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Thread: water supply pressure for Bezzera BZ35

  1. #1
    Junior Member
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    Jul 2008
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    12

    water supply pressure for Bezzera BZ35

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Ive picked up a BZ35 (just like Mals unit but with a beige wrap-around cover) and am trying to get the new toy working.

    Ive fixed the boiler safety valve (O-rings had gone hard) and am about to descale it when i get some citric acid - then work out why the pump stays on (filling the boiler?) when the heater has got the tank up to temp/pressure.

    But firstly Im wondering what water supply pressure to provide it?

    And do these units have to perfectly level to operate correctly?

    Its going to live in an artists ceramics studio and the water there comes from a tank via a fairly powerful Onga pressure pump (and i dont want to plump up a gravity-feed tank).

    cheers and tia,
    Charles.

  2. #2
    Mal Dimal's Avatar
    Join Date
    Oct 2004
    Location
    Warwick, QLD
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    17,124

    Re: water supply pressure for Bezzera BZ35

    Gday tbc,

    Welcome to CoffeeSnobs..... [smiley=thumbsup.gif]

    These little beauties really are the "Wolf in Sheeps Clothing" of espresso machines.... An awful lot of capability built in to a very compact little(31Kg ::)) package. Youll have to post up some photos so that we can all drool over your newly found acquisition ;).

    Just to address your queries as theyve been asked....

    The Boiler "Auto-Fill" is taken care of by a set of immersion probes and the Gicar Electronic Control Box. Its possible that the Boiler Probes may be caked up with scale (especially the high level one which is supposed to turn the pump OFF). Hopefully the Gicar Box is OK as these are quite expensive to replace but easily repaired if you know a friendly Electronics Tech., or one who is amenable to bartering his/her services for some fresh coffee.
    More than likely though, when you descale the Boiler, Heat Exchanger, Element and the immersion probes; this will solve your problems.
    Just on descaling.... I would highly recommend that you use a product called "Clean Machine" available through several of our sponsors and distributed by another of our Site Sponsors, "Bombora". This product leaves plain Citric Acid for dead in my opinion and have no hesitation recommending it to others. Very economical too.

    Regarding water pressure.... Its highly advisable to install a "Pressure Control Valve" to regulate water supply pressure to a maximum of 350kpa. Once again, you can acquire these from one or more of our site sponsors, and maybe stores like Bunnings and specialist plumbing supplies outlets (typically cost around the $100 mark). This will ensure that despite the cyclic operation of the main pressure pump, the water pressure to your espresso machine should remain reasonably constant. Do you know the Cut-In and Cut-Out pressure settings of the main water pump? Ideally, the Cut-In pressure should be higher than the setting of the pressure control valve.
    By the way, is the water tank filled with rain-water or from some other source? If you think theres a chance that highly mineralised water is going to be an issue, it will also pay to install a suitable filter system downstream of the PCV. If using rain-water though, this shouldnt be a problem but it still might be a good idea to install a particulate filter to catch anything picked up by the main pump. There are a lot of very small orifices in the espresso machine which are easily blocked, so is food for thought.

    Dont know that the machine need to be perfectly level to function acceptably but should be reasonably level, all the same. I guess this can be accomplished via the use of some suitably sized packing shims under the machines feet. Ive replaced the feet on my machine so I guess if you wanted to go to that extent, you could buy some adjustable height feet from our good friends at "CoffeeParts" and fit those. This would enable you to level the machine very easily.

    Hope that helps you out "tbc". Keep in touch with your progress.... :)

    Cheers,
    Mal.

  3. #3
    Junior Member
    Join Date
    Jul 2008
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    12

    Re: water supply pressure for Bezzera BZ35

    Mal: thanks for the quick reply!

    The water supply is a large poly tank and the roof is pretty clean (more leaf litter than metal corrosion) but the unit did come with an inline cartridge filter (thats quite hard to blow thru) and ill put in a new filter before I go much further.

    Ill see what regulators we have laying about - am unsure of the Onga pressure but it can pop clipsal fittings if left going long enough.

    The innards of the gicar box look OK and has been checked in the recent past by a workshop - tho the outside looks like it was close to the boiler for some time.

    Some pictures of the unit:



    with sides off and working out how it works.





    More here.

  4. #4
    DONT USE
    Join Date
    Jan 2008
    Posts
    432

    Re: water supply pressure for Bezzera BZ35

    hi thebigchuckster

    one mod i do to these when not hooked up to constant mains water pressure is to invert the pump so that the inlet / outlet face upwards

    to do this you need to
    put spacers between the pump support and machine frame

    relocate the capacitor to the machine frame

    fit flexible braided hose to the pump

    sometimes need to space the top panel


    this mantains water in the pump keeping it wet


    also recomend fitting a non return isolating valve (Duo Valve)
    this stops water being pumped back into your water system if a problem occurs with the internal non return valve

    these are a top machine, have one we use as a backup for smaller mobile work
    graham




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