Brew Pressure is High
Do you have the backflush disk in?
This is the only true test of brew pressure. Coffee has too many variables. The backflush disk gives us a control model. With a rotary pump, and the backflush disk in, the gauge should rise to 9 bars in 4-6 seconds.
- What is the brew pressure with the backflush disk in? Is it over 9 bars?
- What is your water line pressure at?
- It should be about 35 PSI or lower. If your water pressure is really high in your house, like around 60 PSI, this is going to cause a lot of extra pressure on the pump, and will affect the pressure at the group head.
- Try adjusting your OPV. The OPV may be too open and needs to be adjusted down. The OPV and the Pump need to be adjusted together. Example, If the pump pressure is 8 ½ and OPV is open at 9 bar. The OPV will need to be adjusted to open at 11 bar, which will cause the Rotary pump pressure to raise more to 9 bar. Adjust OPV to 11 bar, then adjust pump pressure to 8 ½ bar. If these adjustments are not made together it will cause flow issues while brewing.
Watch the video below for instructions on how to adjust the brew pressure. The machine being used in the video is not the Bezzera Matrix MN, but operates similar enough that the methods used will still apply.