On Wed, 03 Apr 2013 06:25:16 +0100, John Rumm wrote:

On 02/04/2013 21:54, robgraham wrote:
On Apr 2, 4:19 pm, John Rumm wrote:
On 02/04/2013 09:45, newshound wrote:

On 01/04/2013 23:30, John Rumm wrote:

A tale of woe for your entertainment:

http://wiki.diyfaq.org.uk/index.php?
title=The_tale_of_the_rubbing_pipe

Could have been thermal movements, could also have been fretting from
small amplitude vibration in the system.

Pretty sure it was thermal - there is no vibration that you can feel
or hear in the system and it is a very long straight run of 22mm that
is fixed at the far end. Some form of galvanic action was also a
possibility.

Looking at the scale deposit on the pipe, suggests that it had been
leaking for a while - but possibly at a rate where it evaporated
before causing any problems. It also occurred to me, that having
relatively recently fitted a scale inhibitor (phosphate doser) to
house hot water supply, that may have prevented scale from resealing
the hole quite as effectively.

Well written story, John; I'm not sure I would have had the presence of
mind, or the will, to photo it all.. I have a very similar eaves

The driver for the need to photograph, was that I knew I had no other
easy way of looking at the underside of the 22mm pipe given its position
(and my phone was easier to find than a small mirror)

area in our extension section - I'm now passed the three score and ten,
and it is probably 15 years since I last crawled along it.

Your tale of woe had me trying to remember if there were any possibly
similar disaster sources along there, as equally the pipe runs are
long. I don't think there are - and am b****y well hoping my memory is
up to scratch !!

One reason for writing it up (other than "venting" on a rather less than
entertaining weekend) - prior to then I had never really given the
possibility that one pipe might saw its way through another much
thought.

It happened to us, although rather less catastrophically. The CH pipes
were fitted a few years before we moved in, and there were two packed
closely together in a notched joist under the landing. Nothing in between
them. Minute movements as people walked down the landing eventually
caused a pinhole - it must have taken 15 years.

We noticed the water dripping out of the celing fitting in the hall.



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