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exhaust pipe should be insulated with 1/2" (13 mm)
Armaflex or equivalent. In extremely cold climate areas,
3/4" (19 mm) Armaflex or equivalent may be necessary.
Insulation on outside runs of exhaust pipe must be painted
or wrapped to protect insulation from deterioration. Exhaust
pipe insulation may not be necessary in some specific
applications.
IMPORTANT
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze-ups and may
block the terminations.
IMPORTANT
For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches (305
mm).
Maximum Allowable Exhaust Vent Pipe Length (in ft.) without Insulation in Unconditioned Space for Winter Design
Winter Design Temperatures
ºF (ºC)
32 to 21
(0 to -6)
20 to 1
(-7 to -17)
0 to -20
(-18 to -29)
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
1
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm
2
NOTE - Concentric terminations are the equivalent of 5' and should be considered when measuring pipe length.
NOTE- Maximum uninsulated vent lengths listed may include the termination (vent pipe exterior to the structure ) and cannot exceed
5 linear feet or the maximum allowable intake or exhaust vent length listed in Table 7A through Table 7B and Table 8.
NOTE - If insulation is required an unconditioned space, it must be located on the pipe closed to the furnace
Page 22 of 51
Temperatures Single - Stage High Efficiency Furnace
Vent Pipe
1
Diameter
PVC
2 in.
18
2-1/2 in.
13
3 in.
9
2 in.
9
2-1/2 in.
5
3 in.
N/A
2 in.
5
2-1/2 in.
N/A
3 in.
N/A
Conditioned
Space
Figure 28. Insulating Exhaust Pipe in an
Unit Input Size
045
070
PP
PVC
PP
2
2
16
31
28
N/A
24
N/A
9
18
18
8
18
16
N/A
13
N/A
N/A
8
8
3
12
10
N/A
7
N/A
N/A
N/A
N/A
Table 8.
Issue 1917
Conditioned
Space
Pipe Insulation
Unconditioned
Space
Unconditioned Space
090
PVC
PP
PVC
2
50
48
42
N/A
35
35
32
29
24
N/A
19
19
22
19
15
N/A
10
10
Exhaust
Pipe
Intake
Pipe
110
PP
2
30
30
56
N/A
47
47
30
30
34
N/A
26
26
30
27
22
N/A
16
16
507271-02
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