatment to acute inpatient care, cancer treatment, diagnostic services, pulmonary rehabilitation, women’s health services, and many types of surgery.
To overcome recurring cooling tower-related HVAC performance problems, Davis Memorial recently purchased two cooling towers to support its two 300-ton Carrier chillers.
Like the owners of many industrial, business, and institutional buildings, hospital management was looking for a more advanced cooling tower technology that would optimize performance while minimizing maintenance requirements.
“I researched various cooling tower technologies on the Internet and found a unique line of cooling towers that feature a seamless plastic shell,” said Steven Johnson, director of Davis Memorial support services. “The one that attracted my attention was a line that was made of high-density polyethylene (HDPE), manufactured by Delta Cooling Towers (Rockaway, N.J.).”
Johnson and engineers from Davis Memorial, as well as some from Carrier, decided to visit Delta Cooling Towers Inc. for a manufacturing plant tour to get a closer look at the design and construction of the company’s product line, which includes models ranging from 10 to 2,000 cooling tons. “We were all impressed with the plant tour,” Johnson said. “Not only was management helpful in explaining the features and benefits of various product models, but they also helped us confirm our preliminary specs for the cooling towers we had in mind.”
He was also pleased with the standard warranty offered on all products. The HDPE-based cooling tower shells from Delta carry a standard 15-year warranty.
For their expansion project, the Davis Memorial team selected a 250-ton TM Series unit and a 180-ton Paragon Series tower.
Getting Bed Rest
While the avoidance of downtime and the need for unscheduled cooling tower maintenance were critical requirements for Davis Memorial Hospital, other features of the Delta design provided significant value. “The variable-speed, direct-drive motors that run the fans on our new towers provide unexpected benefits,” Johnson said. “First of all, these drives are far more efficient than we initially realized. The fan motors on our old towers were 30 horsepower each, and consumed considerably more energy than the new ones which are only 7 horsepower each, and at least 50 pecent more energy efficient.”
Johnson explained that the hospital’s old fan motors were either on or off. With the new variable-speed drives, they are set up so that it has to be a hot day before they run at 100 percent.
“The new direct-drive fans are usually running at about 40 percent,” he said. “Running at 100 percent, they are only pulling four amps, which is much less energy than before.”
Johnson added that the new direct drives also require far less maintenance, which results in even greater savings. With no belts, shafts, bearings, or other external parts to service, the direct-drive motors are virtually maintenance-free, he said.
Another important benefit of the new direct-drive cooling towers is that they run quietly.
“We’re a hospital, so quiet is expected,” said Johnson. “Also, we’re located right in the middle of a residential community. In the past, we’d receive complaints from people in the neighborhood if the belts were squealing, particularly if it happened at night when they were trying to sleep. That was a serious problem, so our maintenance people often had to fix the belts in the middle of the night. With the direct-drive fan motors, we don’t have that problem.”
Johnson said that the new cooling towers have not only solved his chiller and HVAC problems, but have exceeded expectations.
“These new cooling towers have virtually eliminated unscheduled emergency maintenance,” he said. “That not only makes us happy, but our chiller-maintenance contractor is also very pleased.”
John Flaherty, president of Delta Cooling Towers, estimates that with the combined savings on energy, water usage, maintenance, and chemicals, that the new cooling towers should provide the hospital a complete payback within two years.
Publication date: 2/4/2013