Thanks to all who replied and to sempergoofy
for that installation link.
The "condensation bypass" seems a little odd. I understand the explanation, but I would think that the drain holes in the cap below the tee would slightly compromise the fan's ability to keep a vacuum under the slab. Most of the systems I've seen don't have that feature; perhaps it's only required in colder climates?--
Sarcasm is the Body's Natural Defense Against Stupidity