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

"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

Rob wrote:

This morning I noticed a fairly significant bulge on the top surface of
my hot water cylinder

When you turn the hot tap on, does the pressure seem to be higher
than usual? There does need to be an expansion vent, which in my
country (NZ) is a pipe going straight up and is open at the top,
or else it's a small horizontal pipe going outside with an
expansion valve which may have a flushing lever on it to clear
foreign matter from the valve seat.

"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,


I would drain the system down, to relieve any stress and impending disaster,
and remove the insulation from around these areas. Hopefully it'll just the
insulation which has swelled up due to this leak.

The pressure seems normal, as does the temp. The only vented pipe
appears to run from the top of the central heating pump and is closed
off by a thumbscrew which looks to have a small hole in the top.
Loosening this thumbscrew produced a very small amount of air and some
warm (clean) water. The only other unsealed pipes are the overflows for
the cold tank and the central heating header tank.

If the tank was under enough pressure to change its shape, wouldn't the
hot water just have backed up into the cold storage tank? The cold
water is normal temperature and was first thing this morning (when the
system was still on).

Rob wrote:
This morning I noticed a fairly significant bulge on the top surface of
my hot water cylinder

The alien's eggs have hatched....

RUN.

--
Adrian C

Rob wrote:
Hi,

Is it a cylinder with foamed on polyurethane insulation, or a separate
insulation jacket? If the former, is the bulge in the copper cylinder,
or just in the insulation?

I replaced an immersion heater on a hot cylinder once and a small
amount of water spilt from the immersion heater boss. There was an
alarming crackling sound (it sounded like a bonfire) and the insulation
around the bottom of the cylinder started bulging and splitting. It
appeared to be that the water was evaporating and blowing the
insulation off, or that it was some chemical reaction between the water
and the polyurethane insulation. The cylinder wasn't hot enough to boil
the water.

If it's just the insulation bulging, it might be just a leak from the
immersion heater causing the insulation to separate from the cylinder.
remove insulation and check.

Sadly it doesn't seem to be just the insulation - there's no sign at
all of any leak and I can see that the coupling at the top is raised at
one side where the tank's blown.

Will drain the system as you suggest and get a plumber out tomorrow -
this isn't something I'll be allowed to tackle on my own :-(.

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

Sounds like it is on its last legs. Worrying that the bulge is at the
top. It would be interesting to know if the bulge is just damp
inuslating material or an actual bulge in the copper.

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,

The pipe "in" at the top is actually where the hot water comes out to
feed the taps. The should be another three pipes. One at the bottom from
the header tank in the loft - that is the supply of cold water in. Plus
another two for connections to the boiler. These are normally located
roghly in the middle of one side and at the bottom again.

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?

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. The other will feed the taps. This vent can get
blocked with scale in hard water areas, although there ought to still be
an expansion path available by pushing water back into the cold cistern
via its feed pipe.

- 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.

She would be less keen on 100L+ of hot water cascading down through the
house I would have thought!

- How much is a new cylinder likely to cost?

Depends on size - a 900 x 450 indirect part L compliant one would
usually be in the range of £100 to £140:

http://www.screwfix.com/app/sfd/cat/...10423&ts=86904

You will need to add the cost of some suitable fittings to connect to
your pipework (you may be able to remove and reuse the ones on the
existing cylinder). It might be worth replacing the immersion heater at
the same time. These are cheap enough:

http://www.screwfix.com/app/sfd/cat/...87042&id=63692

Don't forget an immersion spanner and a couple of reels of PTFE tape
(you need plenty on tank connectors)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Now you mention it, the in-laws came to stay a few weeks ago. I always
had my suspicions...

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

On 1 May 2006 03:37:47 -0700, "Rob" wrote:

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

The bulge is due to either over pressure or a local weakness in the
cylinder. Over pressure seems to be unlikely as for that to occur
would require both the vent pipe at the top of the cylinder and the
cold feed pipe from the cylinder, both from the header tank in the
loft, to be blocked at the same time.

A local weakness in the cylinder appears to be equally unlikely.

Both possible causes are not impossible however.

What to do? The cylinder should not be used and replaced. The cost
will be about £120 if you do it yourself. I just replaced a leaking
cylinder, the cost was £104 from Wickes. I also took the opportunity
to replace the immersion heater about £24 if I remember correctly. You
can use all the existing fittings on the cylinder. Time to drain
down, remove the cylinder and refit, about 4 hours provided there is
reasonable access..

Clearly while doing the job you must prove the connection to the
header tank clear.

Good luck!

On Tue, 2 May 2006 06:32:35 UTC, Edward W. Thompson
wrote:

The bulge is due to either over pressure or a local weakness in the
cylinder. Over pressure seems to be unlikely as for that to occur
would require both the vent pipe at the top of the cylinder and the
cold feed pipe from the cylinder, both from the header tank in the
loft, to be blocked at the same time.

A local weakness in the cylinder appears to be equally unlikely.

We had exactly this kind of failure last year. The cylinder (about 20
years old) bulged and failed (luckily just a fast weep) at the top. No
other blockages or problems.
--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

Rob wrote:
The only vented pipe
appears to run from the top of the central heating pump and is closed
off by a thumbscrew which looks to have a small hole in the top.
Loosening this thumbscrew produced a very small amount of air and some
warm (clean) water. The only other unsealed pipes are the overflows for
the cold tank and the central heating header tank.

There should be a pipe coming from the top of the cylinder,
tee'd to taps, that is the vent.


If the tank was under enough pressure to change its shape, wouldn't the
hot water just have backed up into the cold storage tank? The cold
water is normal temperature and was first thing this morning (when the
system was still on).

Hopefully. Cut out a section of lagging to see what's up.

Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The cost
will be about £120 if you do it yourself. I just replaced a leaking
cylinder, the cost was £104 from Wickes. I also took the opportunity
to replace the immersion heater about £24 if I remember correctly. You
can use all the existing fittings on the cylinder. Time to drain
down, remove the cylinder and refit, about 4 hours provided there is
reasonable access..

Don't *forget* to notify the council's "building control" department,
and pay the relevant fee.

In an earlier contribution to this discussion,
Chris Bacon wrote:

Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The cost
will be about £120 if you do it yourself. I just replaced a leaking
cylinder, the cost was £104 from Wickes. I also took the opportunity
to replace the immersion heater about £24 if I remember correctly.
You can use all the existing fittings on the cylinder. Time to drain
down, remove the cylinder and refit, about 4 hours provided there is
reasonable access..

Don't *forget* to notify the council's "building control" department,
and pay the relevant fee.

Did *you* do that?
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
Chris Bacon wrote:
Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The cost
will be about £120 if you do it yourself.

Don't *forget* to notify the council's "building control" department,
and pay the relevant fee.

Did *you* do that?

Bother, I forgot... oh, er, actuelly, I ain't dun one since the
Part P regulationes comed into farce, honest, guv.

In an earlier contribution to this discussion,
Chris Bacon wrote:

Roger Mills wrote:
Chris Bacon wrote:
Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The
cost will be about £120 if you do it yourself.

Don't *forget* to notify the council's "building control"
department, and pay the relevant fee.

Did *you* do that?

Bother, I forgot... oh, er, actuelly, I ain't dun one since the
Part P regulationes comed into farce, honest, guv.


I don't think that Part P has anything to do with HW cylinders!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:

In an earlier contribution to this discussion,
Chris Bacon wrote:

Roger Mills wrote:
Chris Bacon wrote:
Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The
cost will be about £120 if you do it yourself.

Don't *forget* to notify the council's "building control"
department, and pay the relevant fee.

Did *you* do that?

Bother, I forgot... oh, er, actuelly, I ain't dun one since the
Part P regulationes comed into farce, honest, guv.


I don't think that Part P has anything to do with HW cylinders!

Indeed - it's Part L. So even less reason to bother telling anyone
IMHO

Cheers

Tim

On Tue, 02 May 2006 16:59:52 +0100, Tim S wrote:

I don't think that Part P has anything to do with HW cylinders!

Indeed - it's Part L. So even less reason to bother telling anyone
IMHO

Cheers

Tim

Ah, so that's the one that turned "daft" into "total farce". Thanks, I
had forgotten the letter for it. )

Tim S wrote:
Roger Mills wrote:
Chris Bacon wrote:
Roger Mills wrote:
Chris Bacon wrote:
Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The
cost will be about £120 if you do it yourself.
Don't *forget* to notify the council's "building control"
department, and pay the relevant fee.
Did *you* do that?
Bother, I forgot... oh, er, actuelly, I ain't dun one since the
Part P regulationes comed into farce, honest, guv.

I don't think that Part P has anything to do with HW cylinders!

Indeed - it's Part L. So even less reason to bother telling anyone
IMHO

Whooshes from all sides....

Do I need to put in a smiley?

Chris Bacon wrote:

Tim S wrote:
Roger Mills wrote:
Chris Bacon wrote:
Roger Mills wrote:
Chris Bacon wrote:
Edward W. Thompson wrote:
What to do? The cylinder should not be used and replaced. The
cost will be about £120 if you do it yourself.
Don't *forget* to notify the council's "building control"
department, and pay the relevant fee.
Did *you* do that?
Bother, I forgot... oh, er, actuelly, I ain't dun one since the
Part P regulationes comed into farce, honest, guv.

I don't think that Part P has anything to do with HW cylinders!

Indeed - it's Part L. So even less reason to bother telling anyone
IMHO

Whooshes from all sides....

Do I need to put in a smiley?

Probably - my brain is suffering from (mis)management-related spasms
last few weeks...

Ow.

Tim

In article .com
wrote:
snip
If its just an insulation bugle, thats trivial.

But you wouldn't want it playing Reveille at 6:00 am

On Wed, 3 May 2006 03:28:33 +0100, Rob Morley wrote:

|In article .com
| wrote:
|snip
| If its just an insulation bugle, thats trivial.
|
|But you wouldn't want it playing Reveille at 6:00 am


I personally would remove a patch of the insulation where the bulge is, and
examine the copper tank underneath. If the tank is OK I would replace
the insulation with something equivalent.
--
Dave Fawthrop dave hyphenologist co uk Google Groups is IME the *worst*
method of accessing usenet. GG subscribers would be well advised get a
newsreader, say Agent, and a newsserver, say news.individual.net. These
will allow them: to see only *new* posts, a killfile, and other goodies.