Onsideexhaustinstallations,allowfiveinchesofspace
onthesidefortheADT2exhausttransitionplusaddi-
tionalspacefortheductattachedtoit(X).
Makesureductworkdoesnotinterferewithfloorjoists
orwallstuds.
Withconcreteslabconstruction,"box-in"theductwork
andblowerwiringto preventcollapsingorotherdam°
agewhenthewetconcreteis poured.
Crossodraftsoraircurrentsfromadjacentopenwin-
dowsordoors,heating/airconditioningoutlets,ceiling
fansandrecessedceifinglightsreduceventefficiency.
ATD2.
X
Duct Work Design Tips
o Wherever possible, reduce the number of transitions
and turns to as few sharp angbs as possible. Two
staggered 45° angles are better than one 90 °. Keep
turns as far away from the hood exhaust as possible,
with as much space between each bend as possibme.
o For best performance, use round duct instead of rect-
angular when possibb, especially when elbows are
required.
o If muttiple elbows are used, try to keep a minimum of
24" of straight duct between them. Avoid "S" or "back to
back" configurations of adjacent elbows.
. Do not use flexibb metal duct.
CaJcuJafing the Maximum Duct Run Length
. Do not use duct work that is smaller in cross°sectional
area than the required duct sizes in the tabb to the
right.
o For best performance, keep the duct run as short as
possibb and never exceed the maximums stated at the
right.
The maximum straight duct length for the raised vent
system depends on the model of remote or in-line
blower used with the vent system and the number of
elbows and transitions used. The Equivalent Number
of Feet for each elbow and transition (see table) must
be subtracted from the maximum straight length to
compensate for wind resistance. To determine the
maximum allowable length of the duct work, subtract all
of the equivabnt lengths of the elbows and transitions
listed at the right from the Blower Maximum Duct
Straight Length.
For exampme, for a raised vent system using 3 ¼" X
10" rectangular duct, two (2) 3 ¼" X 10" 99° e_bows, a
3 ¼" X 19" rectangular to 19" round transition, and a
REMP16 remote b_ower:
. From the Blower Maximum Duct Straight Length
table bebw, the maximum length without transitions
and elbows is 60 feet.
. The equivabnt length of each 90° elbow is 15 feet.
. The equivabnt length of 45° elbow is 2 feet.
. The equivalent length of the transition is 4 feet.
. The total equivalent length of the above components is:
15 feet + 15 feet + 4 feet + 2 feet = 36 feet.
. The maximum amount of straight duct that can be used
with a REMP16 and the above components is: 60 feet
34 feet = 24 feet.
Equivalent Number of Feet -
Duct E_bows and Transitions
45° elbow 3 ¼"X 10
3 feet 7 feet
8 Inch 45° elbow
45° elbow 3 ¼"X 10
2 feet 15 feet
10 Inch 90° elbow
90° elbow 3 W'X 10
7 feet 20 feet
8 Inch 90 ° fiat elbow
3 ¼"X 10
90° elbow
5 feet to 8" round 4 feet
10 Inch"
transition
90° 3 ¼"X 10 3 %"X 10
to 8" round 25 feet to 10" round 4 feet
transition transition
Roof cap * Wall cap *
The equivalent lengths of roof and wall caps vary with
model and configuration. For equivalent length, contact the
manufacturer or a qualified HVAC specialist.
Duct Size B_ower Maximum Duct Straight Length
Used REMP3 Remote B_ower REMP16 Remote B_ower mLHSF8 mn4ine B_ower mLHSFIO mn4ine B_ower
8 Inch 50 feet (15.2 meters) 60 feet (18.3 meters) 50 feet (15.2 meters) 60 feet (18.3 meters)
10 Inch 40 feet (12.2 meters) 70 feet (21.3 meters) 40 feet (12.2 meters) 70 feet (21.3 meters)
3 ¼" X 10" 40 feet (12.2 meters) 60 feet (18.3 meters) 40 feet (12.2 meters) 60 feet (18.3 meters)
_ 7
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