Product specifications

7
• On side exhaust installations, allow five inches of space
on the side for the ADT2 exhaust transition plus addi-
tional space for the duct attached to it (X).
• Make sure duct work does not interfere with floor joists
or wall studs.
• With concrete slab construction, “box-in” the duct work
and blower wiring to prevent collapsing or other dam-
age when the wet concrete is poured.
• Cross-drafts or air currents from adjacent open win-
dows or doors, heating/air conditioning outlets, ceiling
fans and recessed ceiling lights reduce vent efficiency.
Installation Specifications
ATD2
5”
X
Duct Work Design Tips
• Wherever possible, reduce the number of transitions
and turns to as few sharp angles 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 possible.
• For best performance, use round duct instead of rect-
angular when possible, especially when elbows are
required.
• If multiple 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 flexible metal duct.
Calculating the Maximum Duct Run Length
• Do not use duct work that is smaller in cross-sectional
area than the required duct sizes in the table to the
right.
• For best performance, keep the duct run as short as
possible 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 equivalent lengths of the elbows and transitions
listed at the right from the Blower Maximum Duct
Straight Length.
For example, for a raised vent system using 3 1/4” X
10” rectangular duct, two (2) 3 1/4” X 10” 90° elbows, a
3 1/4” X 10” rectangular to 10” round transition, and a
REMP16 remote blower:
• From the Blower Maximum Duct Straight Length
table below, the maximum length without transitions
and elbows is 60 feet.
• The equivalent length of each 90° elbow is 15 feet.
• The equivalent 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 Elbows and Transitions
45° elbow
8 Inch
3 feet
3 ¼” X 10
45° elbow
7 feet
45° elbow
10 Inch
2 feet
3 ¼” X 10
90° elbow
15 feet
90° elbow
8 Inch
7 feet
3 ¼” X 10
90° flat elbow
20 feet
90° elbow
10 Inch”
5 feet
3 ¼” X 10
to 8” round
transition
4 feet
90° 3 ¼” X 10
to 8” round
transition
25 feet
3 ¼” X 10
to 10” round
transition
4 feet
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
Used
Blower Maximum Duct Straight Length
REMP3 Remote Blower REMP16 Remote Blower ILHSF8 In-line Blower ILHSF10 In-line Blower
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)