Air Conditioning Equipment; Air Conditioning System Guidelines; Air Conditioning System Types; Basic Air Distribution Systems - HP Cluster Platform Introduction v2010 Introduction Manual

C.2.2 Air Conditioning Equipment
The cooling capacity of the installed air conditioning equipment for the computer room should
be sufficient to offset the computer equipment dissipation loads, as well as any space envelope
heat gain. This equipment should include:
• Air filtration
• Cooling and dehumidification
• Humidification
• Reheating
• Air distribution
• System controls adequate to maintain the computer room within the operating ranges
At altitudes above 10,000 feet (3048 m), the lower air density reduces the cooling capability of
air conditioning systems. If your facility is located above this altitude, the recommended
temperature ranges for the cluster might need to be modified.
C.2.2.1 Air Conditioning System Guidelines
The following guidelines are recommended when designing an air conditioning system and
selecting the necessary equipment:
• The air conditioning system serving the computer room should be capable of operating 24
hours a day, 365 days a year. It should also be independent of other systems in the building.
• Consider the long-term value of computer system availability, redundant air conditioning
equipment, or capacity.
• The system should be capable of handling any future computer system expansion.
• Air conditioning equipment air filters should have a minimum rating of 45% (based on the
ASHRA Standard 52-76, Dust Spot Efficiency Test).
• Introduce only enough outside air into the system to meet building code requirements (for
human occupancy) and to maintain a positive air pressure in the computer room.
• Lighting and personnel must also be included in heat-load calculations. For example, a
person dissipates about 450 BTUs per hour while performing a typical computer room task.
C.2.2.2 Air Conditioning System Types
The following three air conditioning system types are listed in order of preference:
• Complete self-contained package units with remote condensers. These systems are available
with up or down discharge and are usually located in the computer room.
• Chilled water package unit with remote chilled water plant. These systems are available
with up or down discharge and are usually located in the computer room.
• Central station air-handling units with remote refrigeration equipment. These systems are
usually located outside the computer room.
C.2.2.3 Basic Air Distribution Systems
A basic air distribution system includes supply air and return air. An air distribution system
should be zoned to deliver an adequate amount of supply air to the cooling air intake vents of
the computer system equipment cabinets. Supply air temperature should be maintained within
the parameters recommended for high heat load, high density computers.
The location of supply and return vents should be designed to facilitate the flow-through pattern
supported by the HP 10000 series rack. Suitable layouts are specified in the Technology Brief
Optimizing Data centers for High-Density Computing (TC040202TB), available at the following
location:
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00064724/c00064724.pdf
C.2.2.4 Humidity Levels
High humidity causes galvanic actions to occur between some dissimilar metals. This eventually
causes a high resistance between connections, leading to equipment failures. High humidity can
also have an adverse affect on some magnetic media.
54 General Guidelines for the Computer Room