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Data Centre Precision Cooling

A server room is not a comfort space. The load is almost entirely sensible heat, the room runs unattended, and the equipment has to hold a band rather than a temperature. Precision cooling is selected on sensible heat ratio, control bandwidth, airflow path and redundancy — then the chiller plant behind it is sized for the part-load hours that actually dominate the year.

CRAC / precision units Chilled water & DX Maglev chillers N+1 layouts
Water-cooled chiller unit supplied for process and data centre cooling
Where it fits

Rooms where the load never stops and nobody is standing there

Each of these fails differently. A server hall drifts out of band slowly; a telecom cabinet fails at the hottest hour of the year; a battery room fails for reasons that have nothing to do with temperature.

Server halls and colocation white space

  • High sensible heat ratio, with almost no latent load to remove
  • Cooling required every hour of the year, including winter part load
  • Containment and aisle layout decide whether downflow or upflow units fit

Edge, telecom and control rooms

  • Small room, no plant room, and often no raised floor
  • Unattended operation, so alarms and auto-restart matter more than aesthetics
  • Site ambient is the design case, not an average summer day

UPS and battery rooms

  • Dedicated cooling, kept separate from the white space
  • Temperature band set by the battery supplier, not by comfort
  • Air change and exhaust requirements that must be respected

The chiller plant behind the room units

  • Water-cooled screw chillers or air-cooled maglev centrifugal chillers, depending on site and load profile
  • Chilled-water supply temperature and temperature difference coordinated with the room units
  • Part-load behaviour that matches a load curve with long low-load stretches
Selection

What is configured per project

Two rooms with the same IT load in kW can need very different equipment. These are the variables our engineers work through once the load and the room are known.

  • Sensible capacity quoted at your design return air condition, not at a generic rating point
  • Airflow path: downflow for a raised floor with containment, upflow or ducted where there is none
  • Control band: temperature and humidity in both directions, with staged or variable capacity instead of on/off cycling
  • Redundancy by unit count (N+1), dual refrigerant circuits and automatic changeover
  • Monitoring interface and the alarm points you want handed to the BMS or DCIM
  • Chilled-water supply and return temperature, temperature difference and plant staging
Air-cooled maglev centrifugal chiller
Before selection

What our engineers will ask for

None of this is needed to start a conversation. It is the list that turns a first reply into a selection you can put in a tender.

IT loadTotal kW, rack density, expected growth, diversity across the year
Control bandTemperature and humidity setpoints with the allowed tolerance, and how tight the room actually has to hold
RoomDimensions, ceiling height, raised floor or not, containment arrangement, aisle layout
RedundancyN+1 or higher, unit count, dual-circuit requirement, changeover expectation
PlantChilled-water supply and return temperature, temperature difference, available plant space, air-cooled or water-cooled
SiteDesign ambient, altitude, power supply, noise limit at the nearest receptor
DocumentsLayout, equipment schedule, specification section, load calculation — any format
Questions buyers ask

Precision cooling, answered plainly

The four questions that come up before a data centre inquiry turns into an equipment schedule.

Not properly. Racks produce almost entirely sensible heat, so the unit has to run at a high sensible heat ratio. A comfort unit spends a large part of its capacity condensing moisture out of the air and then re-humidifying to hold the setpoint, which wastes energy and still leaves the room drifting. A dedicated precision unit is selected at the design return air condition instead of a generic rating point.

Room dimensions and ceiling height, whether there is a raised floor, total IT load in kW with the expected growth, the temperature and humidity setpoints with the allowed band, the airflow path (downflow, upflow or ducted), the redundancy requirement, the power supply, and the site ambient condition. Drawings, an equipment schedule or a specification section are all acceptable formats; none of it is needed to open a conversation.

Yes. Water-cooled screw chillers, air-cooled modular units and air-cooled maglev centrifugal chillers are part of the same range as the precision room units, so the chilled-water supply temperature, the temperature difference and the part-load behaviour of the plant can be coordinated with the room equipment rather than bought as two unrelated packages.

Redundancy is a unit-count and control decision, not a badge on the datasheet. N+1 unit count lets any single machine be serviced without the room drifting out of band; dual refrigerant circuits keep part of the capacity available if one circuit trips; and automatic changeover lets a standby unit take load instead of waiting for a manual switch.

Read next

Related technical notes

Send the IT load and the redundancy target

Give us the room, the kW and the band you have to hold. Our engineers will come back with a unit configuration, the airflow and control assumptions behind it, and a project-specific proposal.

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