Installation guide
Installation
Specifications
Duct
Work
Design
Tips
Calculating
the
Maximum
Duct
Run
Length
For
optimal
performance,
consult
a
qualified
HVAC
specialist
when
designing
the
duct
system.
Do
not
use
duct
work
that
is
smaller
in
cross-sectional
area
than
the
required
duct
sizes
in
the
tables
below.
Keep
the
duct
run
as
short
as
possible
for
best
perfor-
mance
and
never
exceed
the
maximums
stated
in
the
table
below
right.
The
maximum
duct
length
for
the
raised
vent
system
depends
on
the
blower
model
used
and
the
number
of
elbows
and
transitions.
The
Equivalent
Number
of
Feet
for
each
elbow
and
transition
(see
table
below)
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
below
from
the
Blower
Maximum
Duct
Straight
Length
(see
table
right).
For
example,
for
a
raised
vent
system
using
3
4”
X
10”
rectangular
duct,
two
(2)
3
4%”
x
10”
90°
elbows,
a
3%”
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
eibows
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.
*
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.
Blower
Maximum
Duct
Straight
Length
Blower
3
ye"
x
10"
Used
|
8
Inch
Duct
|
10
Inch
Duct
‘x
Duct
40
feet
30
feet
30
feet
CABPS
(12.2
m)
(9.2
m)
(9.2
m)
50
feet
40
feet
40
feet
ILHSF8
(15.2
m)
(12.2
m)
(12.2
m)
60
feet
70
feet
60
feet
ILHSF10
(18.3
m)
(21.3
m)
(18.3
m)
50
feet
40
feet
40
feet
REMP3
(15.2
m)
(12.2
m)
(12.2
m)
60
feet
70
feet
60
feet
REMP16
(18.3
m)
(21.3
m)
(18.3
m)
Equivalent
Number
of
Feet
(Nominal)
-
Duct
Elbows
and
Transitions
45°
elbow
3%
x
10”
8
inch
3
feet
45°
elbow
“feet
45°
elbow
3%
x
10”
10
inch
2
feet
90°
elbow
1S
feet
90°
elbow
3%
x
10”
8
inch
eet
|
90°
flat
elbow
|
2°
feet
°
3%
x
10”
90
elbow
5
feet
to
8”
round
4
feet
10
inch
ae
transition
90°
3%”
x
10”
3%
x
10”
to
8”
round
25
feet
to
10”
round
4
feet
transition
transition
Roof
cap
*
Wail
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.
**
Not
applicable
for
REMP
series
blowers.
dacor
9