I've had my new Bezzera BZ07 for about two weeks now and cannot get the machine to pull a shot with less that a 2 bar fluctuation in brew pressure, usually more. I've read every post I could find on brew pressure fluctuation and find the following three issues to be the culprit 1) electrical 2) bad pump 3) channeling. I don't think my problem is a bad pump since it holds pressure fine with a blind filter. I have noticed that the brew pressure fluctuation coincides with the boiler heat element switching on an off. My research indicates a .5 bar or less fluctuation is normal due to the heating element cycling. My fluctuations are much larger. I have tested the voltage with a kill-a-watt meter which indicates voltage of 118v when the heating element is off and about 111v-113v when it switches on. Also, I'm using a Vario grinder.

Please let me know your thoughts on how to keep my brew pressure more consistent, and also, does brew pressure fluctuation like this ruin the shot?

Thank you

To my eye the flow seems constant, so it might just be the gauge?

You could build an inexpensive portafilter pressure gauge to compare.

Building a Portafilter Pressure Gauge

Thanks for the reply Scott. However, I believe the internal gauge is performing correctly, here's why:

I did a test where I let the machine heat up to brew temp and then turned off the heal element with the PID before brewing. What I got was a perfectly constant 9 bar pull with ZERO fluctuations (my OPV is set to 11 bar). I believe the results of this test leaves only one explanation for the problem, electrical issues. I thinks the results confirm that the coffee, grind, distribution, and pump are all good.

Now, I did another test this morning when the voltage readings were a bit higher (121v). I was able to pull shots with less than a 3v (121v-118v) change when the heat element cycled. However, even with a small 3v drop in voltage, loss of pump pressure caused wild swings in brew pressure. Has anyone else tested their voltage while brewing and measured the drop when the heat element cycles? Is a 3v-5v drop normal or is this too much and causing the inconsistent brew pressure i'm seeing?

I've been emailing 1st-line today who is telling me that the issue is with my electricity. I've tried the machine now in two separate homes, both of which have modern wiring and 20 amp breakers to the kitchen.

Can anyone please tell me if your machine operates normally with a 3-5v drop in voltage when the heat element cycles?