Miele PDW 909 Schéma D'installation page 35

The following
should be avoided:
Use:
Calculating the
total ducting
length
Procedure
- Long vent ducting
- Too many tight bends or elbows
This will help to stop a reduced dryer performance and excessive
time and energy requirements.
- For the vent ducting: exhaust hose* or a plastic waste water pipe
(e.g. HT piping systems) with a minimum diameter of 100 mm.
- For extraction ducting outside: wall pipe* or window connection*.
*optional accessories
The friction of the vent ducting with its bends and various compon-
ents provides resistance to the flow of air. This friction resistance is
expressed as a relative pipe length. The relative pipe length indic-
ates how much greater the resistance of a bend is, for example, when
compared to 1 metre of a straight plastic waste water pipe (table 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 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 in
order to calculate the total ducting length.
4. Refer to table II for the pipe diameter needed for the total duct-
ing length.
en - Installation notes
35