1. Applying Precision Air Conditioning Systems
Canatal International Inc.

2. Introduction Application of Precision Air Conditioning Data Centers
Switching Stations
Co-Location Facilities

3. Topics of Discussion Servers / Switch Gear
Temperature & Humidity Control
Air Distribution
Redundancy
Alternating Cold Aisle, Hot Aisle
Perforated Tile Capacity
Design & Planning Stage
Maintenance

4. Servers / Switch Gear Smaller, More Powerful
Driven by semi-conductor capacity
More transistors on a chip
More power consumption per chip
More heat generation

5. Servers / Switch Gear
Published Power Rating may expect future upgrades, higher energy consumption and greater heat rejection
Initial power consumption and heat generation can be lower

6. Available @www.ashrae.org, Item Number 90431, or D90431
New ASHRAE Document
“Thermal Guidelines for Data Processing Environments”
Equipment Environment Specifications
Facility Temperature & Humidity Measurement
Equipment & Facility Layout
Equipment Manufacturers Heat & Airflow Reporting
Item Number 90431, or D90431

7. “Thermal Guidelines for Data Processing Environments”
Equipment Environment Specifications

8. “Thermal Guidelines for Data Processing Environments”
Equipment Environment Specifications

9. ASHRAE Class 1 Operating Conditions

10. ASHRAE Class 1 Operating Conditions
Increase Equipment Failures

11. ASHRAE Class 1 Operating Conditions
Increase HVAC Energy Use

12. “Thermal Guidelines for Data Processing Environments”
Facility Temperature & Humidity Measurement

13. “Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout
Recommended Airflow Protocol for Computer Equipment

14. “Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout
Recommended Airflow Protocol for Computer Equipment

15. “Thermal Guidelines for Data Processing Environments”
Equipment & Facility Layout
Recommended Airflow Protocol for Computer Equipment

16. “Thermal Guidelines for Data Processing Environments”
Equipment Manufacturers Heat & Airflow Reporting

17. Server / Switch Gear
1U (1.70” H) Server
Back View
Front View

18. Server / Switch Gear
2U (3.50” H) Server
Back View
Front View

19. Server / Switch Gear
4U (6.80” H) Server
Back View
Front View

20. Server / Switch Gear 5U Server – Tower Configuration Back View
Front View

21. Server / Switch Gear
Back View
Front View

22. Heat Density Trends
Source: Uptime Institute

23. What is wrong with this picture?

24. What is wrong with this picture?1b 2 3 4 5 2 2
1a, 1b
Cold aisles. 1a has less airflow then 1b - WHY? 2
Hot aisles 3
Top of hot aisle (from right to left – warm to hot) 4
Insufficient cold air and recirculation from hot aisle to cold aisle 5
Mixed return air path

25. External re-circulation:
Top 1/3 portion likely to have higher failure rate

26. Internal re-circulation:
Add blanking panels to eliminate the problem

27. Positioning of PAC units
Parallel or Perpendicular to aisles

28. Temperature Control Challenges Hot Spots / Hot Zones / Hot Room
Uneven heat load on the floor space
Fluctuating heat loads
Initial low loads

29. Temperature Control Servers/Switches generate sensible heat
Utilize Precision Air Conditioning Systems with high sensible heat ratios
Unwanted dehumidification is a waste of energy and money

30. Humidity Control
Independently operated units will fight - simultaneously humidify and dehumidify
Wasting energy and money
Units should work together as a Team

31. Air Distribution Raised Floor System Generally more flexible
Easy to move perforated tiles
Overhead System
Ducted or Plenum
Make the last length of duct flexible to enable movement of discharge grilles

32. Air Distribution Deliver Cool Air to the Heat Source
Eliminate Short Circuiting
Anytime air returns to the PAC without passing through heat generating servers, routers, switches etc.

33. Air Distribution Short Circuiting - Common Causes
Obstructions to airflow
Air Leakage
Location of discharge grilles and perforated tiles

34. Air Distribution – Obstructions
Raised Floor System
Electric cable trays, especially with shallow floor heights
Water damp

35. Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”
Cabinet should be aligned with one edge along the edge of the cold aisle floor tile
Floor tile cuts should be no larger then necessary to minimize air pressure loss

36. Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”

37. Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”

38. Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Power Distribution Unit (PDU) cables should run under the “Cold Aisles”
Cable trays for telecom cablings should locate under the “ Hot Aisles”

39. Air Distribution – Obstructions
Practice Recommendations for Position Equipment Racks & Cabinets
Cabinet should be aligned with one edge along the edge of the cold aisle floor tile

40. Air Distribution – Obstructions

41. Air Distribution – Oversized Openings
Practice Recommendations for Position Equipment Racks & Cabinets
Floor tile cuts should be no larger then necessary to minimize air pressure loss

42. Air Distribution – Oversized Openings

43. Air Distribution Obstructions
Maximize Floor Height
Floor height restricts air flow volume
High airflow velocities under the floor can negate static pressure differentials and entrain air from above to below
May need scoops

44. Air Distribution Obstructions

45. Air Distribution Obstruction
Overhead System
Light fixtures, overhead cable trays
Equipment that is taller than the discharge plenum

46. Air Flow Obstruction

47. Air Distribution – Obstructions

48. Air Distribution – Obstructions

49. Air Distribution – Air Leakage
Raised Floor System
Behind the PAC unit
Improper Wire/Cable openings - remove one tile to run wires
Around the perimeter of room
Adversely effects the under floor static pressure hindering the control of airflow

50. Air Distribution – Air Leakage

51. Cleanliness and Proper Vapor Barrier in Subfloor

53. What is the right distance from PAC to the 1st Rack

54. None-Direction Airflow
Pressure = Static Pressure + Velocity Pressure

55. Perform Better

56. Air Distribution – Air Leakage
Overhead System
No shut off dampers on redundant units
Back draft dampers or motorized discharge dampers with timers

57. Air Distribution – Airflow Pattern
Raised Floor System
Perforated tile quantity and layout
Perforated tiles too close to the PAC
3 foot clearance above computer racks
Drop ceiling = return air plenum

58. Air Distribution – Airflow Pattern

59. Air Distribution – Airflow Pattern

60. Air Distribution – Airflow Pattern
Overhead System
Discharge diffuser too close to the PAC
Air discharge from one unit enters the return air of another

61. Air Distribution – Airflow Pattern

62. Redundancy N+1 PAC Units i.e. 20 ton load, three 10 ton units
Only one pump on glycol/water loop
Multiple feeds to PAC units, but only one breaker for all rooftop condensers

63. Redundancy of Airflow
Can air reach each part of the room from more than one unit?
If the answer is no, then N+1 may be negated

64. Alternating Cold Aisle, Hot Aisle
Computer Equipment Air Flow Pattern
In the front, out the back
Racks face each other along one aisle
Backs face each other on alternate aisle

65. Alternating Cold Aisle, Hot Aisle

66. Alternating Cold Aisle, Hot Aisle

67. Alternating Cold Aisle, Hot Aisle

68. Air Distribution – Airflow Pattern
Raised Floor System
Controlling the Return Air Drop ceiling = return air plenum

69. Air Distribution – Airflow Pattern

70. Cost Effective Solution

71. Cooling Capacity – One Tile
Perforated Tile Cooling Capacity

72. Cooling Capacity – One Tile
Directly dependent on the airflow volume deliver through each tile
Air volume dependent on static pressure under the floor

73. Cooling Capacity – One Tile
One 2’ x 2’ Perforated Tile
Typical Airflow
” w.c.
” w.c.
Thus, leakage and too many perf. tiles will reduce static pressure and reduce the ability to control air flow

74. Cooling Capacity – One Tile
Maintain high sensible heat ratio
AT 72˚F, 50%RH or 68˚F, 50%RH, excessive condensation occurs after a 17˚F temperature drop

75. Cooling Capacity – One Tile
17˚F

76. Cooling Capacity – One Tile
Cooling Capability
600 cfm x 17˚F x 1.08 = 11,000 Btuh
Airflow volume critical to cooling capacity

77. Cooling Capacity – Per Rack
Four foot wide aisles
22,000 Btuh sensible cooling per two feet of aisle
With racks on both sides of the aisle, the heat load is 3,200 Watts per two feet of racking

78. Downflow Front Discharge

79. Design & Planning Stage
Capacity and placement of PAC
Room Geometry
Initial & final room layout
Initial & final load
Factors affecting air flow distribution
Plenum static pressure
Obstructions beneath plenum
Configuration to prevent air mixing

80. Design & Planning Stage
Mechanical system selection:
Air / water cool
Refrigeration/water piping layout
Keep it simple
Noise concerns:
Local or remote compressor
Condenser / condensing
Energy factor
Dual / Free Cooling
NSB, increase of useable floor space
Free cooling system
Risk factor
Chilled water /water cooled system

81. Maintenance Commissioning of basic systems Programming of controller
Refrigeration, electrical, blower RPM, etc.
Programming of controller
Configure alarm responses
Train End-user
Follow Maintenance Program

82. Maintenance Common Deficiencies Dirty or blocked filters
Undercharged DX systems
Un-calibrated or damaged sensors
Poor water flow, partially closed valves or other piping obstructions
Chilled water supply temp. ( ˚F)

83. Thank You