PhaetonFalling wrote:Just looking at the picture... where the hell is the OPV located...I've been looking for it, but I can't tell where it's supposed to be. I've read about how to turn it down, I just don't know where it is.
Although they're the same part, an OPV (over-pressure valve) and expansion valve serve different purposes. For a vibe pump, an OPV regulates the maximum pressure by releasing water back to the reservoir. A rotary pump uses a bypass valve on the pump itself for this purpose, i.e., water pumped out is routed back to the pump above the setpoint. The expansion valve for a rotary pump espresso machine assures the pressure of the system doesn't exceed a safe limit (usually 12 bar). It cracks open as the boiler heats up, hence why it's referred to as an expansion valve in this case.
If you peruse the
FAQs and Favorites Digest, I believe you'll find more explicit instructions for adjusting a rotary pump espresso machine (just a guess, I haven't looked lately).