Hector Senior Member Joined: 15 Jul 2012 Posts: 4 Location: Boston Expertise: I love coffee
Posted Sun Jul 15, 2012, 12:41pm Subject: Troubleshooting Isomac millennium: shots are taking longer to pull
Hello,
This is my first post on this forum. I have had an Isomac Millennium for 9 years now. This morning I noticed that my shots are taking double the time to pull. I normally pull them in 25 seconds and now they are taking about 40 to 50 seconds. The coffee taste sour - not good. There has been no change in the beans, grind or anything else. Everything ran fine yesterday. I have this system plumbed into the house water supply and have 2 in-line filters (charcoal and ion-exchange). I typically brew coffee at home 2 - 3 times a day and have never encountered this particular issue.
Here are some observations:
The boiler pressure is where i normally have it: 1.1 to 1.25 bar. The pressure stat was replaced with a Jaeger unit within the last 2 years.
I observed that back flushing is a little less intense than it normally is. I am gauging this qualitatively by the lower sound that it makes.
I evaluated the group pressure using a blind portafilter with a pressure gauge. It registered about 8.5 bar. I have never used one of these before and do not know what pressure I should have.
I tried increasing the grind size but the shots still took a long time and ran very thin implying poor extraction.
I also tested the hardness of the water leaving the group head. It was low suggesting that I should not have a scaling issue.
I am not sure if I have a pump issue, expansion valve issue, solenoid value issue, blockage or other. Any recommendations are greatly appreciated.
greattemper Senior Member Joined: 25 Mar 2012 Posts: 19 Location: Tel-Aviv Expertise: I love coffee
Espresso: Andreja Premium by quickmill Grinder: Lelit Roaster: Popcorn
Posted Sun Jul 15, 2012, 1:20pm Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
Did you observe any change in the flow during the cooling flush? cc/min - this is easy, just measure how long does it take to fill up 30cc water without the PF. this will give an indication if scale is building up in the GH. I suspect this is the reason for your problem due to the flow not being effected by increasing the grind size.
randytsuch Senior Member Joined: 11 Jun 2009 Posts: 578 Location: LA, Ca Expertise: I like coffee
Espresso: Expobar Office with... Grinder: Baratza Vario Roaster: Customized Alpenrost,...
Posted Sun Jul 15, 2012, 2:26pm Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
I was also thinking it might be a scale related problem
When was the last time you descaled? Even with water treatments, you still need periodic descaling. If its been a long time, its possible a hunk of scale broke loose, and is now clogging something.
Hector Senior Member Joined: 15 Jul 2012 Posts: 4 Location: Boston Expertise: I love coffee
Posted Sun Jul 15, 2012, 6:40pm Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
I just measured the flow rate without the PF. I measured 100mL/min. Does this seem correct?
I have never descaled before either. I assumed that it was not an issue since I have always used filtered and softened water. It seems that I should attempt to descale first. I have heard that people use citric acid to descale. Are there any recommendations for descalers (citric acid or other), concentrations to use and how long to descale for? I am not sure how the process works. I appreciate the help. Thank you!!!
I just descaled my machine this weekend, it was pretty easy. You may have a little more work in front of you, because you machine is plumbed in, you need to feed it from another water source.
Also, descaling is meant as preventative maintanance, it may take a lot of work to fix it at this point.
Hector Senior Member Joined: 15 Jul 2012 Posts: 4 Location: Boston Expertise: I love coffee
Posted Mon Jul 16, 2012, 6:13pm Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
Thanks everyone for the help. I was able to fixed the problem and am somewhat embarrassed to the admit the root cause.
I removed the machine from its spot in the kitchen and was about to begin dissembling . . but then thought to check the water line feeding the unit. In order to remove the machine, I had to close a valve on the incoming stream. I then took a large container and opened the valve to fill it and in the process measured the flow rate. Only a trickle of water came. I did some further investigating and noticed two kinks in the line. I am not sure how the kinks got there but that solved the problem. I am back in business.
I now get about 500mL per minute out of the group head. I will follow everyone's advice and descale the unit soon. I have had the unit for nine years now without descaling - it's about time. Thanks again.
NobbyR Senior Member Joined: 10 Jul 2011 Posts: 1,613 Location: Germany Expertise: I love coffee
Espresso: Poccino Opus One, Ariete Grinder: Eureka Mignon Istantaneo,... Vac Pot: N/A Drip: Melitta Linea Unica de Luxe Roaster: N/A
Posted Tue Jul 17, 2012, 2:20am Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
Hector Said:
... I did some further investigating and noticed two kinks in the line. I am not sure how the kinks got there but that solved the problem. I am back in business ...
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