Originally Posted by tommytow
Your hot water heater has a check value behind it and that's what the problem is it's in line behind hot water heater.
This is the check valve that caused the same problem for me. No hot water from my water heater. My cold water worked fine. The valve is not on the water inlet to the hot water heater. It is a check valve on the hot water outlet.
In my RV my water heater is under my kitchen cabinets. To find my check valve I had to remove a drawer to access the back side of my water heater.
The check valve is a brass valve about 2.5 to 3 inches long that screws into the side of the hot water heater. Your RV hot water line will connect this this valve.
Once I found it and found a replacement valve it took about a half hour to replace.