Moose1 Senior Member Joined: 24 Aug 2012 Posts: 1 Location: Norway Expertise: I love coffee
Posted Sat Aug 25, 2012, 7:42am Subject: Gaggia Classic produces sour shots
My six year old Gaggia Classic recently started pulling sour shots, which got me thinking that the temperature is too low.
- Recently cleaned grinder - Recently cleaned machine - Coffee is fresh (roasted about a week ago, tried making it in an aeropress just to be sure) - 14 g coffee finely grinded in a double shot - 20-25 seconds to pull 50 ml (1.8 oz) double shot
Measured temperature (in pre-heated paper cup with thermometer) to 82 degrees C (180 F) I changed the thermostat, but there is only a marginal change in temperature (82-84 degrees C - 180-183 F) and the shots are still sour.
Is there anything more I could do, or is my Gaggia ready for retirement?
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,811 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sat Aug 25, 2012, 2:38pm Subject: Re: Gaggia Classic produces sour shots
Not sure where to start. Sounds like you will have well flushed the machine by now as you have had time to acquire and change B-stat. Perhaps you had one lying around.
If you have not flushed the machine, that may well be the cause as suggested.
It is difficult to believe that brew temperature on 2 brew stats. You specified pre-heated cup and I am not sure that I completely understand. I found that I had to heat everything. You probably did everything correctly, but so that we can help, I will cover some of my past mistakes. Not all "instant" read digital thermometers are created equally. Get some idea hot fast it reads by sticking it in boiling water. Most are hardly instant. I keep the thermometer hot, about 180 - 210F, in a cup of water.
I let the machine stabilize for about 30 mnutes with PF on, so that the group and head are up to temperature.
I used styrofoam, and also paper, with similar results. I assume that the cup is much cut down in height and volume and that you have inserted the thermometer through the side. When all is ready, I put the heated thermometer in the cup side and pull about 30 ml, about 3 seconds. Water cools very quickly and you will see the temperature peak and quickly fall.
Where are you in the temperature, brew-stat, switch light cycle; are you surfing or could that be the b-stat low?
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