13
VERTICAL TERMINATION
when (HT) > (VT)
Simple venting confi gurations
FIGURE 12
See graph to determine the required vertical rise VT for the required horizontal run HT.
REQUIRED
VERTICAL
R I S E I N
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 confi gurations requiring more than one 45º and one 90° elbow , the following formulas apply:
Formula 1: HT < 3VT
Formula 2: HT + VT < 40 feet
Example 4:
45°
H |
| 90° |
| 1 | V2 |
|
|
H2
V1
90°
90°
FIGURE 13
V1 | = 1 ft |
V2 | = 1.5 ft |
VT | = V1 + V2 = 1 + 1.5 = 2.5 ft |
H1 | = 6 ft |
H2 | = 2 ft |
HR | = H1 + H2 = 6 + 2 = 8 ft |
HO | = .03 (one 45º elbow + three 90º elbow - 135º) |
| = .03(45 + 90 + 90 + 90 - 135) = 5.4 ft |
HT | = HR + HO = 8 + 5.4 = 13.4 ft |
HT + VT | = 13.4 + 2.5 = 15.9 ft |
Formula 1: HT < 3VT
3VT = 3 x 2.5 = 7.5 ft
13.4 > 7.5
Since this formula is not met, this vent confi guration is unac- ceptable.
Formula 2: HT + VT < 40 feet
15.9 < 40
Since only formula 2 is met, this vent confi guration is unac- ceptable and a new fi replace location or vent confi guration will need to be established to satisfy both formulas.
Example 5:
| 90° | H2 |
| V2 | |
|
|
| |||
| 45° |
|
|
| |
| V1 45° |
|
| ||
| H1 | H3 | 90° | ||
|
|
| 90° |
|
|
|
|
|
| FIGURE 14 |
|
V1 | = 1.5 ft |
|
|
|
|
V2 | = 8 ft |
|
|
|
|
VT | = V1 + V2 = 1.5 + 8= 9.5 ft |
|
| ||
H1 | = 1 ft |
|
|
|
|
H2 | = 1 ft |
|
|
|
|
H3 | = 10.75 ft |
|
|
|
|
HR | = H1 + H2 + H3 = 1 + 1 + 10.75 = 12.75 ft |
| |||
HO | = .03 (three 90° elbows + two 45° elbow - 135°) |
| |||
| = .03(90 + 90 + 90 + 45 + 45 - 135) = 6.75 ft |
| |||
HT | = HR + HO = 12.75 + 6.75 = 19.5 ft |
| |||
HT + VT | = 19.5 + 4.5= 29 ft |
|
| ||
Formula 1: HT < 3VT
3VT = 3 x 9.5 = 28.5 ft
19.5 < 28.5
Formula 2: HT + VT < 40 feet 29 < 40
Since both formulas are met, this vent confi guration is accept- able.
