Immersion heater

[Djthomas2707]

So I need serious help - please help me

I have no hot water. These are the steps I've taken.
- check main fuse box ALL GOOD
- check / replace fuses connected to immersion heater ALL GOOD
- check all wire connections under cap on heater ALL GOOD
- the element was replaced in September
- replace the thermostat, check wiring ALL GOOD

The tank is filling with water but it is not hearing my water.

Any advice, ideas?


Thanks in advance

//www.diynot.com/network/Djthomas2707/albums/
Pictures uploaded

 

[Iggifer]

do you have a multimeter? you will need one to test any further

 

[JohnD]

is the hot-water cylinder heated solely by the immersion heater, or is it sometimes heated by a boiler?

Was the hot tap-water curiously hot before it stopped working?

A photo of the heating connections under the cap, after you have isolated electrical power, might be useful.

 

[ericmark]

To find a fault there are two basic methods.
1) Set by set test and this will need some tester.
2) Stab at likely faults. You have already done that.

The only thing it would seem you have not checked is the immersion heater its self.

So to recap I will run through what can trip or blow.
1) MCB/RCBO/Fuse in Consumer Unit.
2) Fuse in FCU or plug.
3) Thermostat.
4) Thermal fuse or cut out.

Immersion heaters which are the only form of water heating have thermal fuses and the header tank can be thermal plastic. Where there are multi-forms of heating a cut out is used as the other devices could cause the over heating so a cut out is used which can be reset and the heater tank is designed to stand boiling water.

 

[Aragorn84]

The small silver can mounted on the base plate is likely a thermal fuse/safety cutout.

If you follow the live wire, you see it comes into the main thermostat, leaves the thermostat and goes to the cutout, then continues on to the element terminal.

The idea is if the main thermostat fails on, then to stop the tank boiling and creating a serious hazard the safety cutout "pops" and shuts the whole thing down.

It may be resettable, or it might require replacement.

You can use a multimeter to test for continuity thru the main thermostat and then the cutout, with the power safely isolated. Or you can just have a look and see if theres a reset button on it and press it.

 

[Djthomas2707]

You are all so wonderfully helpful- thank you.

I have tested all fuses connected to the unit.

People keep mentioning an over heat/re-set button I can't find this anywhere.

I've uploaded photos - hopefully this will help.

I've still no hot water

 

[Iggifer]

Untitled

• Djthomas2707
• 21 Apr 2015
• 1

see the button marked 'Reset'? Push that

 

[Djthomas2707]

It's a new termastate the button is a little piece of hard plastic I've tried pushing it, it doesn't move.... But I'm now going home to push it harder

 

[Iggifer]

if it doesn't push chances are it hasn't popped.

 

[Taylortwocities]

On that immersion head, the overheat reset button is the silver device that has two brown wires going to it. It is situated at about 10 o'clock in that picture.
Cannot see the button as the brown wire is covering it.

TURN THE POWER OFF before poking your fingers in there!

If not then I see that you have timer on that immersion. It is possible that the timer is knackered, or there is a bad connection in there, or in the FCU.

As stated, again some days ago,

do you have a multimeter? you will need one to test any further

 

[ericmark]

There are many versions of the immersion heater.

This modern one has not re-settable parts.

This report in 2008 when the tank ruptured

pouring boiling water onto a baby has resulted in the reset button becoming rare.

With my fathers house with a solid fuel cooker the water often boiled. But with a metal tank this was not a problem. However after it had boiled before we could use the immersion heater we would have to go and press the reset button.

But after the babies death there was a move to have non resettable cut outs so if the thermostat is faulty and causes an over heat then it has to be replaced. This is good with a tank where only heater is the immersion but rather useless where there is also another form of heating.

There are special plastic heater tanks designed for use with solid fuel heating that will stand boiling water so simply saying plastic tanks need non resettable cut outs is no good. What we can say is steel tanks do not need non resettable cut outs. But unless one asks special for a resettable type you will normally be given and non resettable cut outs.

With the age I would say likely it is the safety cut out but it needs testing.

So take a picture and also say what you have as far as test gear goes. Even a door bell can be used with the wires that normally go to push button being used as test probes will still call it belling out a circuit even though in most cases we use a buzzer or meter. But clearly power needs to be off when using something like that.

 

[Iggifer]

eric - the photo I posted is the OP's, he just didn't add them to his post, so he does have a reset

 

[Djthomas2707]

Thank you for all your wonderful assistance!!


I have now fixed it and have hot water

Thanks again, so much xx
Deborah

 

[Taylortwocities]

Brilliant!

Please, please tell us what the problem was. We may learn something!!

 

[JohnW2]

Brilliant! Please, please tell us what the problem was. We may learn something!!

It would, indeed, be good to know!

I would suspect that she eventually managed to press the reset button, after it's identity/location had been explained to her. From what I understand of the OP, she had already replaced the thermostat - so I suspect that it was the death/malfunction of the old thermostat that had caused the thermal cutout to operate. If so, it proves that these thermal cutouts have their uses!

Kind Regards, John