I posted this question in my wall of shame thread, but thought I get better respond here. So if I violate any double-post rule please forgive me and delete this thread.
The "wall of shame" thread: http://hvac-talk.com/vbb/showthread.php?t=190822
This is referring to my installation which you guy can view here:
The question is:
Can you guy help me understand the problem with drawing combustion air from attic vs. outside? What the effect of trap water in 3x2 adapter?