15
2. Single Dryer Venting
Where possible, it is suggested to provide a separate exhaust duct for each dryer. The exhaust duct
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. It is suggested that the use of 90° turns in the ducting be avoided; use 30° or 45° angles instead.
The shape of the exhaust duct work is not critical so long as the minimum cross section area is provided.
IMPORTANT
:
Minimum duct size for a dryer is 16-inches for a round duct or 14.25-inches for a square
duct. Duct size
must not be
reduced anywhere down stream of dryer.
IMPORTANT
: Exhaust back pressure measured by a manometer at each basket (tumbler) exhaust
duct area
should not
exceed 0.3 inches of water column (W.C.).
It is suggested that the duct work from each dryer be a minimum of 16-inches for horizontal runs with no
more than one (1) elbow and 18-inches for vertical runs with no more than 3 elbows without exceeding
twenty (20) feet (excluding dryer connections and outside exhaust outlets). If the duct exceeds twenty (20)
feet or has numerous elbows, the cross section area of the duct work
must be
increased in proportion to the
length and number of elbows in it. In calculating duct size, the cross section area of a square or rectangular
duct
must be
increased by twenty (20) percent for each additional twenty (20) feet. The diameter of a
round exhaust duct
should be
increased ten (10) percent for each additional fifteen (15) feet. Each 90º
elbow is equivalent to an additional thirty-six (36) feet, and each 45º elbow is equivalent to an additional
eighteen (18) feet.
IMPORTANT
:
DO NOT
use screens or caps on the outside of opening of exhaust duct work.
