Lennox EL296UHE Installation Instructions Manual page 24

Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation
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 5 or 6 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 figure30.
In Unconditioned Space For Winter Design Temperatures
Vent Pipe
Diameter
045
2
PVC PP
2 in. 21 18
2-1/2 in. 16 N/A
3 in. 12 12
2 in 11 9
2-1/2 in. 7 N/A
3 in. N/A N/A
2 in. 6 4
2-1/2 in. N/A N/A
3 in. N/A N/A
Conditioned
Conditioned
Space
TABLE 7
Unit Input Size
070 090
2
PVC PP PVC
33 30 46
26 N/A 37
21 21 30
19 17 28
14 N/A 21
9 9 16
12 10 19
7 N/A 13
N/A N/A 8
Space
Pipe Insulation
Unconditioned
Space
FIGURE 30
Page 24
110
2 2
PP PVC PP PVC
42 30 30 N/A
N/A 36 N/A N/A
30 29 29 42
25 27 24 N/A
N/A 20 N/A N/A
16 14 14 23
16 18 15 N/A
N/A 12 N/A N/A
8 7 7 13
Exhaust
Pipe
Intake
Pipe
135
2
PP
N/A
N/A
42
N/A
N/A
23
N/A
N/A
13