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Thread: Gaggia Classic with PID and EM0480 - Bitter Coffee and Early Blonding?

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    Gaggia Classic with PID and EM0480 - Bitter Coffee and Early Blonding?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hey folks, been quite some time since I have posted on here but getting back into the swing of things again. Having a fair few issues with my Gaggia which after reading countless valuable responses from here seem to not help my problem. The problem I am having is it seems no matter what coffee I am using (currently Proud Mary - Please Say Please Houseblend, roasted on the 11th of June), I am consistently getting a bitter, burnt cup. I mainly drink lattes as the shots are almost undrinkable (bitter, burnt). The Gaggia has a PID, the OPV mod, and is set to 92. I am using a single basket, with the same dose. The grinder is a EM0480, which seems to be fairly consistent in its grind, however I believe may be the underlying problem. As for how I make the coffee, I allow the machine to warm up, PF included, grind to a heap forms and level it off, tamp and insert the PF. Shots seem to blond within about 10 seconds if that, becomes watery and runs fast. So I set the grinder to one or two clicks finer, tamp the same and this then makes the machine choke and instead of espresso I end up getting more or less pure oil drips. Seems no matter what I do (reduce/increase boiler temp, change grind settings etc) all I get is either no coffee or burnt coffee. I am far from ready to get rid of the machine and I am willing to spend some time getting it right. So to all the Gaggia/EM0480 owners out there, what am I doing wrong?!

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    Senior Member Dragunov21's Avatar
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    Try a double basket and see what you can get out of it with that.

    Also, which PID are you using, out of interest? Do you have a way to measure the actual brew temperature for confirmation?

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    It sounds like it might be a roast variation that's upsetting your regular routine? The roasting house might have made a small change in their beans/roasting time/style/ new staff etc... Maybe it's worth experimenting with a lighter tamp with the grind that's choking the GC now?

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    Or a heavier tamp where it's a bit coarser?? I've noticed some fluctuations from my local roaster in recent times so much so your post could have been about my coffee at the moment! Good luck!

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    Have you always used a single basket ?. The same basket ?.

    If so, have you previously had good shots from the same setup ?.

    I no longer use an EM0480 to grind for my Classic, and I hardly ever use a single basket. The few times I tried this combination, I found it very difficult to get the grind right.
    The steps on the 480 were too wide and the single basket was too fussy. The grind, dose, and tamp all had to be just right, and even then the shot would often start to blonde at about 20 seconds or so.

    If I need a small/weak coffee (usually for a visitor) , I use a double basket and stop the shot early.

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    The Pid is just a sestos cheapy with a washer type thermocouple, if I was to measure the temp of the water from the portafilter and adjust accordingly that would be a reasonable idea?, obviously the temperature drop would be the hard thing to work out. I have had mixed successes with the single basket and I'm assuming using that in the first place could be where I am going wrong. The beans themselves I haven't tried before but it's not just unique to these beans, no matter what coffee I put in the thing it always tastes burnt and bitter. Thanks for the responses so far folks

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    If you measured the temperature of the water at the group, the temperature drop/offset would be easy to work out

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    Senior Member Dragunov21's Avatar
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    I'd sort out a way to measure discharge temperature (a bead thermocouple with a resilient sheath that you can stick on top of a spent puck is great).

    If you really want to get into it, you might have a look at this.

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    Hey folks, bit of an update, ended up trying the double basket and wow do they make a difference! Definitely a whole lot better coffee. Il see if I can get some temps today from the group head. What temperature would you all recommend? I've heard 92 is the butter zone but figured I'd get others opinions being how easy it is to set it with the PID. Thanks heaps folks

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    I use 103 degrees Celsius on my Auber PID. They suggest 102. I use a triple basket that I dose with 22.6 grams of ground coffee to yield 42 grams of espresso in about 28 to 30 seconds from start of pump. I am guessing that your shots are over extracted due to channeling and brew temp too cold. Try weighing both the ground coffee and the espresso to not exceed 50% extraction. I use a Eureka Mignon Manual grinder. A bottomless portafilter will also help in pinpointing problems in the process.

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    Jojo, 103C is boiler temp, not group temp (which is reportedly optimal at 92C).

    Colen is asking about brew (I.e. group) temperature.

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    The thing I am wondering about the temps is, the thermocouple for the PID is attached to the outside of the boiler (washer type, where the old thermostat was) and as I have set at only 92 I am wondering if by the time it gets to the group head its probably lost 10 degree or so. Will set the PID SV to 103 and see how that goes just for interest sake.

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    Apologies Jojo, I misinterpreted what Colen had meant.

    Yes, there will be a temperature difference between the boiler external surface and the group water.

    It's likely that the boiler surface will be slightly cooler than the boiler water (and the thermocouple could be slightly cooler again, depending on how it's connected). Insulating the outside should result in a measurement closer to the water temp (note, this would actually increase the difference between the measured temp and the group temp, but should result in a more reliable measurement).

    In any case, measuring the group water temperature and the allowing an offset in the setpoint to account for the difference should give you a reasonable ball park. From there I would adjust to taste (if you can notice a difference).

    Note: You might find the required offset will vary depending on ambient temp, airflow and how long the machine has been on.

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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by Colen001 View Post
    The thing I am wondering about the temps is, the thermocouple for the PID is attached to the outside of the boiler (washer type, where the old thermostat was) and as I have set at only 92 I am wondering if by the time it gets to the group head its probably lost 10 degree or so. Will set the PID SV to 103 and see how that goes just for interest sake.
    There should be an offset programmed in.

    The temperature will also drop substantially over the course of a shot.

    It's also worth noting that because of the boiler-mounted element/TC, you will need to let the machine rest for a substantialy period 5-15mins?) between shots, as once the heating element kicks in you'll have a massive temperature differential between the boiler housing and the water.

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    Idle time will definitely impact the offset. Based on Auber's testing, recovery time is about 4 minutes after pulling a shot or flushing. There are many tricks that you can do with the Gaggia Classic and they can all be found in the Gaggia Users Forum. Some members have built a thermofilter to try to measure the brew temp as accurately as possible. I have not gone that far. I just adjust PID SV based on taste and my roast profile for a particular coffee.

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    Site Sponsor coffee_machinist's Avatar
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    This thread may have some useful data for you
    deegee likes this.

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    Quote Originally Posted by JojoS View Post
    Based on Auber's testing, recovery time is about 4 minutes after pulling a shot or flushing.
    Hmmm...

    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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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by Dimal View Post
    Hmmm...

    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.
    Both element and thermocouple are mounted in the boiler housing, not the water, so there's substantial lag.

    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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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by coffee_machinist View Post
    This thread may have some useful data for you
    If you have time to look at it, I'd be interested to know what you think of the link in post #8?

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    Quote Originally Posted by Dimal View Post
    Hmmm...

    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.
    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.

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    Mal Dimal's Avatar
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    Quote Originally Posted by JojoS View Post
    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.
    Yes, you're right about that...

    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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