And is it true that 'hot' water freezes faster than 'cold' water? When
> the plumber was out here once last fall to check on my pipes, he
> cautioned me, "when the outside temperaure becomes extreme always be
> sure to have your cold water line running slowly (just a slight
> trickle) all night long to prevent freezing. _NOT_ the hot water line
> but the COLD water line, mainly, I suppose, because it is all 'cold'
> water coming from the street through the meter to my house; it only
> gets 'hot' when my hot-water heater inside prepares it. The plumber
> told me that chemicals in the water boiled away during heating and
> that the 'hot' water got cold (and eventually frozen) faster than
> the 'cold' water got colder (and eventually frozen). Any truth to
> that? I know it seems odd to say 'hot water freezes faster than cold > water'.
The plumber's advice was sound because moving water does not freeze as fast as still water.
The "hot water freezes faster than cold water" applies chiefly to water that is open (like an ice cube tray) because the warm water evaporates faster BUT as it evaporates it takes with it more energy! So if you do the experiment in your freezer you should find that the 'hot' freezes faster, BUT you have less ice remaining behind. So it goes;-)