Water heater bypass is on the back of the water heater, if you don’t know where it is look out side for a square cover with a small loop on top center that is your water heater cover, then go inside & look for it you should be able to get to it. There are 3 valves you will close the outer ones & open the center valve that will put it in by pass for winterization. The one next to the water pump is used for closing of the water suction from the fresh water tank & with use of the hose that I think it should be there then you can suction rv antifreeze to winterize it. I think this is what you are trying to do? Good luck
George