14
W415-0811 / A / 04.28.10
3.8 HORIZONTAL
TERMINATION
16.5
Simple venting con
fi
guration (only one 45° and 90° elbow)
(H
T
) < (V
T
)
For vent con
fi
gurations requiring more than one 45° elbow and 90° elbow, the following formulas apply:
Formula 1: H
T
< V
T
Formula 2: H
T
+ V
T
< 40 feet
Example 1:
V
1
= 8 FT
V
T
=
V
1
= 8 FT
H
1
= 2.5 FT
H
2
= 2 FT
H
R
=
H
1
+
H
2
= 2.5 + 2 = 4.5 FT
H
O
= .03 (one 45° elbow + two 90° elbows - 135°) = .03 (225 - 135°) = 2.7 FT
H
T
=
H
R
+
H
O
= 4.5 + 2.7 = 7.2 FT
H
T
+
V
T
= 7.2 + 8 = 15.2 FT
Formula 1:
H
T
< V
T
7.2
<
8
Formula 2:
H
T
+ V
T
< 40 FT
15.2
<
40
Since both formulas are met, this vent con
fi
guration is acceptable.
90°
90°
45°
V
1
H
1
H
2
0
2.5
5
7.5
10
12.5
15
40
10
20
30
17.5
20
39
REQUIRED
VERTICAL
RISE IN
FEET
V
T
HORIZONTAL VENT RUN PLUS OFFSET IN
FEET
H
T
See graph to determine the required vertical
rise
V
T
for the required horizontal run
H
T
.
The shaded area within the lines represents
acceptable values for
H
T
and
V
T
