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 583 to 7264 MBH (171 to 2129 kW). Standard construction includes the patented, high efficiency Sensi-Coil® Technology featuring CrossCool™ Internal Tube Enhancement , EVAPAK Fill and G-235 (Z725-Europe) galvanized steel casing and basin. Type 304 stainless steel construction is available for the basin, the redistribution basin, or the entire unit.

The ESWB stands apart as being the most energy efficient and the quietest axial fan closed circuit cooler on the market today. The ESWB is able to provide superior performance as a result of its full footprint patented Sensi-Coil® Technology. The Sensi-Coil® now features CrossCool™ Internal Tube Enhancement which increases the internal heat transfer coefficient of the coil and thus increases the cooling capacity of the unit.

The ESWB’s Cooling Technology Institute † certified performance, new owner oriented features and independent certification of the International Building Code (IBC) compliance reinforce the ESWB’s position as a premier cooler in the HVAC industry.

Principle of Operation

Evapco was the first to develop a closed circuit cooler with Patented Optimized Technology. The pump is energized, and water is circulated up to the water distribution system. This starts with the large orifice EvapJet nozzles evenly distributing water as a thin film over the extended fill 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 surface whereupon a small portion of the spray water is evaporated. The warm and saturated air is then discharged from the unit dissipating heat to the atmosphere. The spray water exits the fill section as a cooled fluid where it is collected by the redistribution basin for even soaking of the full footprint coil. The hot process fluid enters the coil through the bottom coil connection(s). The heat load is rejected to the circulating water that cascades over the coil surface by means of sensible heat transfer.

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

Sensi-Coil® Technology

Sensi-Coil®, featuring CROSSCOOL™ tube enhancement, 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 50% 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.

TITAN COIL with XT construction is 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

 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 ESWB 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 ESWB Closed Circuit Cooler saves valuable water and water treatment chemicals. The ESWB 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 ESWB 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 ESWB to be available WHEN THE CUSTOMER WANTS IT!

Framed Water Sight Tight Air Inlet Louver

Evapco's innovative air inlet louvers are both water and sight tight to ensure that the water stays in and the sunlight stays out of the cold water basin. Using extensive computational fluid dynamics modeling, Evapco engineers developed a louver to improve “splash resistance” while maximizing airflow. The resulting design maximizes thermal performance while minimizing water loss. This sight tight design also inhibits algae growth more effectively than previous designs. Evapco’s louver design solves the problem of the circulating water and heat transfer surfaces being directly exposed to external contaminants and the harsh surroundings.

Water Distribution System

The water distribution system is enclosed and completely protected by the casing panels and drift eliminators. The eliminators also function as effective debris screens which block sunlight and prevent debris from entering the spray system. The water distribution system is made with non-corrosive materials including schedule 40 PVC pipe for its distribution system and EvapJet® nozzles. The spray branch piping is easily removed and designed with threaded end-caps for easy cleaning. EVAPCO’s EvapJet® nozzles and water distribution system design eliminates the problems of biological growth and clogging that can occur with a system that is open to direct sunlight and the surroundings.

Redistribution Basin

The redistribution basin ensures even water loading of the full footprint Sensi-Coil® The redistribution basin is enclosed and completely protected by the air inlet louvers. The louvers also function as effective debris screens which block sunlight and prevent debris from entering redistribution system. The redistribution basin is easily inspected with the removal of the framed air inlet louvers.

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 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 ESWB 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 wet feet. 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.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The ESWB 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 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 (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 ESWB 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 ESWB Closed Circuit Cooler with inherently better operational and maintenance features. The ESWB is now standard with CTI Certified Performance including the Super Low Sound Fan option. These features are described below.

Fan Motors

All ESWB 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 ESWB 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.

(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 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, sheaves, fan bearings, gear box, flexible coupling, driveshaft and the motor.

Fan Shaft Bearings

The fan shaft bearings on the ESWB 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 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.

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 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 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.

The Super Low Sound Fan is available on all 8.5ft and 12ft (2.4m and 3.6m Europe) wide ESWB 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 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 as well as to the redistribution basin. 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 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.

External Platforms, Ladders & Motor Davits

External platforms provide a sturdy base for access to the drive components, water distribution and drift eliminators. Constructed from heavy gauge galvanized steel, the platform mounts easily to the unit and requires no external support. The platform option includes a vertical aluminum ladder and meets all applicable OSHA requirements. A safety cage for the ladder is also available if required for the installation. The platform option also includes a vertical aluminum ladder to inspect the redistribution basin.

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

SECTION 23 65 00





A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section.


A. This Section includes factory assembled and tested, closed circuit mechanical induced-draft vertical discharge closed circuit cooler.


A. Product Data: For each type of product indicated. Include rated capacities, pressure drop, performance curves with selected points indicated, furnished specialties, and accessories.

B. Shop Drawings: Complete set of manufacturer's prints of evaporative equipment assemblies, control panels, sections and elevations, and unit isolation. Include the following:

1. Assembled unit dimensions.

2. Weight and load distribution.

3. Required clearances for maintenance and operation.

4. Sizes and locations of piping and wiring connections.

5. Wiring Diagrams: For power, signal, and control wiring. Differentiate between manufacturer installed and field installed wiring.

C. Operation and Maintenance Data: Each unit to include, operation, and maintenance manual.


A. Verification of Performance:

1. Manufacturer shall have a thermal performance testing program for water cooling towers certified by the Cooling Technology Institute (CTI) in accordance with CTI Specification Standard STD-201. Manufacturer’s performance guarantees or performance bonds shall also be accepted.

2. Unit Sound Performance ratings shall be tested and certified according to CTI ATC-128 standard. Sound ratings shall not exceed specified ratings.

B. Unit shall meet or exceed energy efficiency per ASHRAE 90.1


A. Submit a written warranty executed by the manufacturer, agreeing to repair or replace components of the unit that fail in materials and workmanship within the specified warranty period.

1. Fan Motor/Drive System: Warranty Period shall be Five (5) years from date of unit shipment from Factory (fan motor(s), fan(s), bearings, mechanical support, sheaves, bushings and belt(s))

2. The Entire Unit shall have a comprehensive one (1) year warranty against defects in materials and workmanship from startup, not to exceed eighteen (18) months from shipment of the unit.

3. Heat Transfer Coil: Warranty Period shall be one (1) year from date of unit shipment from Factory.



A. Manufacturers: Subject to compliance with requirements, provide closed circuit coolers manufactured by one of the following:

1. EVAPCO Model ESWB ________

2. Approved Substitute


A. Each unit shall be capable to cool _____ GPM of water entering at ____ºF leaving at ____ºF at a design wet bulb of ____ºF with a pressure drop across the coil not to exceed ____psi.


A. The unit structure shall be designed, analyzed, and constructed in accordance with the latest edition of International Building Code (IBC) Regulations for seismic loads up to 1.0 g or wind loads up to 145 psf


A. Description: Factory assembled and tested, induced draft counter flow closed circuit cooler complete with fan, coil, fill, louvers, accessories and rigging supports

B. Materials of Construction

1. All cold water basin components including vertical supports, air inlet louver frames and panels up to rigging seam shall be constructed of heavy gauge mill hot-dip galvanized steel.

2. Upper Casing, channels and angle supports shall be constructed of heavy gauge mill hot-dip galvanized steel. Fan cowl and guard shall be constructed of galvanized steel. All galvanized steel shall be coated with a minimum of 2.35 ounces of zinc per square foot area (G-235 designation). During fabrication, all galvanized steel panel edges shall be coated with a 95% pure zinc-rich compound.

C. Fan(s):

1. Shall be high efficiency axial propeller type with aluminum wide chord blade construction. Each fan shall be statically balanced and installed in a closely fitted cowl with venturi air inlet for maximum fan efficiency.

D. Drift Eliminators

1. The eliminators shall be constructed entirely of Polyvinyl Chloride (PVC) in easily handled sections. Design shall incorporate three changes in air direction and limit the water carryover to a maximum of 0.001% of the recirculating water rate.

E. Water Distribution System

1. Spray nozzles shall be precision molded ABS, large orifice spray nozzles utilizing fluidic technology for superior water distribution over the fill media and to minimize water distribution system maintenance. Spray header, branches, and riser shall be Schedule 40 Polyvinyl Chloride (PVC) for corrosion resistance. Branches shall have threaded end caps to facilitate debris removal.

F. Heat Transfer Media

1. Heat transfer coil shall be tightly spaced elliptical tubes of prime surface steel, encased in steel framework with the entire assembly hot-dip galvanized after fabrication. The coil assembly shall be designed with sloping tubes for liquid drainage and tested to 400psig air under water. Coil shall meet strength requirements of ASME/ANSI B31.5.

2. Fill media shall be constructed of Polyvinyl Chloride (PVC) of cross-fluted design and suitable for inlet water temperatures up to 130 F. The bonded block fill shall be bottom supported and suitable as an internal working platform. Fill shall be self-extinguishing, have a flame spread of 5 under A.S.T.M. designation E-84-81a, and shall be resistant to rot, decay and biological attack.

G. Pump

1. Unit shall have an EISA compliant, close-coupled centrifugal pump with mechanical seal. The pump shall be installed in a vertical position so that water will drain from the pump when the cold water basin is emptied. Pump motor shall be totally enclosed with protective canopy for outdoor operation.

H. Bleed-off

1. Unit shall have a waste water bleed line with adjustable valve provided.

I. Air Inlet Louvers

1. The air inlet louvers shall be constructed from UV inhibited polyvinyl chloride (PVC) and incorporate a framed interlocking design that allows for easy removal of louvers for access to the entire basin area for maintenance. The louvers shall have a minimum of two changes in air direction and shall be of a non-planar design to prevent splash-out, block direct sunlight and debris from entering the basin.

J. Make up Float Valve Assembly

1. Make up float assembly shall be brass float valve with adjustable plastic float.

K. Pan Strainer

1. Pan Strainer shall be all type 304 stainless steel construction with large area removable perforated screens.


A. General requirements for motors are specified in Division 23 Section “Motors”

B. Fan Motor

1. Fan motor(s) shall be totally enclosed, ball bearing type electric motor(s) suitable for moist air service. Motor(s) are Premium Efficient, Class F insulated, 1.15 service factor design. Inverter rated per NEMA MG1 Part and suitable for variable torque applications and constant torque speed range with properly sized and adjusted variable frequency drives.

C. Fan Drive

1. The fan drive shall be multigroove, solid back V-belt type with taper lock bushings designed for 150% of the motor nameplate horsepower. The belt material shall be neoprene reinforced with polyester cord and specifically designed for evaporative equipment service. Fan and motor sheave shall be aluminum alloy construction. Belt adjustment shall be accomplished from the exterior of the unit.

D. Fan Shaft

1. Shaft shall be Solid, ground and polished steel. Exposed surface coated with rust preventative.

E. Fan Shaft Bearings

1. Fan Shaft Bearings shall be heavy-duty, self-aligning ball type bearings with extended lubrication lines to grease fittings located on access door frame. Bearings shall be designed for a minimum L-10 life of 75,000 hours.


A. Fan Section

1. Access door shall be hinged and located in the upper casing for fan drive and water distribution system access.

B. Basin Section

1. Framed removable louver panels shall be on all four sides of the unit for pan and sump access.

C. Internal Working Platform

1. Internal working platform shall provide for easy access to the fans, belts, motor, sheaves, bearings, all mechanical equipment and complete water distribution system. The fill shall be an acceptable means of accessing these components.





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