I’ve researched the threads and found only one reference to substantiate not having condensate lines piped directly into vertical plumbing vent stacks.
It is in IRC 2003 P3101.3 Use Limitations. The plumbing vent system shall not be utlilized for purposes other than the venting of the plumbing system.
Is this improper? There are no traps and the units are located in the attic.
Can anyone support this with an appropriate code reference?