American Dryer Corp. MDG-30 - Manual (Page 16)

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E. EXHAUST REQUIREMENTS
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, and shutdown of the
burner by the airflow (sail) switch, burner hi-limit, or lint chamber hi-limit protector thermostat. The dryer must
be installed with a proper exhaust duct connection to the outside.
When possible, it is suggested to provide a separate (single) exhaust duct for each dryer.
CAUTION: IMPROPERLY SIZED OR INSTALLED EXHAUST DUCTWORK CAN
CREATE A POTENTIAL FIRE HAZARD.
CAUTION: DRYER MUST BE EXHAUSTED TO THE OUTDOORS.
IMPORTANT: It is recommended that exhaust or booster fans not be used in the exhaust ductwork
system.
The exhaust 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. The shape of the ductwork is not critical so long as the minimum cross
section area is provided. Single or independent dryer venting is recommended.
It is suggested that the use of 90° turns be avoided; use 30° or 45° angles instead.
The ductwork should be smooth inside with no projections from sheet metal screws or other obstructions,
which will collect lint. When adding ducts, the ducts to be added should overlap the duct to which it is connected.
ALL ductwork joints must be taped to prevent moisture and lint from escaping into the building. Additionally,
inspection doors should be installed at strategic points in the exhaust ductwork for periodic inspection and
cleaning.
IMPORTANT: When connecting ductwork to the dryer exhaust duct, be sure that when screws are
used they DO NOT restrict the operation (both opening and closing) of the damper.
NOTE: When the exhaust ductwork passes through a wall, ceiling, or roof made of combustible
materials, the opening must be 2-inches (5.08 cm) larger than the duct (all the way around).
The duct must be centered within this opening.
To protect the outside end of the horizontal ductwork from the weather, a 90° elbow bent downward should be
installed where the exhaust exits the building. If the ductwork travels vertically up through the roof, it should be
protected from the weather by using a 180° turn to point the opening downward. In either case, allow at least
twice the diameter of the duct between the duct opening and the nearest obstruction (i.e., roof or ground level).
IMPORTANT: DO NOT use screens, louvers, or caps on the outside opening of the exhaust
ductwork.
IMPORTANT: Exhaust back pressure measured by a manometer at the dryer exhaust duct area must
be no less than 0 and must not exceed 0.3 inches (0.74 mb) of water column
(W.C.).