# Experiences with PID on Gaggia Classic



## maarten_booij (Jan 28, 2011)

Hi everybody!

For a while now I have been wondering whether or not I should put a PID kit on my Classic. Auberins.com has several types, with or without pre-infusion, which sounds very interesting. The kit is about 150 pounds, which is worth it for me to get closer to the perfect shot, but it would be a waste of money if it doesn't have a great influence.

Do any of you have experience with PID-ing your Classic? Or any experience with the kits from Auberins?

Any help is much appreciated!


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## ChiarasDad (Mar 21, 2010)

I have the Auber kit (I guess mine is without preinfusion, or at least without controllable preinfusion) for the Classic, and I love the results. Not only am I getting better shots in general, the ability to adjust the temperature differently for different coffees has opened up enjoyment of quite a few coffees that I probably would not otherwise have enjoyed.

The kit is not difficult to install, but it is a little bit fiddly and you should allow some uninterrupted time, and just as importantly a good light source. The design of the kit routes the entire mains voltage out into the little PID box, so you will want to be quite careful that none of the wires you install therein accidentally touches the case.


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## fatboyslim (Sep 29, 2011)

Just out of interest ChiarasDad, how many degrees variation is there when you brew a shot according to the display?


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## RoloD (Oct 13, 2010)

I also have the Auber kit. Very straightforward to install and use and as, ChiarasDad says, not only does it stabilise temperatures but you can adjust the temperature at the click of a button. Thoroughly recommended.

The pre-infusion and steam control models were not available when I bought mine so I can't comment on them.

(only thing is, I don't know why people mount the control horizontally. It makes much sense to me to mount it vertically - it looks better and is still perfectly easy to read and use).


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## oldman (Dec 1, 2011)

Do you put a circuit breaker on the plug for safety?


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## RoloD (Oct 13, 2010)

oldman said:


> Do you put a circuit breaker on the plug for safety?


 The plug is fused - why does it need a circuit breaker?


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## oldman (Dec 1, 2011)

Fuses don't melt fast enough to prevent electrocution. Fuses in plugs are intended to prevent house fires e.g. faulty wiring causes the cable to draw excess current, hear up and start a fire. You need an RCD device to cut out fast enough to prevent electrocution. Modern houses with new will have RCDs installed as the central 'fuse box', but even those I wouldn't necessarily rely on for a self-wired device like a PID installation.


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## maarten_booij (Jan 28, 2011)

Thanks for your feedback guys. I guess I'm going for a PID, still doubting about the pre-infusion, but for 20 dollars extra, I might as well...


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## rodabod (Dec 4, 2011)

I was considering PID'ing my Classic, but having read a little, it seems that the Classic is further limited by its small boiler which can't cope with the influx of cold water at the start of a pour (PID'd or not) which results in falling temperature.

http://coffeesnobs.com.au/YaBB.pl?num=1118552887

I wonder if I might be better learning when to turn the machine on, according to the heating cycle, ie. by keeping an eye on the brew-ready light.


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## SteveyG (Dec 24, 2011)

oldman said:


> Fuses don't melt fast enough to prevent electrocution. Fuses in plugs are intended to prevent house fires e.g. faulty wiring causes the cable to draw excess current, hear up and start a fire. You need an RCD device to cut out fast enough to prevent electrocution. Modern houses with new will have RCDs installed as the central 'fuse box', but even those I wouldn't necessarily rely on for a self-wired device like a PID installation.


The Classic is a Class I device, so as long as you ensure the case is correctly earthed, the risk of shock is no greater than it was before any modifications.


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## fatboyslim (Sep 29, 2011)

I am at this very moment weighing up the choice between PIDing my Gaggia Baby Class or investing in a new machine.

From what I can tell from that chart, regardless of what temperature you set the controller too you still see a big drop in temperature as you brew the shot due to the small size boiler on most small domestic gaggias?

Would this have a profound effect? Is it actually worth it on my second hand Baby class?

The Nuova Simonelli Oscar is just so darn tempting at the moment.


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## jimbow (Oct 13, 2011)

I wonder whether this is a feature of brew boilers in general and whilst bigger boilers are more thermally stable and lessen the effect, cold water entering the boiler will affect the recovery time if not the shot currently being brewed. I know La Marzocco and even Breville, on their domestic dual boiler machine, have started to run the brew boiler feed through a heat exchanger in the steam boiler to preheat it prior to entering the brew boiler to prevent this effect. Lets hope this starts appearing on more machines in the future.


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## rodabod (Dec 4, 2011)

Sounds like pre-heating the water in a PID-controller machine is the simplest answer.

http://www.home-barista.com/espresso-machines/preheating-incoming-water-on-gaggia-classic-t2794.html

However, you have to appreciate the elegance in the simplicity of the original design, and I wonder if it's best to leave it as is. After all, I can currently consistently make very enjoyable drinks from it. I usually operate the pump when the brew light goes out, fwiw.


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## jimbow (Oct 13, 2011)

Looks like a thermoblock passively heated by the boiler - that should certainly work where there is not a second boiler to immerse a heat exchange within. Very impressive stuff!


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## ChiarasDad (Mar 21, 2010)

fatboyslim said:


> Just out of interest ChiarasDad, how many degrees variation is there when you brew a shot according to the display?


 Assuming you mean the temperature drop from boiler to brewhead, I don't have equipment to measure it directly myself, but they supply a helpful table (along with the methodology used to compile it) of PID temp vs. brew temp, specifically for the Gaggia Classic. The delta varies with temperature - it's not a straightforward "subtract N degrees from PID temp to get brew temp" formula.

The table seems reliable enough that when I use it to brew according to a roaster's suggested temperature (when such is supplied), I think my own evaluation of best temperature has always been within 1 degree C of that. Often it's bang-on, as was recently the case with Red Brick.


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## maarten_booij (Jan 28, 2011)

I've been thinking of a passive pre-heat as well, like this one:

Click Here

After reading a couple of these posts, I am doubting though. 9 bar (possibly 15 bar if not OPV modded) is a lot of pressure, so the connections need to be perfect. Have also been thinking about using parts from a pc water-cooling system, but again I'm not sure if these are strong enough to withstand the high pressure.

On the other hand, spending 1000 pounds on a new machine is out of the question atm as well, so this cheep mod is interesting...


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## ChiarasDad (Mar 21, 2010)

SteveyG said:


> The Classic is a Class I device, so as long as you ensure the case is correctly earthed, the risk of shock is no greater than it was before any modifications.


 However the case of the PID itself will not be earthed, if you attach it only with the supplied velcro. You'd have to supply your own earthing lead from PID case back to the main unit for that. So I think the suggestion of an RCD seems well-considered.


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