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19InRow RD 10 kW Air Cooled Operation and Maintenance
Control the Environment
The primary function of the cooling unit is to capture the heat generated by IT equipment and neutralize
it before it mixes with the room. The control strategies employed by the cooling unit depend upon the
deployment strategy of the cooling group.
In an InRow environment, the cooling unit supplies constant-temperature supply air to the common cold
aisle. The fan speed is modulated to ensure that the required volume of air reaches the IT equipment. The
fan speed is determined by the difference between the cooling setpoint and the maximum rack air inlet
temperature of the cooling group.
In a HACS or RACS environment, the cooling unit neutralizes the heat accumulated in the common hot
aisle and expels it into the surrounding environmental space while maintaining the necessary
temperature difference across the IT equipment.
In a Spot cooling environment, the equipment operates like traditional CRAC equipment, providing a
constant return air temperature. In Discrete mode, the fans operate at a user-selectable speed (Fan Speed
Preference) and the compressor operates at maximum capacity. In Prop (Proportional) mode, the fans
are modulated to maintain the required return air temperature and the compressor output is modulated to
maintain the necessary supply air temperature.
Setpoints
Path: Main > Set Group Setpoint
A setpoint is the target value that a cooling group will maintain. The default setpoints are appropriate for
most cooling applications.
The setpoints for each mode must be within the following ranges:
• Cool: 18.0 – 25.0°C (64.4 – 78.8°F)
• Deadband: -17.7 – 5.6°C (0 – 10.0°F)
• Supply Air: 13.8 – 23.0°C (57 – 73.4°F) Spot (Proportional) only
17.7 – 23.0°C (64 – 73.4°F) HACS, RACS or InRow
Note: The Supply Air setting is defined by APC authorized personnel only when the
cooling group is commissioned.
Note: The Supply Air setpoint must never be set higher than the Cool setpoint.
• Fan Speed: When the unit is programmed for HACS or RACS mode, this property specifies the
necessary temperature difference (DT) across the IT equipment. When the cooling unit is
programmed for Spot (Proportional), InRow, HACS or RACS with the Fan Control property set
to Manual, this property defines the fan speed. When the cooling unit is programmed for Spot
(Discrete), the fan speeds are also selected from the following table but the Fan Control property
is irrelevant.
– Low: 16.7°C (30°F) DT (60% of maximum fan speed)
– Med-Low: 13.9°C (25°F) DT (70% of maximum fan speed)
– Med: 11.1°C (20°F) DT (80% of maximum fan speed)
– Med-High: 6.3°C (15°F) DT (90% of maximum fan speed)
– High: 5.6°C (10°F) DT (100% of maximum fan speed)