Thermal Output

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