Immersion heater problem

[cavalier6]

Hi,
I have a problem at work with our immersion heater, it has been far too hot for years apparently. I thought, easy just change the stat, I have tried two new ones now but the water is still at scalding temp, adjusting the temp makes no difference. Could a faulty element cause this problem? I am at a loss on this one! Any help would be much appreciated.

 

[prs1]

Is the cylinder direct of indirect is there a boiler aswell

 

[stevetheplumber]

is it wired right

 

[cavalier6]

Not being a plumber, I would guess at "direct". It is a stand alone tank situated in our cafe to supply hot water to the sinks etc.

Hi,
From memory, the live feed goes to the stat, neutral goes to the pole at the back of it and earth to the cover screw. It would seem that this problem has been there since the system was installed SIX YEARS ago, and nobody did anything about it, go figure!

 

[NellyC]

Hi,
I have a problem at work with our immersion heater, it has been far too hot for years apparently. I thought, easy just change the stat, I have tried two new ones now but the water is still at scalding temp, adjusting the temp makes no difference. Could a faulty element cause this problem? I am at a loss on this one! Any help would be much appreciated.

I doubt its the element as this would have the adverse effect. Is it unvented? can you give a more detailed spec on the system? i.e as far as plumbing goes you just have 1 tank, no boiler?

 

[cavalier6]

Hi,
How/where would I look to confirm vented/unvented? There is no boiler involved, it is floor standing so there is no "head", I assume there is a header tank in roof, will look tomorrow. I cannot understand why the thermostat with what I would class as a really basic setup, does not regulate the temp. If the live feed goes through the stat, basically a switch, why does the water get so hot. Including the original, I have fitted three stats now with no change.
Thanks
Kevin.

 

[NellyC]

Hi,
How/where would I look to confirm vented/unvented? There is no boiler involved, it is floor standing so there is no "head", I assume there is a header tank in roof, will look tomorrow. I cannot understand why the thermostat with what I would class as a really basic setup, does not regulate the temp. If the live feed goes through the stat, basically a switch, why does the water get so hot. Including the original, I have fitted three stats now with no change.
Thanks
Kevin.

It sounds like unvented, all stats come preset at i think 60C. how many immersion heaters are there on the tank? is there anything else happening that is unusual around the tank? There must be something else heating the water besides the immersion heater.

How/where would I look to confirm vented/unvented?


Look on the Tank it should be labelled.

 

[turnpin]

any chance of some pictures one of cylinder and one of wiring in immersion heater/stat regards turnpin

 

[prs1]

Instead of mucking around with stat on immersion why not buy a new immersion for £15.00 and fit that!
Only thing i can think of is that the stat is not the correct one if this is as u say a direct cylinder doent matter wether it vented or unvented.
Try checking continuity whilst turning stat with screwdriver to check its doing what it should,its only a tempeture operated switch.
is the stat the same lengh as the pocket in the immersion?
Something is not right somewhere and the element is obviously working!

 

[cavalier6]

Hi,
There is only one element I can see, I hope there is only one as the plumber has boxed it in leaving a removeable panel at the top to access the element. I am beginning to wonder whether I have just been unlucky and have duff stats! There is another tank in an office next door and I changed the element in that a few months ago, so I know that one works fine. I will take the stat from that and try it tomorrow, will let you know how I get on.
Thanks.

 

[prs1]

On the off chance it could be unvented-any work needs to be done by some one with an unvented ticket.
Also if its at work there is may be other employees/public this should be done by a trades man.
Duties under H & Safty at work act, A plumber would have this sorted in 30 mins.

 

[cavalier6]

Hi,
I can get pictures of wiring, but I am sure it is wired right. I cannot see enough of tank to get any useful snaps.
Thanks.

It may come to changing the immersion, but it works, it is just not switching off when it should. I have turned the stat down to about 40c, but water is still scalding. As I said previously, this is a basic hot water system feeding only two sinks, no bath etc. Whether it makes any difference, this setup is in a single storey building, so the tank is sitting on the floor at close to the same height as the taps. In fact one of the sinks is only 18" away from it.
Thanks.

 

[turnpin]

is the immersion on the dome [top] or on the side and is the cylinder covered with foam insulation an insulation jacket or if just metal is it copper colour or white enamelled steel

 

[cavalier6]

Immersion is at the top, foam insulation I think(didn't notice, but will check) and copper coloured.
As I said to other member, there is tank in another room with the exact same layout except that there is also a bath; and it works fine. I fitted a new immersion and stat to it a while ago, so I am capable.
Just veering off a bit, I have read other posts on here about using a drain off on bottom of tank to empty it to change immersion. This tank was also well boxed in with only a removeable top, so I just switched off cold supply and opened taps untill flow stopped. On removing immersion the tank was still full, which I did not expect, so I simply used a towel to lower water level a bit and used ptfe tape on thread to help seal new immersion, no problems. Did I do anything wrong using that method?

 

[prs1]

It doesnt matter where the cylinder is or the tap the relevant part is the tank that feeds it , this is were your head comes from, immersion come in differnt lengths if ur not putting the right stat in it it wont work,replace the lot then you are getting an element with the correct stat already fitted.
As you have said its simple set up You get water out ofthe taps!
the heating elemet works!
Can only be your replacment stats!

Just do the same with this cylinder!
if the cylinder is old and drain has not been operated for years u could be opening a whole new can of worms.
Just do as u already have done with other cylinder!
good luck

 

[cavalier6]

Many thanks for your help, will post how I get on. Am on hols. next week so will do it following week.

 

[turnpin]

suddenly the penny drops! I think prs1 has hit the nail on the head the stat is too short for the immersion proberbly 7inch in a 27inch immersion or something similar......simples regards turnpin

 

[cavalier6]

Afraid not, the 3 stats are all 18" long! Will change element in a week or so and will report back to you all.
Thanks for your help.

 

[cavalier6]

Hi,
Have finally had time to sort this problem, I fitted new element/stat today and all appears fine now although, to me, the water still feels a little too hot. I turned stat down to about 55c from 60c, but I could not really notice any difference. Anyway i will see how it goes, I would like to thank all for your help and advice.
As is with my luck, my immersion at home packed up yesterday, no time to look at that so have switched to oil fired hot water for the mo. Does anyone have any idea how much electricity an oil fired boiler uses, as my useage appeared to drop when I switched to my economy 7 immersion to save oil?
Thanks
Kevin.