Installation Preparation

DUCT FITTINGS

Use this chart to compute maximum permissable lengths for duct runs to outdoors.

NOTE: Do not exceed maximum permissable equivalent lengths!

Maximum duct length:

100 foot for 6” round duct

75 foot for 3-1/4” x 12” duct

Flexible ducting:

If flexible metal ducting is used, all the equivalent feet values in the table should be doubled.

The flexible metal duct should be straight and smooth and extended as much as possible.

DO NOT use flexible plastic ducting.

NOTE: Any home ventilation system, such as a ventilation hood, may interrupt the proper flow of combustion air and exhaust required by fireplaces, gas furnaces, gas water heaters and other naturally vented systems. To minimize the chance of interruption of such naturally vented systems, follow the heating equipment manufacturer’s guidelines and safety standards such as those published by NFPA and ASHRAE.

This Hood Must Use a

6” Round Duct.

It Can Transition To

3-1/4” x 12” Duct

 

 

 

 

Total

 

 

Equivalent

Quantity

Equivalent

Duct Piece

Dimensions

Length*

Used

Length

 

Round,

1 ft.

 

 

 

straight

(per foot

 

 

 

 

length)

 

 

 

3-1/4” x 12”

1 ft.

 

 

 

3-1/4” x 24”

(per foot

 

 

 

straight

length)

 

 

 

6” Round

 

 

 

 

90° elbow

15 ft.

 

 

 

6” Round

 

 

 

 

45° elbow

8 ft.

 

 

 

3-1⁄4” x 12”

 

 

 

 

90° elbow

11 ft.

 

 

 

3-1/4” x 12” or

 

 

 

 

45° elbow

6 ft.

 

 

 

3-1/4” x 12”

 

 

 

 

90° flat elbow

24 ft.

 

 

 

6” round to

 

 

 

 

3-1/4” x 12”

 

 

 

 

or 3-1/4” x 24” transition

1 ft.

 

 

 

3-1/4” x 12” to 6”

 

 

 

 

round transition

8 ft.

 

 

 

6” round

 

 

 

 

to 3-1/4” x 12” or

 

 

 

 

transition 90° elbow

16 ft.

 

 

 

3-1/4” x 12” to 6” round

 

 

 

 

round transition 90° elbow

17 ft.

 

 

 

6” round

 

 

 

 

wall cap

 

 

 

 

with damper

30 ft.

 

 

 

3-1/4” x 12” wall cap

 

 

 

 

with damper

30 ft.

 

 

 

6” Round

 

 

 

 

roof cap

26 ft.

 

 

 

6” Round

 

 

 

 

roof vent

26 ft.

 

 

*Actual length of straight duct plus duct fitting equivalent. Equivalent length of duct

pieces are based on actual tests conductedTotal Duct Run by GE Evaluation Engineering and reflect

requirements for good venting performance with any ventilation hood.

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GE ZV800 installation instructions Duct Fittings, Duct Piece Dimensions Length Used