Immersion heater died?

[Min]

I have gas fired central heating with a boiler. But when the weather gets hot like this I turn it off altogether and just use the immersion heater.

But the water isn't heating up. The light on the 'socket' (looks like a socket but has think cable coming out of it) has come on.

Probably last used the immersion heater two years ago. Would it just die like that? Or is there a thermostat that might have got knocked? Can't see the top of the 'element' without removing shelves in airing cupboard.

Thanks
Mary

 

[Burnerman]

It looks like its either going to be the element itself Mary (awkward change) or the thermostat that is contained within the element cap (simple change)
Do you have a multimeter at all to do some testing?
John

 

[Bosswhite]

Have a look at the top of the Immersion heater unit there may be a reset button, check the Fused Spur Unit (Switch) there might be a red light indicator, check Fuse in fused spur box . Check circuit breaker in Consumer Unit (Fuse Box)

 

[Hugh Jaleak]

It is probably cheaper to use the gas boiler for hot water purposes during the summer months though. Keep immersion as a back up if boiler breaks down. Immersions can and do fail without warning, if you're unsure then I advise getting a qualified electrician or plumber to look.

 

[Min]

Thank you for your replies.

Multimeter - no I don't have one (do have a small electric testing screwdriver which lights up if you touch something live)

Reset button - couldn't find anything that felt like a button. There is what feels like a screw head on top of the cap. Manager to turn it a few times to tighten it up. It's near the edge of the cap. Might I need to take cap off to find reset button, and is that safe to do?

Fused spur unit - red light is on, so I guess fuse not blown?

Circuit breakers in Consumer Unit - none tripped, all are on

Cost - it's not about the cost of gas, it's about not having hot water circulating through the house from boiler to HW tank. Using immersion heater keeps the house cooler . . and sure does when the immersion doesn't work

Thank you

Mary

 

[Burnerman]

The screw that you have discovered holds the cap onto the immersion heater.
If you remove it (power off, of course) you'll find the thermostat and the element connections.
Only the live (red or brown wire) will be connected to the thermostat first, and then to the element. The neutral (black or blue) will go to one connection to the heater element.
The thermostat will be marked in degrees, and 60 deg is the usual setting. If it's working, and the temperature of the thermostat and therefore the water cylinder is less than 60, the thermostat should be switched on. Once 60 degrees is reached, the stat switches off, keeping the water at that temperature.
All of the testing can be done with your electrical testing screwdriver if you are happy with that, but please forgive me if I sound patronising - not intended! There's a lot of electrical current in there, and the danger is significant.
John

 

[Min]

Thanks John, not patronising but good details.
Can I check:
1. When water in tank is cold, flip circuit breaker in CU for thermostat
2. Remove cover from thermostat, check temp is set to 60 deg.
3. If there's a reset button, unflip circuit breaker. Press reset button (am presuming it's not mechanical so lecky has to be on when I reset). Check to see if it sounds like water now heating up.
4. If no reset button, or if no response to pressing it, identify Live and Neutral
5. Check electric supply to Live.
6. Check electric supply to Neutral - if temp of water below 60 deg, then both should show current. (If temp of water > 60 deg, then there won't be current to Neutral cos stat is off)
7. If no current to Neutral when tank temp is less than stat setting, then replace thermostat only?
8. If there is current to Neutral, element is blown so replace whole unit?

Many years ago I did a lot of stuff with electrics so am confident about use of test screw driver and not touching anything, but just wanted to be sure I understand the steps.

 

[Burnerman]

Yep, that's about it......obviously when you switch off at the consumer unit the lamp on the switch should go out - a double check, if you like.
Deal with the live wires only, forget about the neutral for now.
With the immersion guts exposed and power back on, the screwdriver should glow at the incoming live to the stat, and the outgoing terminal too when the stat is turned right up.
Be aware though that thermostats have hysteresis - that means that even if its set to 60 it wont switch off at 61 or on at 59 degrees, there's always this tolerance. With the stat on max though, it should show continuity across it.
Do be careful - I'm just waiting for a caning here but there's sure to be some google advice anyway.
John

 

[Min]

Thanks John, yes I am too waiting for a caning. But let's address that.
I have rewired a cottage in Wales, replaced an immersion heater, been a site's 'emergency sparks' in that every time the power tripped they got me to sort it (this was in parallel to going round nagging every one about not over stretching extensions, not mixing water and lecky appliances while I continually rewired appliance after appliance). In my current house I have added extra sockets, added extra lights, put in dimmer switches . . even put in two way switching. None of this was less than ten years ago, so I know I can be safe, but my knowledge isn't current for regs and other recent changes.

Anyways, thanks for the advise. If I don't post again, please tell the critics they were right. That's done it, now they'll think I'm flippant about safety. I am a not.

Probably going to rip shelves out of airing cupboard and get busy with the diagnosis tomorrow. Will let you know.

 

[durhamplumber]

I cannot believe in a million years you fancy yourself as some sort of ex emergency sparky and yet don't know the difference between a test screwdriver and your bell end.

 

[Min]

Well I do know the difference, so your disbelief is entirely appropriate.

Better criticism would have been that I couldn't remember the name for the Fused Spur Unit. But then maybe you don't know what it's like to have a poor memory.

 

[ninjacat]

please ignore the advice about the neon screwdriver, they can give false results. For about £10 you can get a two pole multimeter which will give far more reliable results and can be used on a dead circuit for continuity testing as well as measuring voltage on a live circuit. Go to the electrical section for more advice (and warnings ) about testing circuits.

 

[Min]

Magic, thank you very much Ninjacat. Will do.

 

[Agile]

So has the problem been sorted out?