12
7034-277B
May 2, 2014
MT. VERNON AE
F. Equivalent Feet of Pipe
The table below can help you calculate the equivalent feet
of pipe which is a method used to determine pellet vent size.
Figure 12.1
2 ft.
2 ft.
3 ft.
2 ft.
Example of 3 Elbow-Rear Vent Termination Calculation
Pellet Venting
Component
# of
Elbows
Feet of
Pipe
Multiplied
By
Equivalent
Feet
Components
Equivalent Feet
90
o
Elbow or Tee
3
X
5
15
45
o
Elbow
X
3
Horizontal Pipe
7
X
1
7
Vertical Pipe
2
X
0.5
1
Total Equivalent Feet
23
Note: This is a generic example and is not
intended to represent any specific fuel type.
Vent surfaces get HOT, can cause burns if
touched. Non-combustible shielding or guards
may be required.
WARNING
Figure 12.2
3 in. or 4 in. (76mm or 102mm) Diameter Pipe
Equivalent Pipe
Length In Feet
ALTITUDE IN THOUSANDS OF FEET
0
20
30
1 2 3 4 5 6 7 8 9 10
4 in. (102mm) Diameter Pipe Only
10
Example 1
Example 2
Example 1
: If the equivalent length of pipe is 23 feet (7m) with
altitude of 8,000 feet (2438m) you must use 4 inch (102mm)
diameter type “L” or “PL” vent.
Example 2
: If the equivalent length of pipe is 12 feet (3.7m)
with altitude of 6,000 feet (1829m) you may use 3 or 4 inch
(76 to 102mm) diameter type “L” or “PL” vent.
G. Pipe Selection Chart
The chart will help you in determining proper venting size
according to the equivalent feet of pipe calculated previously
and the altitude above sea level of this installation.
Figure 12.2
a. Locate the calculated equivalent feet of pipe on the vertical
left side of the chart.
b. Move to the right horizontally on the chart until you reach
your altitude above sea level.
c. If you fall below the diagonal line, 3 or 4 inch (76 to 102mm)
pipe may be used.
d. If it is anywhere above the diagonal line, a 4 inch (102mm)
diameter pipe is required.
NOTICE:
• A 90° elbow is 5 times as restrictive to the flow of exhaust
gases under positive pressure as 1 foot (305mm) of hori-
zontal pipe.
• A foot of horizontal pipe is twice as restrictive as a foot of
vertical pipe.
Figure 12.1
WARNING
RISK OF INJURY OR PROPERTY DAMAGE!
• Improper installation, adjustment, alteration, service or main-
tenance can cause injury or property damage.
• Refer to the owner’s information manual provided with this
appliance.
• For assistance or additional information consult a qualified
installer, service agency or your dealer.
Fire Risk.
• Only LISTED venting components may be used.
• NO OTHER vent components may be used.
• Substitute or damaged vent components may impair safe
operation.
WARNING
