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New HX machine - boiler pressure too high?

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  • runfast
    replied
    Re: New HX machine - boiler pressure too high?

    Do you have pics?

    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    had a significant "penny drop" this week. I believe the reason that the cooling flush was greatly reduced the day I installed the restrictor was my air conditioning. hadnt really paid enough attention before to when it did or didnt require a longer flush, I was just confused as to why it sometimes seemed to require no flush, and other times needed the same length flush as it did before installing the restrictor. Its no wonder I had trouble getting consistent results...

    I received my digital thermometer from Eric Svendson this week. I noticed that when the air-con is on (in the evenings after work), the group head temp never gets much above 91*C, while in the mornings (and any other time the a/c is off)its up to 99*C within about 45 minutes after startup.
    Im now wondering if a 91*C group temp is too cool. is it?

    Im still working out how to use the thermometer properly - since it supposedly reads a few deg higher than the puck temp - need to experiment a bit more to work out how the different temps it reports relate to taste...

    Geoff

    Leave a comment:


  • hazbean
    replied
    Re: New HX machine - boiler pressure too high?

    "Hazbean do you know if your machine has any restrictor installed?
    also how do you find the steaming performance?"

    I dont know if there is a restrictor -- AFAIK the machine is as
    supplied by the distributor. Ill find out when I get it serviced.

    We dont have much need for steaming any more, so dont use it very
    often. When we first got the machine, the steam pressure was
    overwhelming for our small amounts so my wife fashioned a couple
    of "cotter pins" from ss jewellers wire and stuck them into the two
    holes of the steam wand as a restrictor. Yesterday as a test I
    took 250ml of cold water at 5C and "textured" it (nice whirlpool
    anyway) stopping at 65C (measured with my TC). This took
    50 seconds. Would have been a lot less without the pins, will
    do another test without them when I can.

    Can the distributor offer any suggestions for service?

    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    Originally posted by 25080C000D610 link=1256380339/30#30 date=1263050488
    Still reckon you need to find a reputable, highly regarded technician in your locale to suss everything out properly and adjust/rectify what ever needs doing....
    Theres no-one in my direct area who can help, but I would have thought there should be someone in Perth who can offer the kind of services that the east coast people enjoy - someone knowedgeable enough to have a look and pinpoint where this machine could be improved. The guys at Five Senses sell Isomacs and could help with things like scace testing, but it seems they havent done any basic customisation of the HX machines to improve their performance.
    They seem more into major customisation - theres a blog on their website detailing their custom Mondiale. It is now a PIDd dual boiler machine with a Synesso Cyncra group. That seems like the perfect solution, but when I spoke to them they estimated at somewhere around $3k to modify a standard Mondiale they way theyve done it. They said theyve got a waiting list of people who are interested in having it done to their machines if they decide to offer it.
    so as it stands I might do a ring-around to see if I can find anyone, otherwise if I start with a temperature monitoring device of some sort I can probably live with the machine as it is. The coffee is very good, and the steam performance is ok. Ive thought about buying another steam tip and seeing how it goes with the holes drilled out a bit bigger. if it doesnt work then Ill just put the original one back on...

    Leave a comment:


  • Dimal
    replied
    Re: New HX machine - boiler pressure too high?

    Wow!

    That HX sits high in the Boiler. Doubt it is immersed in water at all so must rely totally on transference via Steam. Such being the case, water level wont make much (if any) difference. Still reckon you need to find a reputable, highly regarded technician in your locale to suss everything out properly and adjust/rectify what ever needs doing....

    Mal.

    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    Originally posted by 5164696E5A466A63636060050 link=1256380339/25#25 date=1262861353
    If the HX is too fat and too short
    here it is
    In...


    where the restrictor has been installed... size of the hole in the fitting at the end of the pipe was 8mm, and as I mentioned above, it now contains a restrictor at about 2.8mm


    Out...


    Out again...


    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    this is very interesting...
    I arrived at the conclusion that my machine was behaving as it was designed to, based largely on it seeming to have the same temperature characteristics as many HX machines in the USA that Ive read about on the HB forums. Considering that many of the machines that are talked about on here as behaving very nicely are apparently modified on request by certain Australian distributors, Ive assumed that mine is an unmodified machine and I need to tweak it so that it plays nice...

    I found another thread a while ago from another Mondiale owner who seemed rapt with his machine, so sent a PM but he doesnt appear to have been active on the forum for a while and I havent heard back... other than that Ive been able to find out very little about other peoples Mondiales.

    dumb HX design is something that would be pretty difficult to fix, but now Im thinking that if other Mondiales only require a 10 second cooling flush when hot, then why is mine different?? The scace test seemed to verify that with the boiler pressure at 1.1-1.3 bar, my machine was running 94-95C after about 30 to 35 seconds flush and seemed to stabilise on that temperature.
    now after installing a (slightly big) restrictor it seems a lot better, but if other people are finding that their unmodified machines are behaving better than mine, maybe something is still amiss??

    Originally posted by 28213A2225212E400 link=1256380339/27#27 date=1263016886
    I did for a while consider looking into restrictor mods etc but
    reached the conclusion that such mods can affect other aspects
    of thermosyphon operation and without knowing more about its
    specific design possibly difficult to get right.
    Hazbean do you know if your machine has any restrictor installed?
    also how do you find the steaming performance? from some of the numbers I mentioned above, Im told mines a tad slow.

    Originally posted by 04292D212C400 link=1256380339/26#26 date=1262868481
    Could even come back to Boiler Water Level
    this isnt something Ive considered before... how might it affect things??
    thanks

    Geoff

    Leave a comment:


  • hazbean
    replied
    Re: New HX machine - boiler pressure too high?

    Hadnt noticed this thread before due to being away ...

    Ive had a Mondiale for a couple of years and now getting what
    I think are very good results from it.

    At first though I did think it was running a bit hot and giving a
    longer cooling flush than expected. It was also adjusted to an
    excessively high brew pressure (13+ on the gauge).

    But since a couple of adjustments its working well. First was
    pressurestat, adjusted down to a 1.1 - 1.3 range. Then the
    brew pressure. It took a while to get around to doing this as
    it required pulling the cover off, but turned out to be
    pretty straightforward (I posted about that a few months ago).
    That is now set to just over 10 on the gauge.

    With this, cooling flush is 10 - 12 seconds when hot, and very
    short pulling consecutive shots (which I dont do very often so
    havent measured it). Warmup time is about 45 minutes but
    could I think get away with less.

    The technicians in the workshop of the Isomac distributor gave
    helpful advice on a couple of occasions about the workings of
    the machine and what I could expect to find when adjusting
    the OPV. Saved me a fair bit of fiddling around.

    I did for a while consider looking into restrictor mods etc but
    reached the conclusion that such mods can affect other aspects
    of thermosyphon operation and without knowing more about its
    specific design possibly difficult to get right.

    Nonetheless I think the evidence is a bit thin to categorize it as a
    dumb HX design ... Would be interesting to run some tests though.

    FWIW a while ago I attempted some temp measurements by poking a
    calibrated TC lead into a group handle stuffed with foil and locked
    into the machine (this can damage the TC wire but I took the risk).
    IIRC this stabilized in the 91 to 93C region after the flush.

    Anyway Im now pulling shots in the 30 second range with good
    crema and most importantly showing the origin characteristics
    that Id been hoping for, and consistent with what I get cupping
    the same beans.


    Leave a comment:


  • Dimal
    replied
    Re: New HX machine - boiler pressure too high?

    Could even come back to Boiler Water Level or HX Mixing too.... :-?

    If this is not right it will alter the characteristics of the actual Heat Exchange to the Brew Water, to the extent that it wont matter what you do any where else in the hydraulic circuit ultimately the Brew Water is going to reach the same temperature as always (give or take) and require the same volume of a cooling flush.

    Personally, Id take it to someone like Chris who has all the test gear on hand combined with the knowledge gathered over many years to properly assess what is going on. It is really very difficult to try and determine the root cause of this sort of a problem via remote control unfortunately....

    Dont know if any other sand-groper CSers can recommend someone to you....

    Mal.

    Leave a comment:


  • TC
    replied
    Re: New HX machine - boiler pressure too high?

    Hi Geoff,

    2.8 is big- you may get better results out of 2 or 2.5....You really do need to play with a Scace to see what its up to. You may also need to experiment with pressurestat settings and different gicleurs as well.

    I have been using my Scace with Andys roast monitor software. Real time curves!  8-) [smiley=thumbup.gif]

    The heat up is concerning though.... :-/

    I have very little experience with this machine but it really sounds like it could be a case of dumb HX design to me. If the HX is too fat and too short, doesnt matter a whole heap what you do...

    Sadly, its pretty much impossible to create smart design from dumb

    Chris

    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    Originally posted by 02373A3D09153930303333560 link=1256380339/23#23 date=1262857453
    Hi Cooper,

    Curious to know how you went with your hot running Mondiale....Any success in settling it down?

    regards

    Chris
    Gday Chris
    jurys still out im afraid.  Im thinking of getting one of Erics TC devices sent over from the US so I can keep a closer eye on it.
    After installing a restrictor ~2.8mm I thought it was fixed, but in reality I think it just takes much longer to warm up.   If I wait half hour to 45 mins after turning on, it barely needs a flush.  after a couple of hours idling, it seems to need just as much flushing as it did before I installed the restrictor.  then after flushing it doesnt heat back up quite as quickly as it used to, but it still needs a bit of a flush between shots (Im not very quick but that time also includes steaming the milk for the first shots).  

    As it stands, the flushing does seem to be reduced overall, and with a way to monitor the temperature Ill probably be quite happy with it how it is.  Erics TC seems to be the neatest option for doing that from what Ive found so far...

    maybe if I install a restrictor with a smaller orifice (2mm or 2.5mm??) it might maintain temperature better once fully warmed up, but could that mean it will be taking up to an hour after turning on before I can start making coffee??

    due to the long warm up times, the machine is usually on all the time except for while Im at work or asleep - turns on by a timer about 45mins before I get up in the morning...  Do most people leave machines running all the time like this or turn them off when not in use?  I only use it a few times a day, but dont like the idea of waiting an hour after I get the urge for a coffee...

    Im getting good tasting results out of it lately anyway which is great.  My wife has noticed an improvement since I modified it, which is good since she was a bit concerned when it was all apart on the kitchen bench that it might never work properly again.  no faith in me  :

    one other thing - after installing the restrictor the machine seems to sound different. It makes sense to me that the restrictor would increase load on the pump - is this likely to be a problem??

    oh and in case you or anyone else wonders what the Cooper69S is all about, when I originally joined the forum, my toy was a 1969 Mini Cooper S.  Awesome car, should never have sold it but thats another story.  One day Ill change my username so that I stop reminding myself about it...

    thanks for the assistance in choosing a better grinder, hopefully it will turn up here in the next few days

    Geoff

    Leave a comment:


  • TC
    replied
    Re: New HX machine - boiler pressure too high?

    Hi Cooper,

    Curious to know how you went with your hot running Mondiale....Any success in settling it down?

    regards

    Chris

    Leave a comment:


  • blanyon
    replied
    Re: New HX machine - boiler pressure too high?

    Excellent, I have just had a couple of examples of when people have been using "recently calibrated" thermometers which were out by 15 degrees. Didnt make for great coffee.

    Leave a comment:


  • Cooper69S
    replied
    Re: New HX machine - boiler pressure too high?

    Originally posted by 7B757877607677190 link=1256380339/19#19 date=1261170478
    I would be a bit wary of your measuring device, those milk thermometers are not super accurate.
    yeah - I understand that even if the thermometer is reading correctly, its not the most scientific way of testing the temperature.
    I verified that the thermometer accurate at 100*C by putting it in a saucepan of water boiling on the stove, but the accuracy below that temp hasnt been tested - I was really just playing trying to get some idea where its at because I was getting impatient having to wait until Monday to test it properly. Ill have a better idea of the real temp then.

    Leave a comment:


  • GregWormald
    replied
    Re: New HX machine - boiler pressure too high?

    Originally posted by 323C313E293F3E500 link=1256380339/19#19 date=1261170478
    I would be a bit wary of your measuring device, those milk thermometers are not super accurate.
    On that point, stick it in a pan of simmering water and check it out. It should of course read 100°C adjusted for your barometric pressure.

    If its accurate, Id say the machine is running hot, but somehow only when idling :-?. This will need someone who is familiar with the innards.

    Greg

    Leave a comment:

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