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TABLE 4—MAXIMUM ALLOWABLE VENT PIPE LENGTH (FT) Continued
ALTITUDE (FT) UNIT SIZE
VENT PIPE
DIAMETER (IN.)
NUMBER OF 90° ELBOWS
123456
5001 to 6000†
024040
036040
1-1/2 57 52 47 42 40 35
2 707070707070
024060
036060
048060
1-1/2 14 9 NA NA NA NA
2 605554494847
036080
048080
060080
2 4136231817 8
2-1/2 70 70 70 70 70 70
048100
060100
2-1/2 29 21 12 11 NA NA
3 706762575247
060120 3* 53 52 50 49 48 47
ALTITUDE (FT) UNIT SIZE
VENT PIPE
DIAMETER (IN.)
NUMBER OF 90° ELBOWS
123456
6001 to 7000†
024040
036040
1-1/2 53 48 43 38 37 32
2 707068676664
024060
036060
048060
1-1/2 13 8 NA NA NA NA
2 575250454443
036080
048080
060080
2 3833211615 6
2-1/2 70 70 68 67 66 64
048100
060100
2-1/2 27 19 10 9 NA NA
3 686358534843
060120 3* 49 48 47 45 44 43
ALTITUDE (FT) UNIT SIZE
VENT PIPE
DIAMETER (IN.)
NUMBER OF 90° ELBOWS
123456
7001 to 8000†
024040
036040
1-1/2 49 44 39 34 33 28
2 666563626059
024060
036060
048060
1-1/2 12 7 NA NA NA NA
2 534846414038
036080
048080
060080
2 3631191412NA
2-1/2 66 65 63 62 60 59
048100
060100
2-1/2 25 17 8 7 NA NA
3 635853484338
060120 3* 46 44 43 41 40 38
ALTITUDE (FT) UNIT SIZE
VENT PIPE
DIAMETER (IN.)
NUMBER OF 90° ELBOWS
123456
8001 to 9000†
024040
036040
1-1/2 46 41 36 31 29 24
2 626058565553
024060
036060
048060
1-1/2 11 6 NA NA NA NA
2 494442373534
036080
048080
060080
2 3328171210NA
2-1/2 62 60 58 56 55 53
048100
060100
2-1/2 23 15 7 5 NA NA
3 595449443934
060120 3* 43 41 39 37 35 34
* Wide radius elbow.
† Vent sizing for Canadian installations over 4500 ft (1370 m) above sea level are subject to acceptance by the local authorities having jurisdiction.
NA—Not Allowed; pressure switch will not make.
NOTES:
1. Do not use pipe size greater than those specified in table or incomplete combustion, flame disturbance, or flame sense lockout may occur.
2. Assume two 45° elbows equal one 90° elbow. Long radius elbows are desirable and may be required in some cases.
3. Elbows and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
4. The minimum pipe length is 5 ft for all applications.
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