Calculating System Thermal Output

The Internet abounds with information on the topic of thermal output.

I’ve collected the following formulas and placed them here for my quick reference.

Watts

=

0.293

*

BTU-Hr

Watts

=

3,530

*

Tons

BTU-Hr

=

3.41

*

Watts

Tons

=

0.000283

*

Watts

 

For example,

  • PacketLight PL-1000TN Optical Transport Unit PSU rated at 70 watts is
    238.7 BTU-Hr = 3.41 * 70 watts
  • HP ProLiant DL120 Generation 7 (G7) PSU rated at 570 watts is
    1943.7 BTU-Hr = 3.41 * 570 watts
  • Dell PowerEdge R410 Rack Server with Non-Redundant PSU rated at 480 watts is
    1636.8 BTU-Hr = 3.41 * 480 watts

Volts will change the wattage; consider the following calculation.

Power (watts) = Voltage (volts) * Current (amperes)

If you are looking for information on sizing the thermal footprint of a datacenter there are other factors to take into consideration in addition to server and network equipment.

For example,

  • People (see note 1)
  • Lighting
  • Powered devices (non-IT gear)
  • Windows (sun light)
  • Heat conduction via exterior (outside) facing walls
  • Raised/non-raised floor
  • Humidity

When I set out to research the formula for determining a system’s thermal output I found myself caught up in the additional information I came across.  To me that’s like finding $5 bill in my pocket.

Note 1
There is general agreement that the human body will produce ~100 watts.  The following link has a brief discussion on the topic – interesting I thought.
http://hypertextbook.com/facts/2003/WeiLiangMok.shtml

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