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Thread: BZ40 - group head pressure not stable when adding water pressure limiter

  1. #1
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    BZ40 - group head pressure not stable when adding water pressure limiter

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

    I just added a pressure limiter (my line water pressure is ~6 BARs). when limiting the line pressure to ~2.5 BARs I need to raise the Pump pressure so that the group head pressure will be 9 BARs.
    This leads to a very unstable group head pressure it jumps in the range of 9 BARs.

    One very important details is that the pipe providing the line water is very narrow - a 6 milimiter pipe, so it might be the cause.
    What do you think?

    /Royi

  2. #2
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    Re: BZ40 - group head pressure not stable when adding water pressure limiter

    6mm may be adequate depending on the length of the line, whether this is an ID or OD measurement, how many bends there are in routing, the radius of the bends, and to some extent the material the lines are made of (friction and stiffness). I usually recommend 9 or 10mm (here it is 3/8") when asked.

  3. #3
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    Re: BZ40 - group head pressure not stable when adding water pressure limiter

    Could be but shouldnt be.....

    Most commercial espresso machines are provided with a 3/8 " ( 10mm) water line as standard however quite a few office (as in commercial fitment) automatic espresso machines are provided with skinny hydraulic (plastic) line that does the job just fine. Ive also on occasion fitted hydraulic line and "quick fit" fittings to single group machines for convenience.

    The difference is in the number of groups that the water source and pump are trying to feed.....machines with multiple groups needs more feed and pumps that can pump more volume.

    One group machines dont need as much feed as multi group machines and your machine should be able to do it without a problem with the type of line you seem to have fitted.

    The only thing you can do (according to your description of things), is first replace the water line with a standard size one (because it is the cheapest thing to do first up), and if that doesnt work then you will have to investigate your new water limiting valve (it could be faulty and it happens from time to time) and after that the pump.

    Looking back at your question....why a 2.5 bar limiting valve? We fit a standard of 3.5 bar and some fit 5.0 bar...it doesnt matter as long as it is below intended pump pressure so you let the pump boost to where it needs to. If it is new and you take it back as suspicious, suggest get 3.5 instead.

  4. #4
    Senior Member Pavoniboy's Avatar
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    Re: BZ40 - group head pressure not stable when adding water pressure limiter

    Hi Pup26,

    Where did you get your 2.5bar PLV? My machine recommends 2.5 but I could only get 3.5.

    Thanks.

  5. #5
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    Re: BZ40 - group head pressure not stable when adding water pressure limiter

    After replacing all the pipes into standard 3/8 with standard pressure regulator everything is fine. pressure during rest is ~2.5 BARs, pressure during a shot is ~8.8.
    Thanks for the help.



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