Heat Release Calculator / Heat Dissipation Calculator

for a Shelf-Level Product

NOTE:  If you are having trouble with this Java Applet, please click here

Heat Release Calculations Per GR-63-CORE

To calculate Heat Dissipation or Heat Release for a shelf-level product:

Need to know:

1. Height of the unit

   1. Includes the height of any required air ramps or spacers.

2. Width of the frame

   1. For a 23-inch mounting, use a width of 26 inches.

   2. NOTE: Equipment mounts on 23 inch, but total width equals 26 inches.  The calculator shows a width of 23 inches, but will use 26 inches in the calculation.

3. Depth of the frame

   1. Depth of the frame (Front and Rear aisle dimensions are from GR-63-CORE):

      i. 12 inch

      1. FrontAisle = 30 inches

      2. RearAisle = 24 inches

      ii. 18 inch

      1. FrontAisle = 54 inches

      2. RearAisle = 30 inches

      iii. 24 inch

      1. FrontAisle = 42 inches

      2. RearAisle = 30 inches

4. Equipment power in Watts

   1. Multiply operating voltage (-48 Vdc) by maximum load current (A).

• Calculate the floor area (use Front and Rear aisle dimensions from item 3):

  • FloorArea = [Width*(depth + (FrontAisle/2 + RearAisle/2))]

• Calculate the Heat Release per Shelf:

  • HeatReleaseperShelf = Equipment Power/FloorArea

• Calculate the Heat Release per Unit Height:

  • HeatReleaseperUnitHeight = HeatReleaseperShelf/Height

• Compare values to Table 4-6 of GR-63-CORE Shelf and use appropriate value based on Forced-Air Fans or Natural Convection.

Example Calculation

Forced-air fans used to cool unit

Height of unit = 24.5 inches (2.042 ft)

Width of Frame = 26 inches (2.167 ft)

Depth of Frame = 12 inches (1 ft)

FrontAisle = 30 inches (2.5 ft)

RearAisle = 24 inches (2 ft)

Equipment power in watts = 457 Watts

• Calculate the floor area (use Front and Rear aisle dimensions from item 3):

  • FloorArea = [Width*(depth + (FrontAisle/2 + RearAisle/2))]

  • FloorArea = [2.167 ft*(1 ft +(2.5 ft/2 + 2 ft/2))] = 7.042 ft2

• Calculate the Heat Release per Shelf: o HeatReleaseperShelf = Equipment Power/FloorArea

  • HeatReleaseperShelf = 457 Watts/7.042 ft2 = 64.95 W/ft2

• Calculate the Heat Release per Unit Height:

  • HeatReleaseperUnitHeight = HeatReleaseperShelf/Height

  • HeatReleaseperUnitHeight = 64.95 W/ft2 /2.042 ft = 31.8 W/ft2/ft

31.8 W/ft2/ft is greater than 27.9 W/ft2/ft therefore this unit does not meet the GR-63-CORE Heat Release Objective.