The Stovebolt Site Forums The Shop Area Engine Shop Heater Core Isolation valves

I was out at the mecum auction in Houston a couple weeks ago, and an old collector was selling about 50 cars out of his collection. I noticed many of the older ones had isolation (ball) valves on the heater hoses both to/from. Sounds like a good idea for autos that mostly sit. How would you drain the core without draining the hole system? Maybe they just close the inlet and outlet valves and unhook the hose on the outlet side and drain into a bucket without draining the whole system. Would that work?