10
Outdoor Terminations - Vertical Venting
Termination spacing requirements from the roof and from
each other are shown in Figure 9. The roof penetration
must be properly fl ashed and waterproofed with a plumbing
roof boot or equivalent fl ashing. Vent and combustion air
piping may be installed in an existing chimney which is
not in use provided that:
• Both the exhaust vent and air intake run the length of
the chimney.
• The top of the chimney is sealed and weatherproofed.
• The termination clearances shown in Figure 9 are
maintained.
• No other gas fi red or fuel-burning equipment is vented
through the chimney.
Outside
Wall
Support
Vent Configuration to
Provide 12" Minimum
height above
Snow Level.
1/2"
Armaflex
Insulation or
Equivalent
(if required)
12" Above
Maximum
Expected
Snow Level
12" Min.
19" Max.
Figure 8. Alternate Horizontal Vent Installation
Figure 9. Vertical Vent Termination
Comb
ustion Air
Exhaust V
ent
Plumbing V
ent
Roof Boot
(Typ
. Both Pipes)
8" Min.
36" Max.
90° Elbow
12’ Above Maximum
Expected Snow Level
(Typ. Both pipes)
Winter Design
Temperature
Maximum Flue Pipe Length
in Unconditioned and
Exterior Spaces
Without Insulation
(feet)
With Insulation
(feet)*
20
45
70
0
20
70
-20
10
60
* = Insulation thickness greater than 3/8 inch, based on
an R value of 3.5 (ft x F x hr) / (BTU x in.)
Table 3. Vent Protection
Vent Freezing Protection
• When the vent pipe is exposed to temperatures below
freezing (i.e., when it passes through unheated spaces,
chimneys, etc.) the pipe must be insulated with 1/2 inch
thick sponge rubber insulation, Armafl ex-type insulation
or equivalent. Insulating pipe is important to avoid
condensate icing.
• Table 3 lists the maximum length of fl ue pipe that can
travel through an unconditioned space or an exterior
space. The total vent length must not exceed the lengths
noted in the Table.
• For extremely cold climates or for conditions of short
furnace cycles (i.e. set back thermostat conditions)
the last 18 inches of vent pipe can be reduced. It is
acceptable to reduce from 3” to 2-1/2”, 3” to 2”, or 2” to
1-1/2” if the total vent length is at least 15 feet in length,
and the vent length is within the parameters specifi ed in
Table 2 (page 9). The restriction should be counted as 3
equivalent feet. Smaller vent pipes are less susceptible
to freezing, but must not be excessively restrictive. The
length of the 2 inch pipe must not be longer than 18
inches.
• If furnace is installed horiziontally, make sure the drainage
port on the in-line drain assembly is pointed downward
to ensure proper drainage of condensate. See pages
32 & 33.
• To prevent debris or creatures from entering the
combustion system, a protective screen may be installed
over the combustion air intake opening. The screens hole
size must be large enough to prevent air restriction.
Condensate Disposal
The method for disposing of condensate varies according
to local codes. Consult your local code or authority having
jurisdiction. Neutralizer kit P/N 902377 is available for
use with this furnace.
Please follow the instructions
provided with the kit.
This furnace has multiple options for positioning the
vent pipe as described in the section, Vent and Inducer
Assembly Options. Each of the condensate drain lines
must be J-trapped using fi eld supplied parts. After the
condensate lines are J-trapped, they may be combined
to run to the drain.
Existing Installations
When an existing furnace is removed from a vent system
serving other appliances, the existing vent system may
not be sized properly to vent the remaining appliances
(for example a water heater). An improperly sized venting
system can result in the formation of condensate, leakage,
or spillage. The existing vent system should be checked
to make sure it is in compliance with IFGC and must be
brought into compliance before installing the furnace.
