18
Vent/Flue Pipe Lengths and Diameters
For installations at or above 7,000 feet altitude, use 3”
venting. Refer to the following table for applicable length,
elbows, and pipe diameter for construction of the vent/
flue pipe system of a non-direct vent installation. In ad
-
dition to the vent/flue pipe, a single 90° elbow should be
secured to the combustion air intake to prevent inadvertent
blockage. The tee used in the vent/flue termination must
be included when determining the number of elbows in the
piping system.
COMBUSTION AIR INTAKE
(OPTIONAL)
*Not required for
single pipe installation
TEE (OPTIONAL)
96”
MA
X. -
3”
MIN
.
ROO
F LIN
E
12” MIN
HEIGHT DIFFERENCE
BETWEEN
INTAKE AND VENT
12” MIN TO ROOF OR HIGHEST
ANTICIPATED SNOW LEVEL
Figure 12
STRAIGHT
ELBOWS
Figure 13
VENT/FLUE TEE (
or
45° ELBOW
TURNED DOWN or
90° ELBOW TURNED
DOWN
OPTIONAL)
12" MIN. ABOVE
HIGHEST ANTICIPATED
SNOW LEVEL
12" MIN.
Horizontal Termination (Single Pipe)
Above Highest Anticipated Snow Level
Figure 14
Vent/Flue Pipe Terminations
NOTE:
If either a 90 degree or 45 degree elbow is used for
termination, it must be pointed downward.
The vent/flue pipe may terminate vertically, as through a roof,
or horizontally, as through an outside wall.
Vertical vent/flue pipe terminations should be as shown in the
following figure. Refer to
Vent/Flue Pipe and Combustion Air
Pipe - Termination Locations
for details concerning location
restrictions. The penetration of the vent through the roof
must be sealed tight with proper flashing such as is used
with a plastic plumbing vent.
Horizontal vent/flue pipe terminations should be as shown
in the following figure. Refer to
Vent/Flue Pipe and Com-
bustion Air Pipe.
To secure the pipe passing through the
wall and prohibit damage to piping connections, a coupling
should be installed on either side of the wall and solvent
cemented to a length of pipe connecting the two couplings.
The length of pipe should be the wall thickness plus the
depth of the socket fittings to be installed on the inside and
outside of the wall. The wall penetration should be sealed
with silicone caulking material.
NOTE: Terminate both pipes in the same pressure zone
(same side of roof, no major obstacles between pipes,
etc.).
Direct Vent (Dual Pipe) Piping
Direct vent
installations require both a combustion air intake
and a vent/flue pipe. The pipes may be run horizontally
and exit through the side of the building or run vertically
and exit through the roof of the building. The pipes may
be run through an existing
unused
chimney; however, they
must extend a minimum of 12 inches above the top of the
chimney. The space between the pipes and the chimney
must be closed with a weather tight, corrosion resistant
flashing. Both the combustion air intake and a vent/flue
pipe terminations must be in the same atmospheric pressure
