21
MAXIMUM ALLOWABLE EXPOSED VENT PIPE LENGTH (FT./M) WITH AND WITHOUT
INSULATION IN WINTER DESIGN TEMPERATURE AMBIENT*
FURNACE SIZE
WINTER DESIGN
TEMPERATURE
°F〈°C)
MAX PIPE
DIAMETER
IN (mm)
WITHOUT
INSULATION
FT. (M)
WITH 3/8–IN. (10 mm) OR
THICKER INSULATION†
FT. (M)
040
20 (---7) 1.5 (38) 51 (16) 70 (21)
0 ( --- 1 8 ) 1.5 (38) 28 (9) 70 (21)
--- 2 0 ( --- 2 9 ) 1.5 (38) 16 (5) 70 (21)
20 (---7) 2 (51) 45 (14) 70 (21)
0 ( --- 1 8 ) 2 (51) 22 (7) 70 (21)
--- 2 0 ( --- 2 9 ) 2 (51) 10 (3) 58 (18)
060
20 (---7) 2 (51) 65 (20) 70 (21)
0 ( --- 1 8 ) 2 (51) 35 (11) 70 (21)
--- 2 0 ( --- 2 9 ) 2 (51) 20 (6) 70 (21)
080
20 (---7) 2 (51) 55 (17) 55 (17)
0 ( --- 1 8 ) 2 (51) 48 (15) 55 (17)
--- 2 0 ( --- 2 9 ) 2 (51) 30 (9) 55 (17)
20 (---7) 2.5 (64) 70 (21) 70 (21)
0 ( --- 1 8 ) 2.5 (64) 47 (14) 70 (21)
--- 2 0 ( --- 2 9 ) 2.5 (64) 28 (9) 70 (21)
100
20 (---7) 2.5 (64) 40 (12) 40 (12)
0 ( --- 1 8 ) 2.5 (64) 40 (12) 40 (12)
--- 2 0 ( --- 2 9 ) 2.5 (64) 38 (12) 40 (12)
20 (---7) 3 (76) 70 (21) 70 (21)
0 ( --- 1 8 ) 3 (76) 50 (15) 70 (21)
--- 2 0 ( --- 2 9 ) 3 (76) 28 (9) 70 (21)
120
20 (---7) 3 (76) 70 (21) 70 (21)
0 ( --- 1 8 ) 3 (76) 61 (19) 70 (21)
--- 2 0 ( --- 2 9 ) 3 (76) 37 (11) 70 (21)
20 (---7) 4 (102) 70 (21) 70 (21)
0 ( --- 1 8 ) 4 (102) 48 (15) 70 (21)
--- 2 0 ( --- 2 9 ) 4 (102) 23 (7) 70 (21)
140
20 (---7) 3 (76) 60 (18) 60 (18)
0 ( --- 1 8 ) 3 (76) 60 (18) 60 (18)
--- 2 0 ( --- 2 9 ) 3 (76) 44 (13) 60 (18)
20 (---7) 4 (102) 70 (21) 70 (21)
0 ( --- 1 8 ) 4 (102) 57 (17) 70 (21)
--- 2 0 ( --- 2 9 ) 4 (102) 30 (9) 70 (21)
* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe
length as specified in Table NO TAG.
† Insulation thickness based on R value of 3.5 per in.
58MXB
