[CaptainGizmo]

I've been in quite a few discussions regarding the water system in the modern coaches; referring to the 201x on.

Does anyone know of a schematic/diagram/layout that details the flow of water, the checkvalves, Headhunter, City supply, etc?

The big "mystery" is the interaction with city water, pressure differential, and how the water is taken from the tank vs. the city supply. Some would argue that, if you reduce the pressure of the city supply, through a regulator, that you force the supply to be taken from the TANK. Whereas, conversely, if you feed the coach with higher pressure, the system will draw its supply only from the CITY.

From what others have gathered, even if you ask 10 guys at Newell, you'll get 10 different answers!
   
So, I've taken a stab at it by labeling my system. The secret lies in this magic silver manifold!

Let's solve the mystery!

[RobSC]

Steve,

It's my understanding if the city water pressure is greater than about 40 psi, then it will supply water to the coach.  If that pressure drops below 40, then the HeadHunter water pump will kick in and draw water from the tank.  The HeadHunter will run until it reaches about 65 psi and then shut off.  Looking at your attached photo, my coach seems to plumbed the same as yours.

[hypoxia]

Methinks the "Mystery Bypass" is just a manifold.  The brass fitting on the left side of it is a check valve to prevent backflow to the 12VDC pump.  Good chance the check valve is seized with deposits.  You can disconnect the hose going to it & see if water flows from the check valve.  That valve is spring loaded with a snap ring.  You can remove it, take it apart to soak it in vinegar, replace the "O" ring and make it like new again.

[arcticdude]

If you think your check valve is giving you problems, they’re a common plumbing part available everyplace. Size is really the only option.

If you’re actively using your coach, it would be easy to swap one out. Then clean the take-out unit to use for the next time.