Installation of the ducting
*INSTALLATION*
62
Calculating the total ducting
length
The entire ducting system (including
bends and components) generates air
resistance that pushes against the ex-
haust air. The relative pipe lengths and
total ducting length have to be calcu-
lated for this reason:
– The
relative pipe length
(table I)
indicates how much greater the air
resistance of a bend is, for example,
when compared to 1 metre of a
straight plastic waste water pipe.
– Adding all of these relative pipe
lengths together gives the
total
ducting length
. This is not the actual
length but a calculated figure. The
total ducting length (table II) ex-
presses the air resistance of the en-
tire exhaust air system.
Because a larger
pipe diameter
(ta-
ble II) reduces the air resistance, a
longer total duct length requires a
greater pipe diameter.
Procedure
Measure the length needed for the
straight sections of ducting. Multiply
the length by the corresponding rel-
ative pipe length from
table I
.
Calculate the number of bends and
elbows needed. Use
table I
to help
you add together their relative pipe
lengths.
Calculate the total duct length: add
together all of the relative pipe
lengths calculated under
and
.
Refer to
table II
for the pipe diameter
needed for the total duct length.
Table I
Components
Relat-
ive
pipe
length
Exhaust air hose (highly flexible)*
1 m, laid straight
45° bend (radius of bend = 0.25 m)
90° bend (radius of bend = 0.25 m)
1.8 m
1.5 m
2.5 m
Exhaust air hose (flexible or flex-
ible aluminium)*/plastic waste
water pipe
1 m, laid straight/straight pipe
45° bend (radius of bend = 0.25 m)
90° bend (radius of bend = 0.25 m)
1.0 m
0.6 m
0.8 m
Wall pipe* or window connection*
With inserted grille
With non-return flap (swinging flap)
3.8 m
1.5 m
Non-return flap* for integration
into the ducting
(see “Shared exhaust air duct”)
14.3 m
Flat ducting (for stacked installa-
tion)*
11.0 m
* Optional accessories
Table II
Total duct length
Pipe diameter
Maximum of 20 m
Maximum of 40 m
Maximum of 80 m
100 mm
125 mm
150 mm
