Hey everyone,

Currently restoring a Breville Cafe Roma.

The machine has an Ulka EP5, which pushes 12-14 bar at 100cc/min (for 12.5 g in, 27 g out at 30s,
considering the puck absorbs equal amount liquid);


The portafilter slides loose @ 2:1 ratios, and the shots are generally sharp. I believe pressure is one of the issues.

What's the recommended route to reduce the pressure?
- I've considered Crem OPV, PWM controllers, dimmer mods... looking for the simplest route possible.
- Perhaps a pump with ideal pressures at this flow rate?

These Ulka models provide ideal pressures, but aren't available online in 100-120v?

[ The E4R is an ideal option, but out of stock: https://www.cerinicoffee.com/products/o ... y-shipping ]

OPV will give constant pressure.

Dimmer will be touchy to adjust consistently.

Pump will not supply constant pressure depending on line voltage and flow volume.

Great thanks

Looking at OPVs now.

Are needle valves a viable option to limit maximum flow, kind of set and forget once it's dialed? Or is an OPV the simplest route, even with overflow reroute to tank?

A needle valve would be harder on the pump if the machine doesn't have an OPV. A needle valve would be actually limiting the flow through the pump while making the pump work harder/hotter (the flow of water is required to cool the nucleus and sleeve. The less the nucleus moves, the less impedance in the coil, the hotter the coil gets). Unless you're talking about having the needle valve leaking excess flow out of the circuit in which case it would be nearly impossible to dial it in and leave it, but if you had it accessible and adjustable during the brew it would give you somewhat beneficial profiling flow control.

The OPV allows the pump to pass the requisite flow for the back-pressure it's working against. The OPV just allows the excess flow to escape the brew circuit.

Much appreciated, JRising

Great to hear from an expert why a needle valve also requires an OPV. I don't intend to leak excess water by needle valve..

So, OPV is king when the goal is to limit maximum pressure.