The water heater by-pass only isolates the water heater from the circulation of water through the tank. Once shut, you still have to pull the drain plug on the water heater and open the pressure relief valve to allow it to drain. The winterizing valve in the wet bay is to draw water from a jug instead of the water tank. In order for the hose to draw water, you must have a faucet open so the antifreeze has someplace to go. I stick the suction hose in a jug or pail of RV antifreeze and go from faucet to faucet in turn, opening and waiting until I see the pink. Doing it with both hot and cold faucets, it doesn't take long to have the antifreeze in every line. At the toilet, you have to hold open the flush valve until the AF shows, also run the sprayer until pink.