When the by pass system is used it takes the cold water going.
Rv hot water heater bypass two valve diagram.
What you will see instead of a valve is a brass fitting at the hot water outlet on the water heater.
Cold water comes in at the bottom and hot water comes out of the top of the heater.
You may need to remove a cover to access it.
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.
If your rv has a bypass valve these two pipes will be connected directly to each other using a third pipe.
Most rv manufactures today install water heater by pass systems on the rvs they sell.
Now go into your rv and find the heater from the inside.