HP Integrity rx7620 Site Preparation Guide, Fourth Editon - HP Integrity rx762 - Page 52

General Site Preparation Guidelines Environmental Elements • Reheating • Air distribution • System controls adequate to maintain the computer room within the operating range Lighting and personnel must also be included. For example, a person dissipates about 450 Btu per hour while performing a typical computer room task. At altitudes above 10,000 ft (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 might need to be modified. For each 1000 ft (305 m) increase in altitude above 10,000 feet (up to a maximum of 15,000 ft), subtract 1.5° F (0.83° C) from the upper limit of the temperature range. Air Conditioning System Guidelines The following guidelines are recommended when designing an air conditioning system and selecting the necessary equipment: • The air conditioning system that serves 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 "ASHRAE 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. Air Conditioning System Types The following three air conditioning system types are listed in order of preference: • Complete self-contained package units with remote condenser. 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. • Scalable overhead distribution system. These systems distribute water overhead to air heat exchangers, which cool the air locally over the servers. A system called DataCoolTM is primarily used in high density environments of 100 to 500 watts per square foot. 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 following parameters: • Ceiling supply system-From 55° to 60° F (12.8 το 15.6° C) • Floor supply system-At least 60° F (15.6° C) 38 Appendix B