Got the antifreeze in the cartridge toilet and worked it through . That was easy . For the rest , I know how to draw it up from a container of antifreeze from below but I cannot get that big plug out of the bottom of the hot water tank to drain it . Reefed as hard as I could with a socket wrench and regular handle .Didn't want to try the long breaker bar for fear of wrecking something . . It only has one bypass valve which I have shut off from the inside . What would you suggest? Maybe run antifreeze through the tank as well as the rest of the plumbing ?