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4
Installation - Ductwork Calculation S heet
Duct pieces
To t a l
Equivalent number
length x used =
31/4”x10”
Rect.,
straight
1 Ft. x ( ) =
Ft.
7” Round,
straight
1 Ft. x ( ) =
Ft.
31/4”x10”
Rect. 90
0
elbow
15 Ft. x ( ) =
Ft.
31/4”x10”
Rect. 45
0
elbow
9 Ft. x ( ) =
Ft.
31/4”x10”
Rect. 90
0
at elbow
24Ft. x ( ) =
Ft.
31/4”x10”
Rect.
wall cap
with damper
30Ft. x( ) =
Ft.
31/4”x10”
Rect. to
6” round
transition
5 Ft. x ( ) =
Ft.
31/4”x10”
Rect. to
6” round
transition
90
0
elbow
15Ft. x ( ) =
Ft.
6” Round,
90
0
elbow
15Ft. x ( ) =
Ft.
6” Round,
45
0
elbow
9 Ft. x ( ) =
Ft.
Ft.
7” Round,
straight
1 Ft. x ( ) =
Ft.
Subtotal column 1 =
Duct pieces
To t a l
Equivalent number
length x used =
6” Round
wall cap
with damper
30 Ft. x ( ) =
Ft.
7” Round
wall cap
with damper
30 Ft. x ( ) =
Ft.
7” Round,
90
0
elbow
15 Ft. x ( ) =
Ft.
7” Round,
45
0
elbow
9 Ft. x ( ) =
Ft.
Ft.
Ft.
Ft.
6” Round,
roof cap
30 Ft. x ( ) =
Ft.
7” Round,
roof cap
30Ft. x( ) =
Ft.
Subtotal column 2 =
Subtotal column 1 =
Total ductwork =
Maximum Duct Length:
For satisfactory air movement,
the total duct length ofa31/4”x10”rectangular, 6” or 7”
diameter round ductshould not exceed 100 equivalent feet.
6” round to
31/4”x10”
rect.
transition
1 Ft. x ( ) =
Ft.
6” round to
3 1/4” x 10”
rect.
transition
90
0
elbow
16Ft. x ( ) =
Ft.
7” round to
31/4”x10”
rect.
transition
8 Ft. x ( ) =
Ft.
7” round to
3 1/4” x 10”
rect.
transition
90
0
elbow
15Ft. x ( ) =
Ft.