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Thread: Bezzera boiler shorting problem

  1. #1
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    Bezzera boiler shorting problem

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All
    I recently put a new seal in the boiler of my old Bezzera 2 gp and did the descale thing. Now with the machine back together I get a short when ever I connect the boiler. I carefully labelled the boiler wires, so Im pretty sure the wire is correct. I used a continuity tester on my meter and none of the contacts on the element terminals are shorting to earth. I assume that the terminals of each individual element should have continuity to the others- they do have. Is this right? What should I look for?
    Boiler is filling ok and cut off works. If I disconnect the elements all is ok, when I connect them I trip the power.

    If I wanted to try just one of the elements, which wires would I connect? At the moment wire 2 from the front element is connected to wire 1 of the rear element- if I disconnect one would the link need to remain?
    Any help appreciated
    Brett

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    Re: Bezzera boiler shorting problem

    Brett,

    Firstly is the breaker which is tripping an earth leakage breaker?

    Secondly did you let any (and by any I mean just a few drops) of water / decaling solution get near the ends of the element (where the white ceramic bit is..... is so it "wicks" up into the ceramic and causes a leakage path to earth..... and trips the breaker. To test this put your meter on the highest ohms range ( say 20 Meg ohms) and measure from the outer sleeve to where the power connects - it should be open circuit... if not - thats your problem. Do this with the leads disconnected both ends (and of course power off!!!)

    Check that first before changing anything else.


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    Re: Bezzera boiler shorting problem


    Hi Brett,

    It sounds like you have a leak to earth, rather than a short. Its hard to check for this with a standard multimeter. Coffee techs use a device that puts about 500V between the element and earth to check for this. This seems to be a very common element failure mode and its usually the first check that is run on the element.

    This fault can be caused by aggressive descaling, as the acid can eat through the element cladding making it micro-porous. It can also be caused by a cracking of the insulation inside the element, causing slightly less resistance to ground... either way its a dead element.

    You should be able to isolate the dead element, as youre suggesting. However, your description isnt too clear, so with respect to wire 1 and wire 2, I cant offer any suggestion. In my Pav, one side of the three elements were bridged together with welded links. The other end of the elements were connected together with shot bridging wires. To run two elements, I needed to remove one of the bridging wires and ensure that the other bridging wire still maintained a connection to the active line from the pressurestat. To run only one element, bother bridges would need to be removed and then the wire from the pressurestat can be attached to each element in turn until the faulty one is found.

    I hope that helps.

    Cheers,

    Mark.

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    Re: Bezzera boiler shorting problem

    Quote Originally Posted by Sparky link=1183263982/0#2 date=1183266345
    Its hard to check for this with a standard multimeter. Coffee techs use a device that puts about 500V between the element and earth to check for this. This seems to be a very common element failure mode and its usually the first check that is run on the element.
    Mark.
    Mark...

    Ah the old Megger..... I remember the hand crank variety (boy did we ever have fun with that ::))

    I have found that generally once water gets in the element will register some resistance on a multimeter - but certainly agree a Megger is a far better test.

    As a general warning to others, most elements in coffee machines (and most other appliances with similar element designs) - the ends of the element are not sealed.... and the white ceramic insulation in them will absorb water.... so not only can you get small pinholes whilst in situ or whilst descaling the element out of the machine but water can wick up from the end - DO NOT LET THE ENDS OF THE ELEMENT GET WET..... that will be a costly mistake! :( :(

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    Re: Bezzera boiler shorting problem

    Yeh- they certainly did get wet!
    Ill have to wait till tomorrow to try the test. From memory it worked with only the front element on- Ill check anyway and let you know.
    Many thanks
    Brett

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    Re: Bezzera boiler shorting problem

    Brett,

    Some have had success in drying out the element by attaching it to a low voltage reasonably high current power supply (say 12 volts or more if you have it).... and leave it there for many hours.

    They generally wont dry out - well at least not quickly - on their own.

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    Re: Bezzera boiler shorting problem

    Brett,

    As another thought - to accelerate the removal of any moisture within the insulation of the elements - you could try putting the elements (after removing any plastic like insulation from the ends) into an oven and heating them for a few hours to drive off the moisture.....

    Never done it myself..... but I think it should work (and it cant do any damage as the interior of the element as during use it reaches a far higher temperature than it will in an oven).

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    Re: Bezzera boiler shorting problem

    Very cool Java
    will try over the next couple of days- oven looks good
    Many thanks to you
    Brett

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    Senior Member phil_jeffery's Avatar
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    Re: Bezzera boiler shorting problem

    Hi Brett,

    I had the same problem with both the Bo-Ema and the Carimali after descaling. In the case of the Bo-Ema, I had immersed the whole element by mistake, as the wire I was holding it with slipped. I must have spilled some liquid on the Carimalis terminals, though I didnt think I had at the time.

    The good news is that I managed to get both working fine by "drying" out in the oven as JavaB mentioned above (talk about convergent thinking!)....see my rebuild post http://coffeesnobs.com.au/YaBB.pl?num=1175840909/23#23

    Good luck!
    Phil


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    Re: Bezzera boiler shorting problem

    Hi Phil- hows the Carimali performing now? Bo-Ema came at the right time considering this element fun. Im aiming to pull the elements out tomorrow. Lets hope it all works!
    Thanks
    Brett

  11. #11
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    Re: Bezzera boiler shorting problem

    Hi Brett,

    Yeah, its all pretty good now, thanks. Its slower to recover thna the Bo-Ema, not surprisingly, but is a neat little machine otherwise. I plan to play around with boiler level next and see what effect that has on group temp. stability.

    A pain in the arse draining the boiler and pulling out elements, lets hope you have a good outcome.

    Regards,
    Phil

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    Re: Bezzera boiler shorting problem

    Quote Originally Posted by JavaB link=1183263982/0#5 date=1183273910
    Brett,

    Some have had success in drying out the element by attaching it to a low voltage reasonably high current power supply (say 12 volts or more if you have it).... and leave it there for many hours.

    They generally wont dry out - well at least not quickly - on their own.
    Hi JavaB
    Im thinking about the low voltage dry out option. The reason is that when I put the machine back together, I also put all the insulation back on etc and its the ceramic fibre stuff and so you have to be a bit careful. Time consuming and also a bit risky (yes am looking at the silicone alternative).
    With the low voltage, I have two 12v supplies, one 3A and the other 1.5A. Would either of these or both be worth trying?
    Brett

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    Re: Bezzera boiler shorting problem

    Brett,

    Both those supplies would have enough current (at 12 volts the heaters will only draw 1/20 of the current they would on 240V.... )

    The only problem is that 12 Volts wont produce a lot of heat..... but certainly better than nothing.

  14. #14
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    Re: Bezzera boiler shorting problem

    Have found that over the years two 12V batteries in series for 24V DC do a reasonable job so if you can borrow or purloin a couple of these, it should do the job for you,

    Mal.



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