Originally Posted by herk7769
No holding tank back there in my floorplan and I have one.
I always thought it was a vent for my Concertone that is right in front of it.
Our rear living room 8528 has the vent as well, and the only thing up there is the cupboards over the recliners, and there are no tanks at the back. So it obviously is not venting anything related to waste tanks.
Besides, the rear wall is far too thin to have any kind of vent pipe going up through it.
So it is either venting the roof as yooroo said, or it doesn't do much of anything.
It is a curiosity though!