To determine the correct model for your application, it is first 
necessary to determine the total heat load to which the control panel is
 subjected. This total heat load is the combination of two factors — 
heat dissipated within the enclosure and heat transfer from outside into
 the enclosure.
To Calculate Btu/hr.:
1. First, determine the approximate Watts of heat generated within the enclosure. Watts x 3.41 = Btu/hr.
2. Then, calculate outside heat transfer as follows:
 a. Determine the area in square feet exposed to the air, ignoring the top of the cabinet.
 b. Determine the temperature differential between maximum surrounding 
temperature and desired internal temperature. Then, using the 
Temperature Conversion Table (below), determine the Btu/hr./ft.2 for 
that differential. Multiplying the cabinet surface area times 
Btu/hr./ft.2 provides external heat transfer in Btu/hr.
 
