Now, I'm going to confuse and discombubulate (how do you like that word?) you even more.
Some of the cutoff valves maybe water bypass valves, used for winterization.
I'll use my Forrest River Lexington as an example.
Under right rear of the coach, my 3 water drain lines exit the coach. One, the fresh water tank drain, has a drain valve inside a storage compartment below the water tank. A no-brainer. But, originally the hot and cold drain lines just simply had a screw on cap, and to drain the lines, the caps were simply removed. Water would slowly drain, and, turning pump on would speed up the process. I have since added a valve to the end of each line using pex sharke bite valve fittings.
But, in the bathroom, behind a drawer, are cutoff valves for each line, and those are the bypass valves to close off the system to add winter fluid, bypassing the hot water heater.
Only way your going to know what you have is to play with them. If you find the lines under the coach, they'll probably be 1/2" lines, and if there is a cap, remove it. If water immediately flows out, thats all you need to drain them, and it means the "upstream" valve is open. If you remove the cap, and nothing flows out at all, then there is a drain valve somewhere in the system.
Sounds crazy, and confusing, but since there's no standardization, you just have to figure what you have and don't have.
Just remember, when finding and playing with a valve, in the open/flow position, the valve handle will be parallel to the line, and in closed position it will be at a right angle to the line. Every valve I've run across only goes through a 90 degree arc between open and closed.
Grumpy
