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CAMPER BLADE
\
TO FRONT
.
'
.
b
FIGURE
5
FIGURE
6
.
Guideline
to Proper
Duct Sizing
for Ventilating
An Indoor
Electric
Grill
These Guidelines
are to insure adequate
ventilation
for an indoor
Electric
Grill.
Indoor
electnc
grills
produce
more smoke
than
normal cooking
and requtres
at least 41 O CFM to provide adequate
ventllatton.
Less sinngent
venttlating
requtrements
can deviate
from these recommendations.
HORIZONTAL
VENTING:
Frgure 2 on page
1 shows
a direct
discharge
to the outside
through
a wall rain cap. Due to the lower CFM rating in this venting
posItron.
duct must be limtted
to a maximum
of 2 feet of 3;/r x 10
Inch duct capped
with a wall rain cap with a free discharge
area of
al least 66 inches
square.
There
should
be no bends
in the
connec:lng
duct between
the hood and the wall ratn cap.
VERTICAL
VENTING:
Figure 1 on page 1 shows an installation
using 3 feet of 3% x 10
inch duct term:nating
in a roof rain cap. In table 1 we see that 3 feet
of 3:. x 10 inch duct is the maxlmum
lengtn of 3';; x 10 Inch duct
recommended.
Figure
7 shcws
an installation
requiring
more duct length.
A
transr!lon
to round
is used as close to the hood as possible
to
elrmtnate
the restriction
caused
by the 3'; x 10 duct. 4jJ bends
should
be used Instead
of 90g bends wherever
possible.
For example,
if the straight
lengihs
of duct In FIN. 7 total 9 ft. the
elbow
IS
45' and the roof rain cap has 113 in' free area. choose the
duct size required.
The -15; elbow can be approximated
by dividing
the equivalent
duct !engths
In Table 2 by two.
Since we already
have9 ft. of straight
duct, Table 1 tells us that 7"
dia.
IS
too small. So we try 8" dia.
9 ft. Straight
Duct
6
Equrvalent
straight
length
of 4.Y elbow
(8" Dia.)
15 ft.
Frfteen feet is ever the maximum
of 13 ft. for 8" dia. duct, so 8"
duct
IS
to small.
!-dove to 9" dia. duct and run :hrough
the calculations
again.
9 ft. Straight
Duct.
7 ft. Equrvalent
stratght
leng!h
cf 9" dia. duct for 45" elbow.
i-6-K
Sixteen
fee!
IS
under the maxrmum
of 25 ft. for 9" dia. duct, so 9"
duct IS
a gocd chotce.
TABLE
I
Vertical
Venting
I
Duct
Size
I 3'/. x 10"
I
7" dm I 8" dia.
I 9" dia.
1 10" dia. 1
,uax
Duct
Length
(Feet)
3
7.
13
25
40
Table
1 shows
the maxlmum
length
of duct
to be used In
COnjunct;on
wltn a roof rain cap i-,avlng a free area of 113 II-I?.
TABLE
2
.
Duct
Equivalent
length of
Size
straight
ducr of same dia.
11 ft.
12 ft.
c
FIGURE
7
CFM vs. DUCT
LENGTH
FOR F?GH SERIES
HOOD
Equivalent
Duct Length
(ft.)
Static
Pressure
/
cFh4
j 3-;;t:0
/ 7" dia.
1 8" dia.
1 9" dia.1
I
L
I
4
.06
460
4
8.5
17
30 i
I
i
~~~ :
.lO
440
7
16.0
31
55.5 1
.15
417
12
25.0
50
.20
/
390
/
18
1
40
1
77
/
142!
.25
355
330
I
.30
250
65
1
1361
-I
.35
180
?40
i
.;
--
l
90"
9" dia.
14 ft.
NOTE:
Tne above table
IS
basec on-~ertlcal
disc
Elbow
10" dta.
:6 ft.
IT&?. Thevaiues
.
In lhls !able are for duct length only and co not account
for Sldtic
pressure
loss :hroucn
roof mounted
rain c. 0s
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