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  • Thermoblock versus Boiler

    I am interested, for interest sakes just how good thermoblock machines are at making espresso and lattes. I know anyone with a boiler machine will put these machines down so I guess I am asking owners past and current how they find these machines.

    Curious, I am.

    Grant

  • #2
    Re: Thermoblock versus Boiler

    I was priveleged to be part of a judging panel that tested 10 different brand / model machines in all different price brackets a couple of weeks ago and the results were interesting....if for no other reason, it showed us (I think) that it is not so much a question of thermoblock VS boiler, but a question of comparing rather, the result (or "performance") obtained (ie coffee & steaming) from the "working end" of any individual model.

    So what I am saying is, some boiler machines "produce" better than others, and some thermoblock machines "produce" better than others, and some boiler machines "produce" better than some thermoblock machines, and vice versa, and there are different pricing brackets to all!

    Some machines just perform better than others...irrespective of their internals....

    Having basically just said such nice things about thermoblock machines in general, I will personally remain biased against anything that has its guts made of aluminium (sorry, but aluminium, HEAT and water dont mix....atleast not in my stomach).

    Notwithstanding, dont forget the other caveats such as the fact that in general, most thermoblock machines are "electrical appliance" brands and their long term repairability including availability if parts and / or availability of service agents is suspect compared to the fact that in general, most of the "better" and / or more expensive domestic machines branded or manufactured through traditional coffee machine channels are boiler machines and whilst this has nothing specifically to do with the thermoblock VS boiler thing, this group of machines has good long term repairability and availability of parts and repairer networks....so is still related to the discussion overall.

    Regardz,
    FC.

    Comment


    • #3
      Re: Thermoblock versus Boiler

      Grant,

      with a bit of tweaking (removing the dual-wall crema-killing baskets, super heating hte thermoblock by running steam for about five minutes prior to running a quick cooling flush, then brewing etc etc), my little sunbeam has performed wonderfully. BUT it only performs wonderfully for one drink at a time. Dont even consider steaming enough milk for two lattes - theres simply not enough power in the steam to do this effectively and efficiently, if youre after microfoam and latte art.

      On tuesday nights, theres a Bible study group at my house, and to make about four milk drinks (a mocha, a latte, a double cap and a hot chocolate for my wife) it can take up to 20 minutes. Bring on the HX!

      Comment


      • #4
        Re: Thermoblock versus Boiler

        Quote from mattyj:
        On tuesday nights, theres a Bible study group at my house, and to make about four milk drinks (a mocha, a latte, a double cap and a hot chocolate for my wife) it can take up to 20 minutes. Bring on the HX!
        Hi mattyj,

        Ive got a good boiler machine and making Lattes for four would take me at least 20 minutes from start to slurp. Maybe I need to sharpen up my act a bit...

        Cheers,
        Mal.

        Comment


        • #5
          Re: Thermoblock versus Boiler

          Originally posted by Mal link=1118073813/0#3 date=1118124645
          Quote from mattyj:
          Ive got a good boiler machine and making Lattes for four would take me at least 20 minutes from start to slurp. Maybe I need to sharpen up my act a bit...
          Wow that would leave some relatively cold coffee at the end.

          I make them 2 maybe 3 at a time (based on volume of milk to be steamed) which would have 4 done in 7-8 minutes at most.

          Comment


          • #6
            Re: Thermoblock versus Boiler

            This is the big difference between a consumer machine and a commercial machine. The ability to pull continous shots and steam at the same time.

            Java "Believes in over-kill" phile
            Toys! I must have new toys!!!

            Comment


            • #7
              Re: Thermoblock versus Boiler

              Hi Wired,

              Usually Im the one to end up with a "warm" brew or Latte since I have to clean up before joining the throng (all shots are doubles). I guess of that 20 minutes, probably 8-10 minutes is cleanup time... never had any compaints from the recipients and I dont mind having the occasional warm one as the company is always welcome and stimulating. Still tastes great though :-*

              I notice that you have a rather special HX machine though Wired and this should halve the usual prep time compared to a single dual purpose boiler machine like Silvias, Mokitas and their ilk. Ahh, maybe one day I can aspire to owning a similar machine, probably a pipe dream though. Dream on McDuff... ;D

              Cheers,
              Mal.

              Comment


              • #8
                Re: Thermoblock versus Boiler

                my concern about thermoblocks is the steam production - not the quality (run it for long enough, and its incredibly dry), but the quantity and force of the steam.

                IME, thermoblocks simply cant produce powerful enough steam to cope effectively with more than one (maybe two) standards drinks at a time.

                While a dual thermoblock machine might enable the user to pull shots and steam simultaneously - is the steam production powerful enough to keep up???

                Comment


                • #9
                  Re: Thermoblock versus Boiler

                  but a dual boiler machine might be nice! ;D

                  Comment


                  • #10
                    Re: Thermoblock versus Boiler

                    Its been an interesting weekend, pairing a mazzer mini with my sunbeam - while some have said that they speak different dialects, Ive been drinking the best espresso ive ever had - making sure the machine is running hot (doing the steam for a few mins trick mentioned above).

                    While the SB and smaller boiler machines may have shortcomings with speed/steam production etc etc, its shown me that the grind is the key factor. As long as the water is delivered at a reasonably consistent temp and pressure, and as long as youve got the distribuition and tamp down pat, its cool - but getting a good grind seems to be the key. With my old delonghi, espresso was good, not great. With the mini maz, its been amazing!

                    Comment


                    • #11
                      Re: Thermoblock versus Boiler

                      Hi,

                      I started this thread some time ago.

                      Still no one has really studied a thermoblock wrt temperature stability.

                      The EM6900 has now come along and seeks to position itself amongst the better quality boiler based machines. This machine is really the first one where people really serious about espresso, might consider a thermoblock machine ie. well built (apparently), fully featured (lots of buttons for predetermining pour volume), twin stainless steel lined thermoblocks (holds out promise of HX level performance) and also a particularly well written manual. It is also available at a reasonable price point of $599.

                      I know some people think if it tastes good then the machine is OK and taste is really important. The only problem with taste is that it is incredibly subjective. If you really wanted to test something based on test then you would need a blind taste test for the same bean on different machines and using several different palates!!

                      The temperature test is also a reliable measure as an espresso machine is just something to supply water at a certain temperature and pressure to the coffee. Really very basic so measuring temperature variation during a shot should give a very objective measure of the machines ability to produce good espresso.

                      Some people seem to be able to readily pick out a 8 degree or so variation in temperature during a pour. This variation is likely to be much more noticeable in a side by side comparison with coffee done in a machine with a much more stable temperature profile. Some experience baristas could probably pick out even a 2C variation although I doubt many of us could do that.

                      I guess that might be a reasonable goal then 2C, something easily achievable with the right technique on most boiler/HX machines.

                      Grant

                      Comment


                      • #12
                        Re: Thermoblock versus Boiler

                        Originally posted by mattyj link=1118073813/0#7 date=1118196365
                        my concern about thermoblocks is the steam production - not the quality (run it for long enough, and its incredibly dry), but the quantity and force of the steam.

                        IME, thermoblocks simply cant produce powerful enough steam to cope effectively with more than one (maybe two) standards drinks at a time.

                        While a dual thermoblock machine might enable the user to pull shots and steam simultaneously - is the steam production powerful enough to keep up???
                        If steam production is what you fear the most, then fear no more. The Sunbeam EM6900 will steam till the cows come home with enough force to microfoam all your lattes.

                        Comment


                        • #13
                          Re: Thermoblock versus Boiler

                          Originally posted by wattgn link=1118073813/0#10 date=1120966090
                          Really very basic so measuring temperature variation during a shot should give a very objective measure of the machines ability to produce good espresso.
                          I see a lot of posts that confidently predict a theoretical ability of a thermoblock to deliver temp stability.  Sorry, I just dont see how.

                          A thermoblock is an array of honeycombed channels that water runs through, picks up heat from, and comes out the other end.  By definition (and plain physics) the thermoblock is going to cool as water runs through it.  The first water that hits the coffee will be hotter than at the end of the shot.

                          Compare this to a boiler machine that dispenses water that is pre-heated to brewing temperature.  No cooling issue here, but it depends a little on boiler temp stability.

                          Now compare to a HX machine.  Conceptually this IS a little closer to thermoblock in that cold water runs through a channel and is heated.  In this case, though, the heat exchange is from a large boiler that has the ability to recover the temperature loss from cold water by using its excess heat reserves.  The pipe that runs through the boiler is heated by boiler water at the same time as the espresso water cools it. Because the same highly conductive agent (water) is doing both the heating and cooling, you can achieve equilibrium.

                          In order for a thermoblock to match either of the above methods, it would need to be enormous and very heavy.  Even then I doubt that most durable metals could conduct heat quickly and accurately enough to recover temperature lost between the start and end of an espresso shot.  Sunbeams new machine boasts stainless steel, which is better than aluminium for durability, but its a poorer heat conducter.  The rest of the industry uses aluminium thermoblocks for heat conduction reasons, at the expense of durability.  Either way you lose. I can see why Sunbeams design team opted for durability in their new high end machine - it fits the rest of the image marketing for that model - but dont take it hook line and sinker, people!

                          Comment


                          • #14
                            Re: Thermoblock versus Boiler

                            Originally posted by ShortBlack link=1118073813/0#12 date=1121159849
                             By definition (and plain physics) the thermoblock is going to cool as water runs through it.  The first water that hits the coffee will be hotter than at the end of the shot.
                            Hi ShortBlack,

                            So, then how do you explain that I can open the steam up full power and it just never slows or looses power at all.  It just keeps on frothing as long as I like.  A thermoblock is creating the steam as well as a thermoblock heats the water for the coffee.  Maybe, there is more to physics than we know?

                            I dont know myself.  But I am not a physics graduate.  
                            But it works on this machine.
                            To be fair, it never worked on my other TB machines I ever tried, though.

                            Comment


                            • #15
                              Re: Thermoblock versus Boiler

                              Shortblack:

                              I dont think it will deliver the same temperature stability either.

                              Mind you as Monti says, the proof is in the tasting. It may be if the temperature stability is reasonable then it may be difficult for most people to taste the difference.

                              I dont think though that there is any evidence yet that it will come close to the stability of lets say more traditional technology.

                              Still if you look at the machine, it has a lot to offer and it looks set to kill off top end consumer machines like the Gaggia which from what Sparky has determined might even be less stable than a good thermoblock machine like the Sunbeam.

                              Grant

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