eco hybrid cooler clark johnson company

Closed Circuit Coolers

eco-ATWB-H Closed Circuit Coolers

The eco-ATWB-H is an induced draft, counterflow design closed circuit cooler with a CTI Certified capacity range of 850 to 16700 MBH (250 to 4895 kW). Standard construction includes the patented, high efficiency  EVAPCO Ellipti-fin Coil, EVAPCO’s new ARID fin Pak™ dry coil, and G-235 (Z-725 Europe) galvanized steel casing and basin. Type 304 or 316 stainless steel construction is available for the basin or the entire unit.



  • Continuous water savings, even when the spray pump is energized
  • Highest dry bulb switchover temperatures
  • Plume abatement
  • Plume elimination

   Design Features

     Maintenance Features

      Drive Systems

      Optional Equipment

Thermal Performance

eco-ATWB-H Closed Circuit Cooler - Design Features


The NEW eco-ATWB-H Hybrid line of closed circuit coolers was designed with the purpose of providing maximum water savings, higher dry bulb switchover temperatures, while achieving plume abatement or elimination.


The eco-ATWB-H is provided with EVAPCO’s new ARID fin Pak™ dry coil. Utilizing stainless steel tubes and aluminum manganese fins, the ARID fin Pak™ maximizes the total surface area available for sensible heat transfer, which results in maximum water savings and higher dry bulb switchover temperatures. Additionally, the eco-ATWB-H is provided with the highly efficient Ellipti-fin® coil in series with the ARID fin Pak™, achieving both latent and sensible cooling simultaneously. Located in the discharge airstream, the ARID fin Pak™ heats the saturated discharge air, abating or eliminating the plume. Because the coils are in series, a significant portion of the heat load will always be dissipated through the dry cooling coil, saving water whenever it is in operation!


The eco-ATWB-H is the ideal solution for: Maximized Water Savings, Highest Dry Bulb Switchovers, Plume Reduction or Plume Abatement.





Principle of Operation Evaporative Mode (Latent Heat Transfer)heat mode evaporator clark johnson company In the evaporative mode, the process fluid enters the  cooler through the top coil connections and circulates through the finned coils. With both pumps energized, the heat from the process fluid is transferred through the coil tubes to the water cascading downward over the coils while simultaneously air is drawn upward over the coil opposite the water flow using the fan drive system (Fan on, Pump A & B on). A small portion of the water is evaporated to dissipate the heat to the atmosphere in a latent heat transfer. This mode of operation provides fan energy savings and lower leaving water temperatures by utilizing evaporative cooling.       Dry Mode (Sensible Heat Transfer)   dry mode evaporator clark johnson co In the dry mode, the recirculating spray pumps are deenergized (Fan on, Pump A & B off). The process fluid enters the cooler through the top coil connection and circulates through the coil with the Fan On. Heat from the process fluid is dissipated to the atmosphere by sensible heat transfer through the tube walls to the air passing over the coils. The coils are finned to promote optimal airflow over the coil and to maximize heat transfer area. Air is drawn over the finned coils by the fan drive system. The process fluid then returns to the heat source via the bottom coil connection. This mode of operation eliminates water consumption when the dry bulb temperature is favorable.       Efficient Drift Eliminators The eco-ATWB-H is equipped with an efficient drift eliminator system that effectively reduces entrained water droplets from the air discharge to less than 0.001% of the spray water flow rate. The eliminators are constructed of non-corrosive PVC with a multi-pass design for maximum drift reduction. They are assembled in modular sections for easy removal and access to the water distribution system. In addition to reducing drift, the eliminators also function as effective debris screens which protect the spray system from sunlight and debris.   Superior Air Inlet Louver and Screen DesignThe air inlet louver screens on the eco-ATWB-H are constructed of corrosion-free PVC. They are a two pass design that minimizes splashout and reduces the potential for algae formation inside the cooler. In single pass louver systems used by other manufacturers, circulating water droplets tend to splashout, especially when the fans are shut off. With the two pass louver system, the water droplets are captured on the inward sloping pass, minimizing splashout problems. This unique louver design completely encloses the basin area. Direct sunlight is blocked from the water inside the cooler, thereby reducing the potential of algae formation. Water treatment and maintenance costs are substantially reduced. While effectively containing the recirculating water and blocking sunlight, the louver design has a low pressure drop. The low pressure drop results in lower fan energy consumption, which reduces the operating costs of the cooler. Ellipti-fin Coil Design  The new eco-ATWB-H Closed Circuit Cooler utilizes Evapco's patentpending Ellipti-fin coil design which assures even greateroperating efficiency. The elliptical tube design allows for closertube spacing, resulting in greater surface area per plan areathan round-tube coil designs. In addition, the revolutionaryEllipti-fin design utilizes elliptical spiral fin coil technology andhas lower resistance to airflow than typical finned coil designs.This permits greater water loading, making the new Ellipti-fincoil the most efficient coil design available on the market.The coils are manufactured from high quality steel tubingfollowing the most stringent quality control procedures.Each circuit is inspected to ensure the material quality andthen tested before being assembled into a coil. Finally, theassembled coil is pneumatically tested at 400 psig underwater to ensure it is leak free. ARID fin Pak™ Dry Cooling Coil The new eco-ATWB-H Closed Circuit Cooler utilizes the ARID fin Pak™ Dry Cooling Coil. Installed in the air discharge of the cooler the ARID fin Pak™ dry cooling coil is piped in series with the evaporative cooling coil. The ARID fin Pak™ dry cooling coil is constructed of 304L Stainless Steel tubes and tubular Stainless Steel header with carbon steel coil connections for easy field piping. The fins have fully drawn collars to maintain consistent fin spacing and continuous surface contact over the entire tube to maximize heat transfer. The fins are constructed of Aluminum/Manganese alloy for superior corrosion resistance.  Multiple Water Distribution Systems   Each coil in the eco-ATWB features its own water distribution system. This allows each coil to operate in a mode independent of the other coil EVAPCO’S Zero Maintenance ZMII® Spray Nozzle remains clog-free while providing even and constant water distribution for reliable, scale-free evaporative cooling under all operating conditions. The heavy duty nylon ZMII® Spray Nozzles have a 1-5/16” diameter opening and a 1-1/2” splash plate clearance enabling EVAPCO to use 75% fewer nozzles. Furthermore, the fixed position ZMII® nozzles are mounted in corrosion-free PVC water distribution pipes that have threaded end caps. Together, these elements combine to provide unequaled coil coverage and scale prevention, and make the industry’s best performing non-corrosive, maintenance-free water distribution system. The water distribution is designed to provide a minimum 6 GPM over each square foot (4 liters per second over each square meter) of unit plan area to ensure proper flooding of the coil.   Water and Energy Conservation Control System  stage 3 control system clark johnson company  The best way to properly control and operate the eco-ATWB-H Closed Circuit Cooler is with the optional Sage2 ® Water and Energy Conservation Control System. The Sage2 ® is designed to optimally control the fan motor(s) and the pump motor(s) of the unit. The Sage2 ® will efficiently reject the building load using the minimal amount of water and energy.Principle of OperationEfficient DriftEliminatorsSuperior Air Inlet Louver and Screen DesignEllipti-fin Coil DesignARID fin PAK Dry Cooling CoilMultiple Water Distribution SystemsStage 2  Control System



eco-ATWB-H Closed Circuit Cooler - Maintenance Features


Designed for easy maintenance, the eco-ATWB-H Closed Circuit Cooler leads the industry in service friendly features. The three most critical areas for closed circuit cooler maintenance are the basin, drive system, and coil. The eco-ATWB-H basin section is designed to allow quick and easy access from outside the cooler. Just like the basin, all service to the drive system can be safely performed from the side of the cooler, and EVAPCO's Power-Band drive system is the easiest belt drive system to maintain in the industry! The exclusive Ellipti–fin™ Technology (Patent Pending) and EVAPCO’s new ARID fin Pak™ dry coil are designed for trouble-free maintenance and long life straight from the factory.


Drive System


The eco-ATWB-H Evaporative Cooler features the highly successful EVAPCO POWER-BAND Belt Drive System engineered for heavy-duty operation. The POWER-BAND Drive System has consistently provided trouble-free operation in the most severe duty evaporative condenser applications. In addition, the complete drive system including the fan motor is standard with a (5) Five Year Warranty.


  •     Fan Motors
  •     Fan Shaft Bearings
  •     Drive System Sheaves
  •     Power-Band Belt Drive


Fan Motors


 Closed Circuit Cooler models utilize heavy duty totally enclosed (T.E.F.C. or T.E.A.O) fan motors designed specifically for closed circuit cooler applications. In addition to the standard motors offered on each cooler, EVAPCO offers many optional motors to meet your specific needs, including:


  • Premium Efficiency Motors
  • Multi-Speed Motors
  •  Inverter-Duty Motors for VFD Applications


3', 4', 8.5' & 17' (0,9; 1,2; 2,6 & 5,2 m) wide ATWB models feature T.E.F.C. motors are located on the outside of the unit, protected by a hinged, swing away cover. 12' & 24' (3,7 & 7,3 m) wide ATWB models have T.E.A.O. motors located inside the fan section on a heavy duty motor base which swings to the outside for repair or removal.





Fan Shaft Bearings


The fan shaft bearings on the Closed Circuit Cooler are specially selected to provide long life, minimizing costly downtime. They are rated for an L-10 life of 75,000 to 135,000 hours, making them the heaviest duty pillow block bearing in the industry used for Closed Circuit Cooler duty.


Power-Band Belt Drive


The Power-Band drive is a solid-back multigroove belt system that has high lateral rigidity. The belt is designed for closed circuit cooler service, and is constructed of neoprene with polyester cords. The drive belt is sized for 150 percent of the motor nameplate horsepower ensuring long and trouble free operation.




Drive System Sheaves


Drive system sheaves located in the warm, moist atmosphere inside the cooling tower are constructed of an aluminum alloy. Those located externally are protected by a hinged cover.

Optional Equipment


The standard design of the EVAPCO eco-ATWB  provides the customer with the most efficient and easiest Closed Circuit Cooler to maintain in the industry. There are additional options which can make maintenance easier, extend the life, or enhance the performance capabilities of the Closed Circuit Cooler.



  • Sloped Access Ladders
  • Stainless Steel Water Basin
  • Electric Water Level Control
  • Electric Immersion Heaters
  • Remote Sump Configuration
  • Low Sound Solutions
  • Pulse~Pure® Water Treatment System

Clark Johnson Company, Inc.       2016