Miele T 80 Series Technical Information page 68

Technical Information
exhaust the air without any problem. If the sum is greater than 66 ft., a
larger duct diameter may be required.
Type of bend or fitting
Smooth bend
Elbow bend (Sharp – no
radius
Corrugated bend
Flexible metal duct
Wall vent with flap
Wall vent with louvers
Smooth Bend
Calculating the maximum allowable length for 5" (125 mm) ducting
When using 5" ducting, adequate air extraction is possible for an effective
duct length of up to 115 ft. (1378 in.)
To calculate the effective duct length, proceed as follows:
A) Measure the total length of the proposed ducting, including any bends.
B) Determine the amount, angle, and type of bends that will be required.
C) Determine what type of fitting will be used to terminate the duct at the
outer wall (flap vent, louvered vent, grill, etc.).
D) Using the chart below, add the additional length factor of the bends and
fittings that will be used to the total length measured in Step A above. If
the sum is less than 115 ft. (1378 inches), the hood will be able to
exhaust the air without any problem. If the sum is greater than 115 ft., an
external fan may be required.
Type of bend or fitting
Smooth bend
Elbow bend
Corrugated bend
Flexible metal duct
Angle of bend
90°
90°
90°
45°
90°
R
90° Elbow
Angle of bend
45°
45°
90°
90°
45°
90°
90°
45°
45°
45°
90°
90°
90°
68
Radius of bend Additional length factor
4 inches
8 inches
Up to 16 inches
Up to 16 inches
Corrugated Bend
Radius of bend Additional length factor
4 inches
8 inches
4 inches
8 inches
5 inches
10 inches
20 inches
5 inches
10 inches
20 inches
T 80xx
14 inches
90 inches
28 inches
12 inches
20 inches
99 inches
142 inches
R
8 inches
4 inches
12 inches
8 inches
18 inches
71 inches
22 inches
8 inches
6 inches
4 inches
14 inches
12 inches
8 inches