Copper unvented hot water tank with horizontal immersion heater at the
bottom on economy 7. Heater is OK as far as I can make out as is the
thermostat. When power is applied the water can be heard to begin
heating but after a minute or so the thermostat kicks in an it stops.
Restarts after a while then stops again. Over a seven hour period the
tank of water gets only lukewarm.

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

Andrew

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

it is probably the problem, that is if the thermostat isnt on it's way out,
is it the type that sits in a pocket in the immersion heater head? usually a
couple of squids to replace if you can't test it,

But as for getting the stuck element out, if it's resisting you, it'll most
likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher up
the tank?

On 28/01/2013 12:02, Gazz wrote:

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

it is probably the problem, that is if the thermostat isnt on it's way
out, is it the type that sits in a pocket in the immersion heater head?
usually a couple of squids to replace if you can't test it,

There is a top-up heater halfway up the tank. I have switched
thermostats but get the same so fairly certain that is it not the
thermostat. The top up immersion is stuck as well otherwise I could go
in through that one.

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher
up the tank?

No. It already has a heater installed.

Andrew May wrote:
On 28/01/2013 12:02, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher
up the tank?

No. It already has a heater installed.

Time to bite the bullet, then. Technically, you could take it out, fill
it with descaler and hope that freed off the heaters, but enough
descaler would probably cost more than a new tank and heaters,
especially by the time you take the scrap value of the old tank into
account.

--
Tciao for Now!

John.

On 28/01/2013 12:34, John Williamson wrote:
Andrew May wrote:
On 28/01/2013 12:02, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher
up the tank?

No. It already has a heater installed.

Time to bite the bullet, then. Technically, you could take it out, fill
it with descaler and hope that freed off the heaters, but enough
descaler would probably cost more than a new tank and heaters,
especially by the time you take the scrap value of the old tank into
account.


I guess that the problem is going to be to find a matching tank with the
inlet and outlet in the same place. The existing one was made by Albion
and looks like it is part of their AquaPak
http://www.albionwaterheaters.com/product-aquapak.html combined hot/cold
water system. I don't know whether it is possible to replace just the
cylinder in this or whether it needs the whole unit to be replaced.
Bloody expensive if it does just for a seized immersion heater.

On 28/01/2013 12:52, Andrew May wrote:


I guess that the problem is going to be to find a matching tank with the
inlet and outlet in the same place. The existing one was made by Albion
and looks like it is part of their AquaPak
http://www.albionwaterheaters.com/product-aquapak.html combined hot/cold
water system. I don't know whether it is possible to replace just the
cylinder in this or whether it needs the whole unit to be replaced.
Bloody expensive if it does just for a seized immersion heater.

I'm a bit confused! The product in this link appears to be vented,
whereas you said yours was unvented. [I wasn't aware that anyone made
unvented cylinders out of copper - I thought they tended to be stainless
steel].

So which *is* yours?
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

Andrew May wrote:
On 28/01/2013 12:34, John Williamson wrote:
Andrew May wrote:
On 28/01/2013 12:02, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher
up the tank?

No. It already has a heater installed.

Time to bite the bullet, then. Technically, you could take it out, fill
it with descaler and hope that freed off the heaters, but enough
descaler would probably cost more than a new tank and heaters,
especially by the time you take the scrap value of the old tank into
account.


I guess that the problem is going to be to find a matching tank with the
inlet and outlet in the same place.

I believe plumbers have learned the art of making *new* bendy bits of pipe.
;-). Even I can do it if I have to.

The existing one was made by Albion and looks like it is part of their
AquaPak http://www.albionwaterheaters.com/product-aquapak.html combined
hot/cold water system. I don't know whether it is possible to replace
just the cylinder in this or whether it needs the whole unit to be
replaced. Bloody expensive if it does just for a seized immersion heater.

Even more when you add in a water softener but that would be more of a long
term investment.

Tim

On 28/01/2013 12:34, John Williamson wrote:
Andrew May wrote:
On 28/01/2013 12:02, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,
i don't suppose there's another immersion heater boss blanked off higher
up the tank?

No. It already has a heater installed.

Time to bite the bullet, then. Technically, you could take it out, fill
it with descaler and hope that freed off the heaters, but enough
descaler would probably cost more than a new tank and heaters,
especially by the time you take the scrap value of the old tank into
account.

Assuming it is limescale, why not buy a tub of Fernox DS3 descaler
(about £20, and enough to make hundreds of litres of descaler), turn the
water off, open a tap to release the pressure in the expansion vessel,
and then remove the pipe from the top connection, pour in some of the
DS3 and leave it overnight. (you can apply some heat with the immersion
heaters to speed it up). Then drain, and refill.



--
Cheers,

John.

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

On Mon, 28 Jan 2013 12:02:50 -0000, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,

From what I've heard use a box spanner rather than ring and gently try
tapping the thing tighter as well as looser. Also do this inital
loosening with the tank full as the weight of water tends to support the
tank but don't get carried away, once it's "given" stop and drain...

--
Cheers
Dave.

On 28/01/2013 12:39, Dave Liquorice wrote:
On Mon, 28 Jan 2013 12:02:50 -0000, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,

From what I've heard use a box spanner rather than ring and gently try
tapping the thing tighter as well as looser. Also do this inital
loosening with the tank full as the weight of water tends to support the
tank but don't get carried away, once it's "given" stop and drain...

I have a box spanner - with a tommy bar. It fits but does seem a bit
sloppy. Were older immersion heaters an imperial size? I have already
had to source 6" tiles for the bathroom.

"Andrew May" wrote in message
...
On 28/01/2013 12:39, Dave Liquorice wrote:
On Mon, 28 Jan 2013 12:02:50 -0000, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,

From what I've heard use a box spanner rather than ring and gently try
tapping the thing tighter as well as looser. Also do this inital
loosening with the tank full as the weight of water tends to support the
tank but don't get carried away, once it's "given" stop and drain...

I have a box spanner - with a tommy bar. It fits but does seem a bit
sloppy. Were older immersion heaters an imperial size? I have already had
to source 6" tiles for the bathroom.

You could drain the cylinder and then heat up immediate around the immersion
heater with a blow lamp.
Put spanner on and give it a good belt.

On 28/01/2013 13:39, Andrew May wrote:
On 28/01/2013 12:39, Dave Liquorice wrote:
On Mon, 28 Jan 2013 12:02:50 -0000, Gazz wrote:

But as for getting the stuck element out, if it's resisting you, it'll
most likely twist the tank if you try harder,

From what I've heard use a box spanner rather than ring and gently try
tapping the thing tighter as well as looser. Also do this inital
loosening with the tank full as the weight of water tends to support the
tank but don't get carried away, once it's "given" stop and drain...

I have a box spanner - with a tommy bar. It fits but does seem a bit
sloppy.

This was one person's solution to that:

http://wiki.diyfaq.org.uk/index.php?...ckground-2.jpg

A few beads of weld around the outside of the spanner to stiffen in,
then welding on a length of pipe and a *much* bigger tommy bar.


--
Cheers,

John.

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

On Mon, 28 Jan 2013 11:40:13 +0000, Andrew May
wrote:

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.

Is this likely.

Very, sometimes if you bang the side of the tank with your fist you
will hear lumps of mineral deposit breaking off the sides and
settling.

The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

It isn't unusual for such heaters to be irremovable. They become
embedded in a virtually solid lump of scale filling a quarter of the
tank and either won't shift or break apart leaving the heating element
in the scale. Sometimes you can remove the tank plus heater and try
to remove the scale sufficiently to allow you to remove the heater but
often a new tank and heater are required.

On 28/01/2013 12:16, Peter Parry wrote:
On Mon, 28 Jan 2013 11:40:13 +0000, Andrew May
wrote:

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.

Is this likely.

Very, sometimes if you bang the side of the tank with your fist you
will hear lumps of mineral deposit breaking off the sides and
settling.

The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

It isn't unusual for such heaters to be irremovable. They become
embedded in a virtually solid lump of scale filling a quarter of the
tank and either won't shift or break apart leaving the heating element
in the scale. Sometimes you can remove the tank plus heater and try
to remove the scale sufficiently to allow you to remove the heater but
often a new tank and heater are required.


+1

On Jan 28, 12:16*pm, Peter Parry wrote:
On Mon, 28 Jan 2013 11:40:13 +0000, Andrew May

wrote:
I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.

Is this likely.

Very, sometimes if you bang the side of the tank with your fist you
will hear lumps of mineral deposit breaking off the sides and
settling.

The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

It isn't unusual for such heaters to be irremovable. *They become
embedded in a virtually solid lump of scale filling a quarter of the
tank and either won't shift or break apart leaving the heating element
in the scale. *Sometimes you can remove the tank plus heater and try
to remove the scale sufficiently to allow you to remove the heater but
often a new tank and heater are required.

********. They cease to work by reason of overheating long before
things get that bad,

On Wed, 30 Jan 2013 01:33:31 -0800 (PST), harry
wrote:

It isn't unusual for such heaters to be irremovable. *They become
embedded in a virtually solid lump of scale filling a quarter of the
tank and either won't shift or break apart leaving the heating element
in the scale. *Sometimes you can remove the tank plus heater and try
to remove the scale sufficiently to allow you to remove the heater but
often a new tank and heater are required.

********. They cease to work by reason of overheating long before
things get that bad,

Well then, that cylinder I removed from a neighbour's house a couple
of years ago, that was filled halfway up with limescale, must have
been a figment of my imagination.
Thanks for putting me right, 'arry.

On Wed, 30 Jan 2013 01:33:31 -0800 (PST), harry
wrote:


********. They cease to work by reason of overheating long before
things get that bad,

Yes dear, keep taking the dried green frog pills and you will soon
feel better.

In message , Andrew May
writes
Copper unvented hot water tank with horizontal immersion heater at the
bottom on economy 7. Heater is OK as far as I can make out as is the
thermostat. When power is applied the water can be heard to begin
heating but after a minute or so the thermostat kicks in an it stops.
Restarts after a while then stops again. Over a seven hour period the
tank of water gets only lukewarm.

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a
hard water area. This means that it heats a small pocket of water
before the thermostat turns it off. It remains off until this pocket of
hot water has dissipated into the tank.

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

There was quite a long thread on just this removal issue some while
back. I guess a search on *immersion heater removal* for uk.d-i-y should
find it.
--
Tim Lamb

I think you are going to have to, as sooner rather than later if what you
suspect is the case, the element will just go pop. The last one I did was
not only lime scaled but twisted and distorted and the water got in due to
the tube being breached in several places.

As for getting it out, well you could try some of the many helpful
substances suggested on here in the past to free it, but in the end it
might be that the tank is also so scaled that the only answer is a new tank.
Depends how old it is and whether its good copper or some kind of alloy I
suppose.

Hate the things but what can be done. Maybe we should sue the water
companies?


Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"Andrew May" wrote in message
...
Copper unvented hot water tank with horizontal immersion heater at the
bottom on economy 7. Heater is OK as far as I can make out as is the
thermostat. When power is applied the water can be heard to begin heating
but after a minute or so the thermostat kicks in an it stops. Restarts
after a while then stops again. Over a seven hour period the tank of water
gets only lukewarm.

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water has
dissipated into the tank.

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

Andrew

On Monday, January 28, 2013 11:40:13 AM UTC, Andrew May wrote:

Copper unvented hot water tank with horizontal immersion heater at the
bottom on economy 7. Heater is OK as far as I can make out as is the
thermostat. When power is applied the water can be heard to begin
heating but after a minute or so the thermostat kicks in an it stops.
Restarts after a while then stops again. Over a seven hour period the
tank of water gets only lukewarm.
I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.
Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.
Andrew


If this is due to massive scaling, the max temp its reaching will have fallen very slowly over years. Does that fit?

Another possibility is a high resistance connection thermally close to the thermostat, resulting in the stat opening prematurely.

Elements that have corroded through tend to cycle on and off, as there's often excess current heating the stat up, but they reach the correct final temperature ok.


And some odd ideas to chew over...

A couple of times I've wondered about applying an external wrap of resistance wire (on glassfibre tape) and driving it with LV to heat a cylinder. 2 microwave transformers with primaries in series and a pc fan would likely do it, if you limit each one to around 750w output. With an SS cylinder you could omit the wire.

Another possibility is converting to mains voltage electrode heating. The regs explain how to do this legally, its common practice in industry, and entirely safe if done correctly.


NT

On Jan 28, 11:40*am, Andrew May wrote:
Copper unvented hot water tank with horizontal immersion heater at the
bottom on economy 7. Heater is OK as far as I can make out as is the
thermostat. When power is applied the water can be heard to begin
heating but after a minute or so the thermostat kicks in an it stops.
Restarts after a while then stops again. Over a seven hour period the
tank of water gets only lukewarm.

I think that what is happening is that the immersion heater is OK but
being at the bottom of the tank it is covered in limescale. It is a hard
water area. This means that it heats a small pocket of water before the
thermostat turns it off. It remains off until this pocket of hot water
has dissipated into the tank.

Is this likely. The obvious thing would be to remove it and have a look
but it is resisting all attempts to do so and I don't want to risk
damaging the tank if it is not necessary.

Andrew

If your IH is modern,it will have an additional overheat device. If
it is scaled up, this could be operating.

Solution is to remove IH and clean it up. Also think about a water
softener.

Needs doing pronto, IH could be damaged by this.

To remove heater, saw out gasket with a hacksaw blade.
Comes out a lot easier.

On Monday, January 28, 2013 11:40:13 AM UTC, Andrew May wrote:
Copper unvented hot water tank with horizontal immersion heater at the

bottom on economy 7. Heater is OK as far as I can make out as is the

thermostat. When power is applied the water can be heard to begin

heating but after a minute or so the thermostat kicks in an it stops.

Restarts after a while then stops again. Over a seven hour period the

tank of water gets only lukewarm.



I think that what is happening is that the immersion heater is OK but

being at the bottom of the tank it is covered in limescale. It is a hard

water area. This means that it heats a small pocket of water before the

thermostat turns it off. It remains off until this pocket of hot water

has dissipated into the tank.



Is this likely.

No. Any water it heats will immediately flow to the top of the tank, limescale or no limescale, so there is no chance for a pocket to form.

It's much more likely your element has burst (they don't last many years) and it's trying to heat the water like an electrode by passing current from the element to the earthed tank.

The The obvious thing would be to remove it and have a look

but it is resisting all attempts to do so and I don't want to risk

damaging the tank if it is not necessary.

Have you got a multimeter? If so, this is super-easy to check from outside the tank.

Isolate the electricity supply to the heater and remove the cover. Put your multimeter on the most sensitive resistance mode and measure the resistance between the two contacts connected to the element. This should be about 19 Ohms (assuming a 3kW element). If it isn't it will most likely read infinity (or 1) on your meter which means the element is bust.

To confirm this further, put your multimeter on the highest (least sensitive) resistance mode and measure the resistance between the live side of the element and the earth rod. If this is anything but infinity (or 1) your element is bust and there is an electrical connection from the inside (which is supposed to be insulated) and Earth via the water.

HTH

Alex


Andrew

On 29/01/2013 21:56, alamaison wrote:

Have you got a multimeter? If so, this is super-easy to check from outside the tank.

Isolate the electricity supply to the heater and remove the cover. Put your multimeter on the most sensitive resistance mode and measure the resistance between the two contacts connected to the element. This should be about 19 Ohms (assuming a 3kW element). If it isn't it will most likely read infinity (or 1) on your meter which means the element is bust.

To confirm this further, put your multimeter on the highest (least sensitive) resistance mode and measure the resistance between the live side of the element and the earth rod. If this is anything but infinity (or 1) your element is bust and there is an electrical connection from the inside (which is supposed to be insulated) and Earth via the water.


On of the first things I tested. Reads 19ohms, exactly the same as the
working element. Hence my conclusion that the element was OK (FSVO OK)
and the problem was localised heating where the hot water cannot easily
rise to the top because it is surrounded by limescale.

Andrew May wrote:
On 29/01/2013 21:56, alamaison wrote:

Have you got a multimeter? If so, this is super-easy to check from
outside the tank.

Isolate the electricity supply to the heater and remove the cover.
Put your multimeter on the most sensitive resistance mode and measure
the resistance between the two contacts connected to the element.
This should be about 19 Ohms (assuming a 3kW element). If it isn't it
will most likely read infinity (or 1) on your meter which means the
element is bust.

To confirm this further, put your multimeter on the highest (least
sensitive) resistance mode and measure the resistance between the live
side of the element and the earth rod. If this is anything but
infinity (or 1) your element is bust and there is an electrical
connection from the inside (which is supposed to be insulated) and
Earth via the water.


On of the first things I tested. Reads 19ohms, exactly the same as the
working element. Hence my conclusion that the element was OK (FSVO OK)
and the problem was localised heating where the hot water cannot easily
rise to the top because it is surrounded by limescale.

If you've got that problem, then it may be the safety cutout operating
before the thermostat has time to respond.

--
Tciao for Now!

John.