DVN 5000
Environmental Guidelines
10
24-10520-22 Rev. –
This document contains confidential and proprietary information of Johnson Controls, Inc.
© 2009 Johnson Controls, Inc.
Rack
– Enclosure, cabinet
Thermal Gradient
– The rate of temperature change in a given direction
Ton
– One Ton of air conditioning = 400 CFM (on most units)
Watt
– One Watt of current draw (Volts RMS X Amps) = 3.413 BTU/Hr.
Objective
Use the following information to calculate and understand when and how to vent a
rack using natural convection, and when to force the air using fans.
When using fans, you will be able to calculate the required amount of airflow (CFM)
and know where to place the vents.
Fan choices, filtering, and environmental variables are discussed, along with a range
of real-world application diagrams and helpful charts on how you can achieve
proper thermal management.
Thermal Design Guidelines
To avoid common mistakes, use the following guidelines when considering the
thermal design of equipment racks and enclosures for use with the DVN 5000
product.
Important Considerations
Consider how the room will exhaust hot air out and draw cool air in.
Keep the room temperature within the DVN’s operating temperature range.
See Table 1 on page 7.
Provide a separate zone in the HVAC system to ensure consistent air flow and
proper room temperature.
Use wide racks for passive convection (no fan) applications.
A fan near the top of the enclosure can move air through a cabinet from
bottom to top.
Verify the fan’s CFM rating is at least the sum of the CFM ratings of all the
equipment when using forced air applications. Use the following equation:
(CFM rating for 1 DVN) X (# of DVNs) = Minimum CFM rating of
enclosure fan(s)
When utilizing a rear fan door, choose one that directs air upwards towards a
return air duct (especially important in hot isle/cold aisle rack arrangements).
Use vented shelf surfaces that overhang the internal natural rise of heat. See
“Vented Shelves” on page 23.