The next case is one is which you have a valve on the cold water line and a bypass valve in the middle but there is no valve on the hot water line.
Rv hot water heater bypass two valve diagram.
You may need to remove a cover to access it.
Now go into your rv and find the heater from the inside.
Cold water comes in at the bottom and hot water comes out of the top of the heater.
Most rv manufactures today install water heater by pass systems on the rvs they sell.
When the by pass system is used it takes the cold water going.
The water heater by pass system is used to separate the water heater from the rv s plumbing system.
The by pass system can be used to drain the water heater and to winterize the rv water system.