"Edwin Pawlowski" wrote in message
...

"jack" wrote in message
Sealing the top doesn't seem right. The one time I had broken pipes,
they were drained, but there was some residue left in low spots. They
had plenty of room to expand into.

I thought a better test would be to put a right angle bend on the pipe;
then fill it and let it freeze. The right angle would reduce the ice's
ability to expand, and would be pretty much like real plumbing.

4 hours at zero and it didn't do anything but freeze. It didn't even
swell.

Apparently my simulation is deficient. Maybe the bottom of the L has to
be much longer?


If you don't seal the water in some manner it will move to the outside and
not exert pressure on the tubing walls. The water in low spots of your
pipe is a different scenario of a test pipe in the freezer. At some point
the water at the ends freezes and makes a plug. Later the center freezes
and exerts pressure in all direction but since the shallow water at the
ends froze first, it can burst the tubing.

You may find this interesting too. Hot water pipes can freeze before cold
water pipes.
http://www.gi.alaska.edu/ScienceForum/ASF4/440.html
Very interesting. Perhaps only a coincidence, but the two pipes I had that
burst were both hot water pipes.

It is also somewhat reassuring that 32 degrees isn't the magic number; that
it must be rather colder to get burst pipes.

Thanks.