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  • #16
    Re: PID on a HX machine?

    Originally posted by 5B5C58575F554050575E390 link=1275439729/14#14 date=1275485498
    SSR (solid state relay) on a machine.
    The KLIIb has SSR as a reley replacement... Was a good move... But due to teh heavy current load need additional cooling.. Then teh fan started to make noises... I think coffee fines and teh odd splash from the drainer got in... And teh bearings dried and and it would squeal like a PIG...

    Still... If done right... Better that a relay and arcing contacts that generate all forts of rf noise..

    All comes back o Fit for purpose and COST

    Comment


    • #17
      Re: PID on a HX machine?

      Originally posted by 71555C5C5F5F6571554957553A0 link=1275439729/12#12 date=1275481075
      Snip from the Bezzera Italy web site
      http://www.bezzera.it/home_ing.html

      PID SYSTEM: on BZ07
      PID temperature control system, replaces traditional pressure switch, shows the boiler temperature on a display, the temperature can be adjusted by the user in a range from 85C ° to 100C °.

      KK
      Youre confusing an electronic thermostat with a PID Controller KK.... Totally different kettle of fish...

      Mal.

      Comment


      • #18
        Re: PID on a HX machine?

        Originally posted by 5F585C535B514454535A3D0 link=1275439729/14#14 date=1275485498
        Silence when not in use so no clicking on and off (much as some may like this to say their machine is on), no points to get earwigs under or burnout and generally easy user adjustment of the Temp from the outside of the machine while a PStat is normally covers off to get to it.
        This just isnt the case with the Mater units that most "Prosumer machine manufacturers use. It is impossible to hear the operation of one of these but maybe a young child or someone with undamaged hearing could hear the micro-relay operating.... Once again, I cant hear it.

        You are no doubt referring to a Sirai type P/stat bf and yes, for a purely domestic usage population, these are quite noisy and waayyy overkill for the intended purpose. They also suffer from a wider dead-band than the latest Mater units, not that that is a really big deal.

        On the other hand SSR installation to switch the heating element current is an excellent thing to do as the early demise of Prosumer P/stats is close to 100% due to the electrical erosion of the main contacts. This upgrade puts an end to that.

        Is an electronic T/stat a worthwhile option for P/stat replacement? My personal opinion based on several decades of working with all manner of instrumentation, electrical and electronic systems from an electrical engineering point of view, is NO. I bet the electronic T/stat in the Bezzera BZ-07 doesnt come cheap..... :

        Mal.

        Comment


        • #19
          Re: PID on a HX machine?

          Mal,

          Re: Toppie!

          Thanks. I assume you are referring to the post immediately above yours, that mysteriously disappeared and no one can see....but if I say so myself, yes it was a toppie

          I removed it because I am not sure that my straightforward / pragmatic / direct style (usually pro KISS principle), is always welcome.

          That said......Most of you blokes need to take a step back and think about the thousands of other readers that are silently looking in on this site at any one time.  The things that are written, influence what people think and ultimately what they end up buying. Too much technical stuff, some of it correct, much of it not correct.....much of it irrelevant....but it still influences those (the majority?) that dont have the skills to sort the truth from the bulldust, or the words from the acronyms.

          Someone needs to stand up and say......the topic is out of control. Of course it is a free topic board, and you blokes can carry on if you wish despite that a great proportion of readers are probably not understanding the discussion.

          Sniff:
          Mate, come on in, have a chat and I will explain. A 15 minute talk blows 24 pages of time consuming writing out of the water.

          Regardz,
          A.

          Comment


          • #20
            Re: PID on a HX machine?

            Originally posted by 4F7B6C7A61564A666F6F6C6C090 link=1275439729/18#18 date=1275517724
            I removed it because I am not sure that my straightforward / pragmatic / direct style (usually pro KISS principle), is always welcome.
            So...  If it needs to be said; to bring the topic  back into perspective.. SAY IT..

            I must admit.. I actively search out your input and posts..

            WHY... Because you can often put in a post what I struggle to say in 10 posts..

            Too much going on and all to often it is about assumptions..

            KISS every time but it is hard when they dont know, what they dont know, and thus detail, is too out there...... >>>

            For me it is this post... http://coffeesnobs.com.au/YaBB.pl?num=1265274280/2#2

            Then again... How many understand, even the detail in that post...


            Originally posted by 4F7B6C7A61564A666F6F6C6C090 link=1275439729/18#18 date=1275517724
            Someone needs to stand up and say......the topic is out of control.  
            Attilio...   In addition to part 1: above; If a Person of your character and background and understanding can not speak their mind as to technical info and your experiences!!!!!!

            Then maybe I have been conned ...

            For if you do not feel comfortable in making a post, then there is something seriously wrong with the forum..


            Speak ya mind.. If you dont; the truth and or another view to consider... Will never be available to anyone.  And that would be a shame...

            PS. I thought your post was right on the nail... Not always 100% in agreement, but 100% support your approach...

            Comment


            • #21
              Re: PID on a HX machine?

              From what I understand an HX system works by heating fresh cool water by passing it through piping that is passed through the boiler - thus temperature of the

              water at this stage is in relation to the boiler temperature.

              The water then enters the group system which is designed to reduce the heat to an acceptable temperature for espresso making.

              The group style is either:
              (a) thermosyphon which uses water from the boiler and depending on the flow of hot water within this system determines the temp of this system.
              (b) electrically heated.
              (c) big lump of metal which is heated by its location near the boiler.
              (d) any others??

              All these systems use a large mass of metal to obtain temperature stability and reduce the water temperature to the group temperature.

              If this is so wouldnt a hotter boiler give hotter water in the end, especially in (a) due to the thermosyphon running hotter water through it and (c)

              the group would be hotter because the boiler is hotter. Option (b) seems to be the least affected by boiler temperature.

              Do I have this totally or partially wrong.
              I dont have any experience in these at all, this is just my understanding and would like to to have it explained more.

              Comment


              • #22
                Re: PID on a HX machine?

                Originally posted by 524940565558210 link=1275439729/20#20 date=1275528366
                I dont have any experience in these at all, this is just my understanding and would like to to have it explained more.
                Actually Of Topic and should be in another Topic..

                Been discussed a few times B4.


                1: http://www.home-barista.com/hx-love.

                and

                2: http://coffeetime.wikidot.com/heat-exchanger-machines-how-they-work

                and

                3: http://www.chriscoffee.com/faq#23

                and

                4: Do a degree in thermo dynamics and specialise in boilers etc..


                Comment


                • #23
                  Re: PID on a HX machine?

                  Originally posted by 110A0315161B620 link=1275439729/20#20 date=1275528366
                  If this is so wouldnt a hotter boiler give hotter water in the end, especially in (a) due to the thermosyphon running hotter water through it and (c)
                  Yes it does, but the thermal mass of the E-61 group stabilizes it, thats why cooling flushes are needed on machines where the pressure stat is set high for increased steam (or through poor thermosyphon design i believe)

                  The difference in boiler temperature is lower than most think in the on/off cycle, some relate the pressure guage to temperature directly when i believe, actual temp within the boiler only changes 2-4 degrees depending on the dead band, someone correct me if im wrong.

                  I was caught up in the thought of an installation of a PID in my GPP, then through the careful guidance of the experts here, i decided it would be pure bling with very little actual difference in the cup, if any at all.

                  Comment


                  • #24
                    Re: PID on a HX machine?

                    i know a pid on HX (in the boiler) is overkill but arent you just replacing a pstat with a PID and creating a tighter dead band? (and adding a SSR)

                    it could be beneficial if you can keep your boiler water stable at any given temp, you can fine tune the ghead to deliver a stable water supply. cant you?

                    that said, on any given day as the temp in the room goes up and down you would need to adjust the PID to compensate for the temp at the Ghead as it is directly effecting the delivery temp of the water.

                    even on normal pstat e61 group heads ambient temp is going to effect it, isnt it?

                    this is heading into theoretical benefits but interesting discussion

                    my HX ghead bolts the boiler, I did think that controlling the boiler water temp via PID may be simpler for me than a piped thermosyphon set up machine.  I still would need 3 temp readings of one at ghead and one at boiler and one on delivery water.

                    eg Ghead sitting on 85" and boiler sitting on 105" would = 93" delivery

                    i could then learn to compensate Ghead temp to delivery via increasing or decreasing PID temp..... (would it work?)

                    crazy idea....... ?? just thoughts really

                    ps to really make it work i am going to need to heat my Ghead to keep it constant arent i = PID X 2

                    Comment


                    • #25
                      Re: PID on a HX machine?

                      Thanks everyone for their contributions and links.


                      Can I summarise so far:

                      1.  The PID together with a SSR in the Bezzera replaces the pressurestat.  PID keeps temp in boiler at steam level (at least above 100 degrees)

                      2.  The PID gives an operating range  on the display of 85 - 100 (see KKs post and the Bezzera website)....this is less than steam level.

                      3.  So presumably the PID temp is referring to brew temp at the grouphead (and in reality the PID is keeping the water temp in the boiler at least 15 degrees higher than the displayed temp to allow for steaming).  

                      4.  Therefore, allowing for the flow / pressure of the water going through the HX, the boffins have calculated that the temp displayed should be the temp of the water coming out at the grouphead.  [Insert Attilios/AMs/Mals/ everyone elses qualifications to this expectation here! :]

                      5.  Thus, the PID on the boiler is not necessarily going to overcome issues of temp surfing on a HX, but perhaps gives the user some bling to play with rather than twisting a screw on a pressurestat.

                      Here endeth the lesson.

                      Yours in slightly less confusion,

                      Sniff  

                      Comment


                      • #26
                        Re: PID on a HX machine?

                        Minor thing too on the Bezz it is actually an electrically heated group not thermosyphon going back to the OP machine in question so raising or lowering boiler temp will have less effect on group temp other than what is heated due to contact to the boiler.

                        Without going into uni level thermodynamics and steam cycles you boiler is over 120 degrees and under pressure which keeps the bulk of the water as a liquid in the bottom of the boiler but wet steam above the water line which is the bit used for milk steaming.

                        Rough chart for general info, please note this is machine specific and will vary machine to machine:

                        Boiler Pressure Boiler Temp HX & Espresso Temp
                        0.84 bar 117.5C 244F 88C-90C 190F-194F
                        1.00 bar 120.0C 248F 90C-92C 194F-198F
                        1.17 bar 122.5C 253F 92C-94C 198F-201F
                        1.33 bar 125.0C 257F 94C-96C 201F-205F

                        Comment


                        • #27
                          Re: PID on a HX machine?

                          Much of this is good and useful information, however

                          Given the level of precision we are discussing in our machines, its prudent to be mindful that the user is likely to be responsible for far greater variation than any of the switching technologies were debating here...

                          Its pretty easy to get all pent up about process rather than outcome, no :-?

                          2mcm

                          Comment


                          • #28
                            Re: PID on a HX machine?

                            Originally posted by 732C342229222E272724242C202F410 link=1275439729/26#26 date=1275536450
                            Its pretty easy to get all pent up about process rather than outcome, no :-?
                            2mcm
                            for sure, its fun to consider but


                            Comment


                            • #29
                              Re: PID on a HX machine?

                              Originally posted by 7671757A72786D7D7A73140 link=1275439729/25#25 date=1275536443
                              Minor thing too on the Bezz it is actually an electrically heated group not thermosyphon going back to the OP machine in question so raising or lowering boiler temp will have less effect on group temp other than what is heated due to contact to the boiler.
                              So if the PID is on the electrically heated grouphead then that should keep it at a pretty stable temperature even if the boiler temperature is raised or lowered and even with contact with the boiler???

                              Comment


                              • #30
                                Re: PID on a HX machine?

                                Originally posted by 48535A4C4F423B0 link=1275439729/28#28 date=1275538122
                                So if the PID is on the electrically heated grouphead then that should keep it at a pretty stable temperature even if the boiler temperature is raised or lowered and even with contact with the boiler???
                                NO and a little yes

                                Just remember NO cooling so if an over shoot (deadband etc etc) then the cooling rate and control  is subject to air temp and flow.

                                If ya boiler is at HOt HOT and it carries through to the group.. The PID or other controller can not cool... Just does not try to heat..

                                That is why temp control on these systems is so interesting..

                                If  too hot...

                                One way would be to dump some boiler water and then fill.  Then one would also need to build in delays and pump / mixing actions to get the layers of hot and cold working.. Then add another delay and dead band for allowing the heat / cooling to be transferred to the rest of the system.

                                Not worth it cause teh temps are not as critical as some like to think... Bigger issue is teh user

                                Oh and if ya think the boiler is at one temp... Forget it... there are layers and depending on temps etc .. can be interesting..  Another reason why temp probes are at particular points and the the Heat Exchange chamber may be at a special placement.

                                Just go and do the advanced Thremo dynamics at uni..  Just ask and diver or  submariner (coms and radar etc) what temp layers can do to you...

                                * the = t e h  :

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