Lennox ML196UHE Installation Instructions Manual page 25

Maximum Allowable Exhaust Vent Pipe Length (in ft.)
Winter Design Temperatures Single - Stage High Efficiency Furnace
Winter Vent
Design Pipe
Temp °F (°C) Diam
1
1-1/2 in
32 to 21
2 in
(0 to -6)
2-1/2 in
3 in
1-1/2 IN
2 in
20 to 1
(-7 to -17) 2-1/2 in
3 in
1-1/2 in
2 in
0 to -20
(-18 to -29) 2-1/2 in
3 in
1Refer 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 ex-
ceed 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 figure31.
3 Vent length in the table is equivalent length. Each elbow is equivalent to 5ft of straight pipe and should be included when mea-
suring total length.
TABLE 7
030
045
PVC PP PVC PP
2 2
25 N/A
18 16
13 N/A
9
15 N/A
9
N/A N/A
5 N/A
1
10 N/A
5
1
N/A
N/A
N/A
Conditioned
Space
3 Without Insulation In Unconditioned Space For
Unit Input Size
070
PVC PP PVC
2
20 N/A
31 28
24 N/A
9 18 18
20 N/A
8 18 16
13 N/A
8 8
1
15 N/A
12 10
3
7 N/A
2 2
Conditioned
Space
Pipe Insulation
Unconditioned
Space
Figure 31
Page 25
090 110
PP PVC
2
N/A N/A N/A
50 48 30
42 N/A 56
35 35 47
N/A N/A N/A
32 29 30
24 N/A 34
19 19 26
N/A N/A N/A
22 19 30
15 N/A 22
10 10 16
Exhaust
Pipe
Intake
Pipe
135
PP PVC PP
2 2
N/A
30
N/A N/A
N/A
47 42 42
N/A
30
N/A N/A
N/A
26 23 23
N/A
27
N/A N/A
N/A
16
13 13