Albert, (Rochester, NY)
Albert, I don’t have a diagram for you, but it is easily understood logic. At the back of the water heater, you’ll find a cold water inlet and a hot water outlet. Obviously, you’ll connect the existing cold water line to the cold inlet. This is the point where you’ll also want to install a one-way check valve; directly to the cold inlet with the directional arrow pointing into the tank. This will prevent heated water from migrating out of the water heater and feeding back into the cold system. This usually isn’t an issue unless the cold water line tee’s off to another fixture very close to the back of the water heater. I have seen where the cold connection to the toilet was tee’d very close to the inlet of the water heater and every time the owner flushed the toilet, steam would rise out of the toilet bowl. Installing a check valve at the water heater inlet curtailed that immediately. Most RV manufacturers now do this at the factory.