39
Table 6 – Maximum Allowable Exposed Vent Pipe Length (Ft / M) with Insulation in
Winter Design Temperature Ambient*
UNIT SIZE
WINTER DESIGN
MAXIMUM PIPE
INSULATION THICKNESS†
WINTER DESIGN
TEMPERATURE
MAXIMUM PIPE
DIAMETER (IN.)
0
3/8
1/2
3/4
1
042060
20
_
F / --6.7
_
C
2
30 / 9.1
55 / 16.8
61 / 18.6
70 / 21.3
70 / 21.3
0
_
F / --17.8
_
C
2
16 / 4.9
33 / 10.1
38 / 11.6
46 / 14.0
53 / 16.2
--20
_
F / --28.9
_
C
2
9 / 2.7
23 / 7.0
26 / 7.9
33 / 10.1
38 / 11.6
042080
060080
20
_
F / --6.7
_
C
2
37 / 11.2
65 / 19.8
70 / 21.4
70 / 21.3
70 / 21.3
0
_
F / --17.8
_
C
2
20 / 6.1
39 / 11.9
45 / 13.7
55 / 16.8
63 / 19.2
--20
_
F / --28.9
_
C
2
11 / 3.4
27 / 8.3
31 / 9.4
39 / 11.9
45 / 13.7
060100
20
_
F / --6.7
_
C
2--1/2
41 / 12.5
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
0
_
F / --17.8
_
C
2--1/2
21 / 6.4
42 / 12.8
48 / 14.6
59 / 18.0
68 / 20.7
--20
_
F / --28.9
_
C
2--1/2
11 / 3.4
28 / 8.5
33 / 10.1
41 / 12.5
49 / 14.9
060120
20
_
F / --6.7
_
C
3
49 / 14.9
70 / 21.3
70 / 21.3
70 / 21.3
70 / 21.3
0
_
F / --17.8
_
C
3
26 / 7.9
51 / 15.5
58 / 17.7
70 / 21.3
70 /21.3
--20
_
F / --28.9
_
C
3
15 / 4.6
35 / 10.7
40 / 12.2
50 / 15.2
59 / 18.0
* Pipe length (ft/m) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable
pipe length as specified in Table ?.
†
Insulation thickness based on R value of 3.5 per in.
58MV
C
