Daikin Applied introduced D60-W on November 10 as a reference design for cooling 60 MW of IT load across six deployable units. The design assigns 92% of the heat load to liquid cooling and 8% to air cooling. It uses a warmer loop for coolant distribution units and a colder loop for rack containment units. Daikin Applied's launch announcement

That split gives project engineers a starting point for sizing and controls. For commissioning, I would use it to ask a more specific question. After a brief power interruption, how long does each rack spend outside its required cooling conditions, and what does the workload do during that interval?

Size both loops for the racks you will install

Start with the expected hardware mix in each deployment phase. Ask the rack supplier for the heat released to air and the heat transferred to coolant under representative workloads. Record the required flow, supply temperature and allowable pressure range alongside the electrical load. Ask how those values change when the rack throttles or the workload shifts.

Use the resulting heat budget to check both loops. A deployment can have spare capacity on the warmer loop while approaching the limit of the colder loop. Check the distribution path to the least favored rack, especially with a pump unavailable or valves repositioning after a restart. Use the reference design's heat split as an input to the comparison and the actual rack mix as the basis for acceptance.

Measure recovery where cooling reaches the equipment

Daikin describes chiller features for brief power disturbances and for restarting after shutdown. It also describes a supervisory layer that coordinates the plant as it moves among dry, hybrid and mechanical cooling. These are design features and vendor claims about how the equipment responds. Daikin Applied's D60-W announcement

In an approved integrated systems test, I would log the power disturbance, the pump and valve response, the return of flow and the recovery of supply temperature at the racks on a common clock. Include server telemetry for thermal throttling, shutdowns and time to resume useful work. Set acceptance limits from the selected equipment's operating envelope before the test.

A chiller may report that it is running while coolant delivery is still recovering at the end of a distribution branch. Rack telemetry shows how long that gap lasts and whether it affects the workload. Repeat the scenario at a representative high load and during a mode transition, when the control sequence has more decisions to make.

Check mode changes against local conditions

The design uses dry coolers for heat rejection, with chillers adding cooling when outdoor conditions require it. Daikin expects dry cooling to carry the load for much of the year in suitable climates. How often the project can operate that way depends on its weather, load and temperature requirements. Daikin Applied's description of the operating modes

Ask the design team to show the predicted operating hours in each mode with the site's weather data and phased load profile. Include fan, pump and compressor power in the comparison. During commissioning, check the conditions that trigger a mode change and verify that temperatures remain inside the rack limits during the transition. That gives operators a baseline for investigating differences between predicted and measured plant behavior.

Put equipment availability on the same schedule

Daikin says its coolant distribution unit and data center dry cooler are under development, with availability targeted for the second half of 2027. Ask suppliers for the orderable configuration and delivery dates for each phase, then track those commitments against the dates when the corresponding racks need cooling. If a component changes, revisit hydraulic performance, controls integration and the test sequence before accepting the substitution. Daikin Applied's equipment availability statement

For a staged handover, keep the rack heat budget, the operating-mode test results and the recovery timeline together. Those records let the receiving team see which loads the installed plant has demonstrated it can support and which scenarios still need to be tested as the next phase comes online.