13
• Concentric vent termination kits are available for use
with these furnaces. For 2 Inch pipe use kit #904177
and for 3 inch pipe use kit # 904176.
Please follow the
instructions provided with the kit.
• When the vent pipe must exit an exterior wall close to
the grade or expected snow level where it is not possible
to obtain clearances shown in Figure 6, a riser may be
provided as shown in Figure 8. Insulation is required
to prevent freezing of this section of pipe. See Table 3
for vent freezing protection.
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.
Vent Freezing Protection
CAUTION:
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 Table 2 (page 11). For Canadian installations,
please refer to the Canadian Installation Code (CAN/
CGA-B149.1 or 2) and/or local codes.
• 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 11). The restriction should
be counted as 3 equivalent feet. Smaller vent pipes are
Winter Design
Temperature
Maximum Flue Pipe Length (FEET)
in Unconditioned & Exterior Spaces
Without Insulation
With Insulation*
20
45
70
0
20
70
-20
10
60
*NOTE:
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
Support
NOTE:
Vent Configuration to Provide
12" Minimum height above Snow Level.
1/2"
Armaflex
Insulation or
Equivalent
(if required)
12" Above
Maximum
Expected
Snow Level
19" Max.
(See Note)
Outside
Wall
Figure 8. Alternate Horizontal Vent Installation
Note 2
Mechanical draft
vent terminal
Direct v
ent
ter
minal
50,000 Btuh
or less
Forced air inlet
Direct vent
terminal - more
than 50,000 Btuh
Mechanical
draft v
ent
ter
minal
Mechanical
draft v
ent
ter
minal
Less
than
10 ft.
3 ft.
NOTES:
1. All dimensions shown are
minimum
requirements.
2. Exterior vent terminations must
be located at least 12” above the
maximum expected snow level.
Note 2
4 ft
4 ft
12 in.
12 in.
9 in.
Note 2
Figure 7. Vent Locations
Figure 9. Vertical Vent Termination
Comb
ustion Air
Exhaust V
ent
12” Above Maximum
Expected Snow Level
(Both pipes)
Elbows on the combustion air
inlet must be positioned pointing
away from the exhaust vent.
8" Min.
36" Max.
Plumbing Vent Roof Boot
(Both Pipes)
Summary of Contents for *TC
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