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Thread: VBM Domobar Super temperature variability

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    VBM Domobar Super temperature variability

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I use my VBM only 2 to 3 times a day and notice that the group-head temperature seems to stabilise at greatly varying temperatures, sometimes barely hot sometimes boiling.* I installed a Eric Svendson digitherm to see what was going on and indeed it shows a huge variation.* BTW, this is a real nifty device, see the pic.* The boiler pressure oscillates nicely around 1 bar so it would seem the pressurestat is OK.* Im going to give it a good descale, as soon as I get some descaler.* Any other ideas?


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    Re: VBM Domobar Super temperature variability

    what you are seeing is thermosyphon stall. It happens when there is an air or vapor gap in the heat exchanger and the convection current cannot overcome it. It is most often caused by doind a short group. Some of the water in the HX flash boils and causes a "gap" in the water. The preventitive measure is, as can be assumed, that when you do a group flush, make it for at least three or four seconds.

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    Re: VBM Domobar Super temperature variability

    Thanks, Im sure thats part of it.* I have been doing small cleaning flushes.* However, that would account for the low temperatures.* What would cause the group to get to 100C as it does sometimes?

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    Re: VBM Domobar Super temperature variability

    Hi Bob,

    How old is your machine?

    Was it an ECA import?

    Cheers

    Chris

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 63565B5C68745851515252370 link=1327895468/3#3 date=1327918663
    Hi Bob,

    How old is your machine?

    Was it an ECA import?

    Cheers

    Chris
    A few years old now. I bought it at Sobonis at Pymble so it may well be an ECA import.

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    Re: VBM Domobar Super temperature variability

    Hi Bob,
    Did you get an answer on the high temp?
    I have the VBM Super Electronica 2009 model with Erics temp as well and my std temp is around 210f if I leave on for a while. I can reduce the temp with back flush and other means and currently I brew at startinging temp 203f but keen to have std temp a bit lower.
    Pressure is between .9 and 1.1 bar with brew pressure showing 9.8 bar which as I understand means actual pressure at the group head is 8.8
    Keen to hear what options I have.
    Thx Rusty

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 577A5056515C250 link=1327895468/5#5 date=1328873307
    Hi Bob,
    Did you get an answer on the high temp?
    I have the VBM Super Electronica 2009 model with Erics temp as well and my std temp is around 210f if I leave on for a while. I can reduce the temp with back flush and other means and currently I brew at startinging temp 203f but keen to have std temp a bit lower.
    Pressure is between .9 and 1.1 bar with brew pressure showing 9.8 bar which as I understand means actual pressure at the group head is 8.8
    Keen to hear what options I have.
    Thx Rusty
    Short answer, "No".* Im still playing with it.* The temperature occasionally sores to 100C, the water boils in the group head forming a vapour lock forms which shuts down the thermosiphon and the group head temp plummets to the 80s.* I have now set the boiler pressure to around 0.7bar.* This seems to help but I need more time to confirm it.* I suspect the 1bar recommendation is if you are pulling shots all day.* I rarely pull more than two at a time.* However, there is always the chance my gauge is inaccurate.

    I descaled the machine.* That certainly got some gunk out but didnt do anything for the overheating.

    I have a group head pressure gauge and find I need about 11bar on the dial to get 9bar at the group head with a double shot basket.

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    Re: VBM Domobar Super temperature variability

    Sounds like its minus the ECA spec thermosyphon restrictor. Assuming its an ECA import, your supplying dealer will be able to fit one. There was a mob selling these some 5 years ago in Australia. The older machines are of different spec. and run hot.

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 7144494E7A664A43434040250 link=1327895468/7#7 date=1328934771
    Sounds like its minus the ECA spec thermosyphon restrictor. Assuming its an ECA import, your supplying dealer will be able to fit one. There was a mob selling these some 5 years ago in Australia. The older machines are of different spec. and run hot.
    I had a look and couldnt see anything that looks like a flow restrictor, so where do I get one? Id like to install it myself. However, one has to ask why this has become such a problem only after a few years of reasonably satisfactory operation. I suspect something else is faulty or needs maintenance. Any ideas?

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    Re: VBM Domobar Super temperature variability

    OK, so I put the VBM in to ECA for a long overdue service.* It came back looking like a new machine.* I mentioned the flow restrictor issue but neither the storeman nor the tech new what I was talking about so I let it go.* Unfortunately the overheating is still there.* Ive got it to stabilise somewhat by setting the boiler pressure to just under 0.8bar.* This gives me a brew temp in the low 90s.

    A warning to all E61 HX users not to install Erics thermometer.* It is a wonderful piece of kit but what it does is tell you how poorly these machines are regulated.* I defy anyone to pull a shot at a consistent 92.* Sure if you are really careful and employ a long flush and wait technique you might be able to average 92 but average is not the same as consistent.* Also, I dont think it acceptable that one should have to use long flushes to get a decent shot out of a machine this expensive.

    Before Im bombarded with derision, I would like to qualify my comments by saying that I have no doubt HX machines work great in a heavy use environment where each shot stabilises the next but for the home user that might pull just a few shots irregularly during the day, the HX just doesnt do the job.* Im thinking PID machines might be the way to go.

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    Re: VBM Domobar Super temperature variability

    I am sorry Bob, but I have to disagree with you.

    Scace II traces prove that these (ECA imports) can and do run beautifully- and consistently.

    The original importers of VBM delivered a totally different configuration- with domestic pressurestats and smaller boilers. They were hot running dogs.

    Personally, I dont place too much trust in a meat thermometer jammed into a group as it has little to do with what occurs at the puck.* :-?

    As youre in Sydney, I suggest you speak with Charlie, Renzo or Dennis (Jetblack, Di Bartoli or cuppacoffee respectively). A Scace calibration together with the installation of appropriate thermosyphon restriction will deliver you a totally changed beast.

    Bottom line is that there are a myriad of brilliant HX machines out in the field and when well designed and calibrated appropriately for the Australian market, they are excellent.

    Chris

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    Re: VBM Domobar Super temperature variability

    I have a VBM Domobar SS, bought through Chris/Dennis. The only time I have heat issues are when I leave the thing running for hours on end without making a brew. When this is the case, I run a long flush (until the water coming out of the grouphead is no longer flash boiling) at which point I start my grind/tamp routine.

    This gives me a pretty decent result on a regular basis.

    Grant

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    Re: VBM Domobar Super temperature variability

    I dont recall ever seeing my VBM Domobar SL flash boiling.

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 6B5E5354607C5059595A5A3F0 link=1327895468/10#10 date=1331422697
    Personally, I dont place too much trust in a meat thermometer jammed into a group as it has little to do with what occurs at the puck.* :-?
    It is a well-designed add-on and it really works. Can be used to easily create a consistency in the temperature of the extraction and costs a LOT less that a Scace which can be used to set an OPV or a pressurestat but will NOT give feedback in actual use. They are two different tools that are designed to do two different jobs.

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    Re: VBM Domobar Super temperature variability

    If a bloke grabs a trout upstream, I dont neccessarily assume Ill get one 3 ponds down.

    Whilst the meat thermometer will measure water temperature, its not at the puck and to presuppose that hot means a hot extraction is by nature an extrapolation. Theyre damn good when shoved up the rear end of a chook though.

    Ill back my Scace as a more accurate approximation. As for the OP, a bead probe at the puck would be well worth a try. My diagnosis and recommendations stand.

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    Re: VBM Domobar Super temperature variability

    was thinking of getting one of these thermometer thingys - surely they arent all bad and some reference is better than nothing?

    looks like the only way to get one of these is direct from o/s ..?

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 2C2A37213A372169616068580 link=1327895468/15#15 date=1331524117
    was thinking of getting one of these thermometer thingys - surely they arent all bad and some reference is better than nothing?

    looks like the only way to get one of these is direct from o/s ..?
    Get one by all means.* Its hardly "...a meat thermometer jammed into a group.".* Its a calibrated thermocouple device.* As far as catching a trout upstream, put your finger in the stream then put it in a fraction of a second down stream and I think you will find a pretty good correlation.* I fact Eric has correlated the Taylor digitherm in the group against the Scace, see the attached graph.* A very consistent correlation I would say.
    Yep the best and cheapest way is to get the gear from Eric Svendson himself.* He is also extremely helpful.


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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 5C717C4A1E0 link=1327895468/9#9 date=1331421734
    , I would like to qualify my comments by saying that I have no doubt HX machines work great in a heavy use environment where each shot stabilises the next but for the home user that might pull just a few shots irregularly during the day, the HX just doesnt do the job.
    Hello Bob,

    Essentially, it comes down to whether or not you would like your problems resolved....

    If you choose not to use the advice, so be it. Ultimately, it wont make much difference to the rest of us but you can have a better performing machine if you want one.

    Your comments re e-61 groups in domestic environments are incorrect though. You simply have one hot running machine which can be relatively easily calibrated.

    Ive seen thousands of e-61 machines and state categorically that your findings do not reflect my experiences.

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 62575A5D69755950505353360 link=1327895468/17#17 date=1331625729
    Quote Originally Posted by 5C717C4A1E0 link=1327895468/9#9 date=1331421734
    , I would like to qualify my comments by saying that I have no doubt HX machines work great in a heavy use environment where each shot stabilises the next but for the home user that might pull just a few shots irregularly during the day, the HX just doesnt do the job.
    No problem Bob,

    Essentially, it comes down to whether or not you would like your problems resolved....

    If you choose not to use the advice, so be it. It makes little difference to the rest of us.

    Your comments re e-61 groups in domestic environments are incorrect. You simply have a hot running machine which can be relatively easily calibrated.
    Calibration will only tell me what I already know. With my digitherm installed, I now have a basis to get some control over taste. My whole point was that it shouldnt be so difficult with such an expensive machine. Flushing till the water stops boiling in the group, tells you only that the water is now <100 and you then have to trust your machines average characteristics to give you a reasonable shot. That is not good enough.

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 705D5066320 link=1327895468/18#18 date=1331627983
    Calibration will only tell me what I already know.
    Nope-* It will resolve the issue.

    Quote Originally Posted by 705D5066320 link=1327895468/18#18 date=1331627983
    My whole point was that it shouldnt be so difficult with such an expensive machine.*
    Its not. Your machine is not representative of other Domobar Super machines. Sadly, regardless of how I write that, you choose to ignore it, so Ill go find a suitable wall to beat my head against and you can suit yourself.

    Good luck with your PID machine. Astute CSers, keep an eye open for a bargain given its so terrible. ::)


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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 0C393433071B373E3E3D3D580 link=1327895468/10#10 date=1331422697
    As youre in Sydney, I suggest you speak with Charlie, Renzo or Dennis (Jetblack, Di Bartoli or cuppacoffee respectively). A Scace calibration together with the installation of appropriate thermosyphon restriction will deliver you a totally changed beast.

    Chris
    BobT - take the free advice and spend the coin with a sponsor - it may be the best thing you do with such a beautiful piece of kit ;)

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    Re: VBM Domobar Super temperature variability

    Been watching this with interest, and getting straight to the point.

    Also I am writing this as the pioneer of E61 heat exchanger machine calibration for these type machines in the Australian market where by and large, before I started doing this, many machines were simply imported in their normal Italian market configuration.....and running hot / burning coffee.


    Bob, your comments re heat exchanger machines not being suitable for home use are I am afraid, simply wrong. That said they do need to firstly have been calibrated correctly either by the manufacturer or the importer or selling agent, BEFORE it comes to the end user, for the market it is being sold into. That is, you wouldnt even know any calibration had been done, and would have a really nice functioning semi commercial heat exchanger machine.

    Machines imported into the Australian market in the normal Italian market configuration, run hot for whatever reason that is acceptable in their market, but not ours.

    The advice you have been given by Chris from Talk Coffee simply, is correct.

    You have two options. Continue using the machine as is and accept that you need to do long cooling flushes before each and every coffee OR, send it to someone in the know for modification to Australian market spec. Not everyone is in the know or cares, and that is what separates the men from the boys in the market for quality coffee machines or machines to produce a quality product.

    As to scaces, thermocouples and other instruments invented to drive people over the deep end with details.....the psychology here is the more instruments you give people, and the more precise these instruments become, the more things their users will find "wrong" ie that dont fit some spec or other.

    Ultimately however, its all about anyones level of understanding of what the level of performance should be, or what the character in the resulting cup of coffee should be, you dont need an instrument to tell you that, and if it were me I would take the thermocouple out and put it in a draw where it cant do any more harm.

    You may be interested to know that when I pioneered the art of "signature speccing" (or "calibrating" if you wish) these machines for my market, I didnt use any instruments at all....I did it the old fashioned way by feel and touch and trial and error just like old time mechanics used to do when setting the timing on an engine distributor. Then I advised my manufacturer what I wanted, and ever since then they have been building the machines I import, to that (my) specification.


    My BFC / Diadema machines dont burn coffee and dont run hot, and there is no reason why yours should either, if the appropriate set up is done.

    So believe it or not, signature speccing or calibration of your machine will work really well if it has not already been done to make it suitable for our market, and if there isnt anything else amiss.

    And / or.....perhaps it is something to do with the way you manage your machine or your level of understanding. EG regarding your advice that the machine stabilizes at different temperatures, it could be said that it doesnt matter a hoot and will be subject to the length of time it is left on but not used where it cant help but overheat, and what actually matters is that it can subsequently be stabilised down to the correct temperature to make coffee and then remain reasonably stable for a period.* Leaving machines like this on for long periods without making coffee, is not best practice.

    Or....the "problem" is caused by the fact of what the operator is seeing on the aftermarket thermocouple display....

    Is there really a problem, or not?

    The only ones that can tell, are service people in the know about your particlar brand model machine.

    Long winded as usual I know, and I hope that helps.

    Attilio
    very first CS site sponsor

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 724651475C6B775B52525151340 link=1327895468/21#21 date=1331683040
    Machines imported into the Australian market in the normal Italian market configuration, run hot for whatever reason that is acceptable in their market, but not ours.
    Quote Originally Posted by 724651475C6B775B52525151340 link=1327895468/21#21 date=1331683040
    many machines were simply imported in their normal Italian market configuration.....and running hot / burning coffee.

    Does anybody know why the Italians like their coffee burnt???

    I still remember that youtube video of the Italian specced Izzo Vivi - it was spluttering boiling water for ages....

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 66616A6A617070040 link=1327895468/22#22 date=1331694727
    Does anybody know why the Italians like their coffee burnt???

    I still remember that youtube video of the Italian specced Izzo Vivi - it was spluttering boiling water for ages....
    Yes, I can.

    Many of their coffees are circa 50% robusta. They also often roast dark (especially roasters in the south). These coffees are best extracted at a much higher temperature than our lighter roasts.

    Please note also that our Vivis also run at a beautiful 93 deg C (give or take). Those interested can keep an eye out for an astonishingly inexpensive Vivi/K3P package deal from Cuppacoffee later on today.

    Chris


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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 35323939322323570 link=1327895468/22#22 date=1331694727
    Does anybody know why the Italians like their coffee burnt???
    I doubt they like it burnt bennett, they certainly do enjoy a darker roast than most Aussies and I prefer mine that way as well, but burnt, never. :)

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 0B3E3334001C3039393A3A5F0 link=1327895468/23#23 date=1331695267
    Please note also that our Vivis also run at a beautiful 93 deg C (give or take). Those interested can keep an eye out for an astonishingly inexpensive Vivi/K3P package deal from Cuppacoffee later on today.
    Hi Chris, thanks for the quick answer. I hope you didnt take offense to my statement about Izzos running hot. I realy did mean the Italian specced ones - I cant imagine anything that comes out of the Talk Coffee stable would be anything but perfect. :)

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    Re: VBM Domobar Super temperature variability

    So is the reverse also true? If I were to put a very dark Italian roast through my Aussie specced VBM Junior - would it be too cold an extraction for that roast level? Or is it more complex than that?

    This also raises a good point. Whilst I disagree with BobT about his thoughts on Hx machines - mine is super stable, I have often wondered about buying a PIDd DB eg Diadema Junior extra DB or Izzo Alex Duetto so I can play around with the temp with different beans at different roast levels. Just cant justify the cost at present when the coffee tastes so good out of my VBM Jnr.

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    Re: VBM Domobar Super temperature variability

    Quote Originally Posted by 3E3932323928285C0 link=1327895468/26#26 date=1331696190
    So is the reverse also true? If I were to put a very dark Italian roast through my Aussie specced VBM Junior - would it be too cold an extraction for that roast level?
    Sure is- and yes, I was aware that you were referring to Italian spec. machines, not ours. All good! ;)

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    Quote Originally Posted by Talk_Coffee View Post
    Nope- It will resolve the issue.



    Its not. Your machine is not representative of other Domobar Super machines. Sadly, regardless of how I write that, you choose to ignore it, so Ill go find a suitable wall to beat my head against and you can suit yourself.

    Good luck with your PID machine. Astute CSers, keep an eye open for a bargain given its so terrible. :
    Chris,

    Just found this thread. I suspect mine is running hot too and I get what you are trying to say. If I am in Brisbane, where do I get this looked at?

    Thanks,
    Merv

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    Hi Merv,

    Not sure I can suggest an answer in Brisvegas.

    Best bet is to let it idle for 30 min then grab a video and post it. I can then offer an opinion.

    Cheers

    Chris

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    I actually figured out how to lower the boiler pressure to 1.25 and at 30mins according to the "meat thermometer" it's now down to 98.8c which is lower than previously above 100. Perhaps I'm ok now?

    The other question I had was many said they "set" their brew pressure to 10.5bar. Mine stops at 9bar. Does it matter? If I were to change it. How? Mine's second hand 4yrs old. The manual's useless and I can't seem to find that instructions online.

    Related note: I am actually pulling good shots. So all these are just extra worries and fine-tuning. Having to flush too much is my big bear at the moment. But the lower of the pressure last night might have fixed it.

    Other related observation - although Eric's temp showed a brew estimate of 97C which is higher than I would like it, it seems to taste good in the cup... I'll take some notes and figure it out. This is one situation where knowing the temp seems to confuse me more than helping...

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    Quote Originally Posted by Talk_Coffee View Post
    Hi Merv,

    Not sure I can suggest an answer in Brisvegas.

    Best bet is to let it idle for 30 min then grab a video and post it. I can then offer an opinion.

    Cheers

    Chris
    Chris,

    Pardon my nativity. Video of what exactly? Of me pulling a shot? Or of the temp changes on the thermometer while pulling the shot?

    Thanks,
    Merv

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    Hi Merv,

    You can give http://coffeesnobs.com.au/sponsors/2...-roasters.html a try, however, I'm not sure if they are willing to look at machines that weren't sold through them.


    Cheers,



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