Jaques d'Alltrades wrote:
:: The message
:: from "Phil L" contains these words:
::
::: The pipe contains 15 mm of water, encased in a 1 mm copper
::: sheath, the tap contains 25mm of water encased in a 10mm brass
::: sheath, which is going to freeze first?
::
:: The water in the tap.

The tap which is fully open with it's supply cut off?
::
::::: Air is not a good conductor, nor does it have a high energy
::::: potential.
:::::
::::: However, leaving the tap open will certainly lessen the
::::: liklihood of a burst, especially if the freezing is very slow.
::::: Ice at or near freezing-point melts readily when under
::::: pressure, resulting in a certain amount of it being pushed
::::: through the tap as ice, and once unconstricted, the fluid
::::: fraction immediately freezes, making it appear as if the ice
::::: has been pushed out as a lump.
::
::: Like I said, it expands out of the open tap.
::
:: Only under *VERY* slow freezing conditions. A hard frost, and the
:: water in the tap freezes hard, and the expansion takes the easier
:: way out - through the copper pipe.
:: God sends the meat, the Devil sends the cooks.

We don't get very rapid hard frosts in this country...it would have to be
instantaneous!
Frosts occur gradually +2 /+1/ 0/ -1 /-2 over a period of a few hours...in
this time what little water remains in the pipe has gone...the outlet of the
tap *is* the lowest point remember.