Installation Guide
12
PLANNING THE INSTALLATION
Ducting Calculation Sheet
Duct pieces
Equivalent 
length x number 
used =
Total
3-1/4" x 10" 
Rect., 
straight
1 Ft.  x ( ) = Ft.
6" Round, 
straight
1 Ft.  x ( ) = Ft.
7"-10" 
Round, 
straight
1 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.90˚ 
elbow
15 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.45˚ 
elbow
9 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.90˚  
at elbow
24 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.
wall cap 
with damper
30 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.to
6" round 
transition
5 Ft.  x ( ) = Ft.
3-1/4" x 10"
Rect.to
6" round 
transition 
90˚ elbow
20 Ft.  x ( ) = Ft.
6" Round, 
90˚ elbow
15 Ft.  x ( ) = Ft.
6" Round, 
45˚ elbow
9 Ft.  x ( ) = Ft.
Subtotal column 1 = Ft.
Duct pieces
Equivalent 
length x number 
used =
Total
6" Round 
wall cap 
with damper
30 Ft.  x ( ) = Ft.
6" Round, 
roof cap
30 Ft.  x ( ) = Ft.
6" round to 
3-1/4" x 10"
rect.
transition
1 Ft.  x ( ) = Ft.
6" round to
3-1/4" x 10"
rect.
transition
90˚ elbow
16 Ft.  x ( ) = Ft.
7" - 10"
Round,
90˚ elbow
15 Ft.  x ( ) = Ft.
7" - 10"
Round,
45˚ elbow
9 Ft.  x ( ) = Ft.
7" - 10"
Round wall 
cap with 
damper
30 Ft.  x ( ) = Ft.
7" - 10"
Round, 
roof cap
30 Ft.  x ( ) = Ft.
7" round to 
3-1/4" x 10"
rect.
transition
8 Ft.  x ( ) = Ft.
7" round to 
3-1/4" x 10"
rect.
transition
90˚ elbow
23 Ft.  x ( ) = Ft.
Subtotal column 2 = Ft.
Subtotal column 1 = Ft.
Total ductwork = Ft.
Maximum Duct Length: For satisfactory air 
movement, the total duct length should not exceed 
100 equivalent feet.










