Follow the guidelines for proper duct sizing in the ducting charts.
DUCTING CHART:
Flow vs. equivalent feet of duct length
300
250
200
150
100
50
0
0
MAXIMUM DUCT LENGTH: For satisfactory air movement, the total duct length of a 3
6" or 7" diameter round duct should not exceed 65 equivalent feet.
Installation Instructions
JV347
JV338
20
40
60
Equivalent Feet of Duct Length
7
80
100
" x 10" rectangular,
1
⁄
4