Announcement

Collapse
No announcement yet.

Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

    Can anyone give a good description of the 3 OPVs in a Livia 90/Bezzera BZ99 and which one should be adjusted to alter brew pressure?

    There is one on the end of the original pump which loops back to the pump input and then 2 further downstream each of which flow back to the water tank. Are all these OPVs design to graduate the pressure build up when pulling a shot?

    Barazi told me that they often replace the original pump (FluidoTech) with one that does not have the OPV + loopback (Ulka) as it is cheaper and the pump OPV didnt serve any worthwhile purpose. Does this sound correct and if so, which of the 2 remaining OPVs should be adjusted?

    None of the other Bezzeras seem to have 2 OPVs downstream from the pump (the vibe pump version of the BZ35 also seems to come with an OPV at the end of the pump but only has a single OPV further downstream from this).

    I have replaced my original failing FluidoTech pump with an Ulka from one of my Gaggias so my BZ99 only has the 2 OPVs downstream from the pump. Static group pressure is about 170 psi (12 bar).

  • #2
    Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

    Hi Kaanage,

    If I were in your shoes I would look at the OPV shown on page 23 in the Bezzera technical diagrams. Ideally if you played with it it should be evident whether small changes in the tightening result in changes in the group head pressure.

    Comment


    • #3
      Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

      OK, just to be sure, do you think that this diagram is referring to the 2nd OPV (from the pump, that is) on page 31, marked TAV.8?

      Can you think of any reason for the other OPV shown expanded on page 31 (and 33 for the plumbed in version)? It seems to be marked as TAV.11 on page 23. Is it possible that this exists to reduce pressure for the plumbed in version and is an afterthought on the pourover version?

      In my machine, both of these OPVs operate when pumping against a blind filter.

      Comment


      • #4
        Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

        Originally posted by 252F2F202F292B4E0 link=1235517955/2#2 date=1235545800
        OK, just to be sure, do you think that this diagram is referring to the 2nd OPV (from the pump, that is) on page 31, marked TAV.8?

        Can you think of any reason for the other OPV shown expanded on page 31 (and 33 for the plumbed in version)? It seems to be marked as TAV.11 on page 23. Is it possible that this exists to reduce pressure for the plumbed in version and is an afterthought on the pourover version?

        In my machine, both of these OPVs operate when pumping against a blind filter.
        Please, do not forget that I am a newby (see my other thread on Bezzera BZ35e)

        I will have a look later today. I have to go to work now, it is just starting here in the UK. If they worked against a blank filter this still does not mean that they will be fine in ensuring 9 bars agains a coffee in the filter. They obviously open at 12 bars as you have observed.

        Cheers.

        Comment


        • #5
          Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

          I guess Ill have to use the suck and see approach. I did check the tech manuals for the other Bezzera machines (inc the BZ35) and was rather surprised to see none of their other machines had this arrangement. I had thought that the BZ02 was simply a BZ99 in a different body.

          Thanks for your help.

          Comment


          • #6
            Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

            Hi Kanage,

            Looking at the diagrams (BZ99) the TAB11 is the one which return water to the tank when the restriction pressure is to high (to fine coffee). The one that you need to adjust is the one after the pump TAB07.

            Question how old is the machine?

            Regards

            Renzo
            PS. Give a call or pm if you need to discuss any ideas about it

            Comment


            • #7
              Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

              Hi Renzo

              TAB7 is the OPV that no longer exists since I changed the pump. From what you say, I might as well juat adjust TAV.11.

              The machine is quite old (about 12 years, I think serial # is around 3300) - it has the o-ring group seal gasket rather than the newer flat ring gasket.

              Thanks
              Greg

              Comment


              • #8
                Re: Which OPV to adjust (of 3)? - Livia 90/Bezzera BZ99

                Greg,

                That is correct, if you do not have the TAV7 OPV, you should adjsut TAV11, look at the diagrams of the BZ02 this machine come like your machine is now.

                good luck

                Renzo

                Comment

                Working...
                X