# The Gaggia Classic PID Reference Thread



## PACMAN (Feb 11, 2021)

After having bought and fitted a PID to your Gaggia Classic, it then needs to be set up to function correctly - but what settings to use and how do you know if you are in the right ball park after an autotune? I'm hoping to collect as many PID users' settings to help out those new installers, or those who've just bought a second hand GC with a PID fitted and want to check them against good or reference settings. There are many variables that will affect the PID settings so I'm also hoping to capture these as well. I might miss some info initially (please let me know) but I'll try to update this thread with all new info presented. Whilst I appreciate some info is not actually what it is, it probably the easiest way to represent - ie Boiler size - mines a 1425W GC but the pump takes 65W so the actual boiler size is 1380W. If you don't know the info, please leave a couple of ?? to identify where info is missing. I can't seem to add a table, so it will need to be carefully formatted in order to keep it easy to read.

PID Types - XTC-7100, MrShades and Auber are, I think, all the same type.

Showerhead Holder type - Aluminium, Brass, Stainless

Owner PID Type GC Rating Showerhead Holder type Thermocouple Sv P I D Psb

@PACMAN XTC-7100 1425W Aluminium pt100 93 4.5 20 5 -8


----------



## PACMAN (Feb 11, 2021)

Does no one else want to share their settings?

From another old thread I've found some values from @Muratoztto add to the (small) list.

@Muratozt XTC-7100 ?? ?? ?? ?? 2.4 40 10 ??


----------



## PACMAN (Feb 11, 2021)

Found another one!!

@greymda XTC-7100 ?? ?? pt100 102.5? 4.5 83 20 0?


----------



## coffeefalafel (Apr 26, 2015)

I have a PID on one of my classics and to be perfectly honest don't understand how it works (or is meant to work) it does some odd things on occasion but I never got around to figuring it out.

I'd tell you if I knew what I was looking at!


----------



## PACMAN (Feb 11, 2021)

@coffeefalafelNo worries, I meant to write another post the other day about how to interrogate it, so here goes!

To interrogate your PID (as long as it is an XMT-7100 type (as used by Mr Shades, though I think some of his early ones might not be this type), press the 'Set' key which should then bring up 0000 on the display. Using the right and arrow and the up and down arrows, enter 0036, then press Set again. You should now be showing P in the display. Press Set to find out the value, then press Set again to return to the letter P, press the up arrow (I think) and it should then show I, repeat as before and again to get d. Keep pressing the up arrow until you see 'End' in the display. Press Set here will exit you from this menu.

Now, press 'Set' again and enter 0089, navigate to the PSb value and press 'Set'. Exit this menu as previous.

Now, press 'Set' again and enter 0001, navigate to Su - this is the temperature you want the PID to stabilise at. It is the 'Set Value' but the PID display can't display a v so displays a u instead, Exit this menu as previous.

If you want to watch a video of it (not mine) - here's one:


----------



## Muratozt (Mar 27, 2021)

Hi, I confirm that the setting I wrote before (as PACMAN quoted above) give a shot stability around 2 degrees Celcius for single and 3-4 degrees Celcius for double shots in 20-25 seconds. P:2.4 - I:40 - D:10. I wrote this message just to add Souf value: 0.2 which I believe is important as well if you are using the same controller as mentioned here (XMT 7100). Just to remind once more, using autotune gave me temperature instability up to 10 degrees during brewing. This is because autotune done during standby mode does not provide sollution for brewing which need prompter and stronger response from controller.

I finished installation of steaming system as well yesterday, using a second SSR AA type and I am ready to give answer to any questions regarding to this subject too.


----------



## robmack (Apr 2, 2021)

Found settings on HB: https://www.home-barista.com/espresso-machines/rancilio-silvia-too-hot-with-pid-t2100.html#p19362

Erics XTM-7100 ??? ??? pt100 109 2.1 28 7 ???


----------



## yardbent (Aug 8, 2015)

Owner PID Type GC Rating Showerhead Thermocouple SV P I D Psb

@yardbent XMT-7100 1425W Brass Pt100 90.0 4.5 64 16 -8

AH1=136.7
AL1 =170.0

Adrian advised--

SV = 93.0 is a good starting point&#8230; 
for lighter roasts you can often go higher - up to 96. for darker roasts go lower, down to 88.
( I'm using med-dark espresso beans so lowered SV to 90.0deg C )

AH1 and AL1
if you want more steam power then increase both by 5deg C

regards


----------



## vzs (Apr 8, 2021)

Hi guys,
I have been following this topic for a while but I just had time to install the PID. I have a 2018 classic "pro" model.
Owner PID Type GC Rating Showerhead Holder type Thermocouple Sv P I D Psb Souf
@vzs XMT-7100 1200W Stainless steel PT100 94 4.8 16 4 -8 0.3

I got these PID values after Autotune was done. I am considering to finetune these values in the future. Now I have a 2-3°C deviation during brewing, copper tubing will increase thermal stability.


----------



## larkim (Sep 3, 2018)

Sorry to resurrect this, but as I'm a newbie to PID settings I hoped this thread would be useful for me. As the XMT7100 autotuned itself I did wonder whether autotuning from cold was really relevant, and that it should tune itself during brew instead as that is the period of time when we want to earn temp stability.

I'll post back later with the settings that are in place but have observed in the last couple of days of use that the temp during brewing drops about 8-10degC so hopefully with some of the settings on here I can get a tighter range of temps in use.


----------



## Bhodgson (11 mo ago)

I did my autotune after the boiler came up to the set temp. No idea if that’s the normal method. But, as an exercise logic, it makes sense.
do you have a way of measuring the water temperature, at the basket?
I found 109c, set on the pid, equated to 96 at the bascket.

dropping 8-9degc seems an awful lot, to me. Mine drips from 109-108, with a lowest of 107.9, during a pull.


----------



## larkim (Sep 3, 2018)

I've nothing other than a digital meat thermometer to measure at the group head. Tried the settings that vss used about and still got 10degC reduction in temp recorded by the PID readout. Though I'm confused by the -8 setting for PSB which (if I understand correctly) means if I want 96deg (say) then the sensor can measure 104degC; is that right?


----------



## Bhodgson (11 mo ago)

That’s, roughly, the figures. But, unless you actually measure the water temp, at the basket. You’re always guessing.

I have a flexible probe, fitted to my Fluke, that lets me measure the temp in the basket. You’ve just gotta make sure the probs tip is not actually touching the basket.

I still can’t track the 10 degree C drop. You’re only taking, say, 32mm out of the boiler at about 1mm per second. The water, after an initial drop, should actually be rising by the time the shot is pulled.
mine doesn’t drop 10 degrees C. When I pull an empty basket shot, to warm my cup. It gets to, about, 106.7c then.


----------



## larkim (Sep 3, 2018)

I'll take some videos tonight for reference. There'll be some other setting I can tweak to get it right I'm sure!


----------



## Bhodgson (11 mo ago)

I’ll try and do the same.


----------



## larkim (Sep 3, 2018)

I may get rid of the -8 offset and see what that does. I'll also record all of the other settings and see what they say, and perhaps reset to factory details all round before experimenting with non-autotuned settings from the range of options listed on this thread.


----------

