13
TOP OR REAR EXIT VERTICAL TERMINATION
when (HT) < (VT)
Simple venting configurations
FIGURE 15
See graph to determine the required vertical rise VT for the required horizontal run HT.
REQUIRED
VERTICAL RISE
IN FEET
VT
HORIZONTAL VENT RUN PLUS OFFSET IN FEET HT
The shaded area within the lines represents acceptable values for HT and VT .
For vent configurations requiring more than zero 90° elbow (top exit) or one 90° elbow (rear exit), the following formulas apply:
FIGURE 16 | V2 |
| 90° |
| H2 |
| 90° |
| V1 |
| H1 |
| 90° |
V1 | =5 ft |
V2 | =10 ft |
VT | = V1 + V2 = 5 + 10 = 15 ft |
H1 | =3 ft |
H2 | =2.5 ft |
HR | = H1 + H2 = 3 + 2.5 = 5.5 ft |
HO | = .03(three 90° elbows - 90°) |
| = .03(90 + 90 + 90 - 90) = 5.4 ft |
HT | = HR + HO = 5.5 + 5.4 = 10.9 ft |
HT + VT | = 10.9 + 15 = 25.9 ft |
Formula 1: HT < VT 10.9 < 15
Formula 2: HT + VT < 40 feet 25.9 < 40
Since both formulas are met, this vent configuration is ac- ceptable.
Formula 1: HT < VT
Formula 2: HT + VT < 40 feet