Closed Circuit Coolers

ESWB Closed Circuit Cooler

ESWB Closed Circuit Cooler

The ESWB is an induced draft, counterflow design closed circuit cooler with a CTI Certified capacity range of 264 to 5,422 kW. Standard construction includes the patented, high efficiency Sensi-Coil® technology, EVAPAK Fill and G-235 (Z725-Europe) galvanised steel casing and basin. Type 304 stainless steel construction is available for the basin or the entire unit.

Design Features

The ESWA Closed Circuit Cooler is an Advanced Technology, induced draft counterflow design closed circuit cooler featuring EVAPCO's patented Sensi-Coil® technology - the most efficient in the industry. The counterflow design provides the ESWA Closed Circuit Cooler with inherently better operational and maintenance features. The ESWA is now standard with CTI Certified Performance including the Super Low Sound Fan option. These features are described below.

Principle of Operation

The process fluid is recirculated through the coil of the closed circuit cooler. Heat from the process fluid is dissipated through the coil bundle to the water cascading downward over the tubes. Simultaneously, air is drawn in through the air inlet louvers at the base of the cooler and travels upward over the coil in the opposite direction to/of the water. A small portion of the water is evaporated which removes the head.

The warm moist air is drawn to the top of the closed circuit cooler by the fan and is discharged to the atmosphere. The remaining water falls to the sump at the bottom of the cooler where it is recirculated by the pump, up through the water distribution system and back down over the coils. 

Sensi-Coil® Technology

The patented Sensi-Coil®, exclusive on the ESWB closed circuit cooler, features the maximum amount of Thermal-Pak elliptical tubes packed closely together in a coil arrangement designed with over 20% additional coil surface area.

EVAPCO's coils are manufactured within the most stringent of quality control procedures. Each circuit consists of high quality steel tubing formed into a continuous serpentine circuit. Each circuit is then inspected and tested prior to being welded into a framed coil assembly. The coil assembly is then pneumatically tested at 400 psig under water to ensure its integrity. The entire coil assembly is then hot-dip galvanised for industrial strength corrosion protection.

Now EVAPCO offers the TITAN COIL. Manufactured from type 304L Stainless Steel, the TITAN COIL is manufactured using EVAPCO's patented elliptical tube Sensi-Coil ® design upgraded to Xtra Tough construction featuring: Xtra Durability, Xtra Corrosion Resistance, and an Xtra long 5 YEAR coil warranty as standard.


The patented EVAPAK® Fill is specially designed to induce highly turbulent mixing of the air and water for superior heat transfer. The fill-pack is constructed of polyvinyl chloride (PVC) sheets which are thermally formed into a cross flute design. The individual fill sheets are bonded together to form rigid fill blocks. The fill blocks are then stacked within the unit's protective casing. The structural strength of the assembled fill deck enables it to be used as a working platform. EVAPAK® fill is impervious to rot and decay, and is self-extinguishing with a flame spread rating of 5 per ASTM Standard E84.

Efficient Drift Eliminators

The ESWB is provided with an efficient drift eliminator system that effectively reduces entrained water droplets from the air discharge to less than 0.001% of the recirculated 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 additon to reducing drift, the eliminators also function as effective debris screens which protect the spray system and coils from sunlight debris.

Superior Air Inlet Louver and Screen Design

The air inlet louver screens are non-corrosive PVC with a multi-pass design to prevent water splashout, and to prevent sunlight and debris from entering the basin. This unique louver design completely encloses and protects the circulating the water system and heat transfer surfaces. The potential for algae formation is greatly reduced since direct sunlight is blocked out from the basin area. Biological growth is further inhibited because the 3/4" openings block leaves and biological contaminants from entering the circulating water system.

Pressurised 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.

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 60 psf wind loads

  • Upgraded Structural Design

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

Thermal-Pak Coil II®

The EVAPCO Thermal-Pak Coil II® features elliptical tube design, first in the industry and now available with the ESWB! The elliptical tube design allows the coil bundle to be densely packed, reducing the number of tubes per bundle up to 10%. This provides weight and cost savings! Additionally, the elliptical tubes have inherent spacing between each other which permits larger amount of air through the tower without impeding the spray water from falling or creating additional static.

This revolutionary design makes the EVAPCO ESWB the leading FRP closed circuit cooler in the industry today! The TPII coils are fashioned out of high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected at the weld seam then tested again before being stacked into a coil. Finally, the coil bundle is pneumatically tested at 2.76 MPa under water to ensure it is leak free.

To protect the coil against corrosion, the coil bundle is placed in a heavy steel frame and dipped in molten zinc (hot-dip galvanised) at a temperature of approximately 427°C.

Note: Closed circuit coolers should only be used on sealed, pressurised systems. Continual aeration of the water in an open system can cause corrosion inside the tube of the cooler leading to premature failure.

Maintenance Features

Designed for easy maintenance, the ESWB 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 ESWB 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 Thermal-Pak Coil II® is designed for trouble-free maintenance and long life straight from the factory.

Easy Basin Access

The cold water basin section is easily accessible from ground level. The basin is provided with solid access panels which are designed to protect the basin water and heat transfer coil from direct exposure to sunlight and debris. The access panels are light-weight and have handles for easy removal. With the access panels removed, a service mechanic has complete access to the basin floor, heat transfer coil, float assembly and pump strainer.

"Clean Pan" Basin Design

The ESWB 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 minimises 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.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The ESWB features a Quick Release Fastener design consisting of two (2) large thumbscrews and a latch system. By loosening the thumbscrews, the latch pulls up and out of the louver frame, allowing the Easy, Removable Air Inlet Louvers with Quick Release Fasteners to be removed while the latch and thumbscrews stay on the closed circuit cooler.

Belt Drive Units - 12' (3,7) Wide Models

The T.E.A.O. fan motor is located inside the fan casing on the large ESWB 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 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 galvanised 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.

Belt Drive Units - 8 1/2' (2,6) Wide Models

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.

Drive Systems

The ESWB Closed Circuit Cooler features the highly successful EVAPCO Power-Band Belt Drive System engineered for heavy-duty operation. The Power-Band Belt Drive System has consistently provided trouble-free operation in the most severe duty closed circuit cooler applications. Click on the features below for more details.

Fan Motors

All ESWB Closed Circuit Cooler models utilise 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

8.5' (2,6 m) wide ESWA 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 ESWB 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 ESWB are specially selected to provide long life, minimising costly downtime. They are rated for a minimum L-10 life of 75,000 hours, making them the heaviest duty flange mount bearing in the industry used for evaporative condensers.

Drive System Pulleys

Drive System Pulleys located in the warm, moist atmosphere inside the evaporative condenser are constructed of an aluminium alloy.

Power-Band Belt Drive

The Power-Band Belt Drive is a solid-back multi-groove 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% of the motor nameplate horsepower ensuring long and trouble free operation.

Five (5) Year Drive Warranty

EVAPCO provides a standard Five (5) Year Motor and Drive Warranty on all Power-Band Belt Drive and optional gear drive ESWB 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, pulleys, fan bearings, gear box, flexible coupling, driveshaft and the motor.

Optional Equipment 

The standard design of the EVAPCO ESWB 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:

304 Stainless Steel Coil

The EVAPCO manufactured Stainless Steel Coil is an elliptical tube, continuous return bend, 304 stainless steel coil. It is available in both the Patented Thermal-Pak Coil II®  design used on AT, UB, LR and LS coolers and condensers and in the patent pending SensiCoil design used in the ESWB. This option has superior corrosion  resistance for open systems and hostile environments and is available with the Standard EVAPCO Lead Time! For more detail on the corrosion resistant properties of 304 stainless steel, see EVAPCO's Maintenance Instructions. The EVAPCO 304 SST coil option can be manufactured as an ASME coil and is CTI certified on the ESWB and ATWB closed circuit cooler.

Sloped Access Ladders

A sloped access ladder is available for 8.5' and 12', (2,6 and 3,7m) wide ESWB 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. 

Stainless Steel Water Touch Basin

The ESWB Closed Circuit Cooler has 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 Water Touch Basin. This option provides Type 304 or Type 316 stainless steel for the entire basin area including the support columns of the closed circuit cooler and the louver frames.

The basin section provides the structural support for the unit and is a critical part of the closed circuit cooler. The Stainless Steel Water Touch Basin provides maximum corrosion protection.

Working Platform & Ladder with Davit

ESWB 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 galvanised 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 galvanised 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. 

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 138 kPa and 345 kPa.

Electric Heaters

Electric immersion heaters are available as an option and are located in the basin of the cooler They are sized to maintain a 4,4º C pan water temperature at -18º 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 energising 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 -18º C ambient temperature. For alternate low ambient heater selections consult the factory.

Other Options

  • Hot Water or Steam Coils

  • Steam Injectors

  • Vibration Isolators (single cell only)

  • Vibration Switches

  • Remote Sump Connections

  • Insulation on Hood and Casing

  • Motors– Energy Efficient / Inverter Duty /2S/1W and 2S/2W / Mill and Chem DutyAutomotive Duty and Many More,Consult the Factory



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 cooling tower thermal performance according to CTI Standard 201.

     2.Test and certify cooling tower 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 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, fill, 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. Evenly distribute of water over fill material with pressurized spray tree. a. Pipes: Schedule 40 PVC, Non-corrosive Materials b. Nozzles: Non-clogging, ABS Plastic, threaded into branch piping.

     2. Maximum pressure at inlet shall be ____ psig.

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 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

     4. Flume plate between cells (for multiple-cell units) or Equalizer connection (for multiple- closed circuit cooler system).

G. Heat Transfer Coil: Heavy Gauge G-235 Galvanized Steel encased in a steel framework, assembly hot-dip galvanized after construction. Type 304 Stainless Steel Optional. Coil assembly completely enclosed and protected from sunlight exposure, environmental elements and debris. Tubes sloped for free drainage of the coil and designed for low pressure drop. Coil assembly pneumatically tested at 400 psig under water. Coil connections beveled for weld, flanged (optional) or grooved (optional).

H. Casing: Galvanized Steel. Type 304 Stainless Steel Optional:

     1. Casing panels shall totally encase the fill media to protect the fill from damage due to direct atmospheric contact.

     2. Fasteners: Corrosion resistance equal to or better than materials being fastened.

     3. Joints: Sealed watertight.

     4. Welded Connections: Continuous and watertight

I. Fill Media: PVC; resistant to rot, decay and biological attack; formed, crossfluted bonded together for strength and durability in block format for easy removal and replacement; suitable for use as a working surface; self extinguishing with flame spread rating of 5 per ASTM E84-81a; able to withstand continuous operating temperature of 130°F; and fabricated, formed and installed by the manufacturer to ensure water breaks up into droplets.

J. Drift Eliminators: Same material as Fill. 0.001% drift rate.

K. 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.

L. Water Level Control: Brass mechanical makeup water valve and plastic float with an adjustable linkage. M. Water Recirculation Pump: Close-coupled, centrifugal type with mechanical seal. The pump motor shall be ____ 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. Motor Speed: Premium Efficient VFD Duty (Option: 2-speed)

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: Mechanical switch to de- energize 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 fill media 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: Aluminum, sloped "ships type" with grabrail or vertical complying with 29 CFR 1910.27.

Low Sound Solutions

The ESWB Closed Circuit Cooler is now available with three (3) options to reduce the overall sound generated from the ends, sides, or top of the unit. Each option provides various levels of sound reduction and can be used in combination to provide the lowest sound level. Consult EVAPCO's 'evapSelect' equipment selection program for full octave band data sheet. 

NOTE: These low sound options may impact the overall installed dimensions and weight of the unit.

Super Low Sound Fan

The EVAPCO Super Low Sound Fan utilises an extremely wide chord blade design for sound sensitive applications where the lowest sound levels are desired. The fan is one-piece molded heavy duty FRP construction utilising a forward swept blade design. The EVAPCO Super Low Sound Fan is capable of reducing unit sound pressure levels 9 db(A) to 15 db(A), depending upon specific unit selection and measurement location. The EVAPCO Super Low Sound Fan is optional on ALL Induced Draft Cooling Towers, ATWB, eco-ATWB, eco-ATWB-E, MTW and ESWB Closed Circuit Coolers and ATC-E, cATC, eco-ATC and MTC-A Evaporative Condensers 2.24 metres wide and larger.

Low Sound Fan*

The EVAPCO Low Sound Fan utilises a wide chord blade design for sound sensitive applications where low sound levels are desired. The fan is a unique soft connect blade-to-hub design which eliminates critical blade passing frequencies at any speed. The Low Sound Fan is capable of reducing the unit sound pressure levels 4 db(A) to 7 db(A), depending upon specific unit selection and measurement location. The EVAPCO Low Sound Fan is optional on ALL Induced Draft Cooling Towers, ATWB, cATWB, eco-ATWB, eco-ATWB-E, MTW and ESWB Closed Circuit Coolers and ATC-E, cATC, eco-ATC and MTC-A Evaporative Condensers.

*The Low Sound Fan will have a CTI Certified thermal performance derate up to 3.5%. Consult the factory or EVAPCO’s evapSelect selection software for actual thermal performance.

Fan Discharge Sound Attenuation

Fan Discharge Sound Attenuation is a factory assembled straight sided discharge hood designed to reduce overall discharge sound levels 5 db(A) to 10 db(A), depending on specific unit selection and measurement location. It is constructed of G-235 galvanised steel as standard (stainless steel construction also available) and includes acoustically lined fiberglass walls and a low pressure drop baffling system. The discharge attenuation option is supported entirely by the unit and is shipped as an assembled section for easy field mounting. Fan Discharge Sound Attenuation is optional on AT and cAT Cooling Towers, ATWB, cATWB, eco-ATWB, eco-ATWB-E and ESWB Closed Circuit Coolers and ATC-E, cATC and eco-ATC Evaporative Condensers.

*Fan Discharge Sound Attenuation will have a CTI Certified thermal performance derate up to 5%. Consult the factory or EVAPCO’s evapSelect selection software for actual thermal performance.