Lennox EL296UHV Installation Instructions Manual page 25

Maximum Allowable Exhaust Vent Pipe Length (in ft.)Without Insulation In Unconditioned Space For
Winter Design Temperatures Two - Stage High Efficiency Furnace
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)
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.
Vent Pipe
Diameter
045
2
PVC PP
2 in. 20 18
2-1/2 in. 15 N/A
3 in. 12 10
2 in 12 11
2-1/2 in. 10 N/A
3 in. 6 5
2 in. 8 7
2-1/2 in. 6 N/A
3 in. 2 1
Conditioned
Conditioned
Space
TABLE 7
Unit Input Size
070 090
2
PVC PP PVC
30 28 40
22 N/A 30
18 15 25
20 18 25
14 N/A 20
10 8 15
12 11 18
8 N/A 12
6 5 10
Space
Pipe Insulation
Unconditioned
Space
FIGURE 30
Page 25
110
2 2
PP PVC PP PVC
36 24 24 N/A
N/A 40 N/A N/A
21 32 28 42
22 24 24 N/A
N/A 24 N/A N/A
12 20 17 22
16 22 20 N/A
N/A 16 N/A N/A
10 12 11 15
Exhaust
Pipe
Intake
Pipe
135
2
PP
N/A
N/A
37
N/A
N/A
18
N/A
N/A
12