PID for an S24

Naki_chap

Hey C-man what is your p-stat set to on your S24?, Currently on my S26 I have it set to cycle off at 1.1 bar, that's with the hot weather here in Perth at the moment. I think it will need to go back up to 1.2 -1.3 when the weather cools. I know you had yours running a bit hot, what was the original setting ?.

Lacehim

It was cycling off at 1.1 - 1.2 when I was there the other day. Don't get me wrong C-Man, but I think your over thinking it all. Temperature surfing is useful for single small boilers like the Silvia, but with a HX, especially one with a big boiler like yours, there are so many factors in play that you'll need degree in themo and fluid dynamics to make sense of it! lol. Ask on Home Barista, I'm sure someone would work it out for you! :laugh: It may well be that the machine you have will never produce what you are looking for in the cup though, but for $100 what can you complain about? It does produce great coffee. Did you try splitting the shot? Have you tried different beans from mycuppa that can produce fruit flavours? Have you tried various doses etc? Different temps (ie don't purge for high temp, purge for low temp). Have you ever had a shot with the fruit flavours your looking for? If so, made on what, with what beans? Personally in regards to cafes I just can't find one that produces a nice consistently quality coffee but I don't get out much so maybe I'm just missing them. Maybe we should go on a Peregian coffee crawl. 😛

C-man

Kelsey do you flush the L! before pulling a shot? How can your BZ07 have a PID? how does it work? MC I think Michael answered your question, I did have it lower before and it did not help much so I cranked it back up, still mucking around with it, thinking of drilling a hole just above it so I can tweek it without taking off the cover. How is your going? Micheal, only once did I get the fruit blast I was looking for, It was with the "Rosco" grinder and I Dosed so low in a triple basket that I nearly lost the tamer! then I flushed the holy snappin duckshit out of the S24 before quickly lockin and loading I was hoping the new grinder would bring on the fruit tastes but it has not happened yet, Jeff has been sending me Fruity beans but all I get is what you tasted, excellent coffee but lacking the fruit depth.

conikal

... How can your BZ07 have a PID?

C-Man, a PID is only a thermostat by another name, same as a pressurestat is. Its more precise than a simple thermostat, has a very small dead band, and can be easily adjusted and programmed to give very accurate temp control. So, inthe case of the BZ07 the PID is replacing the Pressurestat for the main boiler. .. Which is actually a shame,..because the BZ07 has a separate set of electrical heaters in group head, which arguably would be a better application for a PID to better control (and allow adjustment) of the brew temperature. I have always thought Bezzera missed a trick there ! PS: .. i meant to say, the biggest advantage of having a PID is the digital temperature readout so you can see what temp the boiler is at.! PPS: there is another adjustable temperature controller similar to a PID with a digital readout but much simpler, called an "Electronic temperature controller" or Eelctronic thermostat, which again does the same job as a thermostat, but more precisely but without the sophistication or program ability of a PID ..and cheaper.!

C-man

thanks Cone I agree at the group head makes more sense if it is already heated separately. I see they have digital temp gauges for E61 Is they any simple mod I can do to let me control temp a little easier? Maybe just drill a hole above where the P=stat is and attach some kind of handle through to the outside so I can tweek it without having to dismantle every time?

conikal

sure , you could use an extended adjuster to tweek the Pstat,.... but really all you can do with it is take it down to the minimum acceptable for good steam ( probably about 1.1 - 1.3 bar, which is still 120+ deg C water temp) As was said earlier, the way to set up a HX m/c is to install flow restrictors in the thermo syphon loop to prevent excess temp at the group, ..AND .. a controlled flushing ritual to finally set the brew temp. Competant HX users claim to be able to set different brew temp to suit different bean roasts etc, just by a variation of the flush time. A Scace device, or a digital temp probe in the group brew path would be ideal to get a grip on this technique i suspect ! ..That is one area the E61 group has an advantage....It is easily fitted with a temp prob directly in the brew path.

UNM

A PID is more than just a thermostat. It has a feedback loop to adjust heat input dependent on rate of change and difference between current and set point temp. On an HX machine, boiler temperature does not have a direct 1:1 correspondence to the brew temp. A few HX machines idle cool and need a warning flush if left for some time. If you really want to control extraction temperature, you need a means of monitoring it at the brew head. preferably a head with low thermal mass too, so you can easily change it.

QM0996

Its all clever marketing.... Due to Hysteresis and any number of factors... A pid in most cases provides some form of display and slightly quicker response time... However that is where it stops; so many variables as to boiler size / sensor placement / heat transfer rate etc that a PID (as used in coffee machines) can not and will not control temperature. But rather provide feedback and a narrower high range. It can not cool and manage any overshoot. If they were to be set up correctly you would also need to fully spec the thermal mas and response times of the machine over many conditions and then determine a window of acceptability... If one was to look at the complicated cct around a humidicrib to keep temp set and the tolerances, it is hard to understand how a basic PID and element can be quoted as being as accurate as they are.... The temp is never a flat line... It cycles between the low at which stage the element cuts in ( but temp can get lower before the heat is delivered) and the time (rate of change) until the control device says reached temp - stop providing power ( however eat is still being generated transfered for a short time - as the element changes state). Thus while the temp of the pressure stat / PID may say cut in at X and out at Y ( there is a limit) there is also the extra swing caused by the actual physics around conduction of heat and the sensitivity of the sensor. A standard J/K thermo couple etc means that the temp accuracy is already quite large; and an element that is Fully ON or FULLY off. Until an array of platinum thermistors are used in conjunction with an array of elements so that rate of change can be measured and controlled. A PID is nothing more than marketing..... Mind you a nice blue display that tells you what you think you have is a great feature.... OR better still go to an gas heated machine; as like in cooking, a gas flame has much greater control and stability... Analogue Vs Digital... PPS. My PID is also Food safe / Organic and GF :rofl:

conikal

Hey QM, .. whilst i fully agree that a PID is wasted as a temperature controller on a HX M/c,... i do think you are a little harsh on its capabilities . They certainly are fully dependent on the accuracy and positioning of the temp sensor (but that is the same for any control system) , but they are able to "learn" the thermal characteristics of the machine, and heater response , and then calibrate themselves to minimize (even prevent) any significant overshoot and undershoot of temperature within fractions of a degree ( PID's can have temperature resolution down to 0.1 deg C.. and better). . And whilst it is also true that they only work as an "on/off" switch for the heater element, by being able,.. via a SSD,.. to switch many times a second if necessary , they can effectively moderate the power being fed to the element almost infinitely. Of course the functionality and effectiveness of the PID will depend on its type and quality, but even the more basic ($25) ones i have used included all these abilities. But again, as you said, all pretty much wasted on a HX m/c ( However the temp display and easy adjustment alone , may make a conversion worth while !)

QM0996

conikal wrote:

Hey QM, .. whilst i fully agree that a PID is wasted as a temperature controller on a HX M/c,... i do think you are a little harsh on its capabilities . (SNIP) ( However the temp display and easy adjustment alone , may make a conversion worth while !)

I agree with your sentiments without admission. The issue for me is the ever increasing belief that technology can solve all the problems, when often it only masks the root cause. And then via Google and forums it becomes undisputed fact and propagated by many that have never experienced or been involved. While some of us may understand and implement functions (technology) to resolve a performance issue on a machine; most fail to understand that there are many other factors that can be tweaked without having to over engineer the electronics and technology bling. PS. I like my display and ease of adjusting the brew boiler at a moments notice on the dual boiler; but the values displayed are just an indicator and the real reading is done via the cup :thumb:

C-man

What about just a more accurate thermometer? at least I could have something to point me in the right direction P-stat seting and flush wise

UNM

Agree with conikal. My PID made a huge difference on the single boiler gaggia and eliminated overshoot. Totally different thing on an HX machine. Also worth noting, SSRs are more inclined to fail as closed circuit than traditional mechanical relays. This has potential to burn out the element and boiler on an HX machine. A backup method of preventing thermal overheat is wise (my gaggia has a thermal fuse for just this reason). Yes - an accurate digital thermometer at the brew head should help monitor and manage temperature. Since you can get a datalogging Victor 86 multimeter for around $40 with a thermocouple, that might be the way to go.

C-man

What about to remove this Alan head screw (silver one to the right of and almost touching the blue wire in center of photo) that seems to be doing nothing and finding a digital thermometer with a sending unit to fit it to read Brew temps? sort of like what they did on HB with a E61 http://www.home-barista.com/espresso-machines/monitoring-brew-temperature-e61-silvia-t1352.html hope that link is ok otherwise mods can remove

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