Back Flushing Question
Quick one - should the pump be completely stalled when back flushing with a blind filter? I have a feeling the neplex (over pressure) valve on my Simonelli Oscar has been nipped up to tight. I can ease it off so there is some room to breath.
No, I believe that the shaft of the motor should still be spinning.
While back flushing the pump is still pumping and the excess pressure and flow is released back to the water tank by the OPV. When you turn off the pump the three way valve opens to releases the pressure into the drip tray. You can then remove the portafilter without making a mess.
Backflushing helps to remove coffee grounds that may get above the shower screen and keeps the three way valve clean.