Economy 7 Immersion Heater Not Working

[Phill1983]

Hi,

We have an immersion heater that is supposed to run on economy 7 electricity and heat up our water through the night. This stopped working around a year ago for no apparent reason and we're trying to figure out what the problem would be.

Basically, theres 2 switches in the cupboard that the tank is hooked upto. One of them powers the top part of the immersion heater and gives us a boost whenever we need it which is what we've been surviving on. Then the bottom half of the immersion which I presume is the section which controls the overnight heating is also connected to a switch on the wall but this doesn't have a on/off switch so I'm not sure what exactly controls when/how this switches on or off. From reading around I understand that there should be a timer somewhere but we've searched high and low and can't find anything like that.

We've tried changing the fuse but that had no affect, and we haven't changed our electrical supplier so if this is somehow controlled remotely by them then there should be no reason for any change.

We're just not sure what to try next, I presume it could be that the heating element is simply broke or something like that but as we don't understand exactly how it works in the first place we would like some advice on what it could be? What controls when this switches on overnight? Is there a timer/switch somewhere that we could be missing?

We'd really appreciate your feedback an I have a few pics of the current setup an can provide anymore if necessary.

Thanks

 

[Andy™]

there will be a switch somewhere to control it. but the problem could simply be a thermal cutout needing reset

 

[Phill1983]

Hi Andy,

It is plugged into a switch on the wall but the actual on/off switch is fused still, presume this is a common thing for something's that meant to be on all the time?

Can you explain what you mean by thermal cut out? Is this something I can check?

I have pictures of that switch and the whole setup but not sure how I get photos on here.

Thanks

 

[Andy™]

take the cover off the bottom element. usually a small nut holding it on. look for something that says reset. usually a little red button. press it. if it clicks, its tripped and is now reset.

it should be dead during the day, but assume its live and dont touch any wiring

its also unusual for an element to be plugged in, however if it is, then you could plug it into an extension lead, see if the fault is with the element or the controls

 

[Phill1983]

Ive taken that cover off an saw the little red reset button but I couldn't push it in anymore so presume that means it wasn't tripped.

When I say it's plugged in I don't mean with a 3 point plug etc, there is literally just a wire running straight from that bottom element into this fake socket that doesn't have a switch, so no way of detaching it or seemingly controlling power to it.

 

[Doc Hudson]

Welcome to the forum how old is it ? It may be the element gone, they can easily be tested with a suitable test meter. If it is faulty it can be a bit fiddly to replace as the cylinder will need draining down and sometimes the thread can be seized up. The elements themselves don't cost that much but the labour costs do rather ramp the bill up a bit as its not a quick 5 minute swap!

http://www.screwfix.com/search?search=IMMERSION+HEATER+ELEMENT

Doc H.

 

[Essex1]

Do you have two distribution boards?

 

[Phill1983]

Thanks for the welcome Doc, the house was built about 20 years ago so I imagine it was in from day one, so presume a faulty part after 20 years could be realistic? Are the test meters easy enough to get hold of and use?

Essex1 - sorry I'm a compete electrical novice, what's a distribution board?

Just looked up what the distribution boards are, and yes we have 2 of them

Just looked what the distribution boards are, and yes we have 2 of them

 

[Essex1]

One will be your 24 hour supply.  The other your economy 7 supply.  Have you checked all the fuses in the E7 side?

 

[Phill1983]

Every fuse in both boards are up in the on positions, does that rule that out or could the fuse still be broken even in the on position?

 

[Essex1]

Unlikely.  This is looking like the element is knackered.  Normally this would have taken the fuse out however.  Do you have storage heaters?  Are these still working during your off peak times?

 

[Phill1983]

I'll try the storage heaters again tonight, they've been off for the last 6 months or so whilst it's been warm but we used them before that and they worked ok at the same time as the hot water was broke. I'll try that tonight anyway and see if that's still the case.

 

[Essex1]

It sounds as if the element is cream crackered.

If it is please get someone in.  They are awful things to do and can easily go wrong.

Good luck!

 

[Rob_the_rich]

Ive taken that cover off an saw the little red reset button but I couldn't push it in anymore so presume that means it wasn't tripped.

...

Some reset buttons look to be flush to the surface, but they actually reset below the surface. get a small screwdriver and see if it pushes in any further than flush.

As Andy said "it should be dead during the day, but assume its live and dont touch any wiring", also switch off the main switch to the economy 7 distribution board. In fact, switch both boards off, just in case.

 

[Rob_the_rich]

If that doesn't work, beg or borrow a multimeter that reads resistance in ohms ( hms  ) and, with all power off as above, test between the live and neutral terminals of the element (usually two posts with red (or brown) and black (or blue) wires attached)

for a 2KW immersion you should get around 29 hms  if it is ok

for a 2.5KW immersion you should get around 23 hms

for a 3KW immersion you should get around 19 hms

If you feel unsure or unable to do this, please get someone in to do it for you.

Remember that unless you can prove a circuit is dead, assume it is live and don't touch.

 

[Nicky Tesla]

When was your meter last changed?  Sometimes they dont set up the new meter for E7.  Can you see a box with "radio teleswitch" in the meter cupboard.  Do you hear a small bang from your distribution board around 12 at night.  Is there a switch prob in the hall with 3 positions ie ON, OFF , E7 (or heating)

 

[Phill1983]

I tried my storage heaters last night and they came on correctly so I assume the Eco 7 electric supply is all good. Suppose that would mean my meter is ok too, but that hasn't been touched or changed since I've lived in the house.

Regards the reset button on the thermostat it is in a popped out state but it won't budge to be pushed back in, perhaps that's a sign it needs replacing?

I will see if I can borrow a multimeter too to test that out.

Thanks for your suggestions so far!

 

[Phill1983]

We've had an electrician in to test the element and the thermostat an he's confirmed that they look to be ok, and I've confirmed with my electricity company that they've done nothing their side that might affect it which fits as the storage heaters do work overnight.

We've been told the next step is to buy a voltage stick which I believe will tell us if there's a current coming through at night when the E7 power is on, so I've ordered one to be delivered.

Would you agree that this is the next logical step? Is there any other possibilities that we may have narrowed it down too?

 

[NozSpark]

You should have had him test any wiring between the CU and the immersion heater as well...

Your voltstick might show a voltage, however if the N is open circuit anywhere the heater won't heat up

 

[ProDave]

Your electrician should have been able to confirm by dead testing that your immersion heater is connected properly to your off peak consumer unit.

If it is correctly connected to the off peak CU and the heater itself is good, then if the storage heaters work overnight, so will the immersion heater.

Sounds like you need a better more competent electrician.