[Richard]

I stand corrected. Joe Roark was kind enough to let me stare at his setup this morning. Here is what I came away with. The electrically operated slide valve opens and closes to block off the dump plumbing from the grey water discharge. When that valve is closed, the electrically operated solenoid valve below it permits air to enter or evacuate the downstream plumbing and hose. That is how the automatically retracting and extending hose works. It is interesting that the hose actually is stored in a tunnel that penetrates the waste tank. Very clever.

So the diagram I drew does not apply in any way if you have the automatically deploying sewer hose.