Water heater bypass valve confusion during winterizing

The bypass valve is the single most missed step in winterizing and it's the reason people blow out their water heater with antifreeze they thought they didn't need, or worse, skip it and crack the tank with freeze damage. The valve needs to be turned to bypass position BEFORE you start pumping antifreeze, or you'll waste several gallons filling a tank you don't need to protect (or worse, not protect the tank you needed to drain). Check your specific valve type — some are a single lever, some are three separate valves. What system do you have, and have you drained the tank yet?