Determining Equivalent Pipe Length
To determine whether a 3”or 4” exhaust system is required for your installation, review the sample
installation below. Fill out the top chart, and calculate your total equivalent pipe length. After you have
the total equivalent pipe length, use the chart at the bottom of the page to determine if your installation
requires 3”or 4” exhaust pipe.
Type of Pipe
# of Elbows or
Equivalent Feet Total Equivalent Feet
Feet of pipe
90
o
Elbows/Tee(A &G)
2
x
5 ft. (1.5m)
10 (3m)
45
o
Elbows (C)
1
x
3 ft. (1m)
3 (1m)
Horizontal Pipe(B&F)
3
x
1 ft. (.3m)
3 (1m)
Vertical Pipe(E)
8
x
.5 ft. (.15m)
4 (1.2m)
Sample Installation Chart
TOTAL: 20
A
-
90 Deg. Elbow
B
-
1’ Horizontal Pipe
C
-
45 Degree Elbow
D
-
Standoff Braces
E
-
8’ Vertical Pipe
F
-
2’ Horizontal Pipe
G
-
90 Degree Tee
H
-
Wall Thimble
30
20
10
0
1
2
3
4
5
6
7
8
9
1 0
4 INCH DIAMETER ONLY
3 OR 4 INCH DIAMETER
Pipe Selection Chart
Type of Pipe # of Elbows or Feet of pipe
Equivalent Feet Total Equivalent Feet
90
o
Elbows
x
5(1.5m)
45
o
Elbows
x
3(1m)
Horizontal
Pipe
x
1(.3m)
Vertical
Pipe
x
5(1.5m)
Altitude in Thousands of Feet
A
E
F
H
G
B
C
D
