Alliance Laundry Systems 907003062 User Manual

Exhaust Requirements

70420801 (EN)

Individual Venting

For maximum efficiency and performance, it is

preferred to exhaust tumble dryer(s) individually to

the outdoors.

IMPORTANT: At no point may the cross sectional

area of installed venting be less than the cross

sectional area of the exhaust outlet of the tumble

dryer.

The exhaust duct must be designed so the static back

pressure measured 12 inches (305 mm) from the

exhaust outlet does not exceed the maximum

allowable pressure specified on the installation sticker

on the rear of the tumble dryer.

NOTE: Static back pressure must be measured

with the tumble dryer running.

The maximum allowable length of venting of the same

diameter as the exhaust thimble is 14 feet (4.3 meters)

and two 90° elbows or equivalent. If the equivalent

length of a duct required for an installation exceeds the

maximum allowable equivalent length, the diameter of

a round duct must be increased by 10% for each

additional 20 feet (6.1 meters). Cross section area of a

rectangular duct must be increased by 20% for each

additional 20 feet (6.1 meters). Refer to Table 4 to

determine equivalent venting:

With the tumble dryer in operation, airflow at any

point in the duct should be at least 1200 feet per

minute (366 meters per minute) to ensure that lint

remains airborne. If 1200 feet per minute (366 meters

per minute) cannot be maintained, schedule monthly

inspections and cleaning of the ductwork.

NOTE: The maximum length of a flexible metal

duct must not exceed 7.87 ft. (2.4 m) as required to

meet UL2158, claus 7.3.2A.

Manifold Venting

While it is preferable to exhaust tumble dryers

individually to the outdoors, a main collector duct may

be used if it is sized according to Figure 8. This

illustration indicates minimum diameters, and should

be increased if collector length exceeds 20 feet (6.1

meters). Manifold duct may be rectangular in cross

section, as long as area is not reduced. Provisions

should be made for lint removal and cleaning of duct.
Manifold duct must be tapered, as shown in Figure 6.

Individual tumble dryer ducts must enter manifold

duct at a 45° angle in the direction if airflow.

NOTE: Never connect a tumble dryer duct at a 90°

angle to a collector duct. Refer to Figure 6. Doing

so will cause excessive back pressure, resulting in

poor performance. Never connect two tumble

dryer exhaust ducts directly across from each other

at the point of entry to manifold duct.

Figure 6

Exhaust system must be designed so static back

pressure measured 12 inches (305 mm) from exhaust

thimble does not exceed maximum allowable pressure

specified on installation sticker on rear of tumble

dryer. This must be measured with all tumble dryers

running that are vented into collector.
With the tumble dryer in operation, airflow at any

point in the duct should be at least 1200 feet per

minute (366 meters per minute) to ensure that lint

remains airborne. If 1200 feet per minute (366 meters

per minute) cannot be maintained, schedule monthly

inspections and cleaning of the ductwork.

Duct Diameter

Equivalent Length

of Rigid Straight Duct

10 in. (254 mm)
12 in. (305 mm)
14 in. (356 mm)
16 in. (406 mm)
18 in. (457 mm)

One 90° elbow = 11.6 ft. (3.5 m)
One 90° elbow = 14 ft. (4.3 m)
One 90° elbow = 16 ft. (4.9 m)
One 90° elbow = 18.7 ft. (5.7 m)
One 90° elbow = 21 ft. (6.4 m)

Equivalent Length (ft.) = 1.17 x Duct Diameter (in.)

Table 4

Example: A 12 inch (305 mm) diameter duct’s
equivalent length of 14 feet (4.3 meters) of duct and two
90° elbows is:
Equivalent Length: = 14 ft. (4.3 m) + (2) 90° elbows

= 14 ft. (4.3 m) + 14 ft. (4.3 m)

+ 14 ft. (4.3 m)

= 42 ft. (12.8 m)

T438I