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Some Views On Fault Finding Procedures.


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For the professional/experienced guys out there I wonder if you would like to suggest what you would regard as the correct fault finding procedure that would/should be followed in the following scenario.

 

- You receive a call from a woman who simply tells you she has electric heating and her hot water heats during the night but for the last 2 days she has had no hot water.

 

- You visit the customers premises and find she has a combination tank with 2 immersions both of which are connected to a Horstmann Economy 7 quartz controller.

 

So what would you do from here?

 

(I am obviously asking this question because such an occurrence has happened and the whole experience went belly up from the first visit.)

 

Any contributions welcome.

 

Thanks

 

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Never worked on an Economy 7 system but I'd run a quick IR and continuity test on the elements and their thermostats then temporarily rewire to live test that both the heaters are working using the normal supply. Then check the E7 controls (i assume timer, contactor etc) are all operational.

What was the issue that cause the job to go tits-up?

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I assume the boost is working? (day-time immersion heater)

(fuses/mcb tripped? ;))

After isolating, first thing I would check is whether a reset button is present on both the immersion heaters' thermostats (on some I have seen there is a reset button between the element's terminals).

Check resistance of element(s)

Check connections

Dead tests of wiring to controller and from controller to heater(s)

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Simple dead test on the off peak immersion heater circuit.

 

Most simple is go to the fuse / mcb that feeds the immersion in the off peak CU and see if you can measure the resistance of the heating element between L out from the fuse / mcb (with it off or removed of course) and N.

 

Most likely is the element or thermostat, but it could be the fuse or mcb.

 

there might be some form of Horstman or similar boost controller that could be faulty.

 

If no other off peak circuits are working it could be a DNO issue with their time switch.

 

Like others I am intrigued how it went "belly up"

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For the professional/experienced guys out there I wonder if you would like to suggest what you would regard as the correct fault finding procedure that would/should be followed in the following scenario.

 

- You receive a call from a woman who simply tells you she has electric heating and her hot water heats during the night but for the last 2 days she has had no hot water.

 

- You visit the customers premises and find she has a combination tank with 2 immersions both of which are connected to a Horstmann Economy 7 quartz controller.

 

So what would you do from here?

 

(I am obviously asking this question because such an occurrence has happened and the whole experience went belly up from the first visit.)

 

Any contributions welcome.

 

Thanks

 

 

IMHO a standard procedure that I tend to adopt..  which applies to almost any reported fault scenario is:-

 

1/ Listen to what the customer has reported, verify times / dates if or when an item previously worked then failed to work.

1a) verify if any other work has been done recently.

 

 

2/ Do NOT assume the everything the customer tells you is factually correct, they may have missed a key point out or added stuff in that is not correct.

 

3/ Identify the key components...

All circuits have a i) Supply  ii) Control or switch  iii) Load  iv) some interconnecting cables joining the bits together.

 

4) isolate the load, verify if it is electrically sound, (open circuit / short circuit / wired correctly in the first place?)

4a) Try to energise the load via a different source to prove if it is working or not?

 

5) Go through a systematic approach to check power from the supply along cables through control or switch to the load..

 

6) Check that any timers or thermostat control are operating...

 

7) Checking polarity earthing etc.. at all relevant points along the way

 

etc...

 

etc....

 

 

Just basic step-by-step isolate and  prove individual components until the item or items that have failed have been identified.

 

 

Its normally only when you assume something that you haven't proved that things go belly up.

 

Guinness

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Now that it is agreed that simple basic test logic should be applied, perhaps you can enlighten us to the belly up scenario? What did you do or not do? What did the customer fail to tell you?

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Thanks guys -

 

The incident related to my mothers flat and was spread over 3 visits on 3 different days by 2 separate 'engineers'.

I am no electrician but my view of the situation is that neither of the 'engineers' were very diligent. - perhaps rushing to get off on holiday!

 

Here is a copy of the content of an e-mail (which I know they have received and has been read by their receptionist) I sent to the company in question. This explains everything as it happened along with some basic questions.

 

So far (after 2 days) I have had no confirmation that anyone has read the e-mail (I know they have by way of an 'automated return receipt I request for every e-mail I send), nor any other communication.

 

Prior to sending the e-mail detailed below, I had e-mailed the contractor and asked them the same general question I posted here - without giving specific details of the event. On that occasion they did respond stating 

 

 

 

 

Although we appreciate your request, we are not willing to provide specific procedure to an unknown person about a general, unidentified fault

 

For those taking the time to read what follows, if you have any further thoughts after reading I would love to hear them.

 

 

On Monday morning 11th May at 9.00am, Mrs XXXXXX of XXXXXXXX, Taunton called your company and reported that her hot water was not heating, and arranged for one of your engineers to call and deal with the problem.

The engineer arrived at (4.30pm) to investigate. He left at 4.55pm saying a part was needed.  He also stated that as he was going on holiday that evening, a colleague would come at 4.30pm the following day (Tuesday 12th May) to replace the faulty part.

At 4.30pm on the Tuesday the other engineer arrived to replace the faulty part. On looking at the hot water tank he grumbled that he had been supplied with the wrong part and would have to travel over town to get a replacement.

As it was late in the afternoon Mrs XXXXXX said it would be OK if he left it until Wednesday. The engineer agreed but pointed out that it would have to be early as he also was off on holiday that day.

On Wednesday 13th May the engineer returned arriving at 7.50am. He spent a few minutes working on the hot water tank and inspecting the timer and then told Mrs XXXXXX that he had done all he could to try and rectify the problem, but she now needed a plumber. He then proceeded to pack his tools to leave.

Mrs XXXXXX had to ask why a plumber was needed, so the engineer then offered to leave her a note which simply read;
"IMMERSION HEATER – element does not work. Needs changing with new Stat + Timer.”
Mrs XXXXXX said she did not know of any Plumbers so the engineer added the name and telephone number of a plumber to the note.

The engineer left at 8.00am, presumably in a hurry to get off on holiday.

Mrs XXXXXX called me (I am her son) later that morning and explained what had happened.

I was confused as to why after diagnosis and replacement of a part the hot water was still not working.

I rang your offices and explained to the receptionist that I would like more information about the visits. She put me through to a manager who she stated was 'more technical' than her.

This gentleman explained to me that the engineer had called and diagnosed a faulty immersion thermostat, but when the second engineer called and fitted the thermostat he found that the element was also faulty when power was applied to it, and that this had resulted is blowing the replaced thermostat.

There was no mention of the timer.
I asked why only the thermostat had been replaced when in my experience most immersion faults result in a complete immersion replacement rather than just a thermostat replacement. The answer was that the engineers are 'not trained to drain hot water tanks' and a calling a plumber is normally suggested to the customer when this is required.

That afternoon I visited Mrs XXXXXX flat to investigate further.
On inspection the first thing I discovered was that the Horstmann Controller was completely blown on both the off-peak and boost circuits (which I would imagine was the result in the surge of current after fitting a new thermostat to a faulty immersion element).

I also noticed that neither of the immersions on the tank had been replaced since the tank was installed, which was over 20 years ago – both immersions were visibly very old.

I drained the tank and removed the bottom immersion to find that it had 'exploded' i.e. the copper tube was split for about an inch exposing the inner element. (see attached photo).

At this point I decided to replace the immersion and timer as it was late on a Friday afternoon and Mrs XXXXXX (age 87yrs) had now been without hot water for a full week and was getting desperate.

This episode has given rise to various questions;

- What tests did the first engineer conduct and what results did he find to conclude that it was the immersion thermostat, and only the thermostat, that was faulty. (e.g. continuity test, earth leakage test, etc)
- How did it transpire that, on his first visit on Tuesday, the second engineer arrived with the wrong part?
- Why did the second engineer rely totally on his colleagues diagnosis and not, either on his first or second visit, re-check the other parts (e.g. the element), before fitting the replacement thermostat and reconnecting supply to the system.

 

One other point worth raising here is that the timer was obviously working before the second engineer fitted the new thermostat, otherwise there would have been no power to surge and damage the replacement thermostat when he turned power back on. 

 

 

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A tale of incompetence.

 

It should have been easy right from the outset to diagnose that the immersion heater element needed replacing. That's just simple continuity and insulation measurements. A new element comes with a new thermostat so that would have been replaced at the same time.

 

It should also have been possible to establish if the timer had been damaged or not and organise a replacement.

 

Now as to whether it's a plumber or an electricians job to change an immersion heater.  Most electricians I know will replace one, providing the tank looks to be in good condition. There is always the danger with an old tank, or if the wrong sealing compound has been used, that trying to remove the old one may destroy the tank. If that's likely I will refer the job to one of two good plumbers I know, otherwise I do frequently change immersion heater elements.  It would still be the electricians job to test the timer etc.

 

It sounds to me like the job was given to a large company. Perhaps a "property maintenance" type of company who then pass it onto one of their operatives.  I think it's far better to entrust it to a local tradesman, at least then you know the same person will see the job through from start to finish. And as with most things, choose a tradesman who comes recommended for their good work, not one who has a flashy advert.

 

A local tradesman like me (and many on this forum) who gets most of his work from word of mouth recommendations has a vested interest in doing a job well and for a fair price. Someone working for a faceless organisation, and quite possibly on a low wage, has less interest in giving customer satisfaction.

 

It's not always possible to complete a job in the same day, especially if you have to go and get parts. Up here in the far north I can be a long way from a wholesaler to get parts and I can't carry everything with me all the time so sometimes it happens I'm afraid.

 

I would love to see how they are proposing to charge you and for what, as most of what they did should not be chargeable, but again I fear if it was a large faceless organisation you probably have 2 or 3 call out charges in there making it an expensive job paying for someone's incompetence.

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Thanks ProDave.

 

The job was actually done by a local family firm of 'Electrical Contractors' of a reasonable size.

The reason my mum called them was because they have a card up in her block of flats (housing association for the elderly) and she, along with a neighbour, had had them in 6 years ago to replace the E7 timer when they had failed.

 

My suspicion is that when the element first blew it caused the stat to go open circuit. 

As he was in a hurry to go on holiday the first engineer blamed fault on the first thing he found a problem with - the stat - and never bothered to test the rest of the parts.

The second engineer then arrived and replaced the stat - again hurriedly as he was going on his holiday - and never bothered to check other components to confirm the first engineers diagnosis. Then as soon as he applied mains the new stat and timer were blown.

(When I removed the new (now faulty) stat the contacts were welded shut)., 

 

I don't believe that they should not charge for anything.

 

Why?

 

Because, to recap, in my view

-they should have picked up on the faulty element on day one

- when the second engineer returned to fit the thermostat he should have checked the installation instead of just taking his colleagues word for it (as he had not made the diagnosis himself)

- the Timer must have been working up to the point at which the mains was reconnected after the new stat was fitted, otherwise the new stat would not have blown 

- The cost of replacing the timer was over £70 - which I think they should pay as it was their oversight which caused it to blow.

 

But then maybe I'm being naive.

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...

- the Timer must have been working up to the point at which the mains was reconnected after the new stat was fitted, otherwise the new stat would not have blown 

...

not necessarily, why did the boost not work after the first fault, before the engineers turned up?

As I understand it, the boost only controls the upper imm heater, which should have worked if the controller was ok, therefore your mum should have had some hot water. I assume it is working ok with the new controller fitted?

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not necessarily, why did the boost not work after the first fault, before the engineers turned up?

As I understand it, the boost only controls the upper imm heater, which should have worked if the controller was ok, therefore your mum should have had some hot water. I assume it is working ok with the new controller fitted?

The fact they use a timer to activate the bottom, off peak heater, probably means it's all fed from the main consumer unit.  So probably just one feed to the Horstman that can either power the bottom heater at the set times over night, or the top heater on a boost.

 

That all seems a bit unnecessary to me when you have a perfectly good timed feed from the off peak CU and it introduces a single point of failure so not hot water at all until it's fixed.

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yes, the horstman e7 quartz has only one feed from the main CU, so there may well not be an off-peak CU at all and the switchover to e7 is done at the meter.

If it was solely fed from an off-peak CU, you wouldn't be able to boost it during the day. 

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yes, the horstman e7 quartz has only one feed from the main CU, so there may well not be an off-peak CU at all and the switchover to e7 is done at the meter.

If it was solely fed from an off-peak CU, you wouldn't be able to boost it during the day. 

The normal arrangement is the bottom heater to be fed direct from the off peak CU so it comes on whenever the cheap rate is on, no need for a timer. Then the boost heater via a timer from the normal CU.

 

Had that been what you had, they would be completely independent and the boost heater would still have worked so there would have been hot water available to keep her going while the bottom one was fixed.

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I personally don't get how any of the faults that the op has mentioned can cause any of the other faults...

Although the testing that they carried out seems to fall short of what it should have

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Just to clarify.

The timer has a single feed from the mains.

There are 2 switches inside. One is for an immersion at the bottom of the tank and is timed, set to a fixed period off-peak. The second switch is connected to the upper immersion and is powered when a 'boost' dial is turned on the front of the box.

 

@Rob_the_Rich

At 87 mum can be a bit forgetful and as she hadn't used the boost for such a long time she had forgotten about it - but as I mentioned before, if the timer had failed as part of the initial problem, then when connecting the new stat there would have been no power to blow it when the power was reconnected. 

 

@NozSpark.

I'm not sure what is confusing you.

A shorting element would  surely cause a power spike which would easily damage anything between it and the fuse box (ie thermostat and timer) as massive current is drawn - which is what happened.

Below is a photo of the element as I found it after their visits.

post-2387-0-28071100-1432232411_thumb.jp

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If it's the old type Horstman with a mechanical 2 hour rotary timer for the boost, I would be very surprised if that was damaged by a failed heating element.

 

But this still comes back to the fact that anyone competent would have found the fault with the heating element right at the start and sent somebody back next day to change the heater.

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I completely understand that your Mum might not have tested the boost function, but I don't understand why the first "engineer" failed to do so. Surely the main objective was to get her some hot water. If you have 2 imm heaters, testing the both should have been a priority. After all the upper one could have been wired up to the off-peak terminal as a short term solution, saving her from having to use the boost dial.

But we still don't know whether the top one works, or whether it actually worked before the "engineers" turned up. So blaming them for the failed timer might be a step too far.

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ProDave.

Not sure which is the one you are referring to, but it has a one hour rotary dial on the front, and inside there is a circuit board with various components on it.

I spoke to Horstmann about it when I took it out after the problem.

 

I explained what I had done to test both the off-peak and boost output and that neither was functional.

They said that it is most certainly blown, and that in their experience they have never known of a spike large enough to blow BOTH circuits - until I sent them the photo of the element - at which point they commented 'That'll do it'.

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I think I see what NozSpark is saying, if the electrical installation, under fault conditions, is causing contacts to weld and electronic circuitry to fuse, then something else might be wrong, such as no earthing, no RCD protection where necessary (TT), high Zs, incorrect fuse ratings etc.

Things which also should have been checked by the "engineers".

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I think that the only one who gets what I was on about was ProDave...

Whilst the time clocks are electric they are usually "isolated" from the elements by the means of a mechanical switch which is very unlikely to have been damaged by a faulty element.... As for the thermostat contacts welding together,,, how did you test it?.....

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NozSpark

 

I don't have enough technical expertise to disagree with you, but did you read what Horstmann said when I spoke to them?

They said that a spike from a faulty element appeared to have destroyed both 'circuits' - they never used the word 'switches'.

The switches may still be intact (I haven't stripped it down to see) but sufficient components were damaged to the point where the timer will not work , 

 

I took the top cover off the thermostat (it was loose and just slid off) and could see that the contacts were welded.

 

 

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I changed one of these timers last Christmas which had blown due to the same fault, circuit board was blackend in areas after the element    gave up . Customer said it had been replaced about 6- 7 years ago along with the immersion. 

Using one of these timers is normal procedure when you have a duel rate meter, I doubt its 'E7'  I think the  Horstmann part cost  a few pounds less than £70

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By E7 I meant it was a controller for Economy 7 use - although my mother has Economy 10. 

A Sangamo Dual Flexi with multiple programmes would probably be a more flexible solution for her economy 10, but at her age she hates anything 'new and unfamiliar'.

 

I bought the replacement at Screwfix  - the only place locally that sells them - for £69.99.

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Re the heater damaging the controller bit.....

 

assuming its something such as one of these type of beasties..

http://www.free-instruction-manuals.com/pdf/pa_457948.pdf

 

 

From the middle of page 1, Horstmans own words state:-

"In some cases immersion heater failure can damage the economy 7 quartz"

 

 

 

I would be interested to know what supply circuit and fusing and or RCD (if fitted) this arrangement is fed from?

 

The company who supposedly came out to fix the fault are incompetent buffoons IMHO!!!

 

 

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By E7 I meant it was a controller for Economy 7 use - although my mother has Economy 10. 

A Sangamo Dual Flexi with multiple programmes would probably be a more flexible solution for her economy 10, but at her age she hates anything 'new and unfamiliar'.

 

I bought the replacement at Screwfix  - the only place locally that sells them - for £69.99.

I know you don't want to change things now, but really what you have I think is a poor solution.

 

It's way too complicated and introduces an expensive thing to go wrong.

 

ALL that is needed is a feed from the off peak CU to the bottom immersion heater via a switch (which is just for maintenance or when you go away on holiday). That will give you hot water at the cheap rate overnight and a mid day boost as you are on economy 10, something you are missing out on now.  Why install your own timer when the DNO provided one for you?

 

Then in addition to that one of the simpler timers to give a boost to the top heater if really needed.

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