American Dryer Corp. Gas- DSI/Steam ML-82 II - Manual (Page 18)

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It is not necessary to have separate make-up air openings for each dryer. Common make-up air openings are
acceptable. However, they must be set up in such a manner that the make-up air is distributed equally to ALL
the dryers.
EXAMPLE: For a bank of four (4) dryers, two (2) unrestricted openings measuring 2-1/2 feet by 2 feet
(0.76 meters by 0.61 meters), 10 square feet (0.93 square meters) is acceptable.
Allowances must be made for remote or constricting passageways or where dryers are located at excessive
altitudes or predominantly low pressure areas.
IMPORTANT: Make-up air must be provided from a source free of dry cleaning solvent fumes.
Make-up air that is contaminated by dry cleaning solvent fumes will result in
irreparable damage to the motors and other dryer components.
NOTE: Component failure due to dry cleaning solvent fumes will VOID THE WARRANTY.
E. EXHAUST REQUIREMENTS
1. General Exhaust Ductwork Information
Exhaust ductwork should be designed and installed by a qualified professional. Improperly sized ductwork
will create excessive back pressure which results in slow drying, increased use of energy, overheating of the
dryer, and shut down of the burner by the airflow (sail) switches, burner hi-limits, or basket (tumbler) hi-heat
thermostats.
CAUTION: DRYER MUST BE EXHAUSTED TO THE OUTDOORS.
CAUTION: IMPROPERLY SIZED or INSTALLED EXHAUST DUCTWORK CAN
CREATE A POTENTIAL FIRE HAZARD.
The ductwork should be laid out in such a way that the ductwork travels as directly as possible to the
outdoors with as few turns as possible. Single or independent dryer venting is recommended.
When single dryer venting is used the length of ductwork from the dryer to the outside exhaust outlet must
not exceed 15 feet (4.57 meters). The minimum diameter of this ductwork must be at least
14-inches (35.56 cm). In the case of multiple (common) dryer venting, the distance from the last dryer to
the outside exhaust outlet must not exceed 15 feet (4.57 meters). The shape of the ductwork is not critical
so long as the minimum cross-sectional area is provided. It is suggested that the use of 90° turns be avoided;
use 30° and/or 45° angles instead. The radius of the elbows should preferably be 1-1/2 times the diameter
of the duct. Including basket (tumbler) and dryer elbow connections or elbows used for outside protection
from the weather, no more than two (2) elbows should be used in the exhaust duct run. If more than two
(2) elbows are used, the cross-sectional area of the ductwork must be increased.
ALL ductwork should be smooth inside with no projections from sheet metal screws or other obstructions
which will collect lint. When adding ducts, the duct to be added should overlap the duct to which it is to be
connected. ALL ductwork joints must be taped to prevent moisture and lint from escaping into the building.
Inspection doors should be installed at strategic points in the exhaust ductwork for periodic inspection and
cleaning of lint from the ductwork.