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TOP OR REAR EXIT VERTICAL TERMINATION
(HT) < (VT) | Example 6: |
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| FIGURE 17 | 90° | V3 |
| FIGURE 16 | 90° | H2 |
| V2 | ||
| V1 | H1 | 90° |
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| 90° | |
See graph to determine the required vertical rise VT for the | V1 | =3 ft | ||||||||
V2 | =6 ft | |||||||||
required horizontal run HT. |
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| V3 | =8 ft | |||||
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| VT | = V1 + V2 + V3 = 3 + 6 + 8 = 17 ft | ||
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| H | =2 ft | ||
| 35 |
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| H21 | =2.5 ft | ||
| 30 |
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| HR | = H1 | + H2 = 2 + 2.5 = 4.5 ft | |
REQUIRED |
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| HO | = .03(four 90° elbows - 90°) | |||
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| HT | = .03(90 + 90 + 90 + 90 - 90) = 8.1 ft | |||
VERTICAL |
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| =HR + HO = 4.5 + 8.1 = 12.6 ft | |||
RISE IN | 20 |
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| HT + VT | = 12.6 + 17 = 29.6 ft | ||
FEET VT |
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| Formula 1: | HT < VT | |||
17.5 |
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| 12.6 < 17 | |
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| Formula 2: | HT + VT < 35 feet | ||
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| 29.6 < 35 | |
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| Since both formulas are met, this vent configuration is | |||
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| 0 | 5 | 10 | 15 | 17.5 | 20 |
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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:
Formula 1: HT < VT
Formula 2: HT + VT < 35 feet