11
HORIZONTAL TERMINATION
when (HT) > (VT)
Simple venting configuration (only one 45º and 90° elbow)
FIGURE7
See graph to determine the re- quired vertical rise VT for the required horizontal run HT.
REQUIRED
VERTICAL
RISE IN
INCHES (VT)
HORIZONTAL VENT RUN PLUS OFFSETS 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 90° elbow the following formulas apply:
Formula 1: HT < 4.2 VT
Formula 2: HT + VT < 24.75 feet
Example 2:
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| H4 |
FIGURE8 | H3 |
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| 45° |
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| H1 |
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| 90° |
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V1 | = 4 ft |
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VT | = V1 = 4 ft |
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H1 | = 2 ft |
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H2 | = 1 ft |
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H3 | = 1 ft |
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H4 | = 1.5 ft |
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HR | = H1 + H2 + H3 + H4 = 2 + 1 + 1 + 1. 5 = 5.5 ft | ||||||
HO | = .03(one 45º elbow + three 90º elbow | ||||||
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HT | = HR + HO = 5.5 +5.4 = 10.9 ft |
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HT + VT | = 10.9 + 4 = 14.9 ft |
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Formula 1: HT < 4.2 VT
4.2VT = 4.2 x 4 = 16.8 ft
10.9< 16.8
Formula 2: HT + VT < 24.75 feet
14.9 < 24.75
Since both formulas are met, this vent configuration is ac- ceptable.
