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How to determine total equivalent feet
TO ESTIMATE THE EQUIVALENT FEET LENGTH OF THE REDUCER/INCREASER
CHART, FIND THE FIGURE AT THE INTERSECTION OF THE SMALL PIPE SIZE
AND THE LARGE PIPE SIZE.
CALCULATING EQUIVALENT FEET OF A VENT SYSTEM
*10" OR LARGER SHOULD BE 10' MINIMUM ABOVE PUBLIC WALKWAY.
**10" OR LARGER SHOULD BE 4' ABOVE FINISHED GRADE.
EQUIVALENT FEET FOR A REDUCER/INCREASER
SMALL PIPE SIZE
LARGE PIPE SIZE
3" 4" 5" 6" 7" 8" 9" 10" 12" 14"
3" 0
4" 2 0
5" 4 2 0
6" 5 4 2 0
7" 6 5 4 1 0
8" 7 7 6 3 2 0
9" 7 8 7 5 4 2 0
10" 8 8 8 6 6 4 2 0
12" 8 10 10 8 9 8 6 4 0
14" 9 10 12 10 12 11 9 8 3 0
16" 9 11 12 11 14 13 13 11 8 3
18" 9 11 13 12 15 15 15 14 11 7
20" 9 12 14 13 16 17 17 17 15 11
1. Determine the total equivalent feet for each type of fitting used in the
venting system from Tables 2 and 3.
2. Calculate the total feet for the straight lengths of pipe.
3. Add the equivalent feet of the fittings to the total amount of feet of
straight length pipe. This will approximate the total equivalent feet of
the vent system.
4. Find your total equivalent feet in Table 1 to determine the proper
model for your installation.
Example: System Pipe Size= 6"
Step 1 2-90° Elbows (6")= 22 Ft.
Step 2 10-2 Ft. Lengths of 6" Pipe= 20 Ft.
Step 3 6" to 4" reducer= 4 Ft.
Step 4 Total Equivalent Feet= 22 Ft. + 20 Ft. + 4 Ft.= 46 Ft.
TERMINAL LOCATIONS OF A VENT SYSTEM
A
B
D
B
C
F
A. The exit termination of a mechanical draft system must not
be less than 7' above grade when located adjacent to a
public walkway.*
B. The venting systems, with the exception of direct vent appliances,
must terminate at least 4' below, 4' horizontally, or 1' above any
door, window or gravity air inlet into the building.
C. A venting system must terminate at least 3' above any forced air inlet
located within 10'.
D. The bottom of the vent terminal must be located at least 1' above
finished grade.**
E. The vent termination should not be mounted directly above or within
3' horizontally from an oil tank vent or a gas meter
(not shown in diagram).
F. The vent termination point must not be installed closer than 3' from an
inside corner of an L-shaped structure.
G. For basement installations where a window well must be used or in
installations where the vent terminal cannot be mounted to maintain
the minimum 12" clearance above grade, use a Field Vent Riser™.
The Vent Riser ensures the vent termination is above grade or the
snow line and is in compliance with local codes
(not shown in diagram).
Location of the termination of the venting system should
comply with the National Fuel Gas Code, ANSI Z223.1,
manufacturer’s recommendations, and/or applicable local
codes. See diagram for typical terminal locations.
EQUIVALENT FEET FOR VENT PIPE FITTING
VENT PIPE
FITTINGS
VENT PIPE DIAMETER
3" 4" 5" 6" 7" 8" 9" 10" 12" 14"
TEE 19 25 31 38 44 50 56 63 75 89
YCONNECTION 10 13 16 20 23 26 29 32 39 45
90° ELBOW 5 7 9 11 12 14 16 18 21 25
45° ELBOW 3 4 4 5 6 7 8 9 10 13
Table 2
Table 3
PLANNING THE VENT SYSTEM
SWG/CV POWER VENTER
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