John Rumm wrote:
Rob wrote:

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


The pipe that comes out of the very top of the cylinder should fork -
one bit going back into the loft and (usually) terminating over the top
of the main tank.

It sounds truly forked.

To the OP, is it copper or insulation bulging? Running a knife through
it would tell you. If its the copper bulging, you have a serious
problem, either involving an unsuitable tank being under mains
pressure, or a badly blocked system boiling. Either would be unsafe and
imminently destructive, so if the copper is bulging I'd remove both
heat and water supply from it.

If its just an insulation bugle, thats trivial.

If its the copper bulging, replacing the cylinder will not solve the
problem.


NT