CRAC Spare Parts: What to Stock On-Site for Liebert, Uniflair, and Stulz Units

Parts availability is one of the least glamorous aspects of data centre operations, and one of the most consequential. When a CRAC unit trips at 2 am on a Sunday, the gap between a two-hour fix and a two-week outage often comes down to whether the right component is sitting on a shelf in your comms room.

Australian data centres face a particular challenge here. The local precision cooling market is served by a relatively small number of distributors, and factory lead times from Europe or the United States can run four to eight weeks for non-stocked items. For Tier III and Tier IV facilities with N+1 or 2N cooling redundancy, a failed unit sitting idle while parts are on order erodes that redundancy margin every day it remains offline.

This guide covers the spare parts worth holding on-site for the three most common CRAC brands in the Australian market: Vertiv/Liebert (CW and Datamate series), Schneider Electric/Uniflair (InRow and Leonardo series), and Stulz (CyberAir series). The selection logic is based on failure frequency, replacement complexity, and the cost of downtime relative to the cost of carrying the part.

Why On-Site Spares Make Financial Sense

The carrying cost of a spare parts kit for a typical CRAC unit runs between $8,000 and $25,000 depending on the model and the depth of coverage. That figure sounds substantial until you price a single hour of unplanned downtime. Uptime Institute's 2023 Global Data Centre Survey placed the median cost of a significant outage at USD $100,000, with a third of respondents reporting costs above USD $250,000.

For smaller edge deployments and enterprise server rooms, the numbers are lower but the operational impact is often just as severe. A manufacturing plant running on a single precision cooling unit cannot wait three weeks for a control board.

The parts categories below are ranked by the combination of failure probability and lead time risk.

Compressors

Compressor replacement is the highest-cost single event in CRAC maintenance, and lead times are the longest. Scroll compressors from Copeland (used extensively in Liebert DX units) and Bitzer (common in Stulz CyberAir) are not always held in Australian distributor stock. Delivery from the United States or Germany can take four to six weeks for less common displacement ratings.

For most facilities, holding a spare compressor on-site is not practical due to cost and storage requirements. The more realistic approach is to identify the exact compressor model number from the unit nameplate and confirm with your refrigeration supplier whether it is held locally. If it is not, consider a service agreement that includes a manufacturer-held spare allocated to your site.

For Liebert CW (chilled water) units, there is no compressor on-site; the risk transfers to the chiller plant. For Datamate DX units, the Copeland scroll compressor model number is stamped on the compressor body and should be recorded in your asset register.

For Stulz CyberAir 3 units, the Bitzer semi-hermetic or scroll compressor specification varies by cooling capacity. Units in the 15 to 40 kW range typically use Copeland ZH or Bitzer scroll variants. Confirm the model at commissioning.

Condenser and Evaporator Fans

Fan motors and fan assemblies fail more frequently than compressors and are far more likely to be held in local stock. They are also the component most often overlooked in spare parts planning because individual fans are cheap and the failure mode is gradual rather than catastrophic.

The risk is cumulative. A Liebert Datamate or PDX unit running with one of three evaporator fans failed will continue operating, but airflow distribution across the coil changes, cooling capacity drops, and the remaining motors run harder. If a second fan fails before the first is replaced, the unit may trip on high discharge pressure or high return air temperature.

Liebert (Vertiv) CW and Datamate: EC fan motors from EBM-Papst are the dominant fitment. The 250 mm and 310 mm impeller variants used in Datamate units are generally available from Australian HVAC suppliers, but the specific Liebert-branded assembly with the correct mounting bracket and connector may require ordering through Vertiv's parts channel. Stock one complete fan assembly per unit, including the motor, impeller, and mounting hardware.

Schneider/Uniflair InRow and Leonardo: InRow units use EC plug fans, typically EBM-Papst or Ziehl-Abegg, in configurations of two to six fans depending on the model. The Leonardo perimeter units use a different fan arrangement. For InRow RC and RD series, the fan module is a field-replaceable unit (FRU) and the part number is accessible through Schneider's EcoStruxure asset management portal. Stock one fan module per InRow unit.

Stulz CyberAir 3: EC fans from EBM-Papst are standard fitment. The CyberAir 3 uses a modular fan tray in larger configurations, making replacement straightforward. Stock one fan assembly per unit and verify the part number against the unit's serial number plate.

Humidifier Cylinders

Electrode humidifier cylinders are a consumable item with a predictable service life of 12 to 24 months depending on water conductivity. In Brisbane and other areas with higher mineral content in the mains supply, cylinder scaling can shorten that interval considerably. Despite being a known consumable, humidifier cylinders are one of the most common causes of avoidable service calls because they are not stocked on-site.

Cylinder replacement takes 20 to 30 minutes for a trained technician. Waiting two weeks for a cylinder while the data centre operates outside its humidity setpoint is an unnecessary risk, particularly in facilities running equipment sensitive to electrostatic discharge.

Liebert units: Liebert humidifiers use proprietary cylinders specific to the humidifier model (Nortec, Condair, or Liebert-branded). The cylinder part number is printed on the existing cylinder. Stock two cylinders per humidifier unit.

Schneider/Uniflair: Uniflair units often use Condair or Nortec humidifier modules. The cylinder part number varies by steam output rating. Check the humidifier module label and stock two replacement cylinders.

Stulz CyberAir: Stulz uses proprietary humidifier cylinders in the CyberAir 3 series. Part numbers are model-specific. Stock two cylinders per unit and replace proactively at 18 months regardless of visual condition.

For all brands, also stock the cylinder drain valve seat and the fill valve solenoid. These fail independently of the cylinder and are inexpensive parts that can strand a humidifier if not available.

Sensors and Probes

Temperature and humidity sensors are low-cost components that cause disproportionate disruption when they fail. A faulty return air sensor can cause a CRAC unit to run at full capacity continuously, wasting energy and stressing the refrigeration circuit. A failed humidity sensor can cause the humidifier to run without limit, overshooting setpoint and triggering condensation alerts.

Sensor failures are also easily misdiagnosed. A technician unfamiliar with the unit may spend hours investigating a refrigeration fault before identifying that the root cause is a $45 sensor reading 5 degrees high.

Stock the following for each unit:

• Return air temperature and humidity sensor (combination probe)
• Supply air temperature sensor
• Coil frost/freeze stat (where fitted)
• High-pressure and low-pressure transducers (for DX units)

For Liebert units, the iCOM controller uses specific sensor part numbers. For Uniflair InRow, sensors connect to the controller via Modbus or proprietary connectors depending on the generation. For Stulz CyberAir, the CompTrol controller uses Stulz-specific sensor assemblies. In all cases, confirm the part number from the unit's wiring diagram before ordering.

Control Boards and Controllers

Control board replacement is the scenario most likely to strand a unit for weeks if the part is not on-site. Manufacturer lead times for controller boards, display modules, and communication cards can run six to ten weeks for older unit generations.

The calculus on stocking control boards is different from sensors and fans. A complete controller for a Liebert iCOM or Stulz CompTrol unit can cost $3,000 to $8,000. For a single unit, that may not be justified. For a fleet of identical units, one spare controller shared across the fleet is a reasonable investment.

Liebert iCOM: The iCOM controller is used across the Liebert CW, Datamate, and PDX ranges. Earlier iCOM versions (iCOM-S, iCOM-100) are no longer manufactured, making spares scarce. If your facility runs units with iCOM-100 controllers, source a spare now. The iCOM-200 is current production but not always held in Australian stock.

Schneider/Uniflair: InRow units use the NetShelter controller or the EcoStruxure-compatible module depending on the generation. Leonardo units use a separate controller platform. Schneider's local parts channel in Australia is generally better stocked than some competitors, but lead times on controller boards still run two to four weeks.

Stulz CompTrol: The CompTrol III and CompTrol IV are the current controller generations for CyberAir 3 units. Stulz's Australian distributor (Stulz Australia, based in Melbourne) holds some controller stock, but availability varies. For facilities running CyberAir units older than eight years, confirm parts availability directly with Stulz Australia.

Also stock expansion cards and communication modules where your BMS integration depends on them. A failed BACnet or Modbus card will not stop the unit cooling, but it will remove it from your monitoring system, which is a compliance and operational risk.

Building Your Parts Register

The starting point for any spare parts programme is an accurate asset register. For each CRAC unit, record the model number, serial number, controller version, refrigerant type, compressor model, fan part numbers, humidifier cylinder part number, and sensor part numbers. This information is available from the unit nameplate, the wiring diagram inside the unit door, and the commissioning documentation.

With that register in place, cross-reference each critical part against your distributor's current stock position. Parts that are not held locally and have lead times exceeding two weeks should be considered for on-site storage.

Review the register annually. Parts availability changes as units age and manufacturers discontinue older components. A part that was readily available three years ago may now be on a six-week lead time or sourced only from overseas.

Practical Storage and Rotation

Spare parts need to be stored correctly to remain serviceable. Sensor probes and electronic components should be stored in anti-static packaging in a dry, temperature-controlled environment. Humidifier cylinders should be stored upright and away from moisture. Fan assemblies should be stored in their original packaging to protect the impeller.

Establish a rotation schedule for consumables. Humidifier cylinders held in storage for more than three years should be inspected before use. Electronic components have no practical shelf life issue if stored correctly, but firmware versions on controller boards may need updating before installation.

For facilities running multiple units of the same model, a shared spare parts pool is more efficient than per-unit kits. A pool covering four identical units might hold two fan assemblies, four humidifier cylinders, one controller board, and a sensor kit, rather than duplicating everything four times.

Getting the Right Parts

Procurement officers should establish direct accounts with Vertiv Australia, Schneider Electric's parts channel, and Stulz Australia before a failure occurs. Emergency parts requests from unknown customers receive lower priority than requests from established accounts with service history.

For facilities without in-house refrigeration-licensed technicians, a maintenance agreement with a specialist CRAC service provider gives access to parts stock and technical expertise without the overhead of managing it internally. CRAC Services Australia holds parts inventory for Liebert, Uniflair, and Stulz units across Brisbane, Sydney, and Melbourne, and can advise on site-specific spare parts strategies based on your unit fleet and criticality requirements.

For more information on spare parts planning or to discuss a maintenance programme for your facility, visit [crac.services](https://crac.services).