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W415-0661 / C / 02.20.08
REQUIRED
VERTICAL
RISE IN
FEET
V
T
HORIZONTAL VENT RUN PLUS
OFFSET IN FEET
H
T
The shaded area within the lines represents acceptable values
for H
T
and V
T
.
V
1
=5 ft
V
2
=10 ft
V
T
=
V
1
+
V
2
=
5 + 10 = 15 ft
H
1
=3 ft
H
2
=2.5 ft
H
R
=H
1
+ H
2
= 3 + 2.5 = 5.5 ft
H
O
=.03 (three 90° elbows - 90°)
=.03(90 + 90 + 90 - 90) = 5.4 ft
H
T
=H
R
+ H
O
= 5.5 + 5.4 = 10.9 ft
H
T
+ V
T
= 10.9 + 15 = 25.9 ft
Formula 1: H
T
< V
T
10.9 < 15
Formula 2: H
T
+ V
T
< 40 feet
25.9 < 40
Since both formulas are met, this vent confi guration is ac-
ceptable.
when (H
T
) < (V
T
)
Simple venting confi guration (only two
90° elbows)
See graph to determine the required vertical rise V
T
for the required
horizontal run H
T
For vent confi gurations requiring more than zero 90° elbow (top exit)
or one 90° elbow (rear exit), the following formulas apply:
Formula 1: H
T
< V
T
Formula 2: H
T
+ V
T
< 40 feet
Example 6:
90°
90°
90°
H
1
H
2
V
1
V
2
BGD36CF(G) TOP OR REAR EXIT VERTICAL TERMINATION
FIGURE 29
FIGURE 30
MAXIMUM
VERTICAL
RISE IN
FEET
V
T
HORIZONTAL VENT RUN PLUS OFFSET IN
FEET
H
T
The shaded area within the lines represents acceptable values
for H
T
and V
T
.
For vent confi gurations requiring more than two 90° elbows (top exit)
or one 90° elbow (rear exit), the following formulas apply:
Formula 1: H
T
< 3V
T
Formula 2: H
T
+ V
T
< 40 feet
Example 7:
See graph to determine
the required vertical rise V
T
for the required horizontal
run H
T
.
V
1
= 2 ft
V
2
= 1 ft
V
3
= 1.5 ft
V
T
=
V
1
+
V
2
+
V
3
=
2 + 1 + 1.5 = 4.5 ft
H
1
= 6 ft
H
2
= 2 ft
H
R
= H
1
+ H
2
= 6 + 2 = 8 ft
H
O
= .03 (four 90° elbows - 90°)
= .03(90 + 90 + 90 + 90 - 90) = 8.1 ft
H
T
= H
R
+ H
O
= 8 + 8.1 = 16.1 ft
H
T
+ V
T
= 16.1 + 4.5 = 20.6 ft
Formula 1: H
T
< 3V
T
3V
T
= 3 x 4.5 = 13.5 ft
Since this formula is not met, this vent confi guration is unac-
ceptable.
Formula 2: H
T
+ V
T
< 40 feet
20.6 < 40
H
1
H
2
V
3
V
1
90°
90°
90°
V
2
90°
when (H
T
) > (V
T
)
Simple venting confi gurations
FIGURE 31
FIGURE 32
Since only formula 2 is met, this vent confi guration is unacceptable
and a new fi replace location or vent confi guration will need to be
established to satisfy both formulas.