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ROCEDURE FOR CALCULATING TOTAL EQUIVALENT PIPE LENGTH IN FEET
1. Calculate the total equivalent feet for each type of fitting used in the venting system from the chart below.
2. Calculate the total amount of feet for the straight lengths of vent pipe.
3. Add the equivalent feet for the fittings with the total amount of feet of straight lengths. This will approximate the total
equivalent feet of the vent system.
*Reducer or increaser ratio (d/D) small diameter divided by the larger diameter. (See Figure
2) Example 4" to 8" reducer: The reducer ratio is d/D = 4/8 = 1/2. To estimate the equivalent
foot length for the fitting, use the smaller pipe diameter for the equivalent length figure.
Example 4" to 8" reducer; the reducer ratio is 1/2 and the smaller pipe diameter is 4". So,
from the chart, the equivalent feet would be 7 feet.
Example 1: System Pipe Size = 4"
10"
Step 1 Two 4" 90E Elbows @ 7 feet each = 14 Ft.
Step 2 Ten 2 Foot Lengths of 4" Pipe = 20 Ft.
Step 3 Total Equivalent Feet = 14 Ft. + 20 Ft. = 34 Ft.
CAUTION: Failure to install, maintain and/or operate the power venting system in accordance with manufacturer's
instructions will result in conditions which may produce bodily injury and/or property damage.
1. Remove power venter from box and inspect unit for damage. If the carton has been crushed or mutilated, check unit
very carefully for damage. Rotate blower wheel to insure that the motor and blower wheel rotate freely. DO NOT
install if any damage is apparent. Refer to unit sizing chart to check proper venting sizing.
2. Location of the termination of the venting system should be installed in accordance with the National Fuel Gas Code,
A.N.S.I.Z223.1, and/or manufacturer's recommendations which are applicable. See requirements below or refer to
installation location Diagram A for typical locations.
a. The exit termination of mechanical draft systems shall not be less than 7' above grade when located adjacent to
public walkways.
b. A venting system shall terminate at least 3' above any forced air inlet located within 10'.
c. The venting system of other than a direct vent appliance shall terminate at least 4' below, 4' horizontally from, or
1' above any door, window or gravity air inlet into the building.
d. The vent termination of a direct vent appliance with an input of 50,000 BTU's per hour or less, shall be located at
least 9" from any opening through which vented gases could enter the building. With an input over 50,000 BTU's
per hour, a 12" termination clearance shall be required.
e. The vent termination point shall not be installed closer than 3' from an inside corner of an L-shaped structure.
f.
The vent termination should not be mounted directly above, or within 3' horizontally from an oil tank vent or gas
meter.
g. The bottom of the vent terminal shall be located at least 12" above finished grade.
EQUIVALENT LENGTH (FEET) OF VENT PIPE FOR VENT PIPE
VENT PIPE FITTINGS
TEE
90° ELBOW
45° ELBOW
d/D
SUDDEN REDUCER
¼
OR INCREASER
FOR THREE
½
RATIOS* (d/D)
¾
VENT PIPE DIAMETER
3"
4"
5"
6"
7"
8"
19
25
31
38
44
50
5
7
9
11
12
14
3
4
4
5
6
8
11
14
17
19
22
5
7
8
10
12
13
2
3
3
4
4
Example 2: System Pipe Size =
Step 1 Fifteen 2 Foot Lengths of 10" Pipe = 30 Ft.
Step 2 One 10" 90° Elbow = 18 Ft.
Step 3 One 8" to 10" Reducer (Use ¾) = 5 Ft.
Step 4 Total Equivalent Feet = 30 Ft. + 18 Ft. + 5 Ft. = 53 Ft.
Page 4
9"
10"
56
63
16
18
7
8
9
25
28
15
17
5
6
6
Figure 2
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