11
W415-0244 / A / 05.15.03

Example 4:

V
1
=5 ft
V
2
=10 ft
VT=
V
1
+
V
2
=
5 + 10 = 15 ft
H
1
=1 ft
H
2
=3 ft
H
3
=2.5 ft
HR=H1 + H2 + H3 = 1 + 3 + 2.5 = 6.5 ft
HO=.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.
when (Ht) < (Vt)
Simple venting configurations
FIGURE 10 FIGURE 11
For vent configurations requiring elbows, the following for-
mulas apply:
Formula 1: H
T

< V

T
Formula 2: H
T
+ V
T

< 40 feet

See graph to determine the required vertical rise VT for the
required horizontal run HT.
90°
90°
90°
V2
90°
H1
V1
H3
H2
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 HT and VT .
TOP EXIT VERTICAL TERMINATION