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Thread: Does an HX machine provide the right temperature?

  1. #1
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    Does an HX machine provide the right temperature?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Quite new on the coffee journey, excuse my noobosity.


    Does an HX machine provide the "right" temperature?

    After much reading of many manufacturers websites and a lot of snobs, I have not yet been able to find out if HX machines actually provide the correct temperature for brewing. e.g. between 92 and 95.

    I read somewhere, that an e61 HX machine is able to fluctuate madly from 75-120 degrees, (although of course that temperature it will be totally stable from boiler to grouphead.)

    Yet other threads and information suggest that a PID on an HX machine is not necessary, yet often people sell their awesome e61 machines due to not knowing what temp its at. One example is the Piccolo for sale here, because they guy has a Silvia with PID.

    Thanks.
    -----
    For background and reference, my shortlist of possible upgrade machines is really really long at the moment and I'm trying to wittle it down, hence the question.
    1: P41TEMD (current favourite.)
    2: VBM Piccolo
    3: Expobar Office Leva
    4: Breville BES840
    5: VBM Domobar Junior
    6: Lelit Mara
    7: Sunbeam EM7000
    (Lots of pros and cons for each of these, I can share the list if you like.)
    Drinking style right now is 40ml double, no milk no sugar, rarely ever more than one at a time.

    Current: Sunbeam EM3600.... but made massive inroads in quality from using freshest beans, stable temps, correct dosing, grinding correctly, heavy tamp. Often getting great slow honey-ooze pours, that maintain tiger stripe browns at 30seconds. (Candycane brown? I had a laugh)
    But somedays, I have absolutely no idea what went wrong when it was a textbook process. Never getting sourness, but will occasionally get a some bitter or overextraction.

  2. #2
    Senior Member Yelta's Avatar
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    Have a read through this HF, written by Graeme Burton, Five Senses Tech Department. should answer a few of your questions.

    The E61 Group Head: An Oldie but a Goodie






    E61 grouphead on an Isomac Alba









    Our Technical Services Engineer, Graeme Burton, takes everything coffee to a whole new level and explains here the E61 grouphead. Graeme worked in Curtin University’s Physics department for many years before joining Five Senses, where he combines his passion for coffee and his scientific know-how.
    State of the art technology in espresso machine design appears to demand ‘saturated’ brew groups. In the saturated design, as much of the brewing group as possible is open to the brew boiler itself. This results in improved temperature stability because the group is saturated with the same body of water whose temperature is being controlled in the boiler. Synesso and La Marzocco both use saturated groups. Obviously a saturated group can only work with machines that have separate steam and brew boilers.
    Before saturated groups were invented, most, if not all, semiautomatic espresso machines utilised a variation of the famous E61 group head. Despite being almost 50 years old, the E61 group head is still found in many espresso machines being manufactured today. This is probably because most espresso machines being manufactured today are of the single boiler, heat exchanger design. However, these days machines tend to use heavily modified versions of the E61 group, which may not incorporate original E61 features such as the thermosyphon heating circuit and passive pre-infusion.
    [Historical Side Note: Ernesto Valente invented the E61 group (shown attached to an Isomac domestic machine above) and it is known as such because it first appeared on the Faema E61 espresso machine. Incidentally, the name E61 signifies the total solar eclipse that occurred in 1961, the year of its invention.]
    Thermal inertia

    Around 4kg of chrome plated brass is used to manufacture the E61 group, thus providing high thermal inertia. It takes a long time to heat up and cool down, but this is important for temperature stability.
    Thermosyphon heating circuit

    The main internal chamber (#3 in the patent drawing, Fig 1) is connected to the brew boiler by two copper pipes seen in the image (above). The upper pipe goes from the top of the boiler to the top of the group chamber, while the lower pipe goes from the bottom of the boiler to the bottom of the group chamber. When the machine pump is not running, the hottest water in the boiler flows to the top and then into the top of the chamber. The water in the chamber cools because not only is it no longer being heated directly by the boiler, but also because it is transferring heat into the atmosphere. When cooled, that water then falls and exits through the lower pipe and into the bottom of the boiler. This produces a circulating flow of water that continues to heat the group. If the machine pump is activated, water is forced out of the boiler through both pipes and into the group chamber to brew coffee.
    Passive pre-infusion

    The term pre-infusion refers to brew water being applied to the coffee at a pressure lower than the ultimate brew pressure, for a specific period of time. This is supposed to gently wet the coffee and allow it to stabilise before receiving the full force of the pumped brew pressure. This should lead to a more even espresso extraction by improving the uniformity of the coffee density in the basket. Pre-infusion can be implemented in several ways. Firstly, the brew water can be applied at mains pressure before switching the brew pump on. Secondly, the brew pump can be run for a short period to introduce water into the group, and then paused before again running the pump at full brew pressure. A third method is to introduce a small jet, typically around 1 mm or less in diameter, into the brew water path. This jet restricts the flow of water to the coffee, even with the brew pump running, and this produces a slower increase in brew pressure. The term ‘passive’ refers to the fact that the brewing process has started and that no other actions are required, such as turning the pump on and off. A main feature of Valente’s patent is that the E61 group incorporates ‘automatic’ pre-infusion which we refer to as ‘passive’ pre-infusion.
    The E61 group head uses a jet and a special chamber for its method of pre-infusion. In the first stage, the pump is activated and water flows through a jet into a small cavity (#14, Fig 1), which is connected to the space above the coffee basket (#4, Fig 1). During this time, water fills the cavity and flows into the coffee basket. As the pressure in the cavity rises, a spring loaded valve (#8, Fig 1) opens to allow water to also flow into the special pre-infusion chamber (#9, Fig 1). Only when the pre-infusion chamber is full can the brew pressure rise to the ultimate brewing pressure. The time it takes these chambers to fill gives rise to a low pressure, passive pre-infusion stage.
    Although the E61 has been superseded for high-end commercial use, it still finds good and appropriate application in the domestic market. The temperature stability, especially when combined with double boilers (eg Expobar Barista Minore), is excellent for low volume use in a domestic setting, and the pre-infusion system is likely to significantly improve espresso extractions in the hands of an amateur barista.
    Written by Graeme Burton, Five Senses Tech Department.
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  3. #3
    TOK
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    Quote Originally Posted by Holyfrog View Post
    Quite new on the coffee journey, excuse my noobosity.

    1) Does an HX machine provide the "right" temperature?

    2) After much reading of many manufacturers websites and a lot of snobs, I have not yet been able to find out if HX machines actually provide the correct temperature for brewing. e.g. between 92 and 95.

    3) I read somewhere, that an e61 HX machine is able to fluctuate madly from 75-120 degrees, (although of course that temperature it will be totally stable from boiler to grouphead.)

    4) Yet other threads and information suggest that a PID on an HX machine is not necessary, yet often people sell their awesome e61 machines due to not knowing what temp its at. One example is the Piccolo for sale here, because they guy has a Silvia with PID.

    5) For background and reference, my shortlist of possible upgrade machines is really really long at the moment and I'm trying to wittle it down, hence the question.
    1; 2; 3; 4; etc


    Hi there. If you don't ask, you wont find out....so from my perspective, the answers to your questions are:

    1) Yes
    2) Beware of the specs you read on the net. For example, 95 is too hot for the types of coffees/roasts we favour in Australia. And, question already answered in 1.
    3) Wrong. Well made HX machines don't fluctuate like that, and even badly made HX machines wouldn't fluctuate by that much which is way (WAY) out of all proportion. And again, already answered in 1 & 2. The figures you have quoted appear to be theoretical or "raw" figures for a totally uncontrolled Heat Exchanger. Additionally, note HX machines were originally designed to be used continuously, and when left to idle especially for long periods, will heat up. That is normal, and that is what a cooling flush is for (to bring any overheating from not using the machine as designed down to a workable level), and after that a well designed HX will remain within its spec/. Certainly large cooling flushes on the less well designed machines are a frustration, but that comes down to choosing well in the first place (just like when you buy a car).
    4) Yes I am one that believes a PID is unnecessary on an HX machine. If people sell their awesome machine because they don't know what temp it is at, for me that would fall under the category of the client not understanding the equipment and managing it accordingly (i.e. not an equipment problem). PID's are for knowledgeable people (especially professional cupping laboratories) to take espresso to the nth degree for whatever reason (not going into here would make this a lot longer) otherwise, certainly NOT necessary for most coffee drinkers who will never move a PID setting from the setting it was delivered with when new. So by that I mean, there are an aweful lot of PID owners that never move the PID from its original setting when the machine was sold new. So then what is the point of having the PID, if the operator is not going to use it for what it is intended for.....meaning the marketing hype that sold the client the PID machine did its job....for the vendor, to perhaps justify a higher selling price... but not necessarily for the client, who would be making just as good a coffee with a good HX machine.....
    5) I think it you read these forums with your thinking cap firmly in place you will find that there are only a small number of machines that are forever discussed around, and that reflects only what the mix of sponsors sell. There are more excellent machines in the market than are discussed here.... I have a BFC Unico Splendor HX at home which is a cracker, and there are countless happy owners that don't necessarily discuss them around in forums...

    Hope that helps.
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  4. #4
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    As an owner of not one but two known brand hx machines, I can tell you that while you will get the temperature stability you are looking for in an upgrade, narrowing and defining extraction temps down to 2-3dc can be a bother sometimes. Given at 2-3dc, some might say taste in cup is negligible but when you take your coffee seriously enough and have other variables to content with, having temperature accurate to the decimal is a great feature to have. In summary, I can churn out great cups of coffee successively with a hx machine, no doubt, but reproducing the same tasting cup constantly? Quite a feat.
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  5. #5
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    Thanks a lot all, that is very helfpul so far. All of it.

    Just a note, my machine shortlist contains a lot more entries than those I mentioned. I'll check out the Unico too.
    A uniform taste of the shots day to day, when the variables ~should~ be the same, is the next goal.
    Same beans, same grind, same tamp, etc. should = same taste.

    From here, the questions in my head continue - is it worth stretching to an e61 HX, if I'm looking to be in control of the machine variables?

    - Does the HX take the temp variable out of it?
    - Well, yes. The temps (whatever they are) would be consistent day to day from what I read above.
    - Would a learner benefit more from a Lelit P41TEMD against, say, an entry e61 like Isomac Zaffiro Due?
    - what type of machine will tell you more about what is going on?
    - what type of machine would then allow you experiment further with beans and roasts, and baskets, and temps - comparing apples to apples?
    - with which would you be more in control of the process.
    These are not new questions, and probably that's partly why this forum exists and its just a matter of continuing to read and drink.


    Three machine examples:
    Lelit Anna P41TEMD

    • 1100w
    • 250ml brass boiler
    • 230w x 270d x 340h
    Isomac Zaffiro Due

    • 1400w
    • 700ml boiler
    • 230w x 430d x 410h
    Lelit Mara PL62

    • 1400w
    • 1500ml copper boiler
    • 220w x 400d x 360h
    Pros

    • Cost
    • PID controllable
    • Pressure gauge manometre
    • brass boiler
    • three way valve and 9Bar OPV
    • lever switches
    • quick heat up time.
    • Optional naked portafilter (XMC013)

    Cons

    • 57.5mm not as common as 58s.
    • no separate hot water,
    • 250ml boiler is fairly small.
    • Can it take Precision and VST baskets?
    • any preinfusion?
    Pros

    • E61 for stable temps
    • Lever with preinfusion
    • Manometre
    • Lever Switches
    • standard 58mm

    Cons

    • no separate hot water,
    • don't know what temp its at.
    Pros
    • E61 for stable temps
    • Most compact E61 HX in the world.
    • Cool Looking
    • Nice gauges - i.e. twin manometer
    • Settable over pressure valve
    • Separate hot water tap
    • Lever with preinfusion

    Cons

    • cost


  6. #6
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    - Does the HX take the temp variable out of it?
    - Well, yes. The temps (whatever they are) would be consistent day to day from what I read above.

    Without a grouphead thermometer you wouldn’t know better. The cooling flush ritual differs between hx machines (dragon, mixer, agnostic) and once you figure out through your tastebuds what produces the best results, your best bet would be to repeat. Consistent within a 2-3dc range yes, all else being equal. Idle temps might differ 1-2dc day to day and to account for slightly shorter/longer cooling flushes which will affect the heat curve when pulling the shot. Once you get your workflow down, your coffees should be delicious, bar the minute taste differences, which grows in correlation to snobbery level *I had a laugh*.

    - Would a learner benefit more from a Lelit P41TEMD against, say, an entry e61 like Isomac Zaffiro Due?
    I wouldn’t think so apart from longevity of the machine on your bench before upgraditis hits. I’ve used neither of those machines so I can only give an opinion based on specs. A copper boiler is definitely a plus as far as heating capacity and temp stability goes. Dual gauges not necessary unless you have the intention to muck around with the pressure – this affects a variety of things such as temperature recovery, steam power, taste in cup to name a few. All E61 machines have inbuilt preinfusion, only a select few have manual preinfusion with a half engaged lever, best to research if your E61 of choice has it.

    - what type of machine will tell you more about what is going on?
    More about?
    Temperature? P.I.D’ed machines. Erics grouphead thermometer is a must if you would like to understand the temp curves of your HX machine without interfering in the process.
    Pressure? Gauges, LED screens if you have a pressure profile machine.

    - what type of machine would then allow you experiment further with beans and roasts, and baskets, and temps - comparing apples to apples?
    Consistency is key, machine aside, technique and workflow is a huge factor to determining the coffee you output. A HX machine is well capable of facilitating that experimentation once you nail down a consistent workflow, bar the slight temperature differences as mentioned earlier. The more variables you can keep constant the more you are able to analyse the extraction by isolating the root or cause – this is invaluable.

    - with which would you be more in control of the process.
    Next up from the HX is the dual boiler which allows you to define the temperature without trial or error (within this group there is the saturated grouphead which boasts even better temp stability by exposing more of the boiler to the grouphead). Then there’s the pressure profile dual boilers, which not only keep temperatures in check, but also allows tweaking of pressure in multiple stages throughout the extraction process.
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  7. #7
    TOK
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    Hello again.

    Apology in advance....long winded reply.

    Its only my opinion but I think you may now be over complicating things, and you seem to be getting yourself into areas (through reading), that wont make much sense until after you start to master whatever you buy.

    Set a budget.

    Get off the web. Over reading will just confuse you with "pros and cons" written up by other people, that may not be a problem either way for you, and possibly meaningless specs or features.

    The machines you have listed will all do the job *if you learn how to use it* (the one you decide to buy) properly. It is certainly not a 5 minute job to master the black art of making espresso, consistently, after reading hundreds of pages on the web. The info on the web just makes it a little easier, but doesnt take the onus off of you to get to know your chosen model and the black art.

    When you list machines with "pros and cons" it is as if you (anyone) is listing a bunch of equipment all of which seem to have some kind of "problem", and where one will in the end be "better" than the rest. What defines "better"? It differs for each individual. Each model will need you to get to know it to get th best out of it. If you are capable of getting the best out of for example, all three machines you listed, you will probably find no more than something like this:
    More capacity / less capacity.
    More features (whether you actually use them or not) / less features.

    The smaller capacity, cheaper machines you listed, will have....less capacity, and will be more finicky to use.

    The attribute of whether a machine is *finicky to use*, is not usually listed in lists of pros and cons that can be read on the web. But it will mbe something that a pro machine vendor will demonstrate for you.

    The coffee in all cases....should be good...regardless of a machine's capacity, its list of features,and how finicky it is to use (especially when you have people around), and in the end will be up to your capability as the operator.

    The total "package" that any particular model will give the operator therefore, is not equal to the sum of a written list of specs.

    Advise you therefore, to visit an espresso machine specialist and check some machines in the flesh. Not all pro machine vendors are sponsors. Is there one near to your area? Some machines on your list wont be available, but different ones will be....depending on who you visit. Vendors dont all stock everything, and they dont have to stock something that gets keyboard time on the web. Allow the pro to guide you to find what suits you best. If it wasnt even on your initial list, what does it matter if you select a nice machine that suits you and performs really well?

    That is the only way once you have got the basics off the web.

    Hope that helps.
    Last edited by TOK; 25th November 2014 at 07:01 PM.
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  8. #8
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    Quote Originally Posted by Avex View Post
    All E61 machines have inbuilt preinfusion, only a select few have manual preinfusion with a half engaged lever, best to research if your E61 of choice has it.
    Oh interesting, I didn't know that.
    I thought all of them had the lever operated manual preinfusion - where you lioft the lever to horizontal for unpressurised or semi pressurised (1-4bar) preinfusion, then lift the lever to full position for full pressure.



    Quote Originally Posted by Avex View Post
    - More about?
    and
    - Erics grouphead thermometer is a must if you would like to understand the temp curves of your HX machine without interfering in the process.
    Pressure? Gauges, LED screens if you have a pressure profile machine.
    - Yes, More about: Temperature, Pressure, any other machine variables that perhaps I don't yet know about.
    - I like the idea of Eric's grouphead thermometer also. More informative than a PID alone.

    And I have since found out about a few more options:

    from Kostverlorenvaart

    I take it all HX machines have user controllable boiler temperature somehow - whether PIDd or not.
    e.g. just by flushing or by other controls.


    Quote Originally Posted by Avex View Post
    Consistency is key, machine aside, technique and workflow is a huge factor to determining the coffee you output.
    Absolutely true. The Sunbeam EM3600 has been a great teacher in that sense.

    Quote Originally Posted by Avex View Post
    Then there’s the pressure profile dual boilers, which not only keep temperatures in check, but also allows tweaking of pressure in multiple stages throughout the extraction process.
    This is very interesting also and can see how this could be useful for fine tuning a shot. Know of any domestic machines that do this?

  9. #9
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    Thanks Tok.

    Quote Originally Posted by TOK View Post
    It is certainly not a 5 minute job to master the black art of making espresso, consistently.
    I fully agree. The last 24 months amongst other things was learning to smoke meats. Was a similar journey into the black arts and managed to get away with not spending thousands of dollars, due to reading and experimenting. Even got to the point of smoking 40 hocks in one day for Oktoberfest - couldn't have got there without the internet's help.

    I'm at the point where I am making the odd God shot with even my Sunbeam with unpressurised baskets, and doing my utmost to not waste precious coffee beans. Which means I''m pulling up to 6 shots a day while trying to fill my head with knowledge, before I invest in what will likely be a once-in-5-year purchase, especially with a kid on the way. The biggest risk for me is buying something that instantly gives me a reason to upgrade again, so I appreciate these helpful posts.

    Pros and cons are a bit all over the place but they are often relative to my current machine (i.e. better than what I currently have), or are a personal judgement (e.g. lever switches as opposed to plastic buttons)

    Quote Originally Posted by TOK View Post
    The attribute of whether a machine is *finicky to use*, is not usually listed in lists of pros and cons that can be read on the web. But it will maybe something that a pro machine vendor will demonstrate for you.
    A great point. My current process and machine is like this, but its not a huge problem. I try not to rush my shots and preheat, weigh, dry, measure everything.
    I even have a thin pointed Japanese chopstick that assists in settling the initial grinds before tamping. Doesn't actually take that long.

    I live in Darwin, so not a lot of vending going on. There is an Isomac dealer with three different Isomacs on the shelf, but I don't want to lead them on either.
    Last edited by Holyfrog; 26th November 2014 at 02:18 PM.

  10. #10
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    Quote Originally Posted by Holyfrog View Post
    This is very interesting also and can see how this could be useful for fine tuning a shot. Know of any domestic machines that do this?
    LM GS3 has been a longstanding favourite affordability wise.
    Then there are also machines that cost more than a car, 1 group head slayers, hydras, speedsters.

    the newly released vesuvious by ambient espresso is another built more for a domestic environment with the classic e61 grphead:
    http://coffeesnobs.com.au/brewing-eq...t-spresso.html

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    Very nice Avex.
    The Vesuvius looks amazing and the 5 brew profiles are outstanding. So many features - also inspired me to get a timer for my machine.
    Way out of my league price wise, but good to know about it.
    Some of the profiles people are coming out with, are simply coffee pr0nography. Love it.

    I've seen Gail from Seattle use the GS3 a few times and it does look good.
    I cant quite tell if it needs to be modded to do pressure profiles or is it standard. I think the Strada has the profiling as standard.)

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    Quote Originally Posted by Avex View Post
    ... but when you take your coffee seriously enough and have other variables to content with, having temperature accurate to the decimal is a great feature to have.
    Thanks Avex.

    For anyones interest, I ended up going with ECM Classika II PID.
    Single boiler e61 with Gicar PID, seems to be perfectly matched to my coffee style and capacity, and solves any concerns I had about temperature with a HX.


    Image from 1st line equipment.
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  13. #13
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    Behmor Brazen - $249 - Free Freight
    congrats on the new machine holyfrog!

    in all honesty, unless you're churning out consecutive milk-based coffees for guests and you don't like them waiting for too long, a single boiler should suffice for an individual's needs.

    The PID is always nice; knowledge and control of extraction temperatures, coupled with the e61 grouphead for the stability, this machine could you last you a while.

    Hope you bought a good grinder to go with it .



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