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FAILED PCB IN BOILER

Discussion in 'Electrics UK' started by Nick67GT, 17 Apr 2021.

  1. Nick67GT

    Nick67GT

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    We have an LPG ideal boiler branded for MORCO under warranty. It’s fitted to our static caravan which we have just returned to after absence of 4 months. On return we found the pcb has failed with a burnt component. MORCO have refused the warranty stating it is a power surge of 317v ac and therefore not covered by their warranty. Western Power have no record of a power surge during the period in question.
    Q1. From the photo below how can they categorically state that a power surge is the cause?
    Q2. Why couldn’t it be a simple component failure due to say faulty soldering. Do these components never fail in a boiler?
    Q3 The fuse has blown in the boiler rated 4a. The fuse in the main plug 3a has not blown and the consumer unit has not tripped. If a power surge, wouldn't it trip the consumer unit as well?
    Any experts out there who can help please 28C23071-B63E-4259-ADB5-5D37AB1F62BE.jpeg
     
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  3. JohnW2

    JohnW2

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    How on earth could (should!) they say that - even if there had been a 'power surge', how would they know its magnitude?

    Kind Regards, John
     
  4. 333rocky333

    333rocky333

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    Is that not a Varistor thats blown and the supplier i assume knows its value
     
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  5. oldbutnotdead

    oldbutnotdead

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    Do you have your own meter for electricity or is power included in your pitch fees? If the latter then your energy supplier is the site operator, and they could have done who knows what over the last 4 months.
    Question- why leave the boiler powered-up all that time?
    EDIT Different types of fuses. The one in the boiler is quite likely a quick blow or antisurge type, the standard 3a fuse and cu mcb would tolerate more current for longer.
    EDIT 2 By your description, the unit has not failed while operating, the supplier is on fairly safe ground asserting the problem was caused by an external event. Do you know if any other owners on the site have had similar problems?
     
    Last edited: 17 Apr 2021
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  6. JohnW2

    JohnW2

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    Yes, I suppose that's a possibility - but it surely would remain the case that they couldn't be sure whether the it was the result of a 'surge' or failure of the component, wouldn't it?

    \kind regards, John
     
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  7. ericmark

    ericmark

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    317 volt seems a rather precise figure. It seems likely that a caravan site has a three phase supply, and I know from experience one can get neutral faults which can cause the voltage to rise, I had it in a workers camp where three phase plug and socket arrangement was used to expand and reduce camp size, and we did see where over voltage had caused damage, the maximum voltage one could get is 380 where I worked, 400 in UK now, and years ago 415 when we had a 240 volt supply, but the 317 volt does not ring true.

    Only with some monitoring device could anyone say 317 volt, with old car alternators they had a zenor diode and if a battery charger was used that could deliver over 15 volt it could burn out the zenor, so when finding one burnt out we could say damaged by over 15 volt supply, but not simply a 15 volt supply.

    I will guess the blue component is a surge protection device, set at 317 volt, so for it to fail you need a prolonged voltage of over 317 volt, the SPD in the consumer unit is normally around 500 volt, if fitted, so would not stop a spike reaching the boiler, it does seem an odd name surge protection device, as designed to stop spikes of micro second duration, not what I would call a surge.

    But the 500 volt SPD will not protect against a loss or bad connection on a neutral. And with a supply to say 100 mobile homes a poor connection on the neutral could go unnoticed when all the units are drawing a even load, I am sure it was a poor neutral which caused my RCD to trip, rather old before we used electronics, and I would get a batch of tripping, no fault found, then years of no tripping, it had to be some external cause as I tested the RCD with RCD tester many times and always passed all 6 tests, and the loop impedance tests and insulation resistance tests also showed not faults.

    I blamed next door who was a welder, doing some work at home, but then happened when on holiday, but always seemed to happen in batches, with nothing taking power on the whole site, any thing which did cause a spike would not be damped in same way with other equipment.

    My house has a SPD, but not caravan, both have RCD protection, but rare today for them to trip, I suppose a filter socket may help, but although I have fitted them not sure they help. I would guess fault caused by thunder storm and a near miss.
     
  8. Frost protection..
     
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  9. Harry Bloomfield

    Harry Bloomfield

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    I would suggest to go back to Ideal, armed with lots of letters from other's on the site who've no issues with their equipment, plus a letter from your supplier stating they have no record of any surges and a note from you suggesting that the failed component (the varistor) was likely faulty. Varistors failing for no reason is not that uncommon.

    That component failing, would not have caused other damage on the PCB, apart from taking out the fuse - so the chances are, replace the varistor and the fuse it will be good to go. Any TV / radio repairer should be able to do that, if you cannot - five minute job.
     
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  11. I think the whole 317v claim is nonsense....A power surge would blow the tits off the pcb.
     
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  12. Harry Bloomfield

    Harry Bloomfield

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    Varistor specs. quote voltages at which they go short to protect equipment - Ideal are probably quoting that spec. voltage and assuming the component has operated precisely to spec..
     
  13. bernardgreen

    bernardgreen

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    If the blown device is a Varistor intended to protect the PCB then one could say that the manufacturer's design had specified the wrong size of Varistor.

    In an ideal design the Varistor will survive long enough to ensure the fuse blows.
     
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  14. mattylad

    mattylad

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    Also bear in mind that it's not unknown for the assemblers to put the wrong value in place because some numpty kitted them out to them or mixed one up in stores, it got thrown in the wrong bin because it looked the same etc.

    So if the value can be seen on it then that may be a reason, otherwise it may be that it had a lower threshold.
     
  15. Bodgedbuild

    Bodgedbuild

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    This could be a long shot but if you look at the PCB track going to the little blue thing I think you might find the main voltage in goes through that and out the other side, I think it may be wired in series. If that does appear to be the case, it might be a GMOV and it might just require replacing?
     
  16. bernardgreen

    bernardgreen

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    A GMOV is a Varistor produced by Bourns
    Bourns® GMOV™ Hybrid Protection Components

    It would have to be connected between Live and Neutral to short out any spikes.

    In series it would not allow any power to reach the PCB unless the voltage was higher than circa 300 Volts trigger voltage for the device.
     
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  17. Bodgedbuild

    Bodgedbuild

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    My bad, could it now be short circuit then if the manufacturer believes it has been run over voltage? It is the little blue thing isn't it?
     
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