Lennox A97DF2E Installation Instructions Manual page 19

Maximum Allowable Exhaust Vent Lengths Using Ventilated Attic or Crawl Space for Intake Air in Feet
1-1/2" Pipe
Number
of 90°
Model
Elbows
45 70
Used
1 15 10
2 10
3
4
5
6 n/a
n/a
7
8
9
10
NOTE: Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length
calculation.
508391-01
Standard Termination at Elevation 0 - 10,000 ft
90 110 45 70
56 41
51 36
46 31
41 26
36 21
n/a n/a
31 16
26
21
16
11 n/a
Pipe size determined in table 7.
2"
2"
2"
2"
or
DO NOT transition
from smaller to larger
pipe in horizontal runs
of exhaust pipe.
* When transitioning up in pipe size, use the shortest length of 2" PVC pipe possible.
NOTE: Exhaust pipe and intake pipe must be the same diameter.
Figure 23. Typical Exhaust Pipe Connections
2" Pipe
Model
90 110 45
24 85
19 80
14 75
9 70
4 65
n/a
60
11 55
6 n/a 50
1 45
40
Table 7C.
2"
3"
TRANSITION
*2"
DO NOT transition
from larger to smaller
pipe in horizontal runs
of exhaust pipe.
Issue 2327
2-1/2" Pipe
Model
70 90 110 45
85 63 28 103
80 58 23 98
75 53 18 93
70 48 13 88
65 43 8 83
60 38 3 78
55 33 73
50 28 68
n/a
45 23 63
40 18 58
NOTE: 1-1/2" Vent Pipe
Diameter Allowed Only
on 045/070 Units
1-1/2"
or
TRANSITION
*2"
INTAKE
3" Pipe
Model
70 90 110
102 83 83
97 78 78
92 73 73
87 68 68
82 63 63
77 58 58
72 53 53
67 48 48
62 43 43
57 38 38
EXHAUST
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