Pipes don't freeze. It's the water in them that does. If the water in both
pipes becomes stagnant then it will freeze if pipe temperature falls
significantly below freezing long enough. As to which water in which pipe
will freeze first and you're into splitting hairs, then I guess if the last
usage pattern was identical (both hot and cold water used simultaneously at
same pressure levels) then theoretically the water in the cold water pipe
should freeze first since it was originally at a lower temperature. I'm not
a plumber so something could be missing in my reply. What I do know is that
allowing just a trickle of water to flow in either pipe will prevent
freezing and many less fortunate take advantage of this since water bills
are lower than heating (gas, oil or electricity) bills.

"Rettgerinc" wrote in message
...
Hello Everybody,
Merry Christmas from Pittsburgh, PA

It is getting cold here! And I just started a new job with a company
that
does plumbing, heating, and cooling (I am not the plumber for I studied
the
heating and cooling and refrigeration)

Big question!
When the outside temps cause the various inside pipes to freeze and there
are
both hot and cold pipes that have similar exposure, is the hot pipe going
to
freeze first?