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  • I need a dual boiler - or do I?

    G’day fellow coffee snobs,

    A few months ago I asked here for advice about a possible upgrade. Thanks to everyone who responded.

    Since then I have decided - or almost decided - that a dual boiler is the type of machine for me.

    This is because I intend to change the brew temperature. At one point I thought that a HX with PID would be adequate for this. However a number of people here and elsewhere have stated that a PID on a HX is not adequate for working with brew temperature.

    When considering how a HX works this does make sense. The PID on a HX changes the steam temperature. The brew temperature will also change as the brew water is flash heated by passing through the steam boiler, however the resulting brew temperature is more variable and harder to predict than it would be on a dual boiler.

    Some people with PID HX machines seem quite happy with their machine’s capability to change brew temperature, while others are frustrated. Which category would I fall into? That is my question.

    Possibly the question is impossible to answer in a forum like this one. But to try and answer it anyway I thought I’d break down just how I intend to use brew temperature and what I hope to gain from having the ability to change it.

    The first thing I hope to gain is the ability to know what my machine’s brew temperature is. On my current machine - a Breville Barista Express - I don’t know. This annoys me.

    Secondly I want to change brew temperature based on what beans I am using. My workflow would look something like this:
    - Upon buying a new bag of beans, set the machine based on what I think the best temperature for those beans would be
    - Dial in using grind and yield
    - Leave the temperature unchanged unless I’m not getting a good flavour and think changing the brew temperature would fix things
    - When necessary, change the brew temperature at the start of the day when turning my machine on, rather than changing it between one shot and the next

    Is a dual boiler machine necessary to meet these requirements?

  • #2
    I mean, everything you are saying sounds like you want an adjustable and stable brew temperature. A dual boiler would help with that I'm sure, at least froma simplicity point of view. The Breville dual boiler would tick all of the boxes and is probably the cheapest and most capable machine you could get, with lots of flexibility on the options/features front. 1year+ into mine and no regrets.

    Comment


    • #3
      I personally don’t think people change the temperatures as much as you might think. It’s mostly set and forget for most people who have PID etc.

      what about getting something like a BDB (used) and which you could mod with the slayer style enhancements? Perhaps a profiling function would allow you to best play with different beans. Eg preinfusion etc

      Comment


      • viy
        viy commented
        Editing a comment
        Thanks @Phillydelphia

        I’ve heard from salespeople at prosumer espresso machine shops that perhaps 99% of people with PIDs don’t change the settings. However my Breville machine does have a limited brew temperature change functionality, which I have used from time to time. The results have been intriguing enough that I’d like to explore this further.

        The Breville BDB has a lot of fans here and sounds quite a capable machine and great value but I’m looking at getting an Italian machine for longevity and aesthetic reasons.

    • #4
      The first place I start is -
      Do you know the difference the temp cam make to a shot?
      Can you actually taste the difference?

      There are at least 2 ways to change anything. Temp can be increased by slowing the shot/increasing the pressure/ changing the basket & dose size etc.
      In short, a dual boiler is not necessary, but only you can answer if you want one.

      Comment


      • Ronin
        Ronin commented
        Editing a comment
        20in40out Absolutely Boyle's Law. Look out for more coffee related research in this area (not by me)

      • Ronin
        Ronin commented
        Editing a comment
        viy Good info thanks, sounds to me like you need to do some testing. My suggestion is pulling shots at 3 different temp eg. 93, 90 and 87 all with the same coffee to see what you prefer. Keep in mind that result will only give you an answer for the beans used. Over time you will see a pattern of preference and will be able to preempt the result.
        Better coffee faster = winning

      • viy
        viy commented
        Editing a comment
        Ronin good advice. Can’t do that on my current machine though. Something to look forward to once I upgrade.

    • #5
      It really is a game of diminishing returns, and your understanding is pretty solid based on your comments.

      My comments are from someone with not the most amazing palette who drinks milk-based coffee, mostly milk blends with the odd single origin, so take them with a grain of salt. I do drink V60 at work with filter roasts.

      I recently maybe 12 months ago upgraded my home setup from a Rocket Giotto HX machine to and ECM Synkronicha dual boiler with PID.

      The Rocket Giotto I had dialed down to 1 bar on the boiler/steam gauge to get a fairly accurate 93 degrees at the group with little to no flush required (I have a Scace device which I used to set the pressure stat which in turns controls the temperature and also did use a group head thermometer briefly).

      On the ECM Synch I have used 92/93/94/95 temps on the coffee boiler and I can taste only a slight difference; I only use 94/95 with Ethiopian/Kenyan single origins or blends with say >= 50% Ethiopian/Kenyan beans. Didn't really like anything lower than 93 even with darker roasts, 94 seems to taste better with lighter roasts but then sometimes you aren't sure if a) you grind isn't quite right b) have you rested the beans long enough c) if it's a light roast should I run a longer shot anyway.

      I run normal (non-turbo) shots with more 21 grams in 42-45 grams out, so again if you are doing turbo shots you might find different results with varying temps due to different contact times between the hot water and coffee grounds.

      If you had HX machine already I would say try a group head thermometer first and you can vary your flush routine to hit different temps.

      Since you have a barista express jumping to a Breville Dual Boiler or another machine like a Lelit Elizabeth or E61 dual boiler would be somewhere where you really could see something different in the cup. However, I wouldn't do that without factoring in a good grinder, anything less than a Eureka Mignon I think you are not going to be able to the full benefit.

      Comment


      • viy
        viy commented
        Editing a comment
        Thanks @roosterben

        I also drink mostly milk drinks and intend to experiment with different beans so your comments are quite relevant and helpful to my situation.

        I do feel that I’d be happy with either a capable HX or a dual boiler; both would be a substantial upgrade. 90% of the time I wouldn’t want or need to change the temperature so it really is about diminishing returns as you’ve said.

      • viy
        viy commented
        Editing a comment
        Regarding grinders, I have a Baratza Sette 270 grinder which I am quite happy with.

    • #6
      There is one extra consideration - changing the brew boiler temperature on a dual boiler machine isn't going to directly cause the actual groiphead temperature to be at the same set temperature unless the machine has a saturated group head or a cartridge heated grouphead that is controlled independently by a pid. So actually you need independent control of three separate components temperatures - the grouphead, brew boiler and steam boiler. An example of a double boiler in the saturated grouphead category is the LM GS3 pump machine and an example of the latter is the Nurri L-type SA lever.

      Comment


      • viy
        viy commented
        Editing a comment
        Thanks @Primacog.

        What does that mean in practice, assuming that I buy an E61 DB? What is the level of variation in the brew temperature one could reasonably expect, assuming ordinary circumstances and a competent machine user?

        My budget is roughly $3-4k which I don’t think is going to get me a saturated grouphead. I’m eyeing off the Izzo Vivi Duetto at the moment.

      • roosterben
        roosterben commented
        Editing a comment
        Err that's not actually true, E61 groups use a thermo syphon loop which circulates the brew boiler water through the group. This is slow and takes about 30-45 minutes to fully heat the group but it will effectively reaches equilibrium temperature with the boiler.

        Saturated and other actively heated groups have the advantage of much quicker heat up times as low as 5-10mins. The actively heated groups will be more temperature stable between shots as the group is actively heated and even if the boiler temp drops the group can stay at a higher temperature.

    • #7
      AFAIK there can be quite a difference between the temperature of the brew boiler and the joint between the e61 grouphead and tbe boiler and the outside of the grouphead itself. I measured the last two places on my e61 with a thermocouple and confirmed this. In practice the brew boiler is set with an off set to take this into account but is the fixed offset range accurate at that particular time?

      if you can wait a little, Nurri is apparently coming out with a saturated grouphead based pump machine that is cheaper than their L-type SA spring lever. It was called the GTO but they are changing the name and the overall design of the machine.

      Comment


      • #8
        HI Viy.
        E61 dual boilers are, for most people extremely temperature stable.
        If one is only drinking milk drinks they are probably more stable than required(milk hides a lot of sins).

        Folks who are into 3rd wave, light to very light roasts tend to be more particular about the ability to change and maintain temps as they are walking a fine line between acid/sour/fruit.

        The Nurri lever is lovely and competent but it is $9k aud at the moment.
        I doubt a saturated Nurri pump machine will be less than $6k when it hits our shores.

        On the other hand there is a barely used Lelit Bianca V2 for sale on this site for under $3k that a hell of a lot of folks would consider an end game machine..
        I know I have ordered a comparable machine to the Nurri but I aint selling my Bianca until I know the new lever is able to replace it.

        Comment


        • Caffeinator
          Caffeinator commented
          Editing a comment
          GTO is a ring group, no?

        • viy
          viy commented
          Editing a comment
          Just what is a ring group Caffeinator ?

      • #9
        Originally posted by amberale View Post
        HI Viy.
        E61 dual boilers are, for most people extremely temperature stable.
        If one is only drinking milk drinks they are probably more stable than required(milk hides a lot of sins).

        Folks who are into 3rd wave, light to very light roasts tend to be more particular about the ability to change and maintain temps as they are walking a fine line between acid/sour/fruit.

        The Nurri lever is lovely and competent but it is $9k aud at the moment.
        I doubt a saturated Nurri pump machine will be less than $6k when it hits our shores.

        On the other hand there is a barely used Lelit Bianca V2 for sale on this site for under $3k that a hell of a lot of folks would consider an end game machine..
        I know I have ordered a comparable machine to the Nurri but I aint selling my Bianca until I know the new lever is able to replace it.
        Sorry, viy, do you mean your budget is 3-4K USD or AUD? I thought it was the former but if it is AUD then I agree the upcoming Nurri saturated grouphead machine isn't likely to be below such a budget.

        I still have my e61 and I use it for light roast espresso and though its not as good as my nurri, it's not bad. I never even bothered to modify it for flow control so I would agree that once you hook it up to a thermocouple to be able tl get a real time temp reading on tbe grouphead, it will do a pretty decent job if the budget doesn't extend far enough currently.

        Comment


        • viy
          viy commented
          Editing a comment
          That’s $3-4k AUD Primacog

      • #10
        For your budget you could get a Bianca(used) and a Niche(Eeek, not my style but very good).
        Under $100 for a full service kit.

        Comment


        • #11
          amberale I did notice that Bianca V2 in the for sale section. Extremely capable machine. However I won’t be in a position to buy for at least a month from now, and it’ll be long gone by then.

          Comment


          • #12
            You can also buy any used e61 machine and then buy a flow control device to fit to it to produce a result similar to the bianca. For me, i never even bothered to get a flow control device for my e61 as i just jog the lever to engage preinfusion at about 2 bar for as long as i want before fully engaging the lever to switch onthe pump to go full 9 bar.

            Comment


            • #13
              Primacog I’m not planning on getting flow control presently but having the ability to add it in the future is nice - means I’d get something new to play with without having to do a full upgrade.

              Comment


              • Primacog
                Primacog commented
                Editing a comment
                If so then any used e61 that is in excellent condition and that fits your budget should do the trick. But having the bianca to start with would be even better as the profiling option comes with the package then.

              • viy
                viy commented
                Editing a comment
                Primacog a lot of upsides to the Bianca. Downsides for me are features that bump up the price that I’m not interested in, such as the rotary pump and plumbing in ability. But I love the aesthetic of the machine. If a second hand machine comes up when I’m ready to buy I’ll be seriously tempted.
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