My RV (2016 Coachmen Leprechaun) has 2 dump valves for the single blackwater tank.
The blackwater tank is on the passenger side of the rig under the toilet and it has a dump valve just outside that tank, then there's a long pipe that leads to the normal driver side dump outlet where there's another blackwater dump valve (there's the normal graywater valve there too, the graywater tank is near the dump outlet so it just has the single valve).
What's the best way to dump with that 2nd valve? Here's what I'm doing:
1. Hook up sewer slinky and put it in the sewer drain. Both valves are closed.
2. Walk around to the passenger side of the coach and open the valve at the tank. I can hear wastewater filling the pipe to the other side.
3. Walk back to the waste outlet on the driver side and pull that valve, then watch the show in the clear elbow as the waste goes down the drain. I do it in this order so the water doesn't get an 8 foot head start and build up enough speed/pressure to knock my slinky out of the sewer drain.
4. After the tank is empty, I walk back to the passenger side, close that valve, put some water in the tank as a rinse (no blackwater rinse system in this RV), then I pull the valve again and let the rinse water out (I kept the valve at the waste outlet open)
5. Finally, when I'm done, I close the passenger side valve nearest the tank, go back to the driver side dump outlet, make sure the water stopped dripping out of that cross-pipe and then close the valve at the dump outlet, then I'm done with the blackwater. Then I do the graywater.
Am I missing anything? The owners manual doesn't say anything about how to use that second valve so I'm just guessing.
