I’m not quite following that either but if you’re good with it, you’re good with it.
Sometimes there are variations to how things can be plumbed up on these things and sometimes pictures are worth a look.
This is my water heater as it will sit all winter. View attachment 134648
blue line is cold water in.
Red is hot water out.
I pull them out of their fittings on the tank and connect them together with that red jumper. That bypasses the tank and the pink runs through all the hot water lines and faucets via that connection.
Yellow arrow is the pressure relief valve, toggle it to the open position so any trapped water is not held in the valve.
Green is a hose I connect to the tank drain valve to route the water to the bilge. Open that valve and let all the water drain out of the tank. (Most guys just open the valve and let the water run out, it’ll find its way to the bilge pump eventually but I don’t like everything getting wet on the way so I use the hose) I do not put pink in my fresh water tank or hot water heater.
The 2 hose connections that are circled in orange are ports to connect to one of the engines coolant circulation system to use engine heat to heat the water heater. Not usually used on boats that have a generator.
Just the way I do it. Ymmv
