is supposed to be a solution for not being able to drain all the water out of the entire system. That the vodka will act like potable anti-freeze. Of course one should drain out as much water is possible, and then put in a couple of big cheap bottles of vodka, and run the system again... leaving mostly vodka left where liquid doesn't drain well.

Now as I said, I don't winterize... so the above may be some tall tale told to me by an old salt.