11
REAR EXIT / HORIZONTAL TERMINATION
(HT) < (VT)
Example 4:
Simple venting configuration (only two 90° elbows)
FIGURE 12
See graph to determine the required vertical rise VT for the required horizontal run HT
H1
|
| 90° |
| V2 | H3 |
|
| |
|
| 90° |
V1 |
| H2 |
90°
90°
FIGURE 13
39 40
REQUIRED VERTICAL 30 RISE IN FEET
V1 | =9 ft |
V2 | =6 ft |
VT | = V1 + V2 = 9 + 6 = 15 ft |
H1 | =3 ft |
H2 | =2 ft |
H |
|
VT
20
10
0 | 2.5 | 5 | 7.5 | 10 | 12.5 | 15 | 17.5 | 20 |
HR3 |
| =1.5 ft |
| = H1 + H2 + H3 = 3 + 2 + 1.5 = 6.5 ft | |
HO |
| = .03(four 90° elbows - 90°) |
|
| = .03(90 + 90 + 90 + 90 - 90) = 8.1 ft |
HT | + VT | =HR + HO = 6.5 + 8.1 = 14.6 ft |
HT | =14.6 + 15 = 29.6 ft |
HORIZONTAL VENT RUN PLUS OFFSETS IN FEET HT
The shaded area within the lines represents acceptable values for HT and VT .
For vent configurations requiring more than two 90° elbows the following formulas apply:
Formula 1: HT < VT
Formula 2: HT + VT < 40 feet
Formula 1: HT < VT 14.6 < 15
Formula 2: HT + VT < 40 feet 29.6 < 40
Since both formulas are met, this vent configuration is acceptable.
