Worksheet Calculate Total Equivalent Ductwork Length

Installation Instructions

WORKSHEET – CALCULATE TOTAL EQUIVALENT DUCTWORK LENGTH

DUCT	EQUIVALENT NUMBER
PIECES	LENGTH	x USED			= TOTAL
31⁄4″ x 10″	1 Ft.	x	(	)	=	Ft.
Rect.,
straight
7″ Round,	1 Ft.	x	(	)	=	Ft.
straight
6″ Round,	1 Ft.	x	(	)	=	Ft.
straight
31⁄4″ x 10″	8.5 Ft.	x	(	)	=	Ft.
Rect. 90°
elbow
31⁄4″ x 10″	7 Ft.	x	(	)	=	Ft.
Rect. 45°
elbow
31⁄4″ x 10″	24 Ft.	x	(	)	=	Ft.
Rect. 90°
flat elbow
31⁄4″ x 10″	45 Ft.	x	(	)	=	Ft.
Rect.	(7 ft. w/o
wall cap	damper)	x	(	)	=	Ft.
with
damper
31⁄4″ x 10″	4.5 Ft.	x	(	)	=	Ft.
Rect. to
6″ round
transition
31⁄4″ x 10″	11.5 Ft.	x	(	)	=	Ft.
Rect. to
6″ round
transition
90° elbow
6″ Round,	8 Ft.	x	(	)	=	Ft.
90° elbow
6″ Round,	6.5 Ft.	x	(	)	=	Ft.
45° elbow
	Subtotal column 1				=	Ft.

MAXIMUM DUCT LENGTH: For satisfactory air movement, the total duct length of a 31⁄4″ x 10″ rectangular, 6″ or 7″ diameter round duct should not exceed 65 equivalent feet.

DUCT	EQUIVALENT		NUMBER
PIECES	LENGTH	x USED			= TOTAL
6″ Round	34 Ft.	x	(	)	=	Ft.
wall cap	(6 ft. w/o
with	damper)	x	(	)	=	Ft.
damper
6″ Round	30 Ft.	x	(	)	=	Ft.
roof cap
6″ Round	5.5 Ft.	x	(	)	=	Ft.
to
31⁄4″ x 10″
rect.
transition
6″ Round	14.5 Ft.	x	(	)	=	Ft.
to
31⁄4″ x 10″
rect.
transition
90° elbow
7″ Round,	8 Ft.	x	(	)	=	Ft.
90° elbow
7″ Round,	6.5 Ft.	x	(	)	=	Ft.
45° elbow
7″ Round	34 Ft.	x	(	)	=	Ft.
wall cap	(6 ft. w/o
with	damper)	x	(	)	=	Ft.
damper
7″ Round	30 Ft.	x	(	)	=	Ft.
roof cap
7″ Round	5.5 Ft.	x	(	)	=	Ft.
to
31⁄4″ x 10″
rect.
transition
7″ Round	14.5 Ft.	x	(	)	=	Ft.
to
31⁄4″ x 10″
rect.
transition,
90° elbow
	Subtotal column 2				=	Ft.
	Subtotal column 1				=	Ft.

Total ductwork

Ft.