12
VERTICAL TERMINATION
when (HT) > (VT)
Simple venting configurations
FIGURE 11
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 one 45º and one 90° elbow , the following formulas apply:
Formula 1: HT < 3VT
Formula 2: HT + VT < 40 feet
Example 4:
45°
| 90° |
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H1 |
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V1
90° 90°
FIGURE 12
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 configuration is unacceptable.
Formula 2: HT + VT < 40 feet
15.9 < 40
Since only formula 2 is met, this vent configuration is unac- ceptable and a new fireplace location or vent configuration will need to be established to satisfy both formulas.
Example 5: |
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| 45° |
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| FIGURE 13 |
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V1 | =1.5 ft |
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V2 | =8 ft |
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VT | = V1 + V2 = 1.5 + 8= 9.5 ft |
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H1 | =1 ft |
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H2 | =1 ft |
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H3 | =10.75 ft |
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HR | = H1 + H2 + H3 = 1 + 1 + 10.75 = 12.75 ft |
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HO | = .03(three 90° elbows + two 45° elbow - 135°) | |||||||
| = .03(90 + 90 + 90 + 45 + 45 - 135) = 6.75 ft |
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HT | =HR + HO = 12.75 + 6.75 = 19.5 ft |
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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 configuration is ac- ceptable.
