18
BGD42CF VERTICAL TERMINATION
when (HT) > (VT)
Simple venting confi gurations
FIGURE 40
See graph to determine the required vertical rise VT for the required horizontal run HT.
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 45° elbow + three 90° elbows - 135°) = .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 < VT
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:
MAXIMUM
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 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:
FIGURE 41
45° | 90° | V2 | |
H1 | |||
H2 |
| ||
|
| ||
| V1 | 90° | |
| 90° |
FIGURE 42 |
|
|
|
90° |
| V2 | |
|
| ||
45° | H2 |
| H3 |
H1 | V1 | 45° | 90° |
| |||
| 90° |
|
|
V1 = 1.5 ft
V2 = 8 ft
VT = V1 + V2 = 1.5 + 8 = 9.5 ft H1 = 1 ft
H2 = 1 ft
HR = H1 + H2 + H3 = 1 + 1 + 10.75 = 12.75 ft
HO = .03 (two 45° elbows + three 90° elbows - 135°) = .03 (45 + 45 + 90 + 90 +90 - 135) = 6.75 ft
HT = HR + HO = 12.75 + 6.75 = 19.5 ft
HT + VT = 19.5 + 4.5 = 24 ft
Formula 1: HT < VT
3VT = 3 x 2.5 = 7.5 ft
13.4< 7.5
Formula 2: HT + VT < 40 feet
24 < 40
Since both formulas are met, this vent confi guration is ac- ceptable.
