Posted Thu Jun 28, 2012, 11:28am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
The machine was stabilized at 215F and then switched to 230F. The alarm function was off. After about 2 – 3 minutes, an ounce flush was done and then an ounce checked in the Styrofoam cup every minute. The digital thermometer was kept sitting in a cup of about 170 – 180 degree water which allows it to be much more “instant” in its read. I will note again that if you use Styrofoam cup temperatures, check the digital “instant” by sticking it in hot water and see how instant it is to go from room temperature to about 200F. The steel tube blunts the thermistor reading considerable, though the thermistor may be close to instant.
Between 7 and 8 I reheated the thermometer resting water bringing it back up to 185F from the 165ish that it had dropped, but the Polder also gained a little heat.
After that test I let the machine sit for a couple minutes at 230F PID and then flushed and pulled an about 2 oz shot. The temperature after 1 minute recovery in a Styrofoam cup was only about 196F, not as good recovery.
Old dog, me, needs to learn a new trick. Seems like using the higher PID set with our without alarm help could be adapted to use with more than one shot.
Now we need the thermofilter with PID data to refine the temperatures and times. I am still not real happy with the concept as it is a little too labor intensive for me and I think that timing will be an issue, though without the thermofilter, it is difficult to establish a time range that works. It would be nice to have better data than the Styrofoam cup though this gives the idea that it will work. I did not have to flip switches, only worry about timing.
Posted Fri Jun 29, 2012, 8:35am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Interesting to look at both of my tests, using PID function only or the earlier test using the alarm as a higher setpoint than the PID function. The alarm function seemed to work with the Polder temperature at about 230F and the PID function drove the Polder to about 235F. As I recall, you had Polder temperatures of about 230 - 235F on your videos. Though our Polders are in slightly different spots on the boiler, they are similar is that they are away from the heater elements somewhat blunting or damping the temperature swings of the heaters and giving an "average" boiler temperature.
PID sensors are usually placed in more responsive spots, the boiler stat location, which show the temperature bounce up and down with each heat blast. I believe that the PID sensor is recommended there for ease of placement, but also because that place was chosen for the boiler stat to be responsive. It is in a great location to sense the incoming water and to sense the heat response. That sensitivity allows the PID functions to do their work to stabilize.
I believe that someone wanting to get more than one shot could aim for a Polder temperature of about 230 - 235F with the Polder placed between the heater elements or on top of the boiler and away from the heater elements. Once the Polder is at that temperature, then you need to pull shots or flush, and add blasts of heat to keep the temperature fairly stable. Heat may be added by flipping switches or use of electronics, PID or otherwise.
Posted Fri Jul 6, 2012, 7:30pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I have been reading about PIDs and believe that there is a way to switch PID controlled temperature on the more deluxe PIDs. I have been reading the information on Auber 1/16 din units that have Ramp/Soak.
In short, the PID idle temperature can be the set temperature used for the single pull, about 215F. The ramp function would allow the PID to ramp to the next PID controlled temperature over a set few minutes and then Soak, remain at the new temperature with PID control (about 230F), for a selected time, and then return back to the original temperature, safe non-boiling idle. The ramp function would start, when desired for multiple pulls, with a button on the PID. Than is my understanding of how it works not having a Ramp/Soak PID to play with. The PID also has 2 alarms; one could control and cycle the steam temperature at say 280F, and the other for your imagination. In my case, I would still add heat with brew which seems to help impede intrashot drop, along with a blip of steam before the pull. Ramp/Soak functions are timed in minutes on the Auber unit (SYL-2352P), not sure about all brands.
The Auber site has instructions for the PID and Ramp/Soak, a little light reading, not!
Posted Sat Jul 7, 2012, 6:27pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Have a look also at the Delta DTB line of controllers if you want ramp/soak. They make dual display 1/32 DIN units with two outputs, RS485, PC interface software, and ramp/soak profiling standard. Under $100.
Here's a link to the Delta DTB pages at factorymation.com. (I have no affiliation except I am a customer). Made in Taiwan.
Posted Mon Jul 9, 2012, 7:00pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I have done a little further checking and found that I do not have the control of setting of the alarms that I want on the Auber, and the Delta only has one alarm, confirmed with JGG. I could give up steam control since I do not have it now, but time to rethink the project.
I think that it will work with the PID that I have. The old KISS principle and no Ramp/Soak. I tried to set the alarm used for turning on the heater during brew to 273F and off at 272F. The temperature was arbitrary but can also be used for steam. It may be a little low for steam, but I will probably over shoot and not completely settle anyway. One alarm could run 2 functions if I can keep the circuits separate, and I think that I can do that. One PID idle setting at about 215F and one alarm setting about 275F. The brew switch could turn on the alarm, heater, as already done, and the steam switch could also turn on the heater via the same alarm.
I decided to do a test run before trying to wire up the alarm to steam also. I am sure that steam will work if I get the wiring done and the circuits separate.
Temperatures measured in a Styrofoam cup with a preheated digital thermometer previously described. About 4 – 5 seconds of steam switch on pre-pull and then about 5 seconds rest, then pull
Idle brew water temperature PID at 215F is 200 – 201F in a Styrofoam cup. Using an actual double pull and measuring the temperature immediately after not using the “alarm brew” function gives an ending temperature ii the cup of 186F, the expected Gaggia fall.
Above repeated with the brew heater on via alarm temperature of 250F is 196F.
Above repeated with the brew heater on via alarm temperature of 273F is 199 – 200F.
Finally a double pull of about 2 oz. in 25 sec followed by a 1 minute wait and then the Styrofoam cup test, alarm temperature of 273F, gave a cup temperature of 199 – 200F. I happened to notice the Polder temperature this time and it was the magic 230F.
It appeared that though the heater was on full with the brew switch, that with the incoming water cooled the boiler so that even the PID sensor did not reach the alarm set temperature.
This may need a thermofilter to actually confirm it. I will continue to see what I get and hopefully can also somewhat confirm with taste testing and repeatable Styrofoam cup temperatures.
Posted Fri Jul 13, 2012, 10:22am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I now have the Auber 1512 wired in with PID function to control the boiler idle at 215F. The Alarm is set to cycle at about 275F and comes on with the brew switch so that heat is added pulling a shot but shut off and back down to idle when the brew switch is off. That is as before, except for the alarm temperature. Now the steam switch can turn on the alarm function for steaming and cycle the temperature at 275F. All of that is on one PID and one SSR. The brew switch and steam switch physically turn on cell phone chargers to get DC voltage which is the kept separate by diodes so that all can go to one SSR and not interfere with each other. The mechanics work fine and the steam switch could easily be an on/off switch for a 9V battery instead of the cell phone charger. The brew switch is running AC and that needs to stay hooked up. No extra switches and it goes back to idle temperature setting when not brewing or steaming, for safety.
If I started over on this, I would get the generic 1/16 DIN PID with output to SSR and 2 alarms. That way I could have different steam and brew temperatures. I may switch to the Auber 2362.
I have started using the system and it works, but is certainly not automatic. I can actually end a shot higher that I started, intra-shot rise, not drop. I am beginning to collect information on pulling shots and getting second pulls. I am trying to learn timing, volume, vs. temperature. Consistency will be difficult. It all worked on the first try on the post above, but not so simple or reproducible each time.
The better news is that steaming and microfoam got easier and better. It is much better for me not to be temperature surfing the steam switch while steaming. PID alarm steam control is much nicer than I thought. Very easy to add to the PID basic system.
Posted Tue Jul 17, 2012, 12:37pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I am beginning to use and understand the system. As noted previously, either the brew switch or the steam switch cause the alarm circuit to energize the SSR and the temperature set is about 275F. The steam function is straight forward and works great allowing me to concentrate on steaming milk instead of also controlling temperature.
The idle temperature is 215F and gives a Styrofoam cup temperature of about 200 - 201F. I hit the steam switch for about 3 seconds pre-shot and then rest 2 seconds and then the brew switch. With the PID set up as above the main variable is flow of water into the shot and boiler. The parameters work great if I get about 50 ml brew. Much less and the boiler temperature gets too hot. 25 seconds of heater run needs an input of about 50 – 60 ml of water to absorb the heat. I can watch the PID temperature climb to about 265F in that time, with that brew volume. Note that it does not reach the alarm limit of about 275F because of the cool incoming water. If the temperature gets higher than 265F it will usually mean that the brew volume is down, too much heat for the amount of incoming water. If the brew flow is over 60 ml, then the temperature will be low, less than 265F, too much cooling water for the 25 seconds of heat. If the flow is low and the temperature high, I can adjust that by removing the PF and doing a couple seconds and about 10 – 15 ml quick flush just after the shot. In essence make up the low volume. If the temperature is low, then a couple seconds of heat from the steam switch. Adjustments need to be made immediately after the shot, and then the next shot will be ready in about 1 minute post finish of the shot. This seems to work, checking with the Styrofoam cup temperatures and by taste.
Styrofoam cup temperatures are not a very scientific way to document, but it is what I have. The system still requires quite a bit of experience to adjust the temperature and will change mainly with flow rate. Presumable if the pull volume is changed, the brew switch temperature could be changed to accommodate, but not easily when the one alarm is also running the steam. If more than about 60 ml brew volume was desired, then this system would need a longer steam switch blip as it does not reach the alarm temperature now, and would be cooler with more inflow. I doubt that more than 60 ml would be desired for a double, so not a problem. If only 40 – 45 ml was desired, then the system would be too hot for the next double. That would require a cooling flush after each pull when it was going to be followed by another pull. The other option would be 2 separate alarms so that the brew alarm temperature could be set at a lower temperature and the steam temperature not changed. I am trying to confirm that the Auber SYL 2362A2 will do that.
Posted Sat Jul 21, 2012, 7:04pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
I now have the Auber SYL 2362 1/16 DIN PID with 2 separate alarms. Out with the old and in with the new. I just rewired up the new PID and it does exactly as wished. I have an idle PID set temperature at 214F, a brew - alarm 1 which runs the heater to a set alarm temperature, 255F, and a steam alarm 2 at 275F. I will need to generate some numbers. The old PID is now set to read K thermocouples, with no output, just a "k" temperature.
Interesting thing that I found already; I slid the K thermocouple up along the PF in the groove so that it was against the group head. It took about 20 minutes to stabilize and that was at 202F, a couple of degrees higher than I thought, PID at 214F. I also did that with the Polder thermistor bead at the same time and got 201.5F. I solder spliced in a length of 26g wire so that the Polder now has about 18" of lead. I could move it around in the Gaggia innards. The Polder thermometer is quite versatile out of the stainless tube. It does need to be dry however.
I have only seen a picture, not actually had one in hand as a part. Assuming that I can clamp and drill it ok, can the brass group head be drilled with say about 1/8 inch hole for 1+ inches in and still be in brass and not penetrate the boiler cavity? Would a thermocouple in the group head give a useful temperature? Or, if one could seal a penetration into the boiler, then you could get water temperature.
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