18
W415-0672 / C / 08.13.12
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
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
(H
T
) > (V
T
)
18.7
For vent configurations requiring more than one 90° elbow, the following formulas apply:
Formula 1: H
T
< 3 V
T
Formula 2: H
T
+ V
T
< 40 FT
Example:
V
1
= 1.5 FT
V
2
= 5 FT
V
T
=
V
1
+ V
2
= 1.5 + 5 = 6.5 FT
H
1
= 1 FT
H
2
= 1 FT
H
3
= 10.75 FT
H
R
=
H
1
+ H
2
+ H
3
= 1 + 1 + 10.75 = 12.75 FT
H
O
= .03 (three 90° one 45° elbow - 90°)
= .03 (270° + 45° - 90°) = 6.75 FT
H
T
=
H
R
+ H
O
= 12.75 + 6.75 = 19.5 FT
H
T
+ V
T
= 19.5 + 6.5 = 26 FT
Formula 1:
H
T
< 3 V
T
3 V
T
=
3 x 6.5 = 19.5 FT
19.5 = 19.5
Formula 2:
H
T
+ V
T
< 40 FT
26 < 40
Since both formulas are met, this vent configuration is acceptable.
90°
V
1
V
2
H
1
H
2
90°
90°
H
3
45°
