Solutions
The air temperature surrounding the active equipment is affected not only by the heat load (power used) of the
active equipment, but the size of the enclosure, the thermal resistance between the chassis of the active equipment
and the air, the construction material of the enclosure and the air temperature surrounding the outside of the
enclosure. Several cooling techniques are discussed from the simplest to the more complex. Depending on the
cooling option selected (passive cooling solution, fan assisted cooling solution or AC unit cooling solution)
additional penetrations to the enclosure and power sources for the cooling unit may be required.
Information Gathering
To properly select any thermal solution some basic information about system (enclosure and the equipment it
will house) must be collected. Most of this information is available from the equipment vendor in the form of data
sheets, specifications, instruction manuals, deployment guides etc. Below is a bullet list of the information required
to apply any of the cooling solutions.
1. Maximum Ambient Air Temperature.
This is air temperature that will surround the exterior of the enclosure.
2. The Internal Heat-Load.
This is the sum of the power consumed by the equipment mounted inside the enclosure.
3. Maximum Desired Internal Enclosure Temperature.
The equipment with the lowest maximum temperature limit will dictate the maximum allowable internal
temperature for the enclosure. Likewise, the highest minimum temperature limit will dictate the minimum
allowable internal temperature for the enclosure.
4. Two of the first three data points must be known to allow the third data point to be determined from the
charts in the cooling solutions.
5. Enclosure dimensions.
The height, width and depth of the nearest inch (Z23: 36" x 24" x 12").
6. Enclosure Material.
The solutions below are for enclosures constructed from steel (the type of steel e.g. stainless or mild will have a
minimum impact on these calculations).
7. Indoor or Outdoor.
The charts to follow apply only to an enclosure not exposed to direct sunlight.
2
