Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Cheers
Jon N

"jkn" wrote in message
...
Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Cheers
Jon N

I have replaced my immersion heater many times. Once, it was so stuck that I
tore the copper tank trying to unscrew it. I was able to solder copper
patches to repair the breaks, but later, an unknown leak allowed water to
get between the copper and the surrounding foam insulation, which then broke
into pieces at the top. I eventually replaced the whole cylinder.

Your leak might be just a failure of the fibre ring washer under the heater,
in which case the new heater should come with a new one. On the other hand
the leak could be due to a tear in the copper caused by a brutal torque
during the replacement of your existing heater.

I live in a hard water area, and the heater tubes just corrode away
eventually.
--
Dave W

"jkn" wrote in message
...

Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Cheers
Jon N

None. And it's moot anyway.


NT

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Age and general crustyness!


--
Cheers,

John.

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

On Monday, 29 August 2016 14:35:11 UTC+1, John Rumm wrote:
On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Age and general crustyness!

The Leak: age can cause corrosion of the copper or disintegration of the fibre washer. The heating device itself is not likely to be the cause. Crustiness acts to plug leaks.

Open circuit: crustiness does raise element operating temp, but too much crust normally breaks off, and the element is designed to survive this process. It will however accelerate aging to an extent. Age is the killer on this one, these things have finite life.


NT

John Rumm wrote:

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Age and general crustyness!

You talkin' to me?

;-/

Jon N

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much
easier to replace than the whole thing.

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.


If you *do* need to remove the immersion heater, start to unscrew it
with the tank still full of water so that the weight of the water holds
the tank in place. Use a proper immersion heater spanner and tap it
round with a rubber mallet. Be prepared for the tank to split in the
process!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Roger Mills" wrote in message
...
On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much easier
to replace than the whole thing.

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.


If you *do* need to remove the immersion heater, start to unscrew it with
the tank still full of water so that the weight of the water holds the
tank in place. Use a proper immersion heater spanner and tap it round with
a rubber mallet. Be prepared for the tank to split in the process!

And don't do it if the element enters the *side* of the tank, low down,
otherwise hundreds of litres of water will shoot out of the hole :-(

I had a tank like this so obviously I drained it completely first of all.
But when I was describing the hassle to someone at work he said that he knew
someone (cue the apocryphal story) who didn't drain the tank. The thread was
fairly watertight till he'd almost undone it (otherwise the seepage might
have alerted him to what he was about to do!), and then the final turn of
thread couldn't withstand the pressure and the element shot out and broke
the man's arm, and several hundred litres of scalding hot water (heated by
the central heating) cascaded out in a 4"-wide plug of water, burning him in
various unfortunate places and running in a torrent down the stairs into the
living room.

On 29/08/2016 14:42, wrote:
On Monday, 29 August 2016 14:35:11 UTC+1, John Rumm wrote:
On 29/08/2016 10:31, jkn wrote:
Hi All what connection, if any, is there likely to be a
connection between the following two events:

- Immersion heater seems to have failed (power going to terminals
OK) - a small leak around the top of the tank, where the heater
is fitted ?

Of course my next step is to try and unscrew the heater with a
view to replacing; I'm just wondering what failure mode might
account for both symptoms.

Age and general crustyness!

The Leak: age can cause corrosion of the copper or disintegration of
the fibre washer. The heating device itself is not likely to be the
cause. Crustiness acts to plug leaks.

Open circuit: crustiness does raise element operating temp, but too
much crust normally breaks off, and the element is designed to
survive this process. It will however accelerate aging to an extent.
Age is the killer on this one, these things have finite life.

For the avoidance of doubt, I was not using "crusty" as a synonym for
scale. Just as a general comment on the state of the installation. I.e.
if its old / nearing end of life that is one factor that connects both
events.

Beyond that, there is unlikely to be any direct connection unless say
the immersion heater boss is suffering serious corrosion - that may
account for the leak and its non functioning.


--
Cheers,

John.

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

On 29/08/2016 21:09, NY wrote:
"Roger Mills" wrote in message
...
On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection
between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the
input, which includes a thermostat in series with the element? Check
that the stat hasn't failed before doing anything else, because that's
much easier to replace than the whole thing.

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.


If you *do* need to remove the immersion heater, start to unscrew it
with the tank still full of water so that the weight of the water
holds the tank in place. Use a proper immersion heater spanner and tap
it round with a rubber mallet. Be prepared for the tank to split in
the process!

And don't do it if the element enters the *side* of the tank, low down,
otherwise hundreds of litres of water will shoot out of the hole :-(

I had a tank like this so obviously I drained it completely first of
all. But when I was describing the hassle to someone at work he said
that he knew someone (cue the apocryphal story) who didn't drain the
tank. The thread was fairly watertight till he'd almost undone it
(otherwise the seepage might have alerted him to what he was about to
do!), and then the final turn of thread couldn't withstand the pressure
and the element shot out and broke the man's arm, and several hundred
litres of scalding hot water (heated by the central heating) cascaded
out in a 4"-wide plug of water, burning him in various unfortunate
places and running in a torrent down the stairs into the living room.

There is probably one good message to take from that... don't work on a
cylinder when its still full of *hot* water - it only magnifies the
problems when something goes pair shaped! Let it cool down first.


--
Cheers,

John.

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

On Monday, 29 August 2016 22:23:30 UTC+1, John Rumm wrote:
On 29/08/2016 21:09, NY wrote:

And don't do it if the element enters the *side* of the tank, low down,
otherwise hundreds of litres of water will shoot out of the hole :-(

I had a tank like this so obviously I drained it completely first of
all. But when I was describing the hassle to someone at work he said
that he knew someone (cue the apocryphal story) who didn't drain the
tank. The thread was fairly watertight till he'd almost undone it
(otherwise the seepage might have alerted him to what he was about to
do!), and then the final turn of thread couldn't withstand the pressure
and the element shot out and broke the man's arm, and several hundred
litres of scalding hot water (heated by the central heating) cascaded
out in a 4"-wide plug of water, burning him in various unfortunate
places and running in a torrent down the stairs into the living room.

There is probably one good message to take from that... don't work on a
cylinder when its still full of *hot* water - it only magnifies the
problems when something goes pair shaped! Let it cool down first.

So much more fun when it's scalding.


NT

On Monday, 29 August 2016 13:46:51 UTC+1, Dave W wrote:
"jkn" wrote in message
...
Hi All
what connection, if any, is there likely to be a connection between the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.

Cheers
Jon N

I have replaced my immersion heater many times. Once, it was so stuck that I
tore the copper tank trying to unscrew it. I was able to solder copper
patches to repair the breaks, but later, an unknown leak allowed water to
get between the copper and the surrounding foam insulation, which then broke
into pieces at the top. I eventually replaced the whole cylinder.

Your leak might be just a failure of the fibre ring washer under the heater,
in which case the new heater should come with a new one. On the other hand
the leak could be due to a tear in the copper caused by a brutal torque
during the replacement of your existing heater.

I live in a hard water area, and the heater tubes just corrode away
eventually.
--
Dave W

Before removing an immersion heater, you need to saw out the packing ring between the heater flange and the tank.
Hacksaw blade with one end wrapped in tape is the tool.
Clean up flange before fitting replacement heater.

Hi Roger
Roger Mills wrote:

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much
easier to replace than the whole thing.

Fair point - except that now the thing is leaking, which I don't think is
related to any Thermostat issues...

Good stuff about removal snipped. FWIW mine is at the top of the tank.

Ideally I would like a method of determining the length (for obtaining a
replacement) before removing the one at fault, but I doubt that exists...

J^n

On 30/08/2016 08:08, jkn wrote:
Hi Roger
Roger Mills wrote:

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much
easier to replace than the whole thing.

Fair point - except that now the thing is leaking, which I don't think is
related to any Thermostat issues...

Good stuff about removal snipped. FWIW mine is at the top of the tank.

Ideally I would like a method of determining the length (for obtaining a
replacement) before removing the one at fault, but I doubt that exists...

Did it heat just the top of the tank or lower down?

I don't think you can buy that many lengths. Personally I would use a
short one, so to heat just the top as it would only be used for emergencies.

On 29/08/2016 22:23, John Rumm wrote:

There is probably one good message to take from that... don't work on a
cylinder when its still full of *hot* water - it only magnifies the
problems when something goes pair shaped! Let it cool down first.


Or pear shaped, even.

It's still advisable to loosen the heater with the tank full, such that
it can be removed more easily after the tank has been drained - but
obviously don't unscrew it fully with the tank full!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 30/08/2016 14:17, Roger Mills wrote:
On 29/08/2016 22:23, John Rumm wrote:

There is probably one good message to take from that... don't work on a
cylinder when its still full of *hot* water - it only magnifies the
problems when something goes pair shaped! Let it cool down first.


Or pear shaped, even.

It's still advisable to loosen the heater with the tank full, such that

Yup not disputing that - just full though rather than full of hot water.
If the tank decides to split on you big time as you loosen it, you have
far more options open to you than you do if water at 60+ deg C is
spewing everywhere!

it can be removed more easily after the tank has been drained - but
obviously don't unscrew it fully with the tank full!

;-)

I once replaced the temperature sensor probe in the DHW part of a combi.
I forgot to shut off the mains cold feed to it. Needless to say, when it
finally pulled free of its socket, things got damp rather fast, and
sticking my thumb over the source of the jet of water only served to
spread it around over a wider area!
--
Cheers,

John.

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

On 30/08/2016 08:08, jkn wrote:
Hi Roger
Roger Mills wrote:

On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much
easier to replace than the whole thing.

Fair point - except that now the thing is leaking, which I don't think is
related to any Thermostat issues...

Good stuff about removal snipped. FWIW mine is at the top of the tank.

Ideally I would like a method of determining the length (for obtaining a
replacement) before removing the one at fault, but I doubt that exists...

Pulling the stat out will give you some indication - at least you know
it won't be shorter than that!


--
Cheers,

John.

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

"Roger Mills" wrote in message
...
On 29/08/2016 10:31, jkn wrote:
Hi All
what connection, if any, is there likely to be a connection between
the
following two events:

- Immersion heater seems to have failed (power going to terminals OK)
- a small leak around the top of the tank, where the heater is fitted
?

Which terminals have you checked - the element itself or just the input,
which includes a thermostat in series with the element? Check that the
stat hasn't failed before doing anything else, because that's much easier
to replace than the whole thing.

Of course my next step is to try and unscrew the heater with a view to
replacing; I'm just wondering what failure mode might account for both
symptoms.


If you *do* need to remove the immersion heater, start to unscrew it with
the tank still full of water so that the weight of the water holds the
tank in place. Use a proper immersion heater spanner and tap it round with
a rubber mallet. Be prepared for the tank to split in the process!


I have had reasonable success in swapping elements (only one failure) and I
give the spanner a sharp knock to tighten the element before uncrewing it.

--
Adam