17
W415-0434 / G / 08.08.11
(H
T
) > (V
T
)
Simple venting configurations.
See graph to determine the required vertical rise
V
T
for the
required horizontal run
H
T
.
REQUIRED
VERTICAL
RISE IN
FEET
V
T
HORIZONTAL VENT RUN PLUS OFFSET IN FEET
H
T
For vent configurations requiring more than two 90° elbows the following formulas apply:
Formula 1: H
T
< 3V
T
Formula 2: H
T
+ V
T
< 40 feet
Example:
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 (360° - 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
16.1 > 13.5
Since this formula is not met, this vent configuration is
unacceptable.
Formula 2:
H
T
+ V
T
< 40 feet
20.6 < 40
Since only formula 2 is met, this vent configuration is unacceptable and a new appliance location or vent configuration will
need to be established to satisfy both formulas.
The shaded area within the lines represents acceptable
values for
H
T
and
V
T
0
5
10
15
20
10
20
3
25
30
19
90°
V
1
V
2
H
1
H
2
90°
90°
90°
V
3
18.1_2A
