Lennox ML196DF045XE36B Manual page 28

Maximum Allowable Exhaust Vent Pipe Length
Winter Design Temperatures Single - 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) 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 12 or 13 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 figure29.
3
Vent length in the table is equivalent length. Each elbow is equivalent to 5ft of straight pipe length and should be included in
Vent Pipe
Diameter
045
2
PVC
1-1/2 in. 20 N/A
2 in. 18
2-1/2 in. 13 N/A
3 in. 9
1-1/2 in. 15 N/A
2 in 9
2-1/2 in. 5 N/A
3 in. N/A N/A
1-1/2 in. 10 N/A
2 in. 5 N/A
2-1/2 in. N/A N/A
3 in. N/A N/A
TABLE 14
3
Without Insulation In Unconditioned Space For
Unit Input Size
070
2
PP PVC PP
20 N/A
16 31 28
24 N/A
9 18 18
20 N/A
8 18 16
13 N/A
8 8
15 N/A
12 10
7 N/A
N/A N/A
Page 28
090
2
PVC PP PVC
N/A N/A NAA
50 48 30
42 N/A 36
35 35 29
N/A N/A N/A
32 29 27
24 N/A 20
19 19 14
N/A N/A N/A
22 19 18
15 N/A 12
10 10 7
measuring total pipe length
110
2
PP
N/A
30
N/A
29
N/A
24
N/A
14
N/A
15
N/A
7