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Thread: 100 second shots should the OPV engage?

  1. #1
    Join Date
    Nov 2012

    100 second shots should the OPV engage?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Still learning and greatful you guys are here to bounce things off.
    Playing with my kyocera hand mill I went 3 clicks finer. using a 19 gm load and an unpressurised basket it took 100 sec for a 60 ml shot.
    It took perhaps 30 seconds for the first drop. then 100 seconds for the double to be produced.
    I watched and was surprised to see the amount of oil on top of the shot. Not much crema and smelt /tasted overcooked.
    I had expected that the OPV valve might have been triggered but dont think it was.
    I am assuming that the chrome tube at the back left above the spill tray is the return for the OPV, is this correct.
    At any rate I will dial the grinder back 2 notched coarser and see how I go.
    BTW I have been using a cordless drill attached to the grinder at low speed to save on hand winds . works a treat.

  2. #2
    Senior Member
    Join Date
    Sep 2011
    That tube isn't from the OPV, That tube is the spill tube of the three way solinoid, Basicly, it's to relieve pressure on the puck AFTER you have pulled your shot.

    Not sure if your machine has an OPV that relieves pressure from a tight grind, If it does have one, I doubt very much that it would operate the way you seem to be expecting it to be.

  3. #3
    Senior Member
    Join Date
    May 2010
    Sydney North Shore
    It is normal when a machine has a water tank, for the excess pressure to be released back to the tank by the OPV, while the flow from the three way valve when fitted, goes to the drip tray when flow is turned off or during a backflush.

    You should aim for about a 25 to 30 second flow for your shot by grinding coarser.


  4. #4
    Senior Member C-man's Avatar
    Join Date
    Jun 2012
    Sunshine Coast, Peregian beach
    If you have an OPV set near 9 bar and a 15 bar pump

    it will be working all the time

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