14
VERTICAL TERMINATION
when (HT) > (VT)
Simple venting configurations
See graph to determine the required vertical rise VT for the
FIGURE 11
Formula 2: HT + VT < 40 feet 15.9 < 40
Since only formula 2 is met, this vent configuration is unacceptable and a new fireplace location or vent configuration will need to be established to satisfy both formulas.
Example 5:
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| V2 |
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| 90° |
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required horizontal run HT. |
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| 45° |
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| H2 |
| H3 | 90° | |||||
For vent configurations requiring more than one 45º and one |
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| H1 |
| V1 | 45° | |||||||||||
90° elbow , the following formulas apply: |
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| 19 | 20 |
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REQUIRED |
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| 90° |
| FIGURE 13 |
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VERTICAL |
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R I S E I N |
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FEET (VT) | 3 |
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| 0 | 5 | 10 | 15 | 20 | 25 | 30 | V1 |
| =1.5 ft |
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| HORIZONTAL VENT RUN PLUS OFFSET IN FEET | V2 |
| =8 ft |
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| VT |
| = V1 | + V2 = 1.5 + 8= 9.5 ft |
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The shaded area within the lines represents acceptable |
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H1 |
| =1 ft |
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values for HT | and VT. | < 3VT |
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| H2 |
| =1 ft |
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Formula 1: HT |
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| H3 |
| =10.75 ft |
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Formula 2: HT + VT < 40 feet |
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| HR |
| = H1 |
| + H2 | + H3 | = 1 + 1 + 10.75 = 12.75 ft |
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Example 4: |
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| HO |
| = .03(three 90° elbows + two 45° elbow - 135°) | ||||||||
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| = .03(90 + 90 + 90 + 45 + 45 - 135) = 6.75 ft | |||||||||
V1 | =1 ft |
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| HT |
| =HR | + HO = 12.75 + 6.75 = 19.5 ft |
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FIGURE 12 |
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| HT | + VT | = 19.5 + 4.5= 29 ft |
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| Formula 1: | HT < 3VT |
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45° |
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| 3VT | = 3 x 9.5 = 28.5 ft |
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| 19.5 < 28.5 |
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| 90° |
| V2 |
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| H1 | H2 |
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| V1 | 90° | |
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| 90° |
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V2 |
| =1.5 ft |
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VT |
| = V1 + V2 = 1 + 1.5 = 2.5 ft |
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H1 |
| =6 ft |
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H2 |
| =2 ft |
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HR |
| = H1 + H2 = 6 + 2 = 8 ft |
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HO |
| = .03(one 45º elbow + three 90º elbow - 135º) | ||
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| = .03(45 + 90 + 90 + 90 - 135) = 5.4 ft | ||
HT | + VT | =HR + HO = 8 + 5.4 = 13.4 ft |
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HT | = 13.4 + 2.5 = 15.9 ft |
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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 29 < 40
Since both formulas are met, this vent configuration is acceptable.