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Rack densities have moved. A data hall designed a decade ago sized 3 kW to 5 kW per cabinet and pushed cold air out of a floor void to the room at large. A hall carrying GPU compute, virtualisation clusters or dense blade chassis now routinely sees 15 kW, 25 kW or more in a single cabinet, and a room level cooling strategy simply cannot deliver enough air to the front of those racks fast enough. The result is a hot spot: one or two cabinets running well above the rest of the hall while the perimeter CRAC units work hard and over supply everything else.

In row cooling solves that by shortening the air path. The CyberRow is a narrow cabinet, 300 mm, 400 mm or 600 mm wide and 1,950 mm high, that is bolted into the row alongside the racks it serves. Air travels metres rather than tens of metres, and because the unit is measuring temperature at the racks themselves rather than at a return grille on the wall, it responds to what the servers are actually experiencing. STULZ describes the CyberRow as professional server rack cooling with innovative air conduction, and the design intent shows in the details: horizontal air distribution, up to five independent fans, and six temperature sensors across the front and rear faces.

Indigi Power and Cooling is an Indigenous and Veteran owned critical power and cooling specialist, registered with Supply Nation and ICN Gateway. We supply, install, commission and maintain STULZ in row cooling across Australia, and we also service the installed base of in row and perimeter equipment already running in Australian facilities, including units from other manufacturers.

See the CyberRow in operation

STULZ CyberRow (english), 3 minutes 4 seconds. Walks through the housing, filter, fan arrangement, service access and connection options.

Why the CyberRow suits high density rack cooling

Range specification at a glance

Model table: CyberRow DX and hybrid Free Cooling

The 11 kW to 58 kW headline range covers the whole CyberRow family. The DX and hybrid Free Cooling models tabled above run from 11.4 kW to 37 kW at the stated return air condition; the top of the range and the 11,200 cubic metre per hour airflow figure are reached on CW and CW2 chilled water configurations. Ratings move with return air temperature, humidity and chilled water flow and temperature, so treat the table as a selection starting point and let us run the numbers against your actual conditions.

Hot aisle and cold aisle containment

Containment is where in row cooling either works properly or quietly fails. The point of any containment scheme is to stop cold supply air and hot exhaust air mixing, because every degree of mixing is capacity you paid for and did not deliver to a server inlet. The CyberRow supports both of the standard containment strategies, and the correct choice drives which air conduction option you order.

Where no physical containment has been built, the CyberRow still improves on room level cooling because the optimised horizontal air pattern forms what STULZ calls a virtual containment. Cold air is thrown along the front of the rack line and hot air is collected close to where it is produced, so the mixing that normally occurs in an open hall is substantially reduced without erecting doors and roof panels. That matters in Australian comms rooms and small data halls where the room is shared, the ceiling is low, or the building owner will not permit structural aisle work.

Three zone control and Delta T regulation

A tall cabinet does not have one temperature. The top of a 42U rack running dense compute is frequently several degrees warmer than the bottom, and a cooling unit that reads a single average will either starve the top or over cool the whole rack to protect it. The CyberRow addresses this with three temperature sensors on the front, three on the back, and up to five independently variable EC fans.

The controller measures Delta T between supply and return across each of three horizontal zones and adapts cooling capacity in each zone individually. In practice one fan bank may sit at 42 per cent while the two above it run at 65 and 67 per cent, because that is what the racks in front of them are asking for. Hot spots are removed without the energy penalty of an across the board over supply, and because EC fan power varies roughly with the cube of speed, small reductions in fan duty produce disproportionately large savings on a 24 hour a day load.

The controller also carries two mutually independent setpoints, typically a fixed supply air setpoint and a fixed Delta T setpoint between supply and return air. Holding both at once is what allows precise temperature control at the server inlet while still managing the volume of air moved, rather than trading one against the other. STULZ develops the controller in house, which is why the Free Cooling operating modes, the zone logic and the fan redundancy behaviour are handled as one integrated control strategy rather than bolted together from third party parts.

Fan redundancy is worth calling out separately. If a fan fails, the remaining fans automatically speed up to hold capacity, so a single fan fault does not become a thermal event while a technician is dispatched. The controller monitors and reports all faults, and a standard RS-485 serial port allows integration into a building management system over Modbus or STULZ protocols. Optional humidity sensor, electric heater and humidifier are available where the room needs active humidity control as well as sensible cooling.

Choosing between the cooling systems

CW2 deserves a note of its own, because redundancy at the unit is usually cheaper and simpler than redundancy at the row. Connecting a single CyberRow to two mutually independent chilled water circuits means a ruptured pipe, a failed pump or a valve isolation on one circuit does not take that unit offline. For a facility working to an APRA CPS 230 style operational resilience obligation, that is a materially easier story to write up than an N+1 argument that depends on neighbouring units picking up a failed unit's load.

Installation detail that matters on site

Several CyberRow design decisions exist specifically to make the retrofit case work. There is no direct cable or refrigerant connection between the rack and the cooling unit, so the unit can be positioned wherever the thermal model wants it without being tied to a particular cabinet. Water connection openings are pre cut as standard at both the top and the bottom of the cabinet, which means the same unit suits an overhead reticulation design or an under floor one without site fabrication. The housing is powder coated with doors front and rear, and the electrical box pivots out for service, so a technician working in a live aisle is not forced to break containment or shut down a neighbouring rack to reach a component.

The zigzag G4 filter sits in a metal frame and is changed from the aisle. On a continuously running unit the filter is the most common cause of a gradual, unnoticed capacity loss, so filter change intervals should be set against the actual dust load of the room rather than a generic annual schedule. Rooms in industrial estates, near construction, or on sites with regular door traffic will need shorter intervals than a sealed CBD comms room.

Applications

• High density rack cooling for AI and GPU compute, where a handful of cabinets carry far more load than the rest of the hall
• Retrofit cooling into existing server rooms and comms rooms that have no raised floor and no room for a perimeter unit
• Hot aisle or cold aisle containment pods inside a larger colocation or enterprise data hall
• Targeted supplementary cooling alongside existing perimeter CRAC units, resolving hot spots without resizing the whole plant
• Modular and phased build outs, where cooling capacity is added row by row as racks are populated
• Chilled water facilities needing unit level redundancy through CW2, complementing CHW CRAC arrangements
• Combined critical power and cooling projects delivered as server room UPS and cooling packages

CyberRow compared with Vertiv Liebert CRV

Installation, commissioning and maintenance in Australia

A CyberRow deployment is a licensed job on two fronts. Electrical work must be carried out by a licensed electrician to AS/NZS 3000, and any work on the refrigerant circuit of an A, AS, GS or GES unit requires an ARCtick licensed refrigeration technician under the Ozone Protection and Synthetic Greenhouse Gas Management Regulations. Where the installation forms part of a mechanical ventilation system, AS/NZS 3666 hygiene obligations apply to the air handling components and to the cleaning and inspection regime. Indigi handles all of this in house rather than subcontracting the critical path.

Typical scope covers heat load verification against the actual IT draw rather than nameplate figures, rack by rack load mapping so the number and placement of units is right, air conduction selection to match the containment strategy, chilled water or refrigerant pipe design and dry cooler or condenser siting, rigging into a live aisle, controller configuration, BMS integration over Modbus on the standard RS-485 port, and witness commissioning with documented handover. We measure server inlet temperatures at commissioning and confirm they sit within the ASHRAE TC 9.9 recommended envelope of 18 to 27 degrees Celsius, because that is the number an auditor or a hardware vendor will ask about, not the unit's supply air temperature.

Indicative pricing for server room cooling design and installation runs from $8,000 to $15,000 for small rooms, $25,000 to $45,000 for medium installations and $45,000 to $60,000 plus for large projects. A typical in row retrofit of two to four CyberRow units into an existing row, including pipework and controls integration, usually lands in the medium band. Quoted scope always depends on the site, the pipe run and how much work has to happen out of hours.

Once running, the unit needs a maintenance regime that reflects continuous duty. The schedule should cover filter condition and replacement, coil cleanliness, condensate management, refrigerant charge and leak checks on DX models, chilled water valve and actuator operation on CW and CW2 models, fan bearing and EC fan health across all five fans, controller alarm history, and verification that the zone sensors are still reading correctly after any rack moves. See our CRAC unit maintenance services, DX CRAC servicing and CDW CRAC servicing pages for how we structure this.

Frequently asked questions

What is in row cooling and when should you use it?

In row cooling places the cooling unit directly in the rack line, between the server cabinets, instead of at the perimeter of the room. It shortens the air path so cold air reaches the server inlet before it mixes with hot exhaust air, and it lets the unit measure and respond to temperatures at the racks themselves. Use it where rack densities are high, where a hot spot has appeared that perimeter units cannot resolve, or where there is no raised floor to distribute air through.

How many server racks can one STULZ CyberRow unit cool?

STULZ rates each CyberRow unit at up to six server cabinets. The actual number depends on the load per cabinet, the containment arrangement and the air conduction option selected. A row of low density cabinets at 4 kW each is a very different selection to three cabinets carrying 15 kW of GPU compute, so the unit count should always come from a rack by rack load map rather than a rule of thumb.

Does the STULZ CyberRow need a raised floor?

No. The CyberRow is suitable for data centres and server rooms with or without a raised floor, because air is distributed horizontally along the row rather than through a floor void. Water connection openings are pre cut as standard at both the top and the bottom of the cabinet, so overhead and under floor reticulation are both supported without site fabrication.

What cooling capacity does the STULZ CyberRow deliver?

The range covers 11 kW to 58 kW of total cooling capacity with airflow from 3,200 to 11,200 cubic metres per hour, across six sizes in three widths of 300, 400 and 600 mm and two depths. The DX and hybrid Free Cooling models run from 11.4 kW on the CRS/CRL 101 A to 37 kW on the CRS/CRL 361, measured at return air of 35 degrees Celsius and 25 per cent relative humidity. The top of the range is reached on CW and CW2 chilled water configurations.

How does the CyberRow work with hot aisle and cold aisle containment?

Units with a frontal air outlet are used for cold aisle containment and are positioned at an offset to one another so the whole cold aisle is supplied rather than only the neighbouring racks. Units with side air conduction are used for hot aisle containment, expelling cold air sideways for uniform distribution along the length of the aisle. Where no physical containment exists, the optimised horizontal air pattern still creates a virtual containment around the racks the unit serves.

What happens if a fan fails in a STULZ CyberRow?

If one fan fails, the remaining fans automatically increase speed to maintain cooling capacity, so a single fan fault does not become a thermal event while a technician is dispatched. The STULZ controller monitors and reports all faults, and alarms can be passed to a building management system through the standard RS-485 serial port using Modbus or STULZ protocols.

Who supplies and services STULZ in row cooling units in Australia?

Indigi Power and Cooling supplies, installs, commissions and maintains STULZ CyberRow in row cooling units across Australia from hubs in Brisbane, Sydney and Melbourne. Electrical work is carried out to AS/NZS 3000 and all refrigerant work by ARCtick licensed technicians. We also service existing in row and perimeter cooling units installed by others, including Vertiv and Liebert equipment.

Where we install and service

Related products and services

• CRAC unit maintenance services Australia
• CHW CRAC maintenance for chilled water in row and perimeter units
• DX CRAC servicing across Brisbane, Sydney and Melbourne
• CRAC installation and commissioning
• Server room cooling Australia
• Server room heat load calculator
• CRAC topology selector: DX, CHW or CDW
• Server room UPS and cooling packages