"Gassy" machine????
so i hooked up my first semi-auto machine today. actually my first machine ever. its a refurbished 3 group 85 series la san marco. my issue is that im getting air through my group heads when i turn any of them on. Ive tried everything that i know how to do, which obviously isnt much since im new at all the mechanical stuff...thats why im here. any help will be greatly appreciated. thanks
Replies to This Discussion
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Permalink Reply by Mike Sabol on
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Do you let the groups run for a little? You have to run the group valves for a while the heat exchangers fill with water. Hearing some whoosing air durring these first valve tests is normal. If you have already done this and you are talking about steam coming out of the group when you turn it on then you might need to adjust the P-stat a little. Make sure you are keeping the portafilters in the heads when the machine is idle. That helps to regulate temperature. Hx machines like your San Marco will run much hotter when you leave the portafilter out of the head.
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Permalink Reply by Jesse Darwin on
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i did let it run, for a good amount of time. will leave all the portafilters in place. and see what happens. thank you
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and this is just a guess, but im pretty sure its steam. and if so that means the P-stat needs to be backed off?
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Permalink Reply by Brady on
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Yes, if you've fully filled the heat exchangers it's probably steam. The water in the lines is at several bars of positive pressure, even when the pump is off, so any leakage would be out of the system, not in.
Where is your boiler pressure running? Depending on the machine, it shouldn't be much higher than 1.2, though I'm not familiar with the LSMs.
This might be what you meant by "let it run for a good amount of time", but if not, try dispensing lots of water (12 or more oz) and see if things quite down after a bit.
Its not uncommon to have flash-boiling for the first few seconds that you run water through the groups, even if everything is running ok. You may find it necessary to do a quick flush every time before you pull a shot.
Do post back and let us know what you find.
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Just to underscore Brady's point, heat exchanger units like your San Marco will idle hot. I have found, very often, when a Hx machine is pulling good, hot shots, with good extraction, steam will come out at first when the machine has been idle for a bit. A quick cooling flush will bring the group back down to temp and then you can pull your shot. This kind of cooling flush is standard procedure for most Hx units when they are operating properly. So before you mess with the p-stat make some coffee and see how it tastes!
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ok, guys. so ive been running the machine for a while now. at about 1,1 bars...seems to be the sweet spot, anything lower and the shots run blond, anything higher and they burn around the edges, purging before the pull till the spattering quits...but midway through the pull im still getting some air bubbles, the shots taste good to me, although my palet isnt perfect yet. wondering if there is anything that i can do for this issue. anything helps, thank you guys so much, youve been a big help
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Permalink Reply by Joseph Robertson on
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Jesse,
Did any one yet suggest the group here called "Machine Heads" ? You might run this by them.
JoeR
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Permalink Reply by Phil Proteau on
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This can also happen in a heat exchange machine if there is a clog in the inlet going to the heat exchangers themselves. What little water entering the HX will boil off and come out as steam at the group. This can be confused with the "flash boiling", except that the steam never ends. Flash boiling ends in a few seconds time.
Check everything that leads up to the heat exchangers that looks like it could clog. If there is no clog, then I don't know what.
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One thing with hx machines... when the water flow is very slow, you can see an increase in temp as the shot progresses. Think about it... the longer he water takes to flow through the system, the more heat it'll pick up. A flush can drop your temp briefly, but if your machine is too hot the temp will rise again as you pull the shot.
Its probably worth checking out with a Scace to see what is happening. If you don't have one, chances are there is someone in your area that does...
What are your shot times and volumes like?
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Permalink Reply by Solamente Espresso on
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Mike, Brady, and Phil said everything I would have.
To me, sizzling groups after a thorough rebuild and descaling is pay-dirt! Scale thwarts the efficiency of the heat exchangers. Eventually, scale will cause your extractions will come out warm, and that's no good either!
The trade off is to purge after periods of idleness. There also comes into the equation having too much machine for your business. The only places I've seen 3-4 group machine do well is where they are going through upwards of a dozen cases of beans per week. Far less of that, and I could see you purging more often.
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so guys, here is the deal...friday night we had a big party at the shop...lots of drinks going out, all groups going non stop...no air...i believe i just have to much machine. shots still taste good...but dont look perfect, which sucks. so thats my issue. i cant make enough coffee to keep up with my machine unless everybody in the town shows up. so thanks for all the help, its a wonderful learning ex. and it will continue on my end. thanks again so much
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