D. How to Use the Vent Graph | E. Venting Guidelines |
1. Measure the distance from the top of appliance to the center of the 90° elbow. On the graph below, draw a horizontal line from that measurement on the vertical axis across until it intersects with the slanted line.
2.From the point of this intersection, draw a vertical line to the bottom of the graph.
3.The point at which this line meets the bottom line of the graph is the maximum length of the horizontal run.
Example 1: If the vertical dimension from the top of the appliance to the center of the 90° elbow is 7 ft. (2m), the horizontal run to the outer wall flange must not exceed 9
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Example 2: If the vertical dimension from the top of the appliance is 21 ft. (6m), the horizontal run to the outer wall flange must not exceed 4
4.Each 90° elbow is equivalent to 3 ft. (914mm) of vent pipe and each 45° elbow is equivalent to 1 ft. (305mm) of vent pipe, and must be subtracted from vent pipe run. A single vertical to horizontal 90° elbow is already calculated into the allowable 15 ft. (5m) run. Each additional 90° elbow reduces the maximum horizontal distance by 3 ft. (914mm).
Example: The use of three elbows would reduce the allowable horizontal run to 9 ft. (3 - 1 = 2 elbows x 3 ft. = 6 ft.; 15 ft. max. - 6 ft. = 9 ft. max.)
Notes:
•The maximum horizontal vent run is 15 ft. (5m) when the vertical vent rise is 10 ft. (3m).
•Horizontal sections require a 1/4 in. (6mm) rise for every 12 in. (305mm) of horizontal travel.
•Exterior vent diameter =
•Horizontal sections require noncombustible support every 3 ft. (914mm) , e.g. wall straps.
•For any vertical termination a minimum of 6 ft. (2m) vertical must be used.
EXCEPTIONS FOR HORIZONTAL INSTALLATIONS: *The maximum horizontal vent run is 30 in. (762mm).
*The maximum horizontal vent run with a 45° elbow is 18 in. (457mm).
*No external minimum rise is required.
*The minimum horizontal vent run is 6 in. (152mm).
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25 ft. (8m) | 25' |
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Maximum Vertical |
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24' |
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Example 2 |
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| 20' | Adjust |
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| Intake |
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VERTICAL DISTANCE | 16' | Damper |
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FROM APPLIANCE TO |
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90° ELBOW | 14' |
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| Restrictor |
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| 10' |
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Example 1 | 8' |
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6 ft. (2m) Minimum | 6' |
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Vertical Termination | 4' |
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C |
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| 2' | 4' | 6' | 8' | 10' | 12' | 14' | 15' |
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6 in. (152mm) Minimum starter pipe
Figure 5.2
30 in. (762mm) Maximum Horizontal run with no vertical pipe and with 1/4 in. (6mm) rise per foot. Must use approved Termination Cap.
August 1, 2008 | Heat & Glo · Tiara Petite B · | Page 11 |