8514-219-001 REV E PAGE 11
reduce the amount of air the blower can exhaust. This does not affect the dryer operation if
held within practical limits. For the most efficient operation, it is recommended that no more
than 20’ (6 m) of straight 8’ (200 mm) diameter pipe with two right angle elbows is used. The
design of the vent system shall be such that any condensate formed when operating the dryer
from cold shall either be retained and re-evaporated or discharged.
Maintain a minimum of 25 mm (1 in.) clearance between duct and combustible material.
If the exhaust pipe passes through a wall, a metal sleeve of slightly larger diameter should
be set in the wall and the exhaust pipe passed through this sleeve. This practice is required
by some local codes and is recommended in all cases to protect the wall. This type of
installation should have a means provided to prevent rain and high winds from entering the
exhaust when the dryer is not in use. A hood with a hinged damper can be used for this
purpose. Another method would be to point the outlet end of the pipe downward to prevent
entrance of wind and rain. In either case, the outlet should be kept clear, by at least 24”
(600 mm), of any objects, which would cause air restriction.
Never install a protective screen over the exhaust outlet.
When exhausting a dryer straight up through a roof, the overall length of the duct has the
same limits as exhausting through a wall. A rain cap must be placed on top of the exhaust
and must be of such a type as to be free from clogging. The type using a cone shaped “roof”
over the pipe is suitable for this application.
Exhausting the dryer into a chimney or under a building is not permitted. The exhaust air
should not be vented into a wall, a ceiling, or a concealed space of building. In these cases,
there is a danger of lint buildup, which can be highly combustible.
Installation of several dryers, where a main discharge duct is necessary, will need the
following considerations for installation (see Figure 3). Individual ducts from the dryers into
the main discharge duct should be at a 45-degree angle in the direction of discharge airflow.
NOTE: Never install the individual ducts at a right angle into the main discharge duct. The
individual ducts from the dryers can enter at the sides or bottom of the main discharge duct.
Figure 3 indicates the various round main duct diameters to use with the individual dryer
ducts. The main duct can be rectangular or round, provided adequate airflow is maintained.
For each individual dryer, the total exhausting (main discharge duct plus duct outlet from the
dryer) should not exceed the equivalent of 20’ (6 m) and two elbows. The diameter of the
main discharge duct, at the last dryer, must be maintained to exhaust end.
NOTE: A small diameter duct will restrict airflow; a large diameter duct will reduce air
velocity - both contributing to lint build up. An inspection door should be provided for periodic
clean out of the main duct.
NOTE: Exhaust air must not be discharged into a flue which is used for exhausting fumes
from appliances burning gas or other fuels.
WARNING - A clothes dryer produces combustible lint and should be exhausted
outdoors. The area around the clothes dryer should be kept free of lint.
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