rad and coolant,

[Dave Williams]

-> Well you could do that, but I was kinda thinking of a ball valve and
-> a stepper motor, there's gotta be some out there already. It's also a
-> lot easier from the packaging/plumbing standpoint, and I would think
-> would afford infinite control within system capabilities.

 I'd love to find something like that.  All of the commercial valves
I've seen take more torque than a reasonably-sized stepper can give, so
it didn't look practical to cobble something up from pieces.