Professional server rack cooling with innovative air conduction

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For more efficient rack cooling

In the CyberRow, in-line air conditioning unit, innovative horizontal air conduction has been enhanced with state-of-the-art technology that works with power, flexibility and efficiency – directly at the rack. Fluctuating server rack loads, space restrictions, lack of a raised floor, existing high-density server technology – these are exactly the cases from server rack cooling practice for which CyberRow was developed.

Data Center
Data Center
Our units are designed for highest requirements and maximum reliability
No raised floor
No raised floor
Reliable cooling even without raised floor
Small, medium & large rooms
Small, medium & large rooms
Precision air conditioning units for low to high heat loads
Virtual Containment
Virtual Containment
Separation of air flows without structural measures

Product Overview

At a glance

Most important benefits

  • Suitable for server rack cooling in data centers with or without raised floor
  • Indirect Dynamic Free Cooling for maximum potential savings
  • Targeted cooling of high-density racks

Most important features

  • Can be used with racks from any manufacturer
  • Individual supply air boost in three horizontal zones

Most important technical data

  • Cooling capacity (kW): 11 – 58
  • Air conduction: left and right, left, right, forward
  • Suitable for data centers with or without raised floor
  • Indirect Dynamic Free Cooling for maximum potential savings
  • Targeted cooling of high-density racks
  • Each unit can cool up to six server cabinets
  • Innovative technology and high-quality components keep server rack cooling system’s energy consumption to a minimum
  • Two mutually independent setpoints ensure precise temperature control
  • Up to five independent, variable-speed EC fans for need based cooling in three horizontal zones
  • Variable-speed EC compressor for precise cooling capacity and integrated soft start
  • Easy maintenance thanks to access from the front and rear of the unit
  • Can be used with racks from any manufacturer
  • Server rack cooling including individual supply air boost in three horizontal zones
  • Available in three widths and two depths
  • Available in 5 different cooling systems
  • Optimized cooling air pattern creates a virtual containment
  • Easy integration into hot and cold aisle containments
  • RS485 connectivity to standard BMS systems
  • Zigzag G4 filter with metal frame
  • Powder-coated housing with doors at front and rear
  • Pre-cut openings as standard for water connections top and bottom
  • No direct cable or refrigerant connections are required between the rack and the A/C unit, allowing greater flexibility for installation in the Data Center
  • Pivoting E-box (for service and maintenance)
Technical Data
Cooling capacity total (kW)11 – 58
Air conductionleft and right, to the left, to the right, forward
Airflow volume (m³/h)3,200 – 11,200
DimensionsHeight (mm): 1,950

Width (mm): 300 – 600

Depth (mm): 1,200 – 1,375
Cooling SystemsAir-cooled (A/AS), Water-cooled (GS), Hybrid Free Cooling system (GES), Chilled water system (CW/CW2)

R410A (GWP: 2,088)

R134a (GWP: 1,430)

All details about CyberRow

Climate. Customized.

From standard units to fully customized solutions

The ability to offer such a wide range to customers is the embodiment of our philosophy, "Climate. Customized.". Size, design, air conduction, system or control: CyberRow is a model of adaptability and the units can be precisely adapted to your individual requirements regarding server rack cooling. In addition, a variety of options and equipment versions are available to achieve the optimum result.

Learn more about Climate. Customized.

Virtual Containment

Unique air conduction

With the CyberRow, STULZ offers an efficient air conditioning solution that is positioned directly between the racks in the server room. Thanks to the innovative horizontal air conduction, the supply air is directed to the server racks and forms a cold air curtain in front of them. There is no air turbulence, which means that up to six server racks can be cooled simultaneously. The high efficiency of the CyberRow units is possible due to their proximity to the server rack: their unique air conduction prevents hot and cold air from mixing. This air conduction is like a virtual containment, dispensing with the need to build actual containments.

Unique air conduction

No air turbulence during server rack cooling

The virtual containment can be clearly seen in this picture. The air flow virtually sticks to the server racks and there is no air turbulence. The cold air takes a direct route to the front of the rack-based servers.

CFD visualization

The red areas – around the EC fans – show that the fans emit the cold air at a very high speed (approx. 9–11 m/s) at the outlets. However, this is only the case as long as the air is in the housing. The partitions installed between the EC fans channel the air flow and the air baffles at the outlet ensure uniform distribution across the entire height of the racks. 

Conventional Containment
Cold aisle containment


CyberRow units with frontal air outlets are used for the cold aisle containment. Here, the air conditioning units no longer supply air to the neighboring racks, but to the entire cold aisle. To ensure an optimum supply of cold air, the units are positioned at an offset to one another. The containment completely stops the airflows from mixing, ensuring efficient operation.

Hot aisle containment


For a hot aisle containment, CyberRow units with side air conduction are used. Expelling the cold air sideways ensures uniform distribution along the whole length of the aisle, while the containment effectively separates the hot and cold air. The airflows are completely prevented from mixing, further enhancing the server rack cooling’s efficiency.

Fixed setpoints for maximum efficiency

Three temperature sensors on the front and three on the back of the unit, plus up to five fans, ensure precise measurement and regulation of the desired Delta T.

Individual supply air boost in three zones

Cooling capacity in each zone is individually adapted to the cooling needs of the servers. So by increasing the airflow rate, the individually required cooling capacity is delivered and perfect operation guaranteed, even with fluctuating loads. This prevents hot spots from forming, and with no need for energy-intensive oversupply.


Minimal footprint

Maximum efficiency, precise cooling capacity and a small footprint – the CyberRow is available in three widths and two depths and ensures cost-effective and reliable operation in all situations. The individual units are positioned directly between the server racks, and their compact design leaves even more space free for your IT equipment. The units are suitable for racks from any manufacturer, and are available in different depths which enables easy maintenance access from the front and rear at any rack depth.


CyberRow units are available in 300, 400 and 600 mm widths.

The two different unit depths provide easy rear service access to racks of any depth and without any drop in pressure.

Cooling systems

Energy efficiency, capital investment, operating costs, room size, noise protection, redundancy, local climate – every project has its own specific requirements when it comes to precise air conditioning. That’s why STULZ offers you the opportunity to have the units precisely adapted to your project’s individual requirements. The right air conditioning system is a crucial factor here. The CyberRow is available in five different data center cooling systems, to help you achieve the ideal balance between investment, operating costs and energy efficiency.


Air-cooled system (A/AS)

Heat is extracted from the room air as it flows through the evaporator, and is then transferred to the refrigerant. The air conditioning unit and condenser are connected to one another by a closed refrigerant circuit. The refrigerant emits the heat to the outside air via the air-cooled condenser.

Water-cooled system (GS)

Our water-cooled system works like the air-cooled system, with one difference: the heat from the refrigerant circuit is transferred to a cooling water circuit via a brazed plate condenser integrated in the air conditioning unit. This way, the amount of refrigerant required is low. The heat in the cooling water circuit is then discharged into the outside air via an external dry cooler. 

Hybrid Free Cooling system (GES)

This server rack cooling system functions like the GS system, but additionally features an integrated Free Cooling coil. This way, energy-intensive compressor cooling can be wholly or partially dispensed with at low or temperate outside temperatures. The heat is transferred directly to the cooling water circuit by the integrated Free Cooling coil, and discharged into the outside air via an external dry cooler. 

  • Indirect Dynamic Free Cooling
    The GES system features dynamic switching operation and control, which guarantees reliable and efficient operation. The combination of Indirect Free Cooling and variable-speed components enables precise cooling adapted to the current heat load, and cuts overall energy consumption to a minimum.
  • Minimal compressor running time
    Using Indirect Free Cooling, the hybrid Free Cooling system exploits the cooling potential of outside air as soon as outside temperatures allow. This enables energy-intensive compressor cooling to be partially or even wholly dispensed with.
  • No oversupply
    The variable-speed components ensure that precisely the required cooling capacity is generated. There is therefore no energy-intensive oversupply during the server rack cooling process.
  • Minimal refrigerant quantities
    As the hybrid Free Cooling system is water-cooled, it only needs a minimal quantity of refrigerant. The result is environmentally friendly operation with reduced greenhouse gas emissions, for a forward-looking investment in the future.
Chilled water system (CW/CW2)

The air conditioning unit with CW system manages without a refrigerant circuit of its own, but requires a separate chiller. The air conditioning unit and chiller are connected to one another by a closed water-glycol circuit.
For high-availability systems, the CW2 system offers a redundant chilled water supply by connecting one air conditioning unit to two chilled water circuits.

Efficient server rack cooling:
Synchronized complete systems

Air conditioning solutions from STULZ offer synchronized complete systems that work efficiently and reliably. Thanks to energy savings and operational reliability, your investment in the quality, operational reliability and efficiency of STULZ air conditioning and chilled water solutions rapidly pays off during operation.

To ensure optimum integration, STULZ offers an extensive portfolio of chillers for indoor and outdoor installation. Select the right unit for your requirements and enjoy the additional benefits of Free Cooling for your air conditioned server rack.

EC technology

EC compressor

The AS, GS and GES systems are equipped with stepless variable-speed EC compressors, making our systems more efficient than ever. The compressors feature integrated soft start and phase monitoring.

EC fans

Up to 5 speed-controlled EC fans which can be controlled independently of each other for optimum adaptation to different return air and supply air temperatures. 

Control and monitoring
  • Self-developed STULZ controller for regulating and monitoring the air conditioning system
  • Six temperature sensors for precisely controlling Delta T and supply air
  • Controls the operating modes of the hybrid Free Cooling system
  • If a fan fails, the remaining fans speed up
  • Monitoring and reports for all faults regarding server rack cooling
  • Standard RS-485 serial port for connection to BMS using Modbus and STULZ protocols
  • Optional humidity sensor
  • Optional heater
  • Optional humidifier
  • Humidifier
  • Optional humidity sensor
  • Optional heater
  • External temperature sensor
  • Dual mains supply (internal or external)
Service and maintenance

As a company with locations across the globe, we offer everything you need in the extremely dynamic world of information technology - plus professional advice in the right place at the right time.

Our trained and experienced sales and service partners are located in over 140 countries. The resulting proximity to our customers allows fast response times. In addition, regular training courses and an active exchange of information ensure high quality and an extensive knowledge of all our products. This way, you can be sure your products are in the best hands and get the right maintenance – all over the world.

Locations worldwide


Project story: Ideal room climate for optimum printing processes

STULZ optimises critical print production conditions at Paragon Customer Communications

When it comes to guaranteeing the fast turn-around of critical regulatory communications, using the fastest print presses in the world, capable of producing up to two million pages a day, Paragon Customer Communications (Paragon CC) know that effective service delivery is increasingly reliant on room  temperatures and humidity.

Paragon was looking for a tailored Air Conditioning solution for their demanding facilities in both a print room and a data centre. Reliability of equipment, no down-time and energy efficiency were the main  drivers, and this is exactly where STULZ could offer a tailored solution providing the equipment and technology needed for cost efficient perfect environmental conditions.

See the project story here

Test Center

In our state-of-the-art, 700-square-meter Test Center with its various climate chambers, we can perform a variety of tests on precision air conditioning units and chillers. During the development of the CyberRow, we were able to test and optimize it under all climatic conditions encountered around the world.

In addition, we offer you the opportunity to book a witness test in our Test Center. This allows you to have the desired air conditioning system tested according to your exact specifications, creating transparency and providing you with information about your system’s performance and energy consumption.

More information


Find your individual STULZ contact

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Do you have any questions? We will be happy to help! Please call us or follow our contact form.

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Holsteiner Chaussee 283
22457 Hamburg 

Central Office: +49 40-5585-0
Fax: +49 40-5585-352

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