16
(HT) > (VT)
Simple venting configuration (only one 90° elbow)
See graph to determine the required vertical rise VT for the
required horizontal run HT.
147”
150
REQUIRED | 100 |
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VERTICAL |
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RISE IN |
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INCHES VT | 57” |
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| 50 |
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| 29” |
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| 0 | 5 | 10 | 15 | 20 |
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| 2.83’ |
| 12.5’ | 19.5’ |
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 90° elbow, the following formulas apply:
Formula 1: HT | < 4.2 VT |
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Formula 2: HT | + VT | < 24.75 feet | 90° | H1 |
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H
Example 2: |
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V1 | = VT = 6 FT |
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H1 | = 3 FT |
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H2 | = 5 FT |
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HR | = H1 | + H2 | = 3 + 5 = 8 FT |
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HO | = .03 (two 90° elbows - 90°) = .03 (180° - 90°) = 2.7 FT |
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HT | = HR | + HO | = 8 + 2.7 = 10.7 FT |
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HT | + VT | = 10.7 + 6 = 16.7 FT |
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Formula 1: | HT | < 4.2 VT |
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Formula 2: | HT | 4.2 VT = 4.2 x 6 = 25.2 FT |
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+ VT < 24.75 FT | |||||||||
90°
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16.7 < 24.75 |
Since both formulas are met, this vent configuration is acceptable.
Example 3:
V1 = 4 FT
V2 = 1.5 FT
VT = V1 + V2 = 4 + 1.5 = 5.5 FT
H1 = 2 FT
H2 = 1 FT
H3 = 1 FT
H4 = 1.5 FT
HR = H1 + H2 + H3 + H4 = 2 + 1 + 1 + 1.5 = 5.5 FT
HO = .03 (four 90° elbows - 90°) = .03 (360° - 90°) = 8.1 FT HT = HR + HO = 5.5 + 8.1 = 13.6 FT
HT + VT = 13.6 + 5.5 = 19.1 FT
90°
V1
H1 90°
H2 90°
90°
V2
H3
H4
Formula 1: | HT | < 4.2 VT |
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| 4.2 VT | = 4.2 x 5.5 = 23.1 FT |
| 13.6 < 23.1 |
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Formula 2: HT + VT < 24.75 FT 19.1 < 24.75
Since both formulas are met, this vent configuration is acceptable.
16.1_3A
