I forget exactly where I got the instructions, a magazine or a mechanic, but it was back in the dark days.........about 6 years ago when we owned the powerboat for a couple of years. The basis of this is that you don't want to have to buy an extra 6 gallons of antifreeze or take the extra time required to flush your complete fresh water system in the spring. The instructions were to disconnect the in and out pressure water hoses from the heater and fabricate a connector to attach them together. Step two is to open the petcock and drain all the water out of the hot water tank. True there may be a little on the bottom of the tank but that should not be enough to cause problems. Once the pressure water hoses are hooked in a bypass, drain the fresh water tank and add pink antifreeze, run all faucets and showers until they run pink. In the spring, run all the pink out of the fresh water tank, fill with clear water and run the lines again. When the water stops looking and smelling like antifreeze, reconnect the pressure water lines to the hot water tank, close the petcock and fire up the water pump to fill the hot water tank. I also add a small amount of bleach to the fresh water tank and run the lines again to kill off any little bugaroos that may have set up shop over the winter.