Chris Bryant, a member, here, and all-around-nice-guy has a list of service manuals for your appliances, including your
Water heater.
When you mention hoses I think of an exterior hook-up hose, used to connect your RV's inlet port to a campground supply. Typically, fresh water pump, tanks, and water heater are all plumbed together with pipe or a dedicated plastic tubing. There may be valves in certain pipes to close/unclose to get water through the system. These valves are used when Winterizing.
I'd send the Caveman a PM. He doesn't bite and has the same rig.