GMES96-U Installation Manual

16
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 mini-
mum of 12" 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 zone. Refer to Vent/Flue and Combustion Air Pipe -
Termination Locations or Concentric Vent Termination for spe-
cific details on termination construction. For details concerning
connection of pipes to the furnace, refer to the Vent/Flue Pipe
and Combustion Pipe - Standard Furnace Connections or Alter-
nate Furnace Connections.
12" MIN. TO GRADE OR
HIGHEST ANTICIPATED
SNOW LEVEL
6” MAX
10”- 24”
4” MIN
Standard Horizontal Terminations (Dual Pipe)
Figure 15
90°
ELBOWS
12" MIN. ABOVE
HIGHEST ANTICIPATED
SNOW LEVEL
3” - 24”
Alternate Horizontal Vent Termination (Dual Pipe)
Figure 16
VENT/FLUE & COMBUSTION AIR PIPE LENGTHS & DIAMETERS
Refer to the table 3 on page 14 for applicable length, elbows,
and pipe diameter for construction of the vent/flue and com-
bustion air intake pipe systems of a direct vent (dual pipe)
installation. The number of elbows tabulated represents the
number of elbows and/or tees in each (Vent/Flue & Combustion
Air Intake) pipe. Elbows and/or tees used in the terminations
must be included when determining the number of elbows in
the piping systems.
If the combustion air intake pipe is to be installed above a
finished ceiling or other area where dripping of condensate will
be objectionable, insulation of the combustion air pipe may be
required.
90°
ELBOWS
Combustion Air Intake may also be snorkeled
to obtain 12" min ground clearance.
Alternate Vent Termination Above Anticipated Snow Level
(Dual Pipe)
Figure 17
Use ½" thick closed cell foam insulation such as Armaflex™
or Insultube™ where required.
VENT/FLUE AND COMBUSTION AIR PIPE TERMINATIONS
The vent/flue and combustion air pipes may terminate verti-
cally, as through a roof, or horizontally, as through an outside
wall.
Vertical pipe terminations should be as shown in figure 12. Refer
to Vent/Flue Pipe and Combustion Pipe - Termination Locations
for details concerning location restrictions. The penetrations
through the roof must be sealed tight with proper flashing such
as is used with a plastic plumbing vent.
Vent & Combustion Air Intake Measurements for Stan-
dard Horizontal Terminations (Dual Pipe)
Center to center = 10" min / 24" max.
Vertical separation: 0" - 24"
Vent termination from wall = 8" min/ 12" max.
Combustion air intake from wall = 4" min/6" max.
Vent and intake clearance to ground or anticipated snow
level = 12" min.