Siemens LC 46651 Mode D'emploi Et Notice De Montage page 19

Prior to installation
For optimum extractor hood efficiency:
Short, smooth air exhaust pipe.
As few bends in the pipe as possible.
Diameter of pipe to be as large as
possible and no tight bends in pipe.
If long, rough exhaust-air pipes,
many pipe bends or smaller pipe
diameters are used, the air extraction
rate will no longer be at an optimum
level and there will be an increase in
noise.
The manufacturer of the extractor
hoods accepts no liability for complaints
which can be attributed to the design
and layout of the pipework.
If pipes have different diameters:
Insert sealing strip.
For exhaust-air mode, ensure that
there is an adequate supply of fresh air.
Flat ducts must have an internal cross-
section that equates to that of round
pipes.
There should be no sharp bends.
Round pipes
Internal diameter
l 120 mm
Air connector l 120 mm
Flat ducts
Cross-section
113 cm 2
Mount the pipe
directly onto the air
outlet on the hood.
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