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Thread: Basic lever espresso question

  1. #1
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    Basic lever espresso question

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I've been trying to better understand how levers work (with little success, although I recognise that I have a lot more reading to do). Seems like the main differences lie around how the brew temperature ready water gets transported to the group.

    I haven't yet seen a lever where the brew temperature itself can be reliably controlled and changed as with a standard dual boiler machine.

    This seems strange to me as I'm led to believe that two important parameters for properly extracting high note, floral single origins is both lower brew temperature (91-92*C?) and good pressure profiling.

    Does a lever exist where one can specify brew water temperature?

    Thanks,
    Terence

  2. #2
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    Caravel plugged into a PID plug n play control box, thermocouple sits inside the open boiler aka like a sous vide or brewing type set up.

    PID_WIRING_DIAGRAM.jpg

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    Thanks. So nothing that comes straight out of the box, and also nothing that is immediately ready for steaming?

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    If you got enough $ to spare anything's possible. Sounds like you want something similar to what Rick the coffee machinist did to Andy's londinium.

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    Not a Shoe Jimmytheboot's Avatar
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    Precisely specifying the brew temperature at the boiler wont give the temperature you want in the lever cylinder when brewing, it has a large surface area exposed to the atmosphere so loses heat fast, and no circulating water so it will be cooler than the water in the boiler. This is for spring operated levers, non-spring levers may (or may not) share the boiler volume with the cylinder and keep everything at the same temperature, but they are low cost productions so dont come with dual boilers or pids.

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    Thanks for all of the replies... much appreciated.

    Jimmytheboot,

    Just to make it painfully clear for me, a lever group head is inherently difficult to set up in a dual boiler format as it doesn't have the thermal mass of an E61 nor the thermal stability characteristics of a saturated group?

  7. #7
    Senior Member GregWormald's Avatar
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    Quote Originally Posted by kwantfm View Post

    I haven't yet seen a lever where the brew temperature itself can be reliably controlled and changed as with a standard dual boiler machine.
    Izzo Pompei, and (it appears) the new Izzo Ursula.

    Greg

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    Quote Originally Posted by kwantfm View Post
    I haven't yet seen a lever where the brew temperature itself can be reliably controlled and changed as with a standard dual boiler machine.
    Does a lever exist where one can specify brew water temperature?
    It depends on what you mean by "controlled"..
    Remember , lever machines are by definition a "manual" device
    The basic thermal design of a (commercial) lever group is a large mass of brass that maintains a steady temp and will cool the hot incoming boiler water down to the desired brew temperature. Once a boiler temp is established, the brew temp should be very stable.
    Adjustment to brew temp is commonly made by flushing to increase the group temp, or sometimes holding a longer preinfusion to slightly cool the brew water.
    a larger range of temperatures can be obtained by adjustments to the boiler pressure.
    Obviously these are manual adjustments that must be learned by practice and experience..rather than electronically programmed.
    The nearest to a electrically controlled brew temp on a domestic lever machine, would be the Bezzera Strega which has a thermostatically controlled , electrically heated group.....but still no adjustment available "out of the box".

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    Not a Shoe Jimmytheboot's Avatar
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    Quote Originally Posted by kwantfm View Post
    Thanks for all of the replies... much appreciated.

    Jimmytheboot,

    Just to make it painfully clear for me, a lever group head is inherently difficult to set up in a dual boiler format as it doesn't have the thermal mass of an E61 nor the thermal stability characteristics of a saturated group?
    It has thermal mass like an e61 but there is a larger distance for the heat to travel, in an e61 the thermosyphon water reaches the centre of the mass roughly, in a lever maybe it reaches the rear of the cylinder.

    For a double boiler lever it looks like gaggia figured it out 60 years ago but didnt do much with it, boiler volume wrapping the cylinder.


    http://worldwide.espacenet.com/publi...R=751687A&KC=A

  10. #10
    TC
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    Behmor Brazen - $249 - Free Freight
    There are multi group dual boiler levers around- Maling Room has one but I don't think they necessarily make for a better outcome.

    All this discussion may make those interested in this type of machine think that it's too hard. My experience with a well configured lever is the exact opposite. Rather than throw darts randomly at the dartboard, once you know what you want, and maintain a consistent technique, you can then hit the bullseye time and time again. The only gotcha is the thermosyphon stall that we have seen and discussed in the Londinium, Achille etc. Even then, it's not the end of the the world as it can be solved with a temp strip and flush or with Rick's big brain.

    We are getting fantastic results with our Achille post Rick's PID and cartridge heater mod (and it will be for sale once the job is complete and we move onto the next project). Andy's Australium turned from Jeckyl and Hyde to kitty cat.

    The inherent simplicity of a great lever is a winner. A little love now and then and pretty much nothing other than boiler, element and autofill. If I could have done it, a 2 group Pompei would have replaced my GS/3 in the kitchen bench of the new place. Sadly, it was going to be tricky to supply it with 15A so that was that...



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