ECM Giotto Classic overheating. Troubleshooting advice?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
DirkVan
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#1: Post by DirkVan »

After 3 years of trouble-free service (other than standard backflush and de-calcifying), my ECM Giotto is having problems. It's a first generation ECM Giotto, and spent its first 7 yrs or so as a "counter queen" and not used - ever. I bought it 3 yrs ago, and it is now much used and loved. I had Silvia before, so I'm familiar w/ standard maintenance and care.
Overheating is the obvious problem. The heating element seems to not shut off.
Background: A month or so ago, I noticed random, intermittent overheating, but it seemed that something would trip, and after 5 min or so, she returned to normal temp / pressure range. Today, the problem got worse in that the problem didn't go away until enough steam escaped and then the boiler would refill w/ cold water to somewhat mitigate the overheating. The only way to reduce temp is to turn off the machine or run an extended cooling flush through the brewhead.
I was hoping that perhaps a decalcifying might fix the problem, so I took off the cover and went through the thorough process of emptying the boiler and filling w/ decalcify water (removing boiler water fill sensor to completely fill). I ended up turning the machine off and on to avoid overheating. The decalcifying didn't fix the overheating problem.
Troubleshooting clue: In an attempt to get the heating element to turn off, I adjusted the Mater pressurestat, and it had no effect. I guess that only narrows things down to the pressurestat, the wiring, or the Gicar controller.
Given the age and the fact that nothing has been replaced, I imagine it wouldn't be a bad idea to start throwing parts in, starting with cheapest (i.e., pressurestat).
What next? I'm hoping that some of the people on this site who have experience can provide suggestions / advice. E.g., I've read that the pressurestat is a fairly common failure, but it seems there are 3 or so alternatives for replacement, so I'd certainly appreciate some expert advice for which unit to use - if pressurestat is a good place to start.
Thanks,
-Dirk

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HB
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#2: Post by HB »

DirkVan wrote:I bought it 3 yrs ago, and it is now much used and loved... A month or so ago, I noticed random, intermittent overheating...
Sounds like the classic symptoms of a failing pressurestat. Pressurestats do eventually fail, either due to carbon buildup on the contacts (fail open), or the contacts heating/arcing and welding themselves together (fail closed). Yours sounds like the latter case; replacing the pressurestat should resolve the problem.

If you're modestly handy, replacing the pressurestat is straightforward. Two popular pressurestats are the CEME/MATER and Sirai. The former are small and less expensive, the latter are commercially rated for higher amperage, larger, and more expensive. Chris' Coffee Service stocks the Jaegar pressurestats, which they claim are of higher quality. Of the choices available, the Sirai is definitely the beefiest, but not every home espresso machine can accommodate its size. For what it's worth, I'd replace your fried pressurestat with the same one. Three years isn't a bad run for a "much used and loved" pressurestat.

PS: While not likely, it's possible the coil of tubing leading to the pressurestat is clogged with scale, which may result in similar symptoms. Even if that does turn out to be the case, I'd replace the pressurestat anyway, since it's going to fail soon enough.
Dan Kehn

kize
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#3: Post by kize »

A pressure stat that does not shut off will cause the boiler to over heat. It is also the most common failure due to the fact of using a mechanical contact to switch power on and off to the element day in and day out. When the machine is hot - at the high end of pressure range- unplug from power- pull the wires off the p stat and measure the contacts with an ohm meter. If it shows continuity- its toast. If it shows open you most likely have a wiring/relay or control board issue. I've had best luck with Sirai p stats. Descaling will not fix this. You might have to track down a wiring diagram and roll up the sleeves on this one. Here is a link to quite a bit of info on p stats. http://www.espresso-restorations.com/p-stats.html

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uscfroadie
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#4: Post by uscfroadie »

I agree with Dan - time for a p-stat change.

One thing Dan didn't mention about the Sirai is that it's noisier than the smaller Ceme, Ma-ter or Jaeger, but it will outlast all three of the smaller ones. Go with a smaller quiet Ma-ter for $35 or a Jaeger for closer to $60 if you want to keep your machine quiet as it is today. If you don't mind the ticking of the p-stat engaging and disengaging the heating element and have the required room, go with a Sirai for $100.
Merle

DirkVan (original poster)
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#5: Post by DirkVan (original poster) »

Thanks for all the advice. Great community. I've taken a crash course on pressurestats this evening. I think I'll go w/ the OE Ma-ter for the following reasons:
* Siria might be loud, might have fitment issues shoe-horning into Giotto, might require some additional work for relays and such.
* I was going to order Jaeger from Chris's tonight (liked the promise of smaller zone), but the site says: "It is not recommended for use in ECM and Rocket machines."
Current (probably failed) Ma-ter has lasted 3-plus years for me, and is at least 10 yrs old.

Now what site has fastest shipping to west coast? I'm thinking one of the Seattle sites. And hope that the p-stat does the trick.
-Dirk

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homeburrero
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#6: Post by homeburrero »

DirkVan wrote:Current (probably failed) Ma-ter has lasted 3-plus years for me, and is at least 10 yrs old.
Going with the same pressurestat that has worked for years (and that fits) is a good idea.

These ECM Giottos and Rocket Giotto Classics come with a variety of controllers and wiring schemes. On some of them the pressurestat switch does not carry the load (10+ amp) that goes to the element - it has both leads connecting to the controller, and a relay inside the controller handles the big load to the element. (The exception to that would be machines with the GiCAR RL-30 or Giemme RL0, where the controller feeds the element via a wire that goes through the pressurestat and the thermal switch.) Are both leads of your pressurestat wired to the controller? If so, then you should get longer use out of your pressurestat contacts.

When you take it off, give it a good inspection for scale - in the pressurestat as well as the coiled tube that feeds it. I think that's a likely cause of it sticking in the closed position, and if the problem is a scale-clogged tube then the new pStat may not fix your problem.
Pat
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homeburrero
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#7: Post by homeburrero »

DirkVan wrote:Now what site has fastest shipping to west coast? I'm thinking one of the Seattle sites. And hope that the p-stat does the trick.
-Dirk
I just checked and saw that Stefano (http://www.espressocare.com) carries the MaTer. He's in Oregon and has always been fast and responsive for me - and a good source in general for ECM Giotto parts.
Pat
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DirkVan (original poster)
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#8: Post by DirkVan (original poster) »

Thanks again, I have a couple busy days, so not much time to work on the Giotto. I will do that suggested continuity test to hopefully confirm the pressurestat diagnosis. At any rate, given its age, it would be good to have a replacement.
I notice a few fellow cyclists commenting, and I'm thinking that p-stat replacement is similar to cables. Good to have a spare set on hand so that it's a quick replacement when needed, even though you can usually go a good couple years before it's needed.
I actually ordered a couple, so that I'd have a spare on hand. Also to better my chances of getting the old girl up and running sooner. I initially ordered from Orphan Espresso (cheapest on my quick search, and I like the vibe of their site). But then I started worrying that a small company might process orders a bit slower, so I ordered another from espresso-tec. Good news is that Orphan Espresso already shipped.
Homeburro, thanks for the recommending Stefano, but I had already placed the orders by the time I read your recommendation. I've seen him participate on the site, I think, and would like to reciprocate that support.
-Dirk

DirkVan (original poster)
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#9: Post by DirkVan (original poster) »

Hooray, 2 p-stats arrived in yesterday's mail.

But now I have another question. The new models and my old one are all subtly different. Note the different specs and bottom threading length on the 2 new ones.

My old one has the shorter threading and electrical specs 15A-125/250Vac.
I have room for the extra threading, so I think I'll go with the new one that has white lettering - and the same electrical specs.
Will the other one even work? What is "16(4)/250?
Thanks,
Dirk

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homeburrero
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#10: Post by homeburrero »

The same model (Ma-Ter XP110) appears to exist in surprisingly different specs. The one on the right indicates a range from 1 bar to 2.5 bar, which doesn't seem ideal for use on a brew boiler. Might be worth asking the supplier about that.

The notation 16/250~ indicates a switch rated for up to 16 amp and 250V AC. I believe (well, I think I learned after a bit of googling) that when it's written 16(4)/250~ that the 4 has to do with the nominal amperage rating of a motor if you were to use it to switch an AC motor.

[Edit addition - went looking at espressoparts.com and I think you bought one intended for use on the steam boiler of a double boiler machine, which would explain the 1-2.5 bar pressure range.]
Pat
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