Intake/Exhaust CX150 CX199
256)
3-inch Stainless
Sidewall Terminal -
exhaust vent (P-257)
Allow 20 feet
3-inch Stainless
Sidewall Terminal - air
intake (P-257)
No allowance required
Flexible PP 3-inch
Flexible pipe
maximums
Limited to 45 feet Limited to 30 feet
Flexible PP 3-inch
Flexible pipe
equivalents
Allow 2 x actual length (e.g., 10
feet of 3-inch flexible pipe x 2 =
20 feet of rigid pipe)
Allow 3.3 x actual length (e.g., 10
feet of 3-inch flexible pipe x 3.3 =
33 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 CX150:
A CX 150 can be sited up to 50 feet (actual vent length allowance)from the vent
termination using 2-inch pipe, or up to 170 feet using 3-inch pipe.
For 4 x 90º elbows the equivalent length is 4 x 8' = 32', so the maximum lineal (straight)
length of pipe allowed using 2-inch pipe is 18 feet (50’ – 32' = 18'). The same boiler using
3-inch pipe can have up to 138 feet (170' – 32' = 138').
For 3-inch flexible PP pipe, up to 45 linear feet is allowed in vertical orientation (> 45 °).
The equivalent length of 3-inch flexible PP pipe should be calculated using a multiple of 2
(e.g., 45' x 2 = 90').
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