According to johnnymo :

Yea, that is why I thought the idea was a good one, b/c it is a very
short distance, just up 1' and over 1' ft, but the air vent still has a
way to go, so I thought if there was condensation, it is going to drain
down the air stack and into the sewer.

I just want to make sure you guys don't think the sewer gas is going to
make its way past my exhaust fan?

If you interconnected the bathroom vent to the DWV vent, and
if the exhaust fan isn't running, why wouldn't it get
past? It's a _gas_, remember?

Would just need a minor vacuum in the house (eg: woodstove or
stove vent) to make it a high volume blast of stink.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.