Catalogue

22 UV-PRC003-EN
Selection Procedure
Example:
Ventilation cooling capacity = 1.085 x cfm
t
x (T
1
- T
2
)
cfm
t
= Total air capacity of unit with outside air damper open 100 percent.
T
1
= Room temperature.
T
2
= Outside air temperature.
In classrooms with exceptionally heavy air conditioning loads, unit size may be determined by the
total cooling requirement. Good practice dictates 375 to 425 cfm per ton of hydronic cooling
capacity. Normally, however, Trane classroom air conditioner coils have sufficient capacities.
Example:
Given: Air circulation specified = 8 air changes per hour.
Classroom size = 35 ft long x 25 ft wide x 10 ft high
Inside design air temperature = 75 degrees F
Ventilation cooling required at 58 degrees F = 29,000 BTU
Checking ventilation cooling capacity:
29,800 BTU = 1.085 x CFM x (80-58)
CFM = 1250
This indicates that a 1250 cfm unit would have satisfactory ventilation cooling capacity at the
design changeover point of 58°F. Coil capacity will become confirmed when the coil is selected.
Coil Selection
Selecting the correct coil is done through Trane’s Official Product Selection System (TOPSS) For
your convenience, TOPSS has a mixed air calculator built into the program.
CFM required = 8 changes/hr x (35 x 25 x 10)ft
3
= 1170 cfm
60 Minutes/hr
UV-PRC003-EN.book Page 22 Tuesday, June 4, 2013 8:59 PM