Posted Sun Jun 17, 2012, 3:01pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I don't think you are following what I'm suggesting ... or I am not understanding your response.
Even though you are getting a good starting temp with your old method of setting the PID to 215F and waiting 10-15 minutes --- I'm suggesting as an experiment that you try something else instead.
First of all ... I'm suggesting that you disable the alarm function you have that turns the heat on when you start the shot. My suggestion won't work if you have that interfering.
Second ... ignore the Polder thermometer for now (you have it mounted on the top of the boiler so whatever it is reading means nothing to me for this experiment).
Third ... once your PID is simply trying to hold the temp at your set point, try setting it to 227F (or even 230).
Fourth ... With the PID set to 227F and having been idling at that temp for 3-4 minutes, try flushing 1oz into your cup and then setting a timer and watching for 60 seconds to go by and then measure the temp at the brewhead in a styrofoam cup test for about 1oz of hot water.
Fifth ... wait another 60 seconds and try the styrofoam cup test again and this time hit the steam switch for 4 seconds before you start the cup test.
I don't think the 4 second steam switch will make any difference with a styrofoam cup test ... the water has no restriction so it is flowing much faster than a real shot ... but if you find the PID setting and wait time between shots (or after a flush) to get your ideal brew temp ... then I think the 4 second steam switch before the start of your shot will help hold the temp up during the last half of your shot.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sun Jun 17, 2012, 3:28pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
AndyPanda Said:
I don't think you are following what I'm suggesting ... or I am not understanding your response.
Third ... once your PID is simply trying to hold the temp at your set point, try setting it to 227F (or even 230).
Fourth ... With the PID set to 227F and having been idling at that temp for 3-4 minutes, try flushing 1oz into your cup and then setting a timer and watching for 60 seconds to go by and then measure the temp at the brewhead in a styrofoam cup test for about 1oz of hot water.
You were correct, I did not get that out of the prior post.
I stilll am not sure on one point. Are you saying to let the PID run the machine to 215 and stabilize, and then change the set to 227 and begin? Or, are you wanting me to just set it to 227, instead of 215, and not let it stabilize?
I am willing to try this but I will have to keep pulling shots or shut it off. the PID driving it to 227 may, perhaps should, give me steam if it stabilizes there. I cannot imagine this not working as it is essentially what you are doing. I do not believe that I can leave the PID to idle there. Give me a few days and I will see what I get.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sun Jun 17, 2012, 3:43pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
What I would like to do is use the PID to stabilize the temperature so that I can pull a shot with minimal manual manipulation. Mostly I do a pull of one double, and that works fine if the machine is stable at 215 and I hit the steam switch for a couple second and then pull. I doubt that the alarm function puts in enough timely heat to help the intrashot temperature, but is adding heat to the boiler for the water for the next shot.
I would like to be able to have the PID do the work of adding the heat for the next shot. If I can leave the idle at 215, and use the alarm, then I can pull the next shot with the temperature of the boiler still up, putting heat into the water, or if I want to wait, I will return to 215 at idle. No flush and no switches other that a starting bump ot temperature with the steam switch. Because I time the heater off of the brew cycle, the heat goes in at a different time than your method. I do not know whether I can make the PID and alarm method work. I am reasonably sure that I can make your suggested use of the PID work as it is essentially your method with little actual use of the PID. It is a place to start however and I am willing to try that.
Posted Sun Jun 17, 2012, 5:17pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I'm sure some of the confusion is that I don't have a PID so I am not sure what features are available to you. But if I were designing a PID type of device for a Gaggia --- I would want it to have more than one setting that I could choose quickly.
I suppose if you are only going to pull one double shot --- you would just leave it at 215F but disable the alarm thing you have now and instead just hit the steam switch for 4 seconds and start your shot.
But if you knew you were going to make a series of shots for guests --- you could shift the PID to your secondary target temp (227F). I wouldn't let it stabilize there (doesn't that take 15 minutes? according to Auber?) I would just wait some set amount of time (say 60 seconds as a test to start).
Again ... without having a PID to test, I just don't know how they behave when you increase the set point. I don't know if they hold the heat on solid for a few seconds and then start cycling or do they cycle gently until they gradually get up to the new set point?
I'm hoping that when you test -- say your machine is sitting idling at 215F now --- set your PID to 227, flush 1oz to simulate having pulled a shot and hopefully the PID will start reading 227 on the PID display within 10 seconds or so and just be hitting the heat for a split second every second or two ... wait another 40-50 seconds and do a styrofoam cup test. You'll have to experiment --- you may find the set temp for the PID needs to be 224F or 230F --- and you may find the wait period is 90 seconds instead of 60 -- or maybe 30 seconds is the magic number. It all depends on how your PID behaves when you change the set temp.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Sun Jun 17, 2012, 10:10pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
AndyPanda Said:
I'm sure some of the confusion is that I don't have a PID so I am not sure what features are available to you. But if I were designing a PID type of device for a Gaggia --- I would want it to have more than one setting that I could choose quickly.
I suppose if you are only going to pull one double shot --- you would just leave it at 215F but disable the alarm thing you have now and instead just hit the steam switch for 4 seconds and start your shot.
But if you knew you were going to make a series of shots for guests --- you could shift the PID to your secondary target temp (227F). I wouldn't let it stabilize there (doesn't that take 15 minutes? according to Auber?) I would just wait some set amount of time (say 60 seconds as a test to start).
Again ... without having a PID to test, I just don't know how they behave when you increase the set point. I don't know if they hold the heat on solid for a few seconds and then start cycling or do they cycle gently until they gradually get up to the new set point?
I'm hoping that when you test -- say your machine is sitting idling at 215F now --- set your PID to 227, flush 1oz to simulate having pulled a shot and hopefully the PID will start reading 227 on the PID display within 10 seconds or so and just be hitting the heat for a split second every second or two ... wait another 40-50 seconds and do a styrofoam cup test. You'll have to experiment --- you may find the set temp for the PID needs to be 224F or 230F --- and you may find the wait period is 90 seconds instead of 60 -- or maybe 30 seconds is the magic number. It all depends on how your PID behaves when you change the set temp.
The inexpensive PIDs are universal, adapted for espresso, not designed for Gaggia. Auber puts in some numbers and possible some functions, but they are generic, I believe.
I can probably leave the alarm function or not. It may not affect the intrashot, but add heat for the next. If no next, then the temperature slowly declines back to 215F. I can leave it off for a test.
The single PID set temperature is fairly easily changed by pressing the up or down arrow once per degree, or holding it. The PID will start reacting to the new set temperature whether a shot is pulled or not. The noted 15 minutes was time for the whole machine to stabilize from being off, room temperature, to the set of say 215F. Shot recovery is about 4 - 5 minutes, and changing temperature 10 - 15 degrees might be more like between shots, but that is a guess. Not sure why you want me to pull a shot, that will make more heat demand, but I can try it your way.
As long as you are changing set temperature within the "P" range, and this is, then there is no solid blast of heat, just gentle blips to raise to the new set temperature. I could probably take the alarm set point off of the brew switch and put it on an added switch. This would allow the switch to a second non-PID set point with a blast of heat. I may try this at another time, but I do not want another switch to play with. I am trying to keep it simple.
I am still planning on trying this when I get time. I think that I understand what you want, but not entirely clear on the why of parts of it.
Posted Mon Jun 18, 2012, 8:22am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
The why of it ... there are two completely different concepts. The old concept with the PID is let everything stabilize (so the water inside is about the same temp as the boiler metal).
The new concept I want you to test is that the water inside is never as hot as the metal of the boiler - by design - so the boiler is about 10-15 degrees hotter than you would choose for the old way and the water inside is a little cooler than the old way. This way the hotter boiler has a better chance of heating up the water as it is being pumped in.
But it requires that you have pulled a shot or flushed 1-2oz in the last 90 seconds or so - otherwise the water inside the boiler may be too hot (just like in an HX machine the water standing inside the HX tube will be too hot if left to sit there for several minutes).
I know you can get one shot at good temps using the old way - letting everything settle to equilibrium at 215F ... but I think you will get better temps at the end of the shot AND be ready sooner for a second shot if you try my way.
Mainly I'm just curious to see your results - I'll have to order a PID one of these days and then I can test it myself - but I'm starting to think I should design my own Gaggia bolt-on controller designed just for the Gaggia since it is so different from all the other single boiler designs.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Mon Jun 18, 2012, 7:31pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
So you really want a 2 temperature set up, idle and possible single pull, and then flip a switch and have it try to get to the second temperature while you are timing shot pulls based on the moving temperature like you presently do? If that is the correct understanding, then perhaps the PID box, not the PID function can do that in a different way than I am currently doing.
From what I understand, some PIDs allow you to use the PID function and an alarm function, or 2 alarm functions. The 2 alarm functions could be 2 different temperatures, neither of which would be damped or controlled by P, I, or D. A high and low "alarm 1" could be one degree apart at say 215, and "alarm 2" high and low could be one degree apart at 227. Those are full on and off functions and as a consequence will have some overshoot and oscillation, but not of much consequence unless you are trying to dampen and not overshoot. This would function more like your manual switching. If you want this flexibility, I believe the Auber Syl-2362, 1/16 din, does this. You could confirm with a phone call to Auber. The features section describes this and the "outy" section sounds like it is a selectable feature.
The PID function is mostly good for the stable set temperature and idle which you do not really need, or perhaps want. That said, the low alarm of 215 would let the machine idle with on and off at say 215 and 216, but would still allow long unused idle time. There would be some temperature oscillation getting there.
I think that I am beginning to understand our different approaches. I am trying to use the PID function, and you are less in need of that and more in need 2 set temperatures, and have less concern about damping.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu Jun 21, 2012, 2:23pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I finally got a chance to try the PID with the second set point as described above by Andy. I first thought that I would disable the alarm and then raise the PID function to a second point. After some thought, that will not give the desired test. That would have the new point arrived at softly without overshoot, the PID method.
I decided to try what I believe you wanted from the beginning Andy. I pulled the alarm function off of the brew switch and put it on a separate switch. I can now idle at 215F PID function regulated and then with another switch, have the alarm function drive the PID to a second set. This is full on and off function.
I set the second temperature at 230F and tried waiting a short while and then realized that the PID reading and Polder were both going to be about 230F without the benefit of incoming cool water in the boiler, and yep, steam shot. Fortunately I avoided anything other than red skin on a finger as I suspected that it was coming. Almost caught the steam shot in the Styrofoam cup.
I lowered the PID temperature to 214F after rechecking the Styrofoam cup temperature and found 201 – 201.5 baseline.
PID alarm to on below 222F and off above 223F, but of course it overshoots as alarm function is not "PID" regulated.
My current Styrofoam cup method involves preheating the “instant read” digital thermometer in a cup of hot water for all tests. In is far from “instant” trying to get to 200F from room temperature. It is very easy to get variable readings if the thermometer is not hot. The cup temperature is not stable for long enough.
OK, I was really trying to get some data, to follow.
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,191 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu Jun 21, 2012, 5:50pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
At baseline and then at one minute intervals, about 1 oz of brew water was pulled to measure cup temperature. This took about 3 seconds, the flow rate for an unobstructed pump is in the 600ml/min or 10cc/sec and confirmed by noting roughly 1 oz in a shot glass, and that 3 seconds is included in the 60 second interval pull to pull. I quickly found that I needed to start with a pull, flush, at baseline, or the first pull would be too hot. It is very easy to overheat without a flush to get some cool water in.
Sorry for the alignment below, it does not show as it looked when I put it in.
I noticed that though the Alarm temperature is about 223, the PID temperature and Polder are higher. Perhaps it is easier to overshoot the Alarm upper temperature than overshoot on the cool side when it is this close to the baseline.
What does all of this suggest? Andy’s method will work using the PID, but it still takes a fair amount of user input. You need to switch and watch time intervals, and do not leave the switch on and forget it. I am sure Andy can further comment, at least I am looking forward to that.
Posted Fri Jun 22, 2012, 11:43am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Thanks for testing and posting - but I think you keep misunderstanding my suggestion. I want you to try it without using that alarm function at all.
I simply want you to set the PID to a higher temp (since you are worried about steam, try 222-224F) - do a cooing flush (about 1oz) - wait 60 seconds and pull a shot - measure the temp in styrofoam cup. (please don't burn your fingers)
If that shot is too cool set the PID a little hotter (say 226F) and test again --- not sure what the target temp will be on your boiler, probably not the same as my target boiler temp. But if that shot was too hot ... then try a cooler temp or a shorter wait time after the cooling flush (or a larger volume cooling flush).
No need to do the 4 second steam switch prior to hitting the brew switch since that only affects the temp 6-7 seconds later and pertains only to an actual shot that is flow restricted by the coffee puck - with a styrofoam cup test there is no resistance so you will flow a lot more water in a short period - we only care about the the temp of the first 1oz or so into the cup probably 2-3 seconds of pump. Hmm -- or maybe you do want the 4 second steam switch anyway - it shouldn't affect the temp in the styrofoam cup test but it does contribute to the recovery time routine so maybe it is needed for this test.
If any of the above seems to work (if you are able to get 198-202F into a styrofoam cup repeatably with a set amount of wait time after a flush) - then try making a real shot of espresso with the same routine (with a real espresso pull, this time do the 4 second steam switch just before you start the shot).
Thanks for testing these ideas. Ideally it should be just as simple (really it should be much more simple since the PID will do most of what I'm doing) as kicking the PID up to the hotter temp and remembering to do the 1oz flush and wait time (just like the HX folks do). I don't expect it to be a whole complicated routine that would make it not worth the effort when you just want to enjoy a nice espresso.
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