..and the next thing to go wrong in the house is.......

the immersion heater

Ok, full story, so any clever heating engineers can have a think will
the full picture.

About a month or so ago, we got a monster electricity bill for the year
(12 months at £30 a month, then an additional final settlment bill for
another £312). Electricity company never sent us any bills all year,
so didnt' realise how much we were using....anyway, that's another
story.

Investigate the big electricity guzzling devices, starting with the
water tank immersion heater.

Turns out the timer is burnt out...completely, so the immersion heater
has been on for a whole year 24/7 although there is a thermostat in
there...but don't know if that was working properly or not (it was set
to about 75 degrees Celcius). Insulation on all the wires going into
and out of the timer had burnt off/melted and there were black burn
marks on the wall too where it had been.

Bought and fitted a new timer device, which works fine now.

However, since replacing the timer there doesn't appear to be as much
hot water as there was before - as you can barely have enough for 2
people to have showers before the water starts coming through the
shower cooler and cooler.

The immersion heater is currently set to come on at about 4:00am and go
off at 8:30am - so that's a good 2.5 hrs before I use the shower at
6:30am.

I've replaced the thermostat (because the temp adjusting knob snapped
off the old one), and the new one has a thermal safety cut out thing,
so if the water gets too hot it will shut off (but you can reset it).

I tried having the thermostat turned up to about 70 degrees (as it was
before I changed the timer) but the thermostat kept tripping, so I've
gradually been turning it down and down (think it's not at about 60 deg
and it hasn't tripped yet).

There's still hot water out the top of the tank going to hot water
taps, etc - and this water is still plenty hot enough to cause an
'ouch' if you have your hand under it too long!

I think the immersion heater is a 27" one, as it has an 18" thermostat.

Here's pretty much how the hot water tank is (kind of to scale to in
terms of heater and tank outlets):

http://www.randcjones.plus.com/Temp/heating.jpg

You can feel the shower feed pipe is hot, but then it obviously gets
colder as the water is used.

I'm in the shower for literally 5 mins (10 max), and my wife then uses
it after me for about 10 mins (15 max).

So not exactly running the shower forever.

I've got a new immersion heater (27" again, as the guy said that was
the largest that would fit in a tank or that size) and I'm hoping that
the problem is because the end of the immersion heater is either
damaged or the whole thing is calcified.

Just seems really weird how we never had shower hot water shortage
problems when the thing was apparently buggered - yet now with new
thermostat and timer it seems to be crap?

The only thing I can think of is that the heater was literally boiling
the water so that when cold water comes into the tank, it gets heated
by the already raosting water not only the heater. If this is the
case, I need to find a thermostat that will allow the heater to really
heat things again, so that the shower then uses less hot water to mix
with the cold (it's a thermostatic mixer valve on the pumped shower, by
the way).

Any advice or opinions would be most welcome!

Russ wrote:
.and the next thing to go wrong in the house is.......

the immersion heater

Ok, full story, so any clever heating engineers can have a think will
the full picture.

*SNIP*

Here's pretty much how the hot water tank is (kind of to scale to in
terms of heater and tank outlets):

http://www.randcjones.plus.com/Temp/heating.jpg

*SNIP*

Any advice or opinions would be most welcome!

Two comments:

1) Re-routing the shower output to run from a Surrey Flange (at the top
of the tank) would make a huge difference.

2) If the only option you have for heating water is electricity (and
especially if most of your hot water is used for showers) it would seem
to be far more economical to have an electric shower and run the
immersion for only an hour or two a day, set to a much lower
temperature.

The Surrey flange has been mentioned to me by another guy elswehere,
but I'm not sure how to fit it, as I don't rally have much /any
plumbing experience apart from fitting new taps, etc!

Russ presented the following explanation :
Just seems really weird how we never had shower hot water shortage
problems when the thing was apparently buggered - yet now with new
thermostat and timer it seems to be crap?

Water temperature in a tank will be stratified. Only the water above
the bottom of the water heater will normally be warmed and as it is
used up it will be replaced by cold at the bottom, so the hot/cold
interface level will move up. If your diagram is to scale, the shower
take off is not much higher than the lower tip of the element, so not
much hot water available to be drawn before it runs cold.



--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Russ wrote on 04/01/2006 :
Upon having a closer look at things now I've got home, the 27"
immersion heater goes a LOT further into the tank than my guessed
sketch above. THe shower outlet is only about 1/3 of the way down the
immersion heater, so should be plenty of hot water.

The hottest water will still be at the very top of the tank.


Just tried to remove the old heater, as I got a new one at lunch. It's
not budging at all.......not an iota. I've bent the immersion heater
ring spanner and even some stilsons as long as my arm couldn't persuade
it to move.

Calcification can quickly lead to the element over heating and burning
out. You might try tightening it a little before trying to undo it and
as you have nothing to loose - try draining it down and applying some
heat from a blow lamp of heat gun. If its an old tank with a retro
fitted immersion boss, it will have been drilled out and a boss plumbed
into place. Heat would certainly get that out complete with the boss.


Plumbing a boss in takes a little practise, but is quite satisfying :-)


--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

I think it's new tank time, as the tank looks like it's been there
forever - as does it's immersion heater!

Can anyone recommend a plumber in the Weybridge/Surrey area? I don't
fancy getting ripped off by a randomly selected guy from Yellow Pages.

I think the tank I need is approx £200, the immersion heaters are only
£15, so it should be a fairly straight forward swap, with just some
minor modifications to the pipework for the inlets and outlets to meet
the new points on the tank?

Roughly how much should I be looking at for getting this done (so I
know if quotes I get are in the right ballpark!)?

Cheers

Russ wrote:

Upon having a closer look at things now I've got home, the 27"
immersion heater goes a LOT further into the tank than my guessed
sketch above. THe shower outlet is only about 1/3 of the way down the
immersion heater, so should be plenty of hot water.

Just tried to remove the old heater, as I got a new one at lunch. It's
not budging at all.......not an iota. I've bent the immersion heater
ring spanner and even some stilsons as long as my arm couldn't persuade
it to move.

Actually looks like someone tried removing it in the past, as there are
scratch marks where an immersion spanner could have slipped off the
heater nut. I reckon someone else had a go and gave up.

Bottom line is I think we need a new tank. The heater's probably
f*cked and won't come out because it's calcified in place. WHich might
explain why the previous owner left the heater on 24/7 because it's
caked in limescale and takes forever to heat all the water in the tank
properly.

Anyone reommend a good plumber in my area?


You've got this all wrong, and are now in the ass over barrel position,
ready to give your money away for no reason.

Your immersion heater works perfectly, that much we know. The tank is
watertight and does everything it needs to do. The plumbing setup is
also fine, since it all worked fine until recently.

The problem is with the thermostat. Old stats could be set anywhere
upto around 95C, and you'd set it to give as long a showering time as
you need. New stats are required to have cutoffs at relatively low
temp, i forget exactly but something like 65C, which is fine for a lot
of systems, but totally inadequate for some. The solution is to use a
separate strap on thermostat with your existing element, a stat that
you can set to whatevers needed. Screwfix do one, cost about £8.


NT

well...I wish it was that clear cut.

The problem could be as you say....

or it could be that because the timer was knackered, the heater was
just always on (boiling the water to buggery), thus never had a
problem.

or it could be in addition to this that the immersion heater is utterly
calcified, perhaps in particular in the bit that contacts the cold
water first....and hence needed to be on forever to keep the water
hot.....

I just don't know.

The fact I can't replace the apparently original immersion heater means
I can't check it, and also means if it does die in the future, I'm
still going to be in the same situation as I am now.

The tank isn't in great condition, and as for being water
tight.....well.....think it probably was at some stage, then
wasn't....got repaired and now that repair is getting a bit iffy - as
feeling round the immersion heater nut last night when trying to undo
it, I noticed my fingertips were getting wet.

our electricity bill for the year last year (only 2 of us in the house)
was £800, so £160 for a tank with new thermostat and new heater that
I am now going to fit myself doesn't seem like a bad place to start.

The strap on thermostat is a good idea though, and if there's no
improvement with the new tank, etc, then I'll definitely give that a
go.

Cheers

something like this?

http://www.tlc-direct.co.uk/Main_Ind...ating_Other_1/

In an earlier contribution to this discussion,
Russ wrote:

our electricity bill for the year last year (only 2 of us in the
house) was £800, so £160 for a tank with new thermostat and new
heater that
I am now going to fit myself doesn't seem like a bad place to start.

The strap on thermostat is a good idea though, and if there's no
improvement with the new tank, etc, then I'll definitely give that a
go.

Cheers

Be very careful if you go the strap-on stat route. Many stats of this type
are only designed to switch cental heating valves or pumps - and can only
handle about 3amps - making them totally useless for switching an immersion
heater. The Horstmann HCT2 stat sold by Screwfix for 8 quid appears to be
able to handle 16 amps, so may be ok.

Even so, it probably doesn't meet current regs with regard to having to have
a manually re-settable safety stat in addition to the one providing normal
temperature control.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
Russ wrote:

something like this?

http://www.tlc-direct.co.uk/Main_Ind...ating_Other_1/

Probably not! TLC are not very good at providing specs for their kit -
either on their website or in their printed catalogue - but that one looks
to me as if it is only designed to switch low currents.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Russ wrote on 05/01/2006 :
something like this?

http://www.tlc-direct.co.uk/Main_Ind...ating_Other_1/

Er, no....

That stat is only intended for the sort of current you can expect to
control a heating system, 200w or so. Your immersion heater will be
rated at around 3,000watts.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Lol!

THis is quite amusing.....

after all my worrying about direct or indirect tank, I've bought an
indirect one - thinking our one at home here is Direct.....and it's
not!

I've just checked it all roudn again now I'm at home, and sure enough,
hidden away (very difficult to see, as the tank sits righ back in a
cupboard it practically fills) are the 2 connections for the indirect
heating!

Looks like the new tank I've got here has connections in EXACTLY the
same points, which should hopefully make swapping the tanks over a bit
easier!

Thanks for you help on here chaps, I like this forum!

In article . com,
Russ wrote:
our electricity bill for the year last year (only 2 of us in the house)
was £800, so £160 for a tank with new thermostat and new heater that
I am now going to fit myself doesn't seem like a bad place to start.

Sounds like your space heating is electric too?

--
*On the seventh day He brewed beer *

Dave Plowman London SW
To e-mail, change noise into sound.

Nope...have hot air heating.


Well, having never done anything plumbing other than replace the
kitchen taps..I replaced the tank myself at the weekend......even had
to solder a few joints! )

Contrary to information given by the plumbing shop guy, I managed to
get a 36" immersion heater in the tank without it touching the sides of
the internal 'indirect' pipe coil inside.

Managed to have 2 showers this morning (and the missus said she was in
there for ages too) and there was still enough hot water.

Not wanting to be outdone by the old immersion heater, I did get it out
eventually. Once the new tank was in place, I had the old one out on
the patio, on it's side wedged in place with bricks to stop it
rolling...with me sitting on it and literally putting all my body
weight and force onto the very end of a 3 ft long stilson wrench! After
several heaft jolts on the wrench it came out - but there would be no
way in the world I woudl have got it out in situ in the cupboard.

Seems to be lots of lumps of limescale rattling round the old tank
too....cant' have been doing it any favours.

The old immersion measured 32" (??) and was not really as furred up as
I'd expected. However, it was completely black apart from the last 2"
nearest the tip, and the further up towards the nut you go, the blacker
and crustier the immersion was.

On 9 Jan 2006 04:13:06 -0800 someone who may be "Russ"
wrote this:-

Well, having never done anything plumbing other than replace the
kitchen taps..I replaced the tank myself at the weekend [snip]

Contrary to information given by the plumbing shop guy, I managed to
get a 36" immersion heater in the tank without it touching the sides of
the internal 'indirect' pipe coil inside.

That's not surprising. The plumbing shop guy may believe it or not,
but those responsible for the designs are usually not that stupid.

Managed to have 2 showers this morning (and the missus said she was in
there for ages too) and there was still enough hot water.

Long immersion heaters are intended for use with off-peak supplies
[1], when they will generally provide a day's worth of hot water for
a small household, with no top-up. Short immersion heaters heat less
water and so are more suitable for top-up or as a supplementary
heater. However, these should be enough for a bath or a few showers.


[1] in a "conventional" cylinder. Cylinders designed specifically
for electric heating tend to have two short heaters, at different
heights.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54