Hard to tell without being able to see where the various lines go. I'm not even sure that diverter valve is for the water heater. It could be for filling the fresh water tank from the city inlet. That appears to be the fresh tank on the left, and the two hoses to the right might be low point system drains.
Where is the water heater? In Fleetwood coaches, the winterizing valves are most often mounted right along side, where the tubing enters & leaves the heater tank.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC