Many plumbing-related queries could be answered by understanding the Trail Manor plumbing setup. There is a plumbing diagram in my
Bill's Tech Stuff album. It shows, for example, the anti-backflow valves that keep the water where it belongs. It shows what the drain valves under the trailer do. And it shows why a water-heater bypass is not needed.
https://www.trailmanorowners.com/for...&pictureid=435
Questions not answered by this diagram can be asked in the usual Plumbing forum, as always.
Bill