IBC VX Series Installation & Operating Manual page 29

Intake/Exhaust
2-inch Stainless No allowance required
Sidewall
Terminal (P-256)
3-inch Stainless Allow 20 feet
Sidewall
Terminal -
exhaust vent (P-
257)
3-inch Stainless No allowance required
Sidewall
Terminal - air
intake (P-257)
Flexible PPs 3- Limited to 45 feet
inch Flexible pipe (maximum)
Allow 1.2 x actual length
(e.g., 10 feet of 3-inch
flexible pipe x 1.2 = 12
feet of rigid pipe)
Table 4 Maximum air intake pipe and maximum exhaust vent length
Notes
Unused intake travel cannot be added to the exhaust. Unequal intake and exhaust piping
is allowed.
Support should be provided for intake and vent piping, particularly for horizontal runs
(follow local code).
Example of equivalent length calculations for a VX 110:
A can be sited up to 100 feet (actual vent length allowance) from the vent termination
VX 110
using 2-inch pipe, or up to 240 feet using 3-inch pipe.
For 6 x 90º elbows, the maximum lineal (straight) length of pipe allowed using 2-inch pipe is
52 feet (100' – (6 x 8' = 48) = 52'). The same boiler using 3-inch pipe can have up to 192 feet
(240' – (6 x 8' = 48) = 192').
For 3-inch flexible PPS pipe, up to 45 linear feet is allowed in vertical orientation (> 45 °). The
equivalent length of 3-inch flexible PPS pipe should be calculated using a multiple of 1.2
(e.g., 45 'x 1.2 = 54').
VX 110
Not permitted
Limited to 45 feet
(maximum)
Allow 2 x actual length
(e.g., 10 feet of 3-inch
flexible pipe x 2 = 20
feet of rigid pipe)
25
VX 150
Not permitted
Limited to 30 feet
(maximum)
Allow 3.3 x actual length
(e.g., 10 feet of 3-inch
flexible pipe x 3.3 = 33
feet of rigid pipe)
3.7.4 Direct vent
VX 199