theMac Senior Member Joined: 14 Feb 2012 Posts: 6 Location: everywhere Expertise: Just starting
Posted Sat Jul 14, 2012, 1:02pm Subject: Silvia with Auber PID and Determining Offset
I have done a search on this on here and none of the techniques people discuss to determine the offset for my machine and PID seem to be working. It is the Auber PID with pre-infusion and steam control on a V3 Silvia.
The first technique I have seen people using is taking the temp of what the water is when it goes from the grouphead into a styro foam cup. I don't have a styro foam cup, but taking a reading in a regular porcelain cup I have never been able to get an instant read thermometer (Thermapen) to read anything over 186F.
I recall reading someone talking about turning up the temp on the PID until when you turn on the group head to brew it puts out steam, which would mean you were actually brewing at 212F. So if I got to 230 when I produced steam, my offset is 18F. I got up to 233 and still wasn't blowing steam...but I wasn't sure I was letting the temp stabilize long enough, so I didn't want to continue bumping the temp up and mess the machine up. How long should I let the temperature stabilize at a new temp? When i bumped it up to 225 for example I turned the group head on the first time I saw 225 register on the PID. I happened to leave the room when I went to 231 and when I came back the PID was reading 233 so I waited and it went down to 230 and then back to 231, so then it made me wonder how long I should wait after I changed the temp. This might have been why I wasn't blowing steam...I wasn't waiting long enough on each new temp setting. Also with this technique, logically I would think I should only see steam at the very beginning of the pull since the the temp immediately starts dropping, is this a wrong assumption?
Is there a technique I am not aware of? A lot of the posts I found were from 2008-2010. I couldn't find anything asked about this in the last couple years.
I saw several people in the discussions questioning why it matters if the shot tastes good so I thought I would just answer that now to save the question. I want to know the offset so that if I switch beans and they have a recommend temperature to roast at I know what I need to change the PID temp too.
Posted Sat Jul 14, 2012, 1:41pm Subject: Re: Silvia with Auber PID and Determining Offset
I have a Gaggia with an Auber PID, so I do not have a simple offset number. The machine has a moderate amount of mass, so the warm up should be about 30 minutes. It could take several minutes to restabilize when you change temperatures. The PID temperature is the temperature of the PID sensor and will seem to stabilize quickly, but not the mass of the machine and water.
A Styrofoam cup or even paper type cup capable or holding hot water could be used for the test. It must have very low mass and some insulation. Buy a styrofoam cup, or a drink in a cup and make it easy. Your cup is literally absorbing the heat before you can get the temperature. I have to pre-warm the digital thermometer to about 170 - 200F and keep it hot to get a good reading as the temperature will drop quickly in the cup while you are trying to read. It will peak and drop while you watch. I have played with the Styrofoam cup quite a bit lately. The stainless steel sheath/probe makes the "instant" read, not. Perhaps Thermapen is quick enough.
If I let the machine stabilize and repeat the tests I can get fairly reproducible results. All that said, Styrofoam cup is a decent approximation, not near like a thermofilter. It should work for what you are doing.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 8,204 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Vene. A1, La Cimbali M32 Grinder: Azkoyen Capriccio, Major Vac Pot: 40s era Silex Drip: Msl. Com. brewers Roaster: gave it a try, decided no
Posted Mon Jul 16, 2012, 7:02am Subject: Re: Silvia with Auber PID and Determining Offset
You might just want to look at a couple of threads I started on Sylvia rebuilding and PID installation. A quote from one of them gives my offsets as advised from Auber. A partial quote. follows. The links are not directly related to your issue but may be interesting to you as you have a Sylvia and these threads get into the inside of her. http://coffeegeek.com/forums/espresso/machinemods/559841 Click Here (coffeegeek.com)
Craig, First. The offset brew temp when my PID is at 221 is brewing at around 204 according to the temperature relation in Fahrenheit chart supplied with the Auber kit. This was developed by them using several machines of various ages over several tests and measured with a SCACE device and then averaged so that is the long way to say "ball park temp" LOL
The PID unit is a single line one so to see the set temp, you need to go into the settings, I do like the two line display units more but the single line fits nicely between the steam wand and the group head, adding nothing to the sides or top of the machine.
The default temp for the steam came set at 286 which would be logical due to insurance and fear of suing factors. If it came at the default temp for the machine, they are not pushing the design of Silvia so they are off the hook as far as that goes.
The steam setting is "automatic" all I do is just turn on Silvia's normal steam switch and the PID does the rest and stops at 286. When I have finished the 6 oz of milk, it is down to about 260. The advertised advantage of having a PID on the steam side is not to stabilize the steam temp or to make it easily adjustable (though it is), rather it is to make the heater more responsive to the demand for steam. Like I said before, the heater comes on nearly at the same time as I open the steam valve so the deadband must be no more than 2 F for steaming, I would guess.
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