Air handlers bring efficiency, flexibility to lab environment
Well, it’s a rare day on the Piedmont of North Carolina, where winters are cool and damp and summers are hot and sticky.
So when High Point Chemical, a textile and pulp-paper specialty chemical manufacturer in High Point, decided to build a 3,800-sq-ft, quality-control laboratory addition requiring the “perfect day” on the inside, great consideration to the temperature on the outside was required.
Many manufacturers and companies handle residential climate control. Fewer cover commercial climate control, and only a handful supply for the exacting demands of air in the laboratory environment.
“It was difficult to find the right system,” remembers John Pledger, senior analytical chemist at High Point Chemical and the owner representative’s project manager for the new lab.
“We needed once-through air circulated in very high volumes, and that required a cooling system that could handle the preparation of air the first time through to create a safe environment for the employees.”
Last year the search began. “Originally the general contractor brought in a ‘laboratory air specialist’ and got the lowest bid,” notes Glenn Talbert of HVAC Supply, Inc., High Point. “But the customer was disappointed with the cost of that proposal. So, the general and mechanical contractors gave us the chance to produce a viable air-handling solution that lowered the bid and met the customer’s needs.”
At this point HVAC Supply, which has been a Chandler Refrigeration supplier for 10 of its 15 years of operation, went to the manufacturer with a list of requirements from High Point Chemical. These included clean, cool, dry air, circulated at a rate of 16,000 cfm within three lab work areas and two office spaces, 24 hrs/day, 365 days/yr, no matter what the outdoor temperature might be.
And they wanted a quick return on investment.
“Not a problem,” was the response from Larry Smith, an engineer for Chandler. “Glenn was able to let me know exactly what the requirements of the job would be and how he wanted it to come out. Then we put our heads together to custom-build the best package possible.”
The equipment platform Chandler suggested for the main lab included two forward-curved fan air handlers with four glycol-water coils used to either condition incoming air or capture energy from outgoing air.
Each air handler also comes equipped with a flat, pleated air filter, rated at 30% efficiency to keep contaminants and particles out of the atmosphere and from between the coil fins.
Drain pans were added to both units to collect coil condensation when chilled water is circulated. Chilled water is supplied by a 93-ton Chandler chiller.
“Once we developed a working platform of equipment that would meet the load requirements,” adds Talbert, “we at HVAC Supply started focusing on the second part of the client’s needs — efficiency and energy savings through how many Btu we’d be able to squeeze out of the recovery coil system.
“With this information, we developed what we consider to be fairly accurate numbers to present to the customer.”
Energy recoveryIn exhausting 16,000 cfm every day, all year, there is a huge amount of preconditioned air, either cooled or heated, leaving High Point Chemical.
“We wanted to be able to transfer as much energy, represented in Btu, from air leaving via the exhaust handler to air arriving via the makeup handler,” notes Talbert. “So we installed two glycol-filled, eight-row, 12-fpi (fins per in.) run-around or recovery coils, one in each air handler.”
This is what made the job unique to Blair Nicholson, owner of Liberty Mechanical, Liberty, the contractor that installed the system. “The focus on recovering energy seems to be a big part of what Chandler can do for an application such as High Point Chemical, which requires a great deal of air circulation every hour of every day,” says Nicholson.
“In fact,” says Talbert, “one of the reasons High Point Chemical ultimately selected this application was our ability to provide large energy savings. Until now, High Point had not been recovering any of its energy.”
On the heating side, Talbert and Chandler estimated that the recovery coils would generate a gas savings of 17,350 cu ft of gas/yr, based on a 5,195-hr heating season, a load value of 60%, and a heating value of less than 2,500 Btu per cu ft.
On the cooling side of recovery, an estimated 9,224 kWh will be saved each year based on a 3,569-hr cooling season and 10 SEER.
“The bottom line,” says Nicholson, “is that the customer will reach full return on investment within three years. After that, all of the savings are gravy.”
Means to get btu recoveryBtu reclaim or recovery can be done a number of ways: air-to-air, a heat-recovery wheel, or through circulating water through a fluid-transfer system called a heat reclaim coil. Chandler uses the latter.
“From a general technical standpoint, it’s the simplest way to do this,” adds Talbert. “It also happens to be an efficient way for us to do it, because we were able to treat the exhaust system as a separate entity from the makeup air unit, rather than combining the two products into one piece of hardware.”
Beyond the two recovery coils, the system’s makeup air handler comes equipped with a five-row, 10-fpi, chilled-water coil, and a two-row, eight-fpi, warm-water coil to finish conditioning incoming air.
“That’s the beauty of air handlers,” says Nicholson. “You can stack coils, putting a chilled-water coil hitched to a chiller next to warm-water coil hooked up to a heat source to meet the load requirements in any season.”
A 93-ton Chandler chiller provides proportionally chilled water. On the warm-water side, High Point Chemical was able to utilize its supply of steam from its physical plant, which is converted to hot water and fed into the warm-water coils, avoiding any additional investment in boilers or any other heat source. This configuration also eliminates the need for a direct-fired gas appliance.
In a tight spotPulling and pushing this much air requires substantial equipment, which can take up a lot of space.
“At 100 tons, this is a big job,” says Talbert. “We had a lot of equipment to go into a small area, and Chandler’s modular system was advantageous to High Point because of space limitations.”
Mike McMillan, project manager for general contractor Fowler, Jones, Bears, Inc., Winston-Salem, agrees. “The High Point Chemical site is very tight, both fiscally and physically,” says McMillan.
“Our original bid was over budget, but through value engineering — simply deductive reasoning — we suggested alternatives to give the owner some flexibility and lower prices.”
Chandler was a big part of this value engineering equation. High Point Chemical’s labs are located on the second floor, which typically calls for a roof-mounted or ground-level unit. Both of these options were out of the question, because High Point Chemical had misgivings about poking holes in the ceiling and wanted to keep its options open regarding future expansion, something a unit on the ground might prevent.
Chandler’s modular system made it possible to place the equipment on top of an adjacent, structurally enhanced loading dock at a mezzanine, off both the ground and the roof. “With this equipment package we had the flexibility to create a low-cost solution,” notes Talbert.
More information on Chandler air handlers is available from Heatcraft Refrigeration Products: 770-465-5600; 770-465-6018 (fax); www.heatcraft rpd.com (Web site).