Factory Assembled Cooling Towers

AT Cooling Tower

AT Cooling Tower

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

The AT is an induced draft, counterflow design cooling tower with a CTI certified capacity range of 33 to 5,141 nominal tons (144 to 22,596 kW). The largest AT tower - the 14'x26', dual fan "Big AT" is rated for up to 1,332 nominal tons per cell.

Standard construction consists of G-235 (Z-725 Europe) galvanized steel with type 304 or 316 stainless steel available for the basin or the entire tower.

Design Features

The AT Cooling Tower product line is an Advanced Technology design which utilizes induced draft counterflow technology - the most efficient in the industry and the best design for operation in a freezing climate. The counterflow design provides the AT Cooling Tower with inherently better operational and maintenance features. Click on the features below for more details.

  Principle of Operation

Warm water from the heat source is pumped to the water distribution system at the top of the tower. The water is distributed over the wet deck fill by means of large orifice nozzles. Simultaneously, air is drawn in through the air inlet louvers at the base of the tower and travels upward through the wet deck fill opposite the water flow. A small portion of the water is evaporated which removes the heat from the remaining water. The warm moist air is drawn to the top of the cooling tower by the fan and discharged to the atmosphere. The cooled water drains to the basin at the bottom of the tower and is returned to the heat source.

The vertical air discharge of the AT design and the distance between the discharge air and fresh air intakes, reduces the chance of air recirculation, since the warm humid air is directed up and away from the unit. For detailed layout information please consult EVAPCO's Equipment Layout Guidelines.

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 and upgraded structural designs for 1.0 and 1.5 importance factor applications. 

Easy Field Rigging

• A new field assembly seam design which insures easier assembly and reduced potential for field seam leaks.

• Self guided channels guide the fan casing section into position improving the quality of the field seam.

• Eliminates up to 66% of fasteners.

Efficient Drift Eliminators

An extremely efficient drift eliminator system is standard on the AT Cooling Tower. 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 AT Cooling Tower saves valuable water and water treatment chemicals. The AT 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.

The EVAPAK® Fill

EVAPAK® fill design used in the AT Cooling Tower is specially designed to induce highly turbulent mixing of the air and water for superior heat transfer. Special drainage tips allow high water loadings without excessive pressure drop. The fill is constructed of inert polyvinyl chloride, (PVC). It will not rot or decay and is formulated to withstand water temperatures of 130ºF (54,4ºC). Because of the unique way in which the crossfluted sheets are bonded together, and the bottom support of the fill section, the structural integrity of the fill is greatly enhanced, making the fill usable as a working platform. The fill selected for the Cooling Tower has excellent fire resistant qualities. Cooling Tower fill has a flame spread rating of 5 per ASTM-E84-81a. A higher temperature fill is available for water temperatures exceeding 130ºF (54,4ºC). Consult your EVAPCO representative for further details.

Superior Air Inlet Louver and Screen Design 

The air inlet louver screens on the are constructed of corrosion-free PVC . They are a "Sight-Tight" two pass design that minimizes splashout and reduces the potential for algae formation inside the tower.

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.

EVAPCO's unique louver design completely encloses the basin area. Direct sunlight is blocked from the water inside the cooling tower, 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 cooling tower.

Reduced Piping Costs

Each cell of the AT Cooling Tower is furnished with one inlet and one outlet piping connection. This design reduces the amount of external piping and thereby lowers the installed cost of the cooling tower. The water distribution system is pressurized and self balancing. Since field balancing is not required on the AT, the need for flow balancing valves is eliminated, further reducing the cost of tower installation. The wide orifice nozzles with anti-sludge ring used in the AT water distribution system helps prevent clogging, reducing the maintenance costs of the water distribution system.

Pressurized Water Distribution System

The water distribution system is made of schedule 40 PVC pipe and ABS plastic water diffusers for corrosion protection in this key area. The piping is easily removable for cleaning. The water diffusers have a minimum opening of 3/8 by 1 inch (9,5 mm by 25,4 mm) and are practically impossible to clog. They also have an anti-sludge ring extending into the headers to prevent sediment from building up in the diffuser opening.

The spray pressure for all AT Cooling Towers is between 1 and 6 psig (6,9 and 42 kPa) at the
inlet header. The actual spray pressure will be shown on the certified drawings which are prepared for each unit.

View Product Video

EvapJet®   Nozzles



Optimum Design for Freezing Climates

The counterflow fill design used in the AT Cooling Tower is well suited for winter operation. The wet deck surface is totally encased, and protected from freezing winds thus inhibiting ice formation on the fill section.

The even temperature gradient of the counterflow fill design makes the AT Cooling Tower the ideal unit for operation in freezing climates.

The counterflow design of the AT Cooling Tower fill section reduces the chance of ice formation and with bottom support, eliminates fill collapse should ice form.

Fast, On-Time Shipments

The AT is a completely factory assembled cooling tower manufactured by a dedicated professional workforce, expert in building cooling towers. 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 AT to be available WHEN THE CUSTOMER WANTS IT!

Maintenance Features

Designed for easy maintenance, the AT cooling tower leads the industry in service friendly features. The two most critical areas for cooling tower maintenance are the basin and the drive system. The AT basin section is designed to allow quick and easy access from outside the cooling tower. Just like the basin, all service to the drive system can be safely performed from the side of the cooling tower. This eliminates the need to stand in the cold water basin or add costly fan deck handrails and safety cages for routine service to the bearings, belts, or electrical equipment. Evapco's Power-Band drive system is the easiest belt drive system to maintain in the industry! Click on the features below for more details.

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 cooling tower and lifting out the lightweight louver.

The basin can be accessed from all (4) four sides of the cooling tower. The bottom of the fill section is a minimum of four (4) feet (1,2 m) above the basin floor. This open basin design enables the AT basin to be easily cleaned.

Louver Access Door

• Hinged access panel with quick release mechanism.

• Allows easy access to perform routine maintenance and inspection of the make-up assembly, strainer screen, and basin.

• Available on models with 5 foot and taller louvers.

Easy, Removable Air Inlet Louvers with Quick Release Fasteners

The AT 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 Easy, Removable Air Inlet Louvers with Quick Release Fasteners to be removed while the latch and thumbscrews stay on the cooling tower.

Clean Pan Basin Design

The AT 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 cooling tower 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 cooling tower subject to excessive wear and corrosion. With stainless steel construction, this component will last the life of the cooling tower.

8.5' Wide Units, 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.


10', 12' and 14' Wide Units, Power Band Belt Adjustment and Bearing Lubrication

The T.E.A.O. fan motor is located inside the fan casing on the large AT Cooling Tower, 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.

The AT Cooling Tower 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 cooling tower applications. In addition, the complete drive system including the fan motor is standard with a (5) Five Year Warranty. Click on the features below for more details.

Fan Motors

All AT Cooling Tower models utilize heavy duty totally enclosed (T.E.F.C. or T.E.A.O) fan motors designed specifically for cooling tower applications. In addition to the standard Inverter Capable, Premium Efficient motors offered on each cooling tower, EVAPCO offers many optional motors to meet your specific needs, including:

•Multi-Speed Motors
•Mill and Chemical Duty
•Motor Space Heaters 

The T.E.F.C. motors are located on the outside of the unit in 4' and 8.5' wide units, and are protected by a hinged, swing away cover.

10', 12' and 14' wide AT units 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.

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 cooling tower service, and is constructed of neoprene with polyester cords. The drive belt is sized for of the motor nameplate horsepower ensuring long and trouble free operation.

Drive System Sheaves

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

Fan Shaft Bearings

The fan shaft bearings on the AT cooling tower 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 cooling tower duty.

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 AT Cooling Towers. 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.

The standard design of the EVAPCO AT provides the customer with the easiest cooling tower to maintain in the industry. There are additional options which can make maintenance easier and extend the life of the cooling tower. These options are listed below.

Sloped Access Ladders

A sloped access ladder is available for all AT 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.


Working Platform & Ladder with Davit

AT Cooling Towers 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  bracket is constructed of heavy duty galvanized steel and is factory mounted on the side of the unit. The light weight aluminum davit ships loose and is installed in the field. (The working platform and ladder meet all applicable OSHA requirements.)

Stainless Steel Water Touch Basin

The AT Cooling Tower has a modular design which allows specific areas to be enhanced for increased corrosion protection. The basin area of the cooling tower 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 cooling tower and the louver frames.

The basin section provides the structural support for the unit and is the most important part of the cooling tower. The Stainless Steel Water Touch Basin provides maximum corrosion protection.

EVAPCO Gear Drive System

The AT Cooling Tower is available with an optional precision gear drive system on 8.5', 10', 12', and 14' wide units (with the exception of 6' and 7.5' long units)  and standard on the 100HP 14' wide units. The EVAPCO Gear Drive System has been carefully designed to provide long life and troublefree operation, even in severe duty cooling tower applications. All gear drive system component manufacturers have been selected utililizing the leaders in the industry. The EVAPCO Gear Drive System is designed with a minimum 2.0 service factor and meets or exceeds AGMA and CTI gear drive standards.

Internally and externally mounted motors are available in gear driven applications, making use of rubber flex couplings and composite drive-shafts respectively.

Electric Heaters

Electric immersion heaters are available as an option and are located in the basin of the tower. They are sized to maintain a +40° F (4,4º C) pan water temperature at 0°F (-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 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 (-18º C) ambient temperature. For alternate low ambient heater selections consult the factory.

Electric Water Level Control

EVAPCO cooling towers 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).

Other Options

  • Heater Control Package
  • Hot Water Steam Coils or Steam Injectors
  • Bottom Suction Connections
  • Bottom Inlet Connections
  • Vibration Switches
  • Remote Sump Connections
  • Special Motors - 2 Speed / 1 Winding, 2 Speed / 2 Winding, Mill & Chem Duty, Automotive
  • Titan-Pak Stainless Steel Fill & Wide-Pak Fill
  • Many More - Consult the Factory


at_spec.doc46 KB



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

1.2 SUMMARY: A. This Section includes factory assembled and tested, open circuit, induced draft counterflow cooling tower.

1.3 SUBMITTALS A. General. Submit the following: 1. Certified drawings of the cooling tower, 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 (AT & UT): One (1) year from start-up, not to exceed eighteen (18) months from shipment on the unit. C. Unit (USS): Five (5) year comprehensive warranty against materials and workmanship for complete unit.



A. Manufactures: Subject to compliance with requirements, provide cooling towers 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 cooling tower complete with fill, fan, louvers, accessories, and rigging supports.

B. Cooling Tower Characteristics and Capacities: Refer to the Cooling Tower schedule.

C. Fan(s):

1. Type and Material (AT & USS): 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 (AT) or Stainless Steel (USS) fan guard.

2. Type and Material(UT): Axial propeller, one piece heavy duty FRP hub and blade construction. Galvanized steel closely fitted fan cowl with venturi air inlet for maximum fan efficiency, covered with a heavy gauge hot dip galvanized steel fan guard. (Optional Type 304 stainless steel) 3. 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 (AT/UT - Type 304 Stainless Steel Optional) or Type 316 Stainless Steel (USS):

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-cooling-tower system).

G. Casing: Galvanized Steel (AT/UT) or Type 304 Stainless Steel (USS - Type 316 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

H. 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.

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

J. Air Inlet Louver Screens: Formed PVC mounted in G-235 galvanized (or Type 316 stainless) steel frames for easy removal; designed "Sight Tight" to completely block direct sunlight from entering and water from splashing out of the cooling tower.

K. Water Level Control: Brass mechanical makeup water valve and plastic float with an adjustable linkage.


A. General requirements for motors are specified in Division 15 Section "Motors".

B. Enclosure Type: TEAO or TEFC

C. Motor Speed: Single Speed (Option: VFD Duty, 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 cooling towers. If a crossflow tower 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

at_49pt_table_ip.pdf266.21 KB

The Big AT

EVAPCO, Inc., continues its dedication to advancements in induced draft, counterflow cooling tower technology and easy maintenance with the Advanced Technology Cooling Tower... The EVAPCO AT! The expanded AT line offers higher tonnage units and is designed with IBC compliance construction and CTI certified performance.

Available in multi-cell arrangements with a capacity range of 1,003 to 5,141 Nominal Tons (4,444 to 22,596 kW)! The AT has a model for every application.