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REAR EXIT / HORIZONTAL TERMINATION
(HT) > (VT) | Example 5: |
| 90° |
Simple venting configuration |
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| 90° | H4 | |
(only two 90° elbows) |
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| V2 |
| H2 |
| 90° |
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| H3 |
| FIGURE 14 | V1 | 45° |
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H1 | FIGURE 15 | |
90° | ||
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See graph to determine the required vertical rise VT for the required horizontal run HT
| 150 |
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| V1 | =4 ft | |
147 |
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| V2 | =1.5 ft | ||
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REQUIRED |
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| VT | = V1 + V2 = 4 + 1.5 = 5.5 ft | |
VERTICAL |
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| H1 | =2 ft | |
RISE IN |
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| H2 | =1 ft | |
INCHES VT |
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| H3 | =1 ft | |
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| H4 | =1.5 ft | ||
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| 100 |
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| HR | = H1 | + H2 + H3 + H4 = 2 + 1 + 1 + 1.5 = 5.5 ft |
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| HO | = .03(four 90° elbows + one 45° elbow - 90°) | |
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| = .03(90 + 90 + 90 + 90 + 45 - 90) = 9.45 ft | |
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| HT | =HR + HO = 5.5 + 9.45 = 14.95 ft | |
66 |
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| HT + VT | = 14.95 + 5.5 = 20.45 ft | |
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| Formula 1: | HT < 3.5VT | ||
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| 50 |
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| 3.5VT = 3.5 x 5.5 = 19.25 ft |
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| 14.95 < 19.25 |
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| Formula 2: | HT + VT < 24.75 feet | |
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| 20.45 < 24.75 |
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| Since both formulas are met, this vent configuration is | ||
12 | 10 |
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| 0 | 5 |
| 15 |
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| 3.4 | 12.5 | 19. |
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HORIZONTAL VENT RUN PLUS OFFSET IN FEET HT |
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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 < 3.5VT
Formula 2: HT + VT < 24.75 feet