Closed Circuit Coolers

eco-ATWB Closed Circuit Cooler

eco-ATWB Closed Circuit Cooler

Independently certified to withstand seismic and wind load forces at ALL Building locations in North America.

The eco-ATWB is an induced draft, counterflow design closed circuit cooler with a capacity range of 150 to 38280 MBH (42 to 10813 kW). Standard construction includes the patented, high efficiency  EVAPCO Ellipti-fin 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.

Design Features

The New eco-ATWB line of Closed Circuit Coolers has been specifically designed to dramatically increase both the evaporative (latent) and dry (sensible) modes of cooling. With this new revolutionary design, the EVAPCO eco-ATWB will also save water and energy by increasing the unit’s efficiency in both the evaporative and dry  cooling modes of operation. The eco-ATWB utilizes the EVAPCO Ellipti-fin coil which features elliptical spiral fin technology to maximize the surface area available for heat transfer. The eco-ATWB is the ideal solution for: Reducing Water Consumption,Lower Energy Costs, High Dry Bulb Switchover, Super Low Sound Levels. This new product is designed with IBC Compliant construction and CTI Certified Performance. These features are described below.

Evaporative Mode (Latent Heat Transfer)

In the evaporative mode, the process fluid enters the cooler through the top coil connection and circulates through the finned coils. With the pump and fan energized, the heat from the process fluid is transferred through the tube wall and fins to the water cascading downward over the coils while simultaneously air is drawn upward over the coil opposite the water flow. 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 due to enhanced evaporative performance and lower leaving water temperatures by utilizing evaporative cooling.


Dry Mode (Sensible Heat Transfer)

In the dry mode, the recirculating spray pump is deenergized (Fan on, Pump off). The process fluid enters the eco-ATWB cooler through the top coil connection and circulates through the finned coil with the fan energized. Heat from the process fluid is dissipated to the atmosphere by sensible heat transfer through the tube wall and fins 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 coil 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!

eco-ATWB Operating Benefits

The eco-ATWB features the new EVAPCO Ellipti-fin coil, which utilizes elliptical spiral fin coil technology. This technology allows for a significant increase in thermal performance with up to a 40% lower operating horsepower (HP) than a typical evaporative cooler! This will results in tremendous energy savings throughout the year. If minimizing the footprint of the unit is of greater concern, the increased thermal capacity of the Ellipti-fin technology will allow a selection that yields up to a 40% smaller plan area! Additionally, the Ellipti-fin coil technology enables the eco-ATWB to be operated in a 100% Dry Mode, whereby the switchover temperature is significantly higher than that of a typical bare tube coil. This leads to a significant increase in dry operating hours, thus increasing your water savings. This combination of features allows the eco-ATWB to be operated with both energy and water efficiency in mind, making it the ideal choice for many installations.


eco-ATWB Operational Savings:

Consider a Data Center cooling application for Minneapolis, MN where the unit is required to reject a constant heat load of 216 tons with 650 gpm of water entering at a temperature of 95°F and a leaving temperature of 85°F. The process operates 24 hours a day 7 days a week. Both the eco-ATWB and the eco-ATWB-E are compared to:

• Cooler A – an evaporative cooler without dry cooling capability
• Cooler B– an induced draft counter-flow cooler capable of some dry operation






The eco-Coolers require lower pump HP than Cooler A and lower pump HP and fan HP than Cooler B. Additionally, the eco-Coolers provide either a similar or smaller footprint along with the HP savings. With the increased dry cooling efficiency of the eco-ATWB and eco-ATWB-E and the use of the Sage® Water and Energy Conservation Control System, each unit is able to operate dry for 48.00% of the year. Additionally, the revolutionary design of the eco-ATWB-E allows the unit to operate in a Water Efficient Mode for an additional 47.9% of the year, further reducing water consumption. This is illustrated below:














Due to the Dry Operation capabilities of the eco-Coolers and the added Water Efficient Mode of the eco-ATWB-E the reduced costs associated with water usage is illustrated below: 







Summarizing these costs, the eco-Coolers will save the operator a minimum of $18, 864 per year in associated water costs vs. a typical cooler and up to $10,000 vs. an induced draft counter-flow cooler with some dry capacity.

 Ellipti-fin Coil Design

 The new eco-ATWB Closed Circuit Cooler utilizes Evapco's patent
pending Ellipti-fin coil design which assures even greater
operating efficiency. The elliptical tube design allows for closer
tube spacing, resulting in greater surface area per plan area
than round-tube coil designs. In addition, the revolutionary
Ellipti-fin design utilizes elliptical spiral fin coil technology and
has lower resistance to airflow than typical finned coil designs.
This permits greater water loading, making the new Ellipti-fin
coil the most efficient coil design available on the market.
The coils are manufactured from high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected to ensure the material quality and then tested before being assembled into a coil. Finally, the assembled coil is pneumatically tested at 400 psig under water to ensure it is leak free.

To protect the coil against corrosion, it is placed in a heavy steel
frame and then the entire assembly is dipped in molten zinc
(hot-dip galvanized) at a temperature of approximately 800°F.
Note: Closed circuit coolers should only be used on sealed,
pressurized systems. Continual aeration of the water in an
open system can cause corrosion inside the tubes of the cooler
leading to premature failure.

Maintenance Free ZMII® Water Distribution System


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.

Superior Air Inlet Louver and Screen Design

The air inlet louver screens on the eco-ATWB 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.

Efficient Drift Eliminators

An extremely efficient drift eliminator system is standard on the eco-ATWB Closed Circuit Cooler. The system removes entrained water droplets from the air stream to limit the drift rate to less than 0.001% of the recirculating water rate. With a low drift rate, the eco-ATWB Closed Circuit Cooler saves valuable water and water treatment chemicals. The eco-ATWB Closed Circuit Cooler can be located in areas where minimum water carryover is critical, such as parking lots.

The drift eliminators are constructed of an inert polyvinyl chloride (PVC) plastic material which effectively eliminates corrosion of these vital components. They are assembled in sections to facilitate easy removal for inspection of the water distribution system.

Fast, On-Time Shipments

The eco-ATWB is completely factory assembled and manufactured by a dedicated professional workforce, expert in building closed circuit coolers. Factory trained mechanics and EVAPCO's strict quality control and inspection procedures guarantee the quality of every unit shipped.

EVAPCO's controlled factory environment ensures fast on-time shipments, allowing the eco-ATWB to be available WHEN THE CUSTOMER WANTS IT!

IBC Compliant

 What is IBC?  

  • The International Building Code requires that evaporative cooling equipment must meet the same seismic or wind load forces as the building to which they are attached.

How does it apply? 

  • Based on project zip code and site design factors, calculations are made to determine the equivalent seismic "g force" and wind load on the unit.

What does EVAPCO offer?

  • Standard Structural Design

                    -Projects with ≤ 1.0g seismic or 145 psf wind loads

  • Upgraded Structural Design

                    -Projects with > 1.0g seismic or 145 psf wind loads

  • The upgraded structural design package for the New ATWB is designed for 5.12g and 145psf, making it applicable to ALL building locations in North America.

Maintenance Features

Designed for easy maintenance, the eco-ATWB 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 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–finTechnology (Patent Pending) is designed for trouble-free maintenance and long life straight from the factory.

Click on the features below for more details.

Motor Mount, Power Band Belt Adjustment and Bearing Lubrication

The fan motor and drive assembly are designed to allow easy servicing of the motor and adjustment of the belt tension from the exterior of the unit. The T.E.F.C fan motor is mounted on the outside on these models and is protected from the weather by a cover which swings away for maintenance.

A large hinged access door is located on the side of the unit for easy access to the fan drive system. The belt can be adjusted by tightening the J-Bolts on the motor base and the tension can be checked easily through the access door, all while standing at the side of the unit. 

The bearings can also be lubricated from the side of the unit. The bearing lubrication lines have been extended to the exterior casing and are located by the access door, thus making bearing lubrication easy.

Sloped access ladders and working platforms are available as an option to facilitate maintenance.

Go to Optional Equipment for details.

Motor Mount, Power Band Belt Adjustment and Bearing Lubrication 

The T.E.A.O. fan motor is located inside the fan casing on the large eco-ATWB Closed Circuit Cooler, and is mounted on a rugged heavy duty motor base. The motor base is designed to swing completely to the outside of the unit through a very large, hinged (14 square feet) (1,3 square meters) access door greatly simplifying motor maintenance.

The unique swinging motor mount designed for these models features easy belt adjustment from the exterior of the unit. The T.E.A.O. fan motor is mounted on an adjustable base which is supported by two heavy duty galvanized steel pipes. The belt is adjusted by tightening an all-thread which runs through the motor base.

The innovative motor base features a unique locking mechanism for a positive belt adjustment and is also used to adjust the belt tension if a wrench is not available.

Bearing lubrication fittings are extended to the side of the unit inside the access door to allow easy application of the bearing lubricant. This external location allows for easy servicing of the bearings and is another important advantage of EVAPCO equipment.

To facilitate motor removal, an optional motor davit is available.

Go to Optional Equipment for details.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The eco-ATWB features a Quick Release Fastener design consisting of (2) two large thumbscrews and a latch system. By loosening the thumbscrews, the latch pulls up and out of the louver frame, allowing the louver to be removed while the latch and thumbscrews stay on the closed circuit cooler.

 Easy Access

The cold water basin section is easily accessible from ground level by simply removing the (2) two Quick Release Fasteners on the inlet louver assemblies surrounding the closed circuit cooler and lifting out the lightweight louver.

The basin can be accessed from all (4) four sides of the cooler. This open basin design enables the eco-ATWB basin to be easily cleaned.

Clean Pan Design

The eco-ATWB features a sloped basin from the upper to lower pan section. This "Clean Pan" design allows the water to be completely drained from the basin. The closed circuit cooler water will drain from the upper section to the depressed lower pan section where the dirt and debris can be easily flushed out through the drain. This design helps prevent buildup of sedimentary deposits, biological films and minimizes standing water.

Stainless Steel Strainers

The EVAPCO standard for many years, the stainless steel strainer is one component of the closed circuit cooler subject to excessive wear and corrosion. With stainless steel construction, this component will last the life of the cooler.

Drive System

The eco-ATWB 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

All eco-ATWB 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 

8.5' (2,6 m) wide eco-ATWB models feature T.E.F.C. motors are located on the outside of the unit, protected by a hinged, swing away cover. 12' (3,7 m) wide eco-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.


Five (5) Year Warranty

EVAPCO provides a standard five (5) year motor and drive warranty on all direct drive Power-Band belt drive and optional gear drive eco-ATWB Closed Circuit Coolers. This unique warranty is designed to offer the end user optimum protection against fan drive and motor failure. It is a comprehensive plan which includes the fan, fan shaft, belts, sheaves, fan bearings, gear box, flexible coupling, driveshaft and the motor.

Fan Shaft Bearings

The fan shaft bearings on the eco-ATWB 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.

Drive System Sheaves

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

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.

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. These options are listed below.

Sloped Access Ladders

A sloped access ladder is available for 8.5' and 12', (2,6 and 3,7m) wide eco-ATWB models. The EVAPCO designed access ladder features a sloped "ships type" ladder arrangement which provides fast and easy access to the water distribution system and drive components. A grab bar is attached to the sloped ladder for safe and easy ascent and descent. There is no need for safety cages or railings with this design. The ladder(s) will ship loose and must be field mounted. The sloped ladder meets all applicable OSHA requirements.

Stainless Steel Water Basin

EVAPCO coolers have a modular design which allows specific
areas to be enhanced for increased corrosion protection. The
basin area of the cooler experiences turbulent mixing of air
and water, in addition to silt build-up. In conjunction with the
EVAPCOAT Corrosion Protection System, EVAPCO offers an optional Stainless Steel Basin. This option provides Type 304 or 316 stainless steel for the entire basin area including the support columns of the cooler and the louver frames. The basin section provides structural support for the unit; it is also the part of the unit that is most prone to corrosion. For maximum protection against corrosion, EVAPCO can provide a Stainless Steel Basin as an affordable option.

Working Platform & Ladder with Davit

eco-ATWB Closed Circuit Coolers are available with an external working platform and ladder to allow easy servicing of the fan motor and water distribution system. Providing a convenient platform to perform work, the heavy duty galvanized steel platform is self-supporting which eliminates the need for any external support. A less expensive alternative to field erected catwalks, the working platform option uses a straight ladder as standard and ships in sections for easy installation. The davit option eliminates crane rentals and facilitates the removal of motors and gear drives. The davit and bracket are constructed of heavy duty galvanized steel and are mounted on the side of the unit. The optional fan motor and gear davit ships loose and is installed in the field. (The working platform and ladder meet all applicable OSHA requirements.)

Electric Water Level Control

EVAPCO closed circuit coolers are available with an optional electric water level control system in place of the standard mechanical makeup valve and float assembly. This package provides very accurate control for the basin water level and does not require field adjustment, even under varying operating conditions.

The control was designed by EVAPCO and is manufactured exclusively for EVAPCO. It consists of multiple heavy duty stainless steel electrodes. These electrodes are mounted external to the unit in a vertical stand pipe. For winter operation, the stand pipe must be wrapped with electric heating cable and insulated to protect it from freezing.

The weather protected slow closing solenoid valve(s) for the makeup water connection is factory supplied and is ready for piping to a water supply with a pressure between 5 and 125 psig (35 kPa and 860 kPa).

Electric Immersion Heaters

Electric immersion heaters are available as an option and are located in the basin of the cooler They are sized to maintain a +40°F (4.4°C) pan water temperature at 0°F (-18°C) ambient with the fans off *. They are furnished with a thermostat and low water protection device to cycle the heater on when required and to prevent the heater elements from energizing unless they are completely submerged. All components are enclosed in rugged, weather proof enclosures for outdoor use. Heater control packages that include contactor, transformer or disconnects are available.

(*) - Electric heater selection based on 0°F (-18° C) ambient temperature. For alternate low ambient heater selections consult the factory

Remote Sump Configuration

For units operating in areas where temperatures may be very low, or where low temperatures may occur during periods when the unit is not operating, a sump located inside the building is the preferred means of ensuring that the basin water will not freeze. For these applications, the cooler will be supplied without the spray pump, suction strainers and all associated piping, but is furnished with an oversized bottom outlet.

Solutions for Sound Sensitive Applications

The eco-ATWB Closed Circuit Coolers are now available with four (4) equipment options to reduce the overall sound generated from the side or top of the eco Closed Circuit Cooler. Each option provides various levels of sound reduction and options can be combined to provide the lowest sound level. Consult EVAPCO’s evapSelect selection program for unit sound levels. If a detailed analysis or full octave band data sheet is required for your application, please consult your EVAPCO Sales Representative.

NOTE: These low sound options may impact the overall installed dimensions of the eco-ATWB & eco-ATWB-E Closed Circuit
Cooler selected.

Water and Energy Conservation Control System

The best way to properly control and operate the eco-ATWB 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.

Pulse~Pure® Water Treatment System

The eco-ATWB is available with EVAPCO’s optional Pulse~Pure® non-chemical water treatment system. The Pulse~Pure® Water Treatment System utilizes pulsed-power technology to provide CHEMICAL FREE Water Treatment and is an environmentally responsible alternative for treating water in evaporative cooled equipment. It does not release harmful by-products to the environment and eliminates costly chemicals completely from cooler drift and blowdown. The Pulse~Pure® system delivers short, high-frequency bursts of low energy electromagnetic fields to the recirculating water in the eco-ATWB and will:

  • Control Bacteria to Levels Well Below Most Chemical Water Treatment Programs 
  • Control the Formation of Mineral Scale on Heat-Exchange Surfaces.
  • Save Water by Operating at Higher Cycles of Concentration
  • Yield Corrosion Rates Equivalent to Chemical Water Treatment

More benefits of offering EVAPCO’s Pulse~Pure® Water Treatment System on the new eco-ATWB are:

  • Pulse~Pure® Factory Mounting - Factory Installation of the Pulse~Pure® System Guarantees Your Water Treatment is Installed to Factory Specifications. 
  • Integral Cutting Edge Conductivity Control and Blowdown Packages that are contained in a single feeder panel:


Conductivity Control Package – Measures Conductivity Utilizing a Non-Fouling Torodial Probe
and Features:

  • One power connection of 120 volt or 460 volt is all that is required.
  • USB port for downloadable 60 day audit trail of system operation.
  • Self draining conductivity loop.

Motorized Blowdown Valve – Standard for the most reliable operation in bleed control. Three-way valve operation provides good bleed flow without a standing column of water.


Because ongoing water treatment service is an absolute requirement for any evaporative cooled system, each purchase of a Pulse~Pure® Water Treatment System includes, as standard, a 1 year water treatment service and monitoring contract provided by your EVAPCO Representative EVAPCO’s Pulse~Pure® system offers eco-ATWB & eco-ATWB-E owners a single-source of responsibility for equipment, water treatment and service. Patent #: 7,704,364

eco-ATWB Specification142.5 KB


A. Furnish and install as shown on the plans on EVAPCO Model ______ induced draft counterflow closed circuit cooler. Each unit shall be CTI Certified (with water) and have the capacity to cool ______ GPM of ______ from ______°F to______ °F with a _______ °F entering wet bulb temperature and a dry bulb switchover temperature of ______ °F (Dry Capacity is not CTI Certified). Optional: (If dry operating condition are different than the wet operating conditions) Each unit shall also cool ______ GPM of______ from______ °F to______ °F with a ______ °F entering dry bulb temperature.

B. Controls shall be provided with unit. See Controls Technical Specifications.



A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 1 Specification Sections, apply to this section.


A. This Section includes factory assembled and tested, closed circuit, induced draft counterflow cooling tower (also known as a closed circuit cooler).


A. General. Submit the following:
1. Certified drawings of the closed circuit cooler, sound data, recommended steel support indicating weight loadings, wiring diagrams, installation instructions, operation and maintenance instructions, and thermal performance guarantee by the manufacturer.


A. Verification of Performance:
1. Test and certify closed circuit cooler thermal performance according to CTI Standard 201.
2.Test and certify closed circuit cooler sound performance according to CTI ATC-128.
B. Meet or Exceed energy efficiency per ASHRAE 90.1.


A. Motor/Drive System: Five (5) year comprehensive warranty against materials and workmanship including motor, fan, bearings, mechanical support, sheaves, bushings and belt.
B. Unit: One (1) year from start-up, not to exceed eighteen (18) months from shipment on the unit.



A. Manufactures: Subject to compliance with requirements, provide closed circuit coolers manufactured by one of the following:
1. EVAPCO, Inc.
2. Approved Substitute


A. Galvanized Sheet Steel casing and fan housing complying with ASTM A 653/A 653M and having G-235 designation.
B. Optional Type 304 and/or 316 Stainless Steel as specified.


A. Description: Factory assembled and tested, induced draft counterflow closed circuit cooler complete with coil, fan, louvers, accessories, and rigging supports.
B. Closed Circuit Cooler Characteristics and Capacities: Refer to the Closed Circuit Cooler schedule.
C. Fan(s):
1. Type and Material: Axial propeller, individually adjustable wide chord blade extruded aluminum installed in a closely fitted cowl with venturi air inlet for maximum efficiency, covered with a heavy gauge hot dipped Galvanized Steel fan guard.
2. Maximum sound pressure level of _____dB(A) measured at 5 feet above the fan discharge during full speed operation in accordance with CTI Standard ATC-128.
D. Water Distribution System: Non-corrosive materials.
1. Each coil shall have a dedicated recirculation pump and water distribution system, which are completely separated by a water tight partition which begins above the water distribution systems and ends at the basin in order to allow for simultaneous wet and dry operation.
2. Evenly distribute of water over coil with pressurized spray tree.
a. Pipes: Schedule 40 PVC, Non-corrosive Materials
b. Nozzles: Non-clogging, nylon, threaded into branch piping.
E. IBC Compliance: The unit structure shall be designed, analyzed, and constructed in accordance with the latest edition of the International Building Code (IBC) Regulations for seismic loads up to _____ g and wind loads up to __ psf.
F. Collection Basin Material: Galvanized Steel. Type 304/316 Stainless Steel Optional:
1. Removable stainless-steel strainer with openings smaller than nozzle orifices.
2. Joints: Bolted and sealed watertight or welded.
3. Overflow, makeup and side drain connections
G. Heat Transfer Coil: Each row of the heat exchanger coil shall be provided with elliptical spiral fins to increase the evaporative and dry thermal performance of the unit as
well as lowering the air pressure drop. Cooling coil(s) shall be all primed surface steel, encased in a steel framework and hot-dip galvanized after fabrication as a complete assembly. The tubes shall be arranged in a self-spacing, staggered pattern in the direction of airflow for maximum heat transfer efficiency and minimum pressure drop. The coil(s) shall be pneumatically ested at 400 psig, under water.
H. Casing: Galvanized Steel. Type 304/316 Stainless Steel Optional:
1. Casing panels shall totally encase the heat transfer coil.
2. Fasteners: Corrosion resistance equal to or better than materials being fastened.
3. Joints: Sealed watertight.
4. Welded Connections: Continuous and watertight
I. Drift Eliminators: PVC, for long life and durability resistant to rot, decay and biological attack; formed, bonded together for strength and durability in block format for easy removal and replacement; self extinguishing with flame spread rating of 5 per ASTM E84-81a; 0.001% drift rate.
J. Air Inlet Louvers: Formed PVC; designed “Sight Tight” to completely block direct sunlight from entering and water from splashing out of the closed circuit cooler.
K. Water Level Control: Brass mechanical makeup water valve
and plastic float with an adjustable linkage.
L. Water Recirculation Pump: Close-coupled, centrifugal type with mechanical seal. The pump motor shall be ESA Compliant, ____ horsepower totally enclosed for outdoor service on ____ volts, ____ hertz, and ____ phase.


A. General requirements for motors are specified in Division 15 Section “Motors”.
B. Enclosure Type: TEAO or TEFC
C. Fan Motor Speed: Premium Efficient VFD Duty (Option: 2-speed)
1. Motors shall be provided with space heaters.
D. Drive: Power Band Belt designed for 150% of the motor nameplate HP.
1. Belt: Mutli-groove, solid back V-belt type neoprene reinforced with polyester cord.
2. Sheaves: Aluminum alloy if located inside the airstream.
3. Bearings: Heavy duty, self-aligning pillow block bearings with lubrication lines extended to side access door. Minimum L10 life for bearings shall be 75,000 hours. Provide extended grease lines and fittings.
4. Vibration Cutout Switch: (optional) Mechanical switch to deenergize fan motors if excessive vibration in NEMA 4 enclosure.


A. Internal Working / Service Platforms: Provide a complete internal working platform and ladder system for service of all drive components. A suitable working platform may be constructed of the heat transfer coil for counterflow closed  circuit coolers. If a crossflow cooler is used, provide an internal walkway with ladder and elevated working platform to allow for service and maintenance to motor and drive assembly.
B. Handrails/Grabrails: Galvanized steel pipe complying with 29 CFR 1910.23. If access to fan deck is required, supply a perimeter handrail with ladder from grade to fan deck.
C. Ladders: (optional) Aluminum, sloped “ships type” with grabrail or vertical complying with 29 CFR 1910.27.

Thermal Performance

Flow tables431.92 KB
Flow tables 30%PG458.83 KB
Flow tables 30%EG550.7 KB

Watch the eco-ATWB product video: