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Target Brew Temperature??

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  • Target Brew Temperature??

    I have a 2008 La Cimbali Junior S (tank and vibe pump) machine. I have reduced the boiler pressure via the pstat to the range 0.65 bar to 0.7 bar. I did this as I only use it at home and its easier to manage its temperature profile at this setting with shorter cooling flushes. Steam production is still excellent.

    I have just purchased a K type thermocouple which I have located in my filter basket which I can use to measure temperatures during my cooling flush and occassionally when running a shot.

    If I am aiming for a target brew temperature of say 90 celsuis, should the 90 degrees be the temperature at the start of the shot or half way though the shot for instance?


  • #2
    Re: Target Brew Temperature??

    Hello GCM58.

    Shorter cooling flushes are not the be all and end all....

    Manufacturers usually get it pretty right. By reducing your boiler pressure (esp to such a low figure) you run the risk of negating the machines ability to recover during successive your successive shot temps will get cooler and cooler as the machine will be slow or unable to recover, thereby adversely affecting your "temperature stability" at the low end, and making it less able to cope with groups such as at dinner parties etc. where coffees are to be made one after the other. And your coffees will be sour.

    Certainly all of this depends on the brand and model of machine, some are better than others.

    Remember, HX machines are designed to be used in commercial situations and with continuous use.

    In the home situation you dont get the continuous use side of it, and this is complicated by some owners wanting to leave their machines on all the time. This results in they want to cool them down. Cooling down adversely affects the machines ability for continuous use......ergo, you have one effect working against another.  

    There is a compromise, and the manufacturers of good quality semi commercial espresso machines have usually already worked it out for you through their internal design.

    If you fiddle further you run the risk of upsetting the balance, especially by making such a large reduction in boiler pressure and placing it well below design standard.

    Also, once you start reading temperatures with your thermocouple, and you see normal variations that you can get with a quality HX machine that is working quite normally and as it should, it may set you off on a tangent trying to fix something that aint broke.

    Suggest setting boiler pressure back to the range of 0.9 to 1 bar, leaving it at that, doing appropriate cooling flushes as required dependent on how long the machine is left idle between sessions, and enjoying your machine and coffee.

    very first CS site sponsor.


    • #3
      Re: Target Brew Temperature??

      great post Attilio


      • #4
        Re: Target Brew Temperature??

        Thanks Attilio

        I will re-examine the pstat settings next week-end and look at increasing them as you have suggested.

        The Cimbali Junior is rated by the manufacturer as being able to make 90 espressos an hour. Consequently in a home setting, it has a reputation of running extremely hot and thats why I decreased the pstat setting. Normally I only make 3 or 4 coffees a day in total, so it is sitting idle for long periods (several hours) and requires a series of long cooling flushes to bring its temperature down. As its a commercial machine, its temperature rebound time is also extremely quick so I have to do cooling flushes between making successive coffees. By having a lower pstat setting it did reduce its rebound time and reduce my cooling flush regime.

        Im still unclear if Im aiming for a target brew temperature of 90 degrees celsuis, should this be the temperature at the start of the 25 second shot or for example half way through?




        • #5
          Re: Target Brew Temperature??

          Gday Graham....

          Lots of useful info about this aspect of espresso around the web, such as this info here...

          Basically, there is no set temperature which is ideal for all espresso pours - Different beans can taste better at one temperature over another but the main criterion has been temperature stability for the duration of the pour. Everything that Attilio has written above needs to be taken into account when deciphering this sort of information too as playing around with adjustments of a single parameter which directly affects many outputs is never going to provide an ideal outcome.

          Anyway, have a read of the linked article and see if that helps out at all....



          • #6
            Re: Target Brew Temperature??

            Hi Graham,

            another help along the way to keeping it cooler is to throttle the Thermosyphon lines to the head by adding an oriface plate or valve. By slowing the flow past the group it will stay cooler but as was mentioned above this is playing with the thermodynamics of a system so it is possible to make it stall or become to cool if you get it wrong.

            In an ideal world you need a scace device some various sized plates to play until you get what you want. Have a read here for a start

            Benifit of this if you get it right is all you then need to cool is the HX water rather than a 6-10kg lump of brass


            • #7
              Re: Target Brew Temperature??

              Thanks for the feedback. I checked out the HX Love article as suggested. From the sounds of it, my aim is for temperature stability during the course of the shot. If I am aiming for a target brew temperature of 92 celsuis then the brew temperature should be around this temperature for the majority of the shot.

              In terms of the suggested winding back of the thermosyphon lines going to the group head to reduce temperature, the Cimbalis group head is attached directly to the boiler so Im assuming it doesnt have any thermosyphon lines to play around with.

              I will have another play around with my thermocouple this week-end so that I can see what my flushing regime is doing to the brew temperature during a shot.


              • #8
                Re: Target Brew Temperature??

                Hi GCM58

                I recently picked up one of these, but the Faema E98 version rotary plumbed (or tank). inside it is the La Cimbali group .

                I noticed it does seem to need a good flush if it sits for any time. I put my TC on it and saw it hit 100 on the flush.

                I have not spent that much time with it as I am cleaning it up for my sister but need to get back to it. Mine has volumetrics so I intend to set a "flush button" that should provide about the right flush once its been sitting.

                you should be able to sort of rough out a "i need a 3 sec flush if X" sort of rule to guide you. thats how i use my Brugnetti HX, or just flush to the "spitting" stops then run shot.

                keep us posted on how you go, they seem a very solid little machine


                • #9
                  Re: Target Brew Temperature??

                  Honestly, the best advice is to:

                  Throw the thermocouple away and

                  Originally posted by 5559505D5D54380 link=1277690279/7#7 date=1278038139
                  ....just flush to the "spitting" stops then run shot.......  
                  Also, manage the machines regime by not leaving on all the time, only switch on when you know you are going to want coffee (say within the hour), then switch off if you are not going to want coffee again for atleast an hour. Eg, do not leave on for hours for it to wear itself out cycling but doing nothing just waiting.....HX machines are not designed to sit and wait. They are designed to work continually....that is how the principle works best and well designed hx machines do not reqiure much of a cooling flush when used as intended.

                  My own personal example is as follows, and I have a 2 litre BFC Diadema Regal at home.

                  My wife and I want coffee in the morning at end of breakfast. Switch on. Come back around half an hour later or more (or less) and start the process.  Around 20 minutes after the first cuppa, have a second round. Switch machine off....

                  Switch machine on again at lunchtime and make a round. Switch off.

                  No coffee for us in the evening but if there was it would be the same as above switch machine on yarteh yarteh yarteh.

                  And so on the next day.

                  No point leaving machines on all the time to make them overheat, use electricity, and wear themselves out resulting in shortened intervals between "service" as components cycle to the end of their designed in lives, while the machine actually isnt doing anything for you.

                  Hope this helps.



                  • #10
                    Re: Target Brew Temperature??

                    Attilio i understand what your saying, but how do home users get around this issue? (overheating HX if sitting)

                    considering my Brug 5L commercial HX (it also has a attached Ghead a bit like the La Cim)

                    if I make my 1st coffee at 7am and have my 2nd at 7.30 then my third at 9am should i switch off at 7.35 am? and turn back on at 8.30?

                    i know if it sits for 10 mins it gets hot, i flush and then make my coffee. I have to flush on that 2nd cup at 7.30

                    I would have thought that this would be fairly normal behavior for home users on say a weekend time frame wise.

                    I use the TC to give me a guide to what the machine is doing, i then can use a routine to try to make consistent shots.

                    It also allows me to somewhat change the temp in a pour to see what happens to the taste, eg want cooler shot flush a bit longer, want hotter shot flush shorter. (not perfect I know).

                    I would have thought using the TC or a scace would give us a bit of baseline to work of.


                    • #11
                      Re: Target Brew Temperature??

                      Hello L,

                      some machines run hotter than others, size of cooling flushes is relative to each and their set up.

                      I generally dont turn off if Im having another one in an hour, but I will if Im planning another in 2 hours. My thoughts were aimed more at those that leave their machines on 24/7, or all day.

                      I have never had a problem making coffee using my own inbuilt analogue pid and thermocouple....namely, my brain   by doing exactly as you stated above and just doing a quick flush to see what is happening and if it is spitting and gurgling, just flush until it settles then insert group handle.

                      Anything else to my way of thinking, is just too hard..and it doesnt need to be that hard.

                      The problem with academic discussions about specifications and instruments,  is in many instances they send people off on tangents not understanding or knowing how to interpret what they are reading, perhaps not even understanding how to take the readings, and wanting to fix things that werent broke when the readings seem to differ from a specification they read. Specifications are usually clinical and do not come with a book full of explanations as they should.....

                      "KISS" is one of the greatest philosophies known to man.



                      • #12
                        Re: Target Brew Temperature??

                        great post as usual

                        thanks for our thoughts and ideas

                        Originally posted by 457166706B5C406C65656666030 link=1277690279/10#10 date=1278048339
                        Anything else to my way of thinking, is just too hard..and it doesnt need to be that hard.

                        "KISS" is one of the greatest philosophies known to man.

                        lol often at 7am just getting a nice shot is all i am thinking.....


                        • #13
                          Re: Target Brew Temperature??

                          Thanks all of you for your advice.

                          I now have the first coffee of the day flushing regime sorted out so that it doesnt produce a bitter shot. The La Cimbali Junior needs at least and hour and a half to warm up properly. It then needs a long flush to settle the group head temperature down and cool down the water in the HX.

                          My flushing regime may seem large but detailed reviews of this machine have also confirmed that it needs a big flush to settle it down in the morning. My first flush is 175mls, grind, dose and then tamp (approximately 2 minutes) then a 125ml flush and lock in straight away and run the shot.

                          On my machine this regime gives me a nicely balanced espresso for the first shot of the day which my wife loves. Now I need to work out the flushing amount before running the second shot for me and subsequent shots if visitors are around to get the same result. That is something that I hope the TC will assist me with. Without using the TC I believe this is around 50 - 75mls at this stage.

                          According to the manufacturers specifications the Cimbali Junior is capable of making 90 espressos an hour and loves hard work. However, in a home environment it runs hot and that is why I have reduced the boiler pressure down to 0.7 bar which Ken Fox in Canada uses for his Junior S (tanked machine) as well. Even at that lower boiler pressure you can see that it still requires a large flushing regime.

                          I love the machine as its built like a tank, has never missed a beat and makes great espressos. It just takes a bit of time to master it which is half the fun. Drinking its output is the other half!!