14
W415-0153 / E / 05.28.12
3.5 DEFINITIONS
14.1
For the following symbols used in the venting calculations and examples are:
> - greater than
> - equal to or greater than
< - less than
< - equal to or less than
H
T
- total of both horizontal vent lengths (Hr) and offsets (Ho) in feet
H
R
- combined horizontal vent lengths in feet
H
O
- offset factor: .03 (total degrees of offset - 90°*) in feet
V
T
- combined vertical vent lengths in feet
3.6 VENTING APPLICATION FLOW CHART
13.1
TOP EXIT
Horizontal Termination
Vertical Termination
Vertical rise is equal
to or greater than
the horizontal run
Vertical rise is less
than horizontal run
Vertical rise is equal
to or greater than
the horizontal run
Vertical rise is less
than horizontal run
Horizontal run +
vertical rise to
maximum of 40 feet
Horizontal run +
vertical rise to
maximum of 24.75
feet
Horizontal run +
vertical rise to
maximum of 40 feet
Horizontal run +
vertical rise to
maximum of 40 feet
4.2 times the
vertical rise equal to
or greater than the
horizontal run
3 times the vertical
rise equal to or
greater than the
horizontal run
3.7 ELBOW VENT LENGTH VALUES
15.1
FEET
INCHES
1° 0.03
0.5
15° 0.45 6.0
30° 0.9 11.0
45° 1.35 16.0
90°*
2.7
32.0
* The
fi
rst 90° offset has a zero value and is shown in the formula as - 90°