[lawdog130]

As Dave DC mentioned in his first sentence, flush everything first then open the hot water bypass valve. I got ahead of myself last spring and opened the bypass valve first and the hot water tank filled with antifreeze. It took forever to flush it all out and even at the end of the camping season I would occasionally notice a faint smell the antifreeze when running the hot water. I always use city water and have never filled the fresh water tank so I just hook up a hose with a pressure regulator and work my way around the camper opening all the sink and shower valves, then the toilet until the water runs clear. After that I empty the gray water tank.