Closed Circuit Coolers

ESWA Closed Circuit Cooler

ESWA Closed Circuit Cooler

The ESWA is an induced draft, counterflow design closed circuit cooler with a CTI Certified capacity range of 900 to 18500 MBH (264 to 5422 kW). Standard construction includes the patented, high efficiency Sensi-Coil® technology, EVAPAK Fill and G-235 (Z725-Europe) galvanized steel casing and basin. Type 304 stainless steel construction is available for the basin or the entire unit.

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 warm process fluid circulates from the heat source to the coil of the closed circuit cooler. The fluid in the coil transfers its heat through the coil tube walls in a sensible exchange to the spray water that floods over the tubes. Having gained heat from the coil, the spray water then falls to the sump where it is circulated by the spray pump up through distribution piping to the spray nozzles. The warmed spray water is then distributed as a thin film over the fill-deck surface for maximum cooling efficiency. The fan system operates simultaneously, moving large volumes of air through the unit in a direction opposite the falling water. The air and water contact directly across the fill-deck surface whereupon a small portion of the spray water is evaporated. The evaporation process provides a latent exchange of heat from the spray water to the air passing through the unit. The air is then discharged from the unit as a warm and saturated stream with a final dissipation of heat to the atmosphere. The spray water exits the fill-deck module as a cooled fluid where it floods across the coil in a repeat cycle.

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

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

Patented Sensi-Coil® Technology

(US Patent #7,296,620) 

The Sensi-Coil®, exclusive on the ESWA 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 galvanized 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.

 Patented EVAPAK® Fill

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

An extremely efficient drift eliminator system is standard on the ESWA 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 ESWA Closed Circuit Cooler saves valuable water and water treatment chemicals. The ESWA 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 ESWA 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 ESWA to be available WHEN THE CUSTOMER WANTS IT!

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.

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.

Designed for easy maintenance, the ESWA 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 ESWA 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 is designed for trouble-free maintenance and long life straight from the factory.

Easy 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 basin of the ESWA is sloped toward a depressed area where the drain is located. With the "Clean Pan" design, it is easy for a service mechanic to flush the pan without getting his feet wet. Other fluid cooler designs may necessitate getting inside of the unit for complete cleaning.

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.

Thermal-Pak Coil


EVAPCO's exclusive elliptical Thermal-Pak® coil is manufactured at EVAPCO from high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected to assure the highest material quality and then is tested at 400 psig (2758 kPa) 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 (427° C). The tubes are pitched in the direction of fluid flow to provide good liquid drainage.
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.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The ESWA 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.

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


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


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.

The ESWA Closed Circuit Cooler is an Advanced Technology, induced draft counterflow design closed circuit cooler featuring EVAPCO's patented THERMAL-PAK® COIL - 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.

Fan Motors

All ESWA 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 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 ESWA 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.

(5) Five Year Warranty

EVAPCO provides a standard (5) five year motor and drive warranty on all direct drive Power-Band belt drive and optional gear drive ESWA 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 ESWA 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.

The standard design of the EVAPCO ESWA 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.

Evapco Manufactured 304 Stainless Steel Coils

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 design used on AT, UB, LR and LS coolers and condensers and in the patent pending SensiCoil design used in the ESWA. 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 Instruction Bulletin, 112AA. The Evapco 304 SST coil option can be manufactured as an ASME coil and is CTI certified on the ESWA and ATWB closed circuit cooler.

Super Low Sound Fan

9 - 15 db(A) Reduction versus Standard Fan!

The Super Low Sound Fan offered by EVAPCO utilizes an extremely wide chord blade design available for sound sensitive applications where the lowest sound levels are desired. The fan is one-piece molded heavy duty FRP construction utilizing a forward swept blade design. The Super Low Sound Fan is capable of reducing the unit sound pressure levels 9dB(A) to 15dB(A), depending upon specific unit selection and measurement location. The fans are high efficiency axial propeller type and operate with no loss of thermal performance and provide CTI Certified Performance.

The Super Low Sound Fan is available on all 8.5ft and 12ft (2.4m and 3.6m Europe) wide ESWA Closed Circuit Coolers.

View Product Video

Super Low Sound Fan 

Sloped Access Ladders

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

The ESWA 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

ESWA 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 25 and 50 psig (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 +40°F (4.4°C) pan water temperature at 0°F (-18°C) ambient with the fans off *. They are furnished with a combination thermostat/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

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
ESWA Specification59 KB



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.

Thermal Performance

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