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E. EXHAUST REQUIREMENTS
1. GENERAL EXHAUST DUCT WORK INFORMATION
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,
overheating of the dryer, and shutdown 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 DUCT WORK CAN
CREATE A POTENTIAL FIRE HAZARD.
NOTE: When a dryer is exhausted separately, it is recommended that a back draft damper be
installed.
NOTE: When dryers are exhausted into a multiple (common) exhaust line, each dryer must be
supplied with a back draft damper.
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. Single or independent dryer venting is
recommended.
When single dryer venting is used, the duct work from the dryer to the outside exhaust
outlet should not exceed twenty (20) feet. In the case of multiple (common) dryer venting, the distance
from the last dryer to the outside exhaust outlet should not exceed twenty (20) feet. The shape of the
duct work is not critical so long as the minimum cross section area is provided. It is suggested that the
use of 90º turns in ducting be avoided; use 30º and/or 45º angles instead. The radius of the elbows should
preferably be 1-1/2 times the diameter of the duct. Excluding basket/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 section area of the duct work must be increased
i n
proportion to number of elbows added.
ALL 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 clean-out of lint from the 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.
NOTE: Where the exhaust duct work passes through a wall, ceiling, or roof made of
combustible materials, the opening must be 2-inches larger (all the way around) than
the duct. The duct must be centered within this opening.