Technical Requirements -
Computer Room
room. This heat is attributable only to the UPS loads and the heat loss due to the
CRAC units and the UPS itself (typically 7%-10 % for modern in-line systems.) Heat
load from the CRAC unit's compressors and fan(s) should be taken into account.
Capacity should be allowed to remove 110% of the UPS rated KW load with both
compressors operating. The unit should be specified with an internal infrared
humidifier to maintain the determined cubic foot room volume between 40- 60%
relative humidity. Alternately, if low pressure steam is available or planned, it may
be cost effective to use steam humidification.
The raised floor will act as the cool air supply plenum and shall provide cooling to
equipment and the room using cutouts and vent tiles (a minimum of one vent tile per
ton of cooling is recommended or 1 vent/100 sf.)
A fresh air supply from the building HVAC system should be provided to the
computer room with a fire damper where the ductwork passes through the computer
room fire walls. This should keep the room at a positive pressure and provide
cooling for lighting and personnel load of the room. Design for 200- 300 CFM
building air (minimum.) Reference the VA HVAC Design Guide for additional
information on Building HVAC systems.
Subfloor water detection system
Under each CRAC unit and in a minimum of two additional locations in the
computer room, (near piping unions, floor drains, etc., to identify problems install
subfloor water detectors. These detectors should alarm to a local annunciated
panel that sounds an alarm and indicates which detector is alarming. This panel
should be co-located with the fire and smoke alarm panels.
Plumbing
Provide drainage for A/C leakage and condensate water in the form of floor drains.
An automatic flushing system should be installed to keep the drains free and clear
and to provide a water seal to prevent odors in the associated trap. Humidifier lines
should be valved at each A/C unit. Provide water or steam hookup for use by A/C
humidifiers. No plumbing lines, chilled water lines, etc., other than sprinklers will be
located above the ceiling or pass through the computer room ceiling.
VBA Design Guide
Page 4-9
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