Lennox EL296DFV Installation Instructions Manual page 24

Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For
Winter Design
1
Temperatures °F (°C)
32 to 21
(0 to -6)
20 to 1
(-7 to -17)
0 to -20
(-18 to -29)
1
Refer to 99% Minimum Design Temperature table provided in the current edition of the ASHRAE Fundamentals Handbook.
2
Poly-Propylene vent pipe (PP) by Duravent and Centrotherm.
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 7 or 9 which ever is less.
NOTE - If insulation is required in an unconditioned space, it must be located on the pipe closest to the furnace. See figure32.
Winter Design Temperatures Two - Stage High Efficiency Furnace
Vent Pipe
Diameter
045
PVC
2 in. 21
2-1/2 in. 16
3 in. 12
2 in 11
2-1/2 in. 7
3 in. N/A
2 in. 6
2-1/2 in. N/A
3 in. N/A
Conditioned
Space
TABLE 8
Unit Input Size
070
2 2
PP PVC PP
18 33 30
N/A 26 N/A
12 21 21
9 19 17
N/A 14 N/A
N/A 9 9
4 12 10
N/A 7 N/A
N/A N/A N/A
Conditioned
Space
Pipe Insulation
Unconditioned
Space
FIGURE 32
Page 24
090
2
PVC PP PVC
46 42 30
37 N/A 36
30 30 29
28 25 27
21 N/A 20
16 16 14
19 16 18
13 N/A 12
8 8 7
Exhaust
Pipe
Intake
Pipe
110
2
PP
30
N/A
29
24
N/A
14
15
N/A
7