Isomac Mondiale - shot boiler element?

[bmawebb]

My Isomac has flipped the safety switch in the box, it happened once about 2 months ago (one off, let it sit and it went fine after an hour or so), but yesterday morning it set the RCD switch off three times in a row. I tried another power outlet, same result.

I've pulled the sides and back off the machine, and sat a multimeter on the boiler elements (with the clips taken off). It read 0, which indicates a short in the boiler element. Is that correct? I'll be honest, electrical terms confuse the heck out of me.

Every other switch I put the multi meter on gave me a 1.00 reading.

Am I on the right track?

[dumiya]

While it is disconnected from the power, are you getting a short between either element posts and the boiler. This would indicate a dead heating coil as well. This is what trips the RCD I think.

[Gitney]

Hi bmawebb,

Your diagnostics sound correct. If you have pulled both lugs off the heating element and the resistance is 0 Ohms then you have a short circuit across the element and your RCD circuit breaker is tripping on overcurrent. Just FYI this isn't technically the RCD Component of the breaker which detects current leaking to Earth, but it is likely tripping on over current because of the very low resistance due to the following relationship:
Volts=Current*Resistance
On a working 2000W/8.3ish Amps heater element:
240=8.3Amps*Resistance
Resistance =29ish Ohms

For your example:
240=(Amps) * 0
Almost infinite current so a standard 10 or 20Amp breaker will trip every time.

Hope this makes a bit of sense.
Thanks,
Chris

[bmawebb]

thanks Gitney.

I'll order a replacement boiler element and see how we go replacing it.

I'll keep this thread updated.

[Gitney]

Hi bmawebb,
Just a quick thought. I hope your multimeter is OK. Might be worth checking ideally a resistor that you know the resistance of, or even an incandescent light bulb (40W bulb should have a resistance of 1200Ohms).
Thanks,
Chris

[bmawebb]

I've thought some more, and given my limited confidence in my own knowledge, I'm going to box it up and send it off to a professional in Perth for a service and parts replacement.

[Dimal]

Great decision "bmawebb"...

Always best to play it safe with electrical issues...

Mal.

[sprezzatura]

No one, in my experience, has ever regretted getting a new heating element.

[bmawebb]

Ok, a good number of weeks and dollars later, and I've set the machine back on my bench. Twenty minutes of running time and the boiler pressure is showing 0, but the pump operates when I turn on the handle. water is lukewarm. One quarter turn of the thermostat, and now I have no heat at all. Pump still works when I lift the handle.

I'm bitterly disappointed after five weeks and $1100.

[sprezzatura]

What did they do to it?

[dumiya]

Where did you send the unit for repairs? Could be helpful for others

[bmawebb]

I'm not disclosing where it went until I can talk to them today.

[-Alchemist-]

Kudos for giving them a chance to explain / discuss the issue before any 'naming and shaming' - it's always good to seek and if relay a balanced perspective.

My nine year old Mondiale has had three elements fail over the time I've had it, but it's always been a routine repair - I'm interested to understand, what cost $1100?

Cheers,

-A-

[dumiya]

I hope it all goes well for you

[bmawebb]

Okay, I've printed off the receipt to have a good look.

As the tech discussed with me over the phone, the whole boiler needed replacing ($460) plus the heating element ($85) plus a complete overhaul service, showerscreens, solenoids, probes, valves and labour. There were some pinholes in the boiler, and the fittings had seized. They tried to revive it, but it wouldn't seal.

In their favour, it did travel the 750km there and the 750km back in a non original box, though I packed it pretty well.

I've called this morning and told the tech what happened when I turned it on, and that there's pump working but no heat in the boiler. He's under the impression that it's the pressurestat (thermostat?) and is sending another one to me at no cost to install myself.

I'm happy with that result, though I'm very grumpy that I received a kilo of roasted beans the morning it died, so they're sitting unopened in my cupboard 5 weeks later... and likely to have peaked already.