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).
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).


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