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Installation
Use:
Calculating the to-
tal ducting length
Procedure
96
This will help to stop a reduced dryer performance and excessive
time and energy requirements.
- for the vent ducting: exhaust air hose* or a plastic waste water pipe
(e.g., HT piping systems) with a minimum diameter of 4" (100 mm).
Observe local codes.
- for the extraction ducting outside: wall pipe* or window connec-
tion*. Observe local codes.
*optional accessories
The friction of the vent ducting with its bends and various compo-
nents provides resistance to the flow of exhaust air. This friction resis-
tance is expressed as a relative pipe length. The relative pipe length
indicates how much greater the resistance of a bend is, for example,
when compared to 1 meter of a straight plastic waste water pipe (Ta-
ble I).
Adding together the relative pipe lengths for all of the components
gives the total ducting length. The total ducting length expresses the
resistance of the entire exhaust air system.
As a larger duct diameter has a lower flow resistance, a longer duct
requires a greater duct diameter (Table II).
1.
Measure the length needed for the straight sections of vent
ducting. Multiply this value by the corresponding relative pipe
length from Table I.
2.
Calculate the number of bends and components needed. Use
Table I to help you add together their relative pipe lengths.
3.
Add together all of the relative pipe lengths calculated above to
calculate the total ducting length.
4.
Refer to Table II for the pipe diameter needed for the total duct-
ing length.
Table I
Components
Exhaust air hose (flexible aluminum)* / pipe (tempera-
ture resistance min. 175°F (80°C))
– 3' 3" (1 m) laid straight or 3' 3" (1 m) straight pipe
– 45° bend (radius of bend = 10"(0.25 m))
– 90° bend (radius of bend = 10" (0.25 m))
The use of a wall pipe or window connection is regarded as an exception to
the design principles of the exhaust air management system. This must be
carried out in accordance with the applicable local building regulations. Seek
approval from the relevant building inspector where necessary.
Wall pipe* or window connection*
– with inserted grate
– with non-return flap (swinging flap)
Non-return flap*
* optional accessories
Relative pipe length
3' 3" (1.0 m)
2' (0.6 m)
2' 7 1/2" (0.8 m)
12' 5 5/8" (3.8 m)
4' 11" (1.5 m)
46' 11" (14.3 m)
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