12
E. EXHAUST REQUIREMENTS
Exhaust duct work
should be
designed and installed by a qualified professional. Improperly sized duct work 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-heat protector thermostat.
Where possible, it is suggested to provide a separate (single) exhaust duct for each dryer.
CAUTION: IMPROPERLY
SIZED
OR
INSTALLED
EXHAUST
DUCT
WORK
CAN
CREATE
A
POTENTIAL
FIRE
HAZARD.
CAUTION
: DRYER
MUST BE
EXHAUSTED TO THE OUTDOORS.
The exhaust duct work
should be
laid out in such a way that the duct work travels as directly as possible to the
outdoors with as few turns as possible. The shape of the duct work 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 duct work
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
duct work 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 duct work for periodic inspection and
cleaning.
IMPORTANT
: When connecting duct work 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 duct passes through a wall, ceiling, or roof made of combustible materials,
the opening must be 2-inches (5 cm) larger (all the way around) than the duct. The duct
must
be
centered within this opening.
To protect the outside end of horizontal duct work from the weather, a 90° elbow bent downward
should be
installed where the exhaust exits the building. If the duct work 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 or caps on the outside of opening of exhaust duct work.
IMPORTANT
: Exhaust back pressure measured by a manometer at the dryer exhaust duct area
must
not
exceed 0.3 inches of water column (0.75 mbar).