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Thread: VBM Domobar Super brew temp modification

  1. #1
    ev
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    VBM Domobar Super brew temp modification

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi Everybody.

    My VBM has been getting very noisy of late when the element is running (Creaks, knocks, rattles, etc). I thought Id pull it apart & see if I could spot anything obvious. No such luck but while I was there, I had a go at dropping the brew temp. Mine is a 2004 model & has always run too hot. A little while back, Chris was good enough to have a go at it. It apparently caused him no end of grief but he did improve it a little. Unfortunately the boiler pressure had to be dropped just a tad. Since then, the cooling flushes have been getting longer & longer.
    I disconnected the pipe going from the HX to the group & located a 5mm brass restrictor. I figured I was on the right track so I cut up an old SS showerscreen & made my own additional 3mm restrictor. I sanded a little off the brass one & fitted them both together.
    I then increased the boiler pressure back to 1.1Bar & gave it a test run. Still early days but it seems to have tamed it even with the higher boiler pressure. The noise during warm up has also improved. It only seems to occur after the boiler refills now. Time will tell.

    Id be interested to hear opinions from others regarding my mod. Im not even sure that Ive attacked the correct part of the machine! *:-/
    What have others done to tame their beasts!

    Evan.






  2. #2
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    Re: VBM Domobar Super brew temp modification

    Thats interesting because I would have thought if you restricted and slowed the flow to the group the water would be in the HX longer and therefore heat up more (?) Has it affected the group pressure at all?

  3. #3
    TC
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    Re: VBM Domobar Super brew temp modification

    Quote Originally Posted by 67657B78657E7970170 link=1283060285/1#1 date=1283129654
    Thats interesting because I would have thought if you restricted and slowed the flow to the group the water would be in the HX longer and therefore heat up more (?) Has it affected the group pressure at all?
    Not so Pete,

    Thermosiphon restriction decreases the volume of heating water from the boiler to the group. The result is more rapid cooling of the group leading to lower shot temp.

    I would have thought that restricting the flow through the HX could also result in a heating effect dependent on restrictor location. *:-/

    NB that this is not required on ECA machines imported in the last few years. The older Crixxxli machines are notorious for running red hot and have little other than external appearance in common with current ECA imported VBM machines.

    Chris

  4. #4
    ev
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    Re: VBM Domobar Super brew temp modification

    Pete, I didnt notice a change in the brew pressure.

    Chris, is that the correct restrictor? I know its been a while but do you by any chance recall if the 5mm restrictor was the original one?

    Evan.

  5. #5
    TC
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    Re: VBM Domobar Super brew temp modification

    Hello Evan,

    The original one was who knows what? As received, nothing whatsoever was fitted. I recall trying about 5 different settings. *Never again on one of these. Nasty butt busting machine it was ::)

    Chris

  6. #6
    ev
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    Re: VBM Domobar Super brew temp modification

    Butt busting or not, its built like a tank & has served us well for almost 5 years. I wonder how many home machines would survive running 24/7 for that length of time? Ive done alot of tinkering over those years but thats just me. Between the coffee machine & the car, theres always a mod to be made! ;D

    Evan.

  7. #7
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    Re: VBM Domobar Super brew temp modification

    Chris - of course, sorry, didnt realise this was a thermosyphon :-[
    So are there any valve like mods out there that people use to have adjustable thermo flow (some kind of screw in/out valve like the pressure adjuster on the procons)?




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