"Rob" wrote in message
oups.com...
Hi,

This morning I noticed a fairly significant bulge on the top surface
of
my hot water cylinder (standard gravity fed system, gas heated with
a
backup immersion that we never use). The insulating material is
cracked
around the immersion heater and the pipe that goes in at the top
(which
I guess feeds the coil from the boiler?). There's no sign of any
leak,
although some silicone-like substance has oozed out around the
immersion heater.

It's obvious that I probably need a new cylinder but I have some
questions:

- What might've caused it? I thought the system was vented, so no
high
pressure was involved?
- Is it safe to carry on heating the water or should I leave it
switched off? I guess the latter, but my wife is nonplussed about
that
idea.
- How much is a new cylinder likely to cost?

Thanks in advance,

Rob


Expansion pipe blocked maybe ?

AWEM