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Gaggia Classic with PID and EM0480 - Bitter Coffee and Early Blonding?
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Hmmm...Originally posted by JojoS View PostBased on Auber's testing, recovery time is about 4 minutes after pulling a shot or flushing.
That time seems inordinately long for a 1,300W element Boiler using PID control. My first true espresso machine was an Imat Mokita (basically a rebadged Lelit) and this used the same sized boiler as a Silvia with a 1,200W element. With the PID values set optimally, and with an optimally located t/couple, the Mokita's recovery time was just over a minute for a double shot and always beat me locking in the Group Handle for subsequent shots.
I think more investigation and optimisation should be pursued to improve this performance...
Mal.
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Thanks again to all, the thread you directed me to coffee_machinist was very insightful. From what I can gather your saying the data showed a 20 degree temp drop from the boiler to the grouphead. So in theory the best setting would be around 112 for the SV on the PID to get 92 from the grouphead. This seems high, and id assume once the boiler/grouphead are warm from say the first shot, the second and so on would be above 92 (unless recovery time is fast due to the loss of temp from the pouring of the shot). My sleeping patterns are gonna be way off from all this "testing" haha. For interest sakes I had my first attempt at roasting some beans today in a popper, so easy, so much cheaper, and of course I couldn't help myself and try a bit; a whole new level of coffee quality was experienced! Why didn't I do this years ago???
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Both element and thermocouple are mounted in the boiler housing, not the water, so there's substantial lag.Originally posted by Dimal View PostHmmm...
That time seems inordinately long for a 1,300W element Boiler using PID control. My first true espresso machine was an Imat Mokita (basically a rebadged Lelit) and this used the same sized boiler as a Silvia with a 1,200W element. With the PID values set optimally, and with an optimally located t/couple, the Mokita's recovery time was just over a minute for a double shot and always beat me locking in the Group Handle for subsequent shots.
I think more investigation and optimisation should be pursued to improve this performance...
Mal.
The metal of the boiler housing heats up fast and is held at temperature, but the time it takes for the heat to transfer to the water takes a substantial amount of time (and the rate at which it does so decreases as the temperature differential decreases, I imagine).
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If you have time to look at it, I'd be interested to know what you think of the link in post #8?Originally posted by coffee_machinist View PostThis thread may have some useful data for you
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Getting the PID to reach SV after the shot is usually under a minute but that does not mean the temp of the water inside the boiler is stable enough for a repeatable temp shot profile. The small boiler size of 100 ml. on the Gaggia simply can not be compared with those of a Silvia or other machines with a much bigger boiler.Originally posted by Dimal View PostHmmm...
That time seems inordinately long for a 1,300W element Boiler using PID control. My first true espresso machine was an Imat Mokita (basically a rebadged Lelit) and this used the same sized boiler as a Silvia with a 1,200W element. With the PID values set optimally, and with an optimally located t/couple, the Mokita's recovery time was just over a minute for a double shot and always beat me locking in the Group Handle for subsequent shots.
I think more investigation and optimisation should be pursued to improve this performance...
Mal.
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Yes, you're right about that...Originally posted by JojoS View PostGetting the PID to reach SV after the shot is usually under a minute but that does not mean the temp of the water inside the boiler is stable enough for a repeatable temp shot profile. The small boiler size of 100 ml. on the Gaggia simply can not be compared with those of a Silvia or other machines with a much bigger boiler.
And that was one of the issues which was causing me to wonder about the optimisation of the installation design. A 100ml/1,300W boiler versus a 400ml/1,200W boiler... The Gaggia should be capable of very decent performance with regards to recovery time. In fact, one of our members (going back a few years) was able to achieve the sorts of recovery (brew water Temp.) that I was referring to. I can't remember the configuration of his installation, but being a theoretical physicist, he put a lot of thought into it.
Mal.
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There are many mods and electronic mods that are toyed around with by some Gaggia Classic users. Pre-heating coils wrapped around the boiler that is connected between vibe pump and boiler plus some arduino board to trigger the boiler to turn on full power instead of PID pulsing for better intra shot temp stability. The boiler ends up with higher temp after the shot and recovery time is reported to be much much shorter. I am ok with just the PID to control starting brew temp and steam for my daily use. I make my lattes one at a time.
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