Hector Senior Member Joined: 15 Jul 2012 Posts: 4 Location: Boston Expertise: I love coffee
Posted Mon Jul 23, 2012, 3:08am Subject: Troubleshooting Isomac millennium: shots are taking longer to pull
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.
Posted Sun Jul 29, 2012, 6:33pm Subject: Re: Troubleshooting Isomac millennium: shots are taking longer to pull
Those sound like similar symptoms my Isomac had a while back. The cause turned out to be a partially plugged intake filter. Water pumps generally don't like restricted inlet flow. Check your feed line for any restrictions.
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