Coffeenephrin Senior Member Joined: 17 Nov 2008 Posts: 14 Location: Canada Expertise: I love coffee
Posted Wed Apr 6, 2011, 5:08am Subject: My Explosive Aroma!
No! It's not what you think... ;)
One morning last week, I made my usual morning latte with my Saeco Aroma, tamped the coffee, slotted the portafilter into the brew head, drew the coffee, then switched on the steamer, frothed my milk... had a sip... ahhh!
Then I went to remove the portafilter to clean it and BANG!! The pressure behind it was really high it came smashing down into the tray (which it bent!), this spreading a couple of meters of coffee grinds all around the machine. Not so "ahhh!" ;)
Then I noticed lots of steam coming out of the brew head. I decided it was time to descale (got a bit negligent in the last 6 months...). The steam wand tightened up (it was a bit leaky) but a lot of steam keeps coming out of the brew head when I turn on the steamer. I can avoid the explosion issue if I remove the portafilter before I turn on the steamer, but clearly something is still wrong. I don't think this is a descaling issue because it happened suddenly: I never noticed any steam coming out of the brew head before. So either there's a lot more pressure in the boiler than there should be, or the valve at the bottom of the boiler feeding the brew head is leaky.
I also noticed that if I just leave the Aroma in brew mode without turning on the steamer switch and open the steamer valve, lots of steam comes out of the wand, but maybe this is normal. Could this suggest a faulty thermostat? I'm knowledgeable enough to work with electricity (I'm an experienced DIYer and know how to use a VOM... and about the caution required to work with live AC!). How do you check for a thermostat fault? And how complicated is it to mechanically change the thermostat on the boiler?
I'm a bit stumped. Has anyone here experienced this problem? Thanks for any insights!
[****POST ISSUE UPDATE: Read my April 14th post later in this thread for the most plausible explanation of why this happened.]
My Aroma Classico stopped heating water on Sunday. A day short of my intended fix date... when I opened the top, I found some serious arcing had been taking place at one side of the heater (see pic). Could the faulty valve have caused this? This is very strange; looks like I'll have to replace the coil now because it measures 2.5 megaOhms which is really high for an AC element. And maybe while I'm doing that, it might be a good idea to change the brew thermostat, since maybe its cutoff temp was too high. I've had the machine for over 4 years now. Should I change both thermostats?
At least the stainless steel shell isn't going to fail any time soon...
Yep. See the pic for what a catastrophic failure of the heating element looks like... I got new thermostats and I'm cleaning parts before re-assembly. I spent about $80 in parts, including the heater, 2 thermostats, gaskets, valve + spring, and a new power switch.
But I'm concerned about rust (see pic in next post): the basket pipe leading down to the coffee exit is clearly rusted. Should I change the basket? There must be tons of Aroma's out there functioning with this and at this point in time, I don't really want to spend more unless it's essential. Then there's the bolt connecting the steamer valve to to top of the boiler: it's brownish and so is what I can see of the steamer valve pipe interior. But since these parts are brass, I suspect it's less critical. Opinions?
Couldn't wait... Re-assembled the machine as is, rewired, turned on: everything is normal again! I ran a couple of tanks through to clean anything out (I was very careful to keep the internal water-contacting areas clean while I worked).
Thanks to Fixya for their Barrista teardown: the parts are practically the same. It's nice working on this machine; sort of the difference between working on a 50's Chevy and a modern Honda: room under the hood, and very simple in design. I've seen the insides of some of the automatic machines and I really wouldn't dare to open one.
So I made a latte: tamped the coffee, slotted the portafilter into the brew head, drew the coffee, then switched on the steamer, frothed my milk... had a sip... ahhh! Nice to get my brew + foam back! And this time without the earth shattering kaboom...
One last thing: anyone care to comment on the "rust" issue? The reason I went ahead and reassembled is that the central spigot of the boiler looks more like brass corrosion than iron rust, like the steamer wand tubing, and I don't find there's anything wrong with the taste of the coffee, so...
A short post-mortem on this issue: in retrospect it seems to me that the real culprit in all this was the blowout of the heating element. The element has a resistive string running through it. When the element blew, it exposed the string directly to the water, causing super-heating of the water which then manifested as steam coming out of the boiler head when in brew mode. The boiler valve was doing its job, it was just subject to high pressure so it naturally opened, as it was designed to do. The portafilter was subjected to pressure buildup from this which resulted in a powerful punchdown when this pressure was released on removal. And as I had surmised, the thermostats were fine since while the heater was still working, both brew and steam lights would go out as per spec.
In the end, I don't regret changing all the parts I did because I'm set now for good while, but it could have cost me half of what it did. The new brew thermostat turns on/off faster than the original, so that's good, and the new valve spring was longer than the original so higher pressure is needed to open it, also good. And I now know how to take this machine apart and put it back together... I'm going to start reading the Ranchero wand swap and PID threads...
I'm still wondering about the brass corrosion and I'm surprised no one here knows about it. But the coffee is fine, so that's the important thing :-)
Nemec4 Senior Member Joined: 14 Jul 2013 Posts: 2 Location: New york Expertise: I love coffee
Posted Sun Jul 14, 2013, 1:30am Subject: Re: My Explosive Aroma!
This exact situation just happened to me..... Pretty much word for word, inlcuding bent metal tray. I guess it was the heating element. I got a squaretrade warranty so i will get 200 toward a new machine. Can i tell it was the heating element pretty easily or something else.. But the pressure of the portafilter makes me think it was the heating element.
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