GE JGP989 manual Ductwork Calculations, Calculate Total Equivalent Ductwork Length

Installation Instructions

DUCTWORK CALCULATIONS

Calculate Total Equivalent Ductwork Length

	Equivalent		Number			Equivalent
Duct Pieces	Length* x		Used		=	Length
6″ round
straight	1 ft.	x	(	)†	=	ft.
31⁄4″ x 10″
straight	1 ft.	x	(	)† =		ft.
6″, 90°
elbow	15 ft.	x	(	) =		ft.
6″, 45°
elbow	9 ft.	x	(	) =		ft.
24″ max.
flexible
metal offset
adapter	34 ft.	x	(	) =		ft.
31⁄4″ x 10″
90° elbow	16 ft.	x	(	) =		ft.
31⁄4″ x 10″
45° elbow	5 ft.	x	(	) =		ft.
31⁄4″ x 10″
90° flat elbow	18 ft.	x	(	) =		ft.
6″ round
to 31⁄4″ x 10″
transition	7 ft.	x	(	) =		ft.
	Subtotal Column 1 =					ft.

*Equivalent lengths of duct pieces are based on actual tests and reflect requirements for good venting performance with any downdraft cooktop.

†Measure and list feet of straight duct used. Count and list the quantity of all other duct pieces for the “Number Used” of each type.

IMPORTANT:

For maximum efficiency, use the shortest and straightest duct run possible, with as few fittings as possible. For satisfactory performance, the duct run should not exceed 100 feet equivalent length.

Venting performance is improved by using larger diameter duct.

		Equivalent		Number		Equivalent
Duct Pieces		Length* x		Used	=	Length
	6″ round
	to 31⁄4″ x 10″
	transition
	90° elbow	20 ft.	x	(	) =	ft.
	31⁄4″ x 10″
	to 6″ round
	transition	5 ft.	x	(	) =	ft.
	31⁄4″ x 10″
	to 6″ round
	transition
	90° elbow	12 ft.	x	(	) =	ft.
	6″ round
	wall cap
	with damper	21 ft.	x	(	) =	ft.
	31⁄4″ x 10″
	wall cap
	with damper	27 ft.	x	(	) =	ft.
	6″ round
	roof cap	20 ft.	x	(	) =	ft.
	6″ round
	roof vent	24 ft.	x	(	) =	ft.
		Subtotal Column 2 =				ft.
		Subtotal Column 1 =				ft.
		TOTAL DUCTWORK =				ft.
		Should not exceed 100 feet.

DO NOT use flexible plastic ducting.

Vent installation should not exceed 100 feet equivalent length.

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