Yahoo Message Number: 67692 (http://groups.yahoo.com/neo/groups/Country-Coach-Owners/conversations/messages/67692)
Marvin,
I seem to be missing your point. Since there are no pumps involved then all waste liquid flows by gravity just like a stick house. Both the black water and gray water system are open by virtue of the fact that they both have a roof vent.
I go beyond your recommendation of closing the gray water dump valve when dumping in that I never have both the black and gray dump valves open at the same time. I just don't like mixing the gray and black water if I can avoid it. However if one elected to dump the black water with the gray water dump valve open then the roof vents in both tanks would prevent vent any vacuum from pulling any of the gray water traps. That is one of the reasons for the separate vents stacks at each tank.
Don Seager
2004 Allure 31046
Yahoo Message Number: 67693 (http://groups.yahoo.com/neo/groups/Country-Coach-Owners/conversations/messages/67693)
I'm not sure I understand the rational but, if I recall correctly, the directions that came with my coach recommended that the grey valve be left closed when the black tank was dumped and that after that had been done it was OK to have both valves open while dumping the grey tank. No doubt the idea was to prevent black tank stuff from contaminating the grey tank and to get a little extra "flushing" by getting a little back flow of grey water into the black pipe.
The advice on keeping the traps full makes sense. In addition we use a large flat rubber drain stopper over the shower drain plate since, if there's a trap there, it's easy to forget and let run dry.
Jim M
'02 Intrigue #11410 ISL 400
Yahoo Message Number: 67704 (http://groups.yahoo.com/neo/groups/Country-Coach-Owners/conversations/messages/67704)
Don, Maybe my explanation was a little rough, I do not have a pump on the sewer. But when you let almost 100 gal go all a once it pull a large suction, that was my point, stick house runs all the time, therefore less suction. With a Studor vent that could possibly be stuck or malfunctioning, the suction (all at once) will draw all the water out of the P-traps, it is a little different than a stick house..I do not leave my gray and black tank valve open at the same time, unless I am at a dump station, I will open the Gray when the Black tank is finishing up, this will help clean out the hose..This of course is my explanation and does not have to be for everyone..
Marvin, 07 Allure #31459