Post By tannin
Bezzera BZ02 weirdness
I am in the process of resuscitating a 2005 BZ02 purchased for a song on gtree.
Under the hood I find two silicon tubes feeding back to the water tank one connected to the OPV and one immediately before it connected to an "assembly check valve" according to my readings of the technical diagram.
However it seems the check valve is only meant to be used if the machine is going to be plumbed. Strange. More weirdly, whenever the pump is activated- even with no portafilter in place, the check valve silicon flows water freely into the tank. OPV is locked down- never flows- even with blind filter.
I decided to close off the check valve (put a rancilio plug in there) and it now doesn't flow at all. Loosened the OPV and it flows as it should when making a shot. And the shots are very good now (previously thin and lacking crema)
I imagine the setup when I first got it was incapable of developing more than 2 bar brew pressure- no idea why it was set up that way- just hoping it will keep working nicely now and the check valve isn't essential. Some of the old models don't have one on the technical diagrams. Seems to be related to being plumbed.
To the lower right check valve to the mid right the OPV
Nice outcome "tannin"...