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PROPER AIR MOVEMENT
AND VELOCITY
(USE METAL
DUCTING
ONLY)
Flexible
Ducting:
Due to the irregular
surface
of flexible
ducting,
each foot
of the flex
duct
counts
as two
feet of
straight
metal
duct.
Elbows
made
of flex
ducting
would
count
twice
as much as a standard
metal elbow,
Attic
Venting:
Never
vent
to either
attrc
or crawl
space.
Unit must always
be ducted
to the outside.
Uniform
Size:
All
ductrng
should
be umform
throughout
the complete
system
for proper
performance.
Duct Restrictions:
Never
Install
two elbow
fittings
next
to
each other,
This causes unusual
air patterns
and subsequen-
tly interrupts
velocity
and the end result
IS poor ventrlation.
Sealing joints:
All joints
in the duct system
must be tightly
taped
to avoid
smoke
and odor
in the home.
Also,
be sure
to caulk
thoroughly
all joints
in floor
or wall
where
duct
system
goes to the outside.
DUCT LENGTH
RECOMMENDATIONS
(MAXIMUM)
6" Dia. or 3-l/4"
x
10" Duct
Use 6"
or 3-l/4"
x 10"
duct
on
island
or
peninsula
in-
stallations.
For
best
performance,
it IS suggested
that
no
more than three
90° elbows
with
6" or 3-l/4"
x 10" duct
be used.
1 Maximum
Calculated
Length
1
26 feet
I
When using
flexible
tubing:
6" System Calculation
(Maximum
allowable
calculated
length
26 feet)
3-l/4"
x 10" System Calculation
(MaxImum
allowable
calculated
length
26 feet)
90° Elbows
b-
6
Ft.-(
Wall
(1) 90° Elbow
(3-l/4"
x 10")
Wall Cap
(1) 6" to 3-1/4"xlO"
Elbow
-t
(2) 90' Elbows @ 5 Ft. Ea. = 10 Ft.
Surface
Wall Cap
= 0 Ft.
8 Ft. Straight
6" Pipe
= 8 Ft.
= 5 Ft.
= 0 Ft.
= 5 Ft.
Length of 6" Run
= 18 Ft.
8 Ft. Straight 3-1/4"xlO"
= 8 Ft.
Length of 3-l/4" x 10" Run = 18 Ft.
INDEX OF RECOMMENDED
STANDARD
FITTINGS
6" Svstems:
Eauivalent
length
of 6" Duct
3-1/4"xlO"
Systems:
Equivalent
lenqth
of 3-114"xlO"
Duct
T
3-1/4"xlO"
to 6"
3-1/4"xlO"
to 6"
90° Elbow
Equiv. Length 4.5
Ft.
Equiv. Leng
6" to 3-1/4"xlO"
90° Elbow
3-1/4"xlO" to 6"
6" to 3-1/4"xlO"
90° Elbow
6" to 3-114"xlO"
th
5 Ft.1 Equiv. Length
9
Ft
Equiv. Length
6 Ft
Equiv. Length
1 Ft.
Equiv. Length 4.5
Ft.
3-1/4"XlO"
90° Elbow
Equiv. Length
5
Ft
L
T
90° Elbow
@
-7
Equiv.
Lenuth
5
Ft
45O Elbow
6" Wall Cap
0
Equiv.
Lenoth
0 Ft
6" to
3-1/4"XlO"
3-1/4"XlO"
Flat Elbow
3.1/4"XlO"
Wall Cap
Equiv.
Lensth
1 FI
Equiv.
Length
2.5
Ft
Equiv. Length
0 Ft
Equiv. Length
12
F
Note;
Never use laundry
type wall caps.
5
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