On Sun, 08 Sep 2013 11:19:59 -0400, John Albert
wrote:

Just as an aside...

The times I've gotten almost-burned taking a shower, were
always with a one-handle control.

Seems if you move it towards "hot", it gets _very_ hot
unpredictably.
If you move it towards "cold", it gets _very_ cold,
unpredictably.
Almost impossible to control it in small increments of
temperature.

Your hot water must be very hot. We had a similar problem but the hot
water went up to 180F (right out of the domestic coil on the boiler).
One got used to controlling it, though. It sure surprised some
visitors. Oh, and don't flush! In short, the plumbing in that house
sucked. It wasn't the mixing valve(s).

With a two-handle (hot/cold) control setup, you can set "one
side" (say, the hot side), and then gradually add cool water
to balance things out.

I would never want a single-knob control.

Dumb. Dual valve controls always leak. The single valve models have
an easily replaced cartridge. That said, not all single knob mixing
valves are alike. Some only have temperature control, no volume.

In short, Id *never* have the individual hot/cold knobs, anywhere
outside, perhaps, a slop sink.