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11
W415-0210 / E / 06.25.03
See graph to determine the required vertical rise V
T
for the
required horizontal run H
T
For vent configurations requiring more than two 90° el-
bows the following formulas apply:
Formula 1: H
T
< V
T
Formula 2: H
T
+ V
T
< 40 feet
REQUIRED
VERTICAL
RISE IN
FEET
V
T
HORIZONTAL VENT RUN PLUS OFFSETS IN FEET H
T
Example 4:
V
1
=9 ft
V
2
=6 ft
V
T
=
V
1
+
V
2
=
9 + 6 = 15 ft
H
1
=3 ft
H
2
=2 ft
H
3
= 1.5 ft
H
R
=H
1
+ H
2
+ H
3
= 3 + 2 + 1.5 = 6.5 ft
H
O
=.03(four 90° elbows - 90°)
=.03(90 + 90 + 90 + 90 - 90) = 8.1 ft
H
T
=H
R
+ H
O
= 6.5 + 8.1 = 14.6 ft
H
T
+ V
T
=14.6 + 15 = 29.6 ft
Formula 1: H
T
< V
T
14.6 < 15
Formula 2: H
T
+ V
T
< 40 feet
29.6 < 40
Since both formulas are met, this vent configuration is ac-
ceptable.
FIGURE 12
FIGURE 11
H
1
H
2
V
1
V
2
H
3
90°
90°
90°
90°
The shaded area within the lines represents acceptable
values for H
T
and V
T
.
REAR EXIT / HORIZONTAL TERMINATION
when (H
T
) < (V
T
)
Simple venting configuration (only two 90° elbows)