Immersion timer - no power

[itslifejim]

The story so far!
- Old mechanical immersion heater timeswitch stopped clicking power as ratchet appeared to stop working
- Replaced with new digital timer .. water only got luke warm
- Put back just swithced power switch on and off to heat water until new mechanical timer purchased
- after three days this stopped working resulting in no hot water
- replaced with new mechanical timer .. checked have wired correctly about five times, including looking at immersion wiring and mains switch wiring.
- timer not even moving .. no sign of power going to immersion
Now out of ideas and expertise so would appreciate help
- MCB in mains unit has not tripped at any stage

 

[electronicsuk]

Can we have some pictures of the internal wiring of the unit? Is the supply permanent or on an economy 7 feed?

 

[itslifejim]

photos of the timer wiring or of the mains unit?
or both?

 

[itslifejim]

Photos of the items in the post

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//media.diynot.com/143000_142594_22690_43538062_thumb.jpg
//media.diynot.com/143000_142594_22689_21962743_thumb.jpg

Hope you can see them

 

[electronicsuk]

Looking at those pictures, it would seem that the immersion heater is not fed from a switch economy 7 supply or anything along those lines, so there should be power to the isolator switch 24/7.

All I can suggest at this stage is that, assuming you have the equipment to do so, you check for power at the incoming and outgoing side of the switch. Operate the switch a few times, preferably with the immersion heater connected so that there's some load on there, and come back with the results. You'll need a multimeter or proper 2-pole voltage tester to do this, NOT a neon screwdriver.

I suspect there is a high resistance joint somewhere, and given that the switch looks to be getting on a bit, it could be part of the problem. Equally, there could be a joint in the cable somewhere under the floor or a loose connection in the consumer unit, but that's just speculation with the information we have right now.

Obviously you should not carry out any of the aforementioned tests if you do not feel confident in doing so. You can check continuity of the switch with the circuit isolated, but if you really want to get any meaningful results then it would be better measuring voltages with the circuit energised and loaded, otherwise you may not be able to find a high resistance joint.

 

[bongos]

Those pics are really small!

Do you have E7? It looks like you have only one supply and for some reason it is connected via a lightswitch? I might be wrong though but not ideal with an immersion heater.

Is power definitely getting to the timeclock? Unfortunately we need a lot more info here!

Do you have a multimeter? No? Then get one! With a multimeter you can confirm where exactly the fault is. It it could be with the fixed wiring, light switch, timeclock or immersion!

 

[electronicsuk]

Those pics are really small!

If you visit OP's profile then the full size images are in their album.

 

[TicklyT]

Are the 'line' and 'load' connections the right way around?
If they are reversed, the clock will run fine when the timer is on, but it will cut the power to it's own clock motor when it switches off.

 

[electronicsuk]

Are the 'line' and 'load' connections the right way around?
If they are reversed, the clock will run fine when the timer is on, but it will cut the power to it's own clock motor when it switches off.

Well spotted - I don't think they are, AFAIK the input should be on the L/H side on those timers. OP?

Mind you, still doesn't explain why the heater wouldn't work when the timer was removed the the immersion wired directly to the isolator.

 

[itslifejim]

Thanks for the comments and suggestions .. sorry photos are a bit small but here is some extra info:
- connection is from a switched outlet, not light switch, in to the timer then out to the immersion
- there appears to be no current to the timer as it is not moving at all
- when I originally took the old timer off, I think the wiring was the other way round from the photos (i.e. the shorter length of lead from the switch went to the left hand side of the timer and the longer length of lead to the right hand side and on to the immersion heater). I didn't look too closely at the time as I was going to put a new one on, and the instructions for the new unit are to wire it as it is now.

As you can see though the wiring would be tidier if left anf right was reveresed.

If I change this back am I likely to cause any further problems?

Beyond that I think it's an electrician or multimeter next

 

[electronicsuk]

If I change this back am I likely to cause any further problems?

The problem is unlikely to get any worse, but even with the timer in/out wired backwards, you should still be able to turn on the immersion manually using the small switch on the top right of the timer, which is usually present on those mechanical types. If the timer mechanics also start to run then you'll know for sure that it's wired the wrong way around.

 

[itslifejim]

I wired the lead from the immersion to the switch direct and there is no sign of any power reaching the immersion when switched on.

Is there another fuse in the mains unit, or is the only thing which can happen that it trips out.

I think I've reached the time to call in an electrician!

 

[bongos]

If you want to try further then you will need a multimeter. You can pick one up from somewhere like Maplins for around £6.

Otherwise you will have to call a spark because trying to locate the fault without so much as a multimeter will prove dfficult and time consuming!

 

[itslifejim]

Thanks for the advice from all who helped.

I'll get a multimeter when I come back from holiday in a wseek's time