13
W415-0210 / R / 02.27.08
H
1
H
2
H
3
H
4
V
1
V
2
90°
90°
45°
90°
90°
Simple venting confi guration
(only two 90° elbows)
Example 5:
V
1
= 4 ft
V
2
= 1.5 ft
V
T
=
V
1
+
V
2
= 4 + 1.5 = 5.5 ft
H
1
=
2
ft
H
2
=
1
ft
H
3
=
1
ft
H
4
=
1.5
ft
H
R
=
H
1
+
H
2
+
H
3
+
H
4
=
2 + 1 + 1 + 1.5 = 5.5 ft
H
O
= .03(four 90° one 45° elbow - 90°)
= .03(90 + 90 + 90 + 90 + 45 - 90) = 9.45 ft
H
T
=
H
R
+
H
O
= 5.5 + 9.45 = 14.95 ft
H
T
+ V
T
= 14.95 + 5.5 = 20.45 ft
Formula 1:
H
T
< 3.5V
T
3.5
V
T
= 3.5 x 5.5 = 19.25 ft
14.95 < 19.25
Formula 2:
H
T
+ V
T
< 24.75 feet
20.45 < 24.75
Since both formulas are met, this vent confi guration is
acceptable.
FIGURE 14
For vent confi gurations requiring more than two 90° elbows
the following formulas apply:
Formula 1: H
T
< 3.5V
T
Formula 2: H
T
+ V
T
< 24.75 feet
See graph to determine the required vertical rise
V
T
for the
required horizontal run
H
T
FIGURE 13
The shaded area within the lines represents acceptable
values for H
T
and V
T
.
REAR EXIT / HORIZONTAL TERMINATION
0
5
15
25
100
50
150
3.5
19.25
12.5
12
66
147
1
(H
T
) > (V
T
)
REQUIRED
VERTICAL
RISE IN
INCHES
V
T
HORIZONTAL VENT RUN PLUS OFFSET IN FEET
H
T
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