Magister Stella Pro OPV Adjustment

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#1: Post by mook613 »

Does anybody know how to adjust the OPV on a Magister Stella Pro?

There is no obvious screw on it.

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#2: Post by Nunas »

Unless they've changed the design since I had mine, they are not adjustable. That said, it would be relatively easy to substitute an adjustable one. The one in my Stella was white plastic. Most adjustable ones are brass.

mook613 (original poster)

#3: Post by mook613 (original poster) »

The one on mine is certanily brass.
If I remove the lower fitting on it then there is a spring in there. But by backing off the fitting (which I thought would reduce the spring tension) it doesn't reduce the pressure with the blind basket.


#4: Post by ObbieNL »

I have the same Stella machine and the same OPV as I see on the picture.

I am used to see a screw to adjust pressure buit it seems missing here. How to adjuist pressure with this OPV?
To just unscrew the bolt seems tricky


#5: Post by ObbieNL »

By all means necessary as the pressure is at 14 bar from factory setting :shock:


#6: Post by 2wheeler »

I need help with this too as my newly purchased Stella is running at 12-14 bar to get a shot. If anyone has figured out how to downregulate the pressure please advise.

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#7: Post by Nunas »

Although many brass OPVs are adjustable, apparently these are not. In the earlier version of the Stella PRO, the OPV was plastic (at least mine was) and it was not adjustable either. If these machines were mine, I'd be inclined to pull the OPV, measure the thread size, and buy a new, adjustable one. Stefano's lists several.

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#8: Post by cafeIKE »

Strange OPV with one brass and two plastic hose connections. Usually the other way around.

Could be the group pressure is much lower than the gauge. The panel gauges in general are sort of close :roll:


#9: Post by JRising »

That's a combination valve, the skinny side is the vacuum breaker and the thicker side is the safety valve. Don't screw around with the safety valve. The whole purpose of a safety valve is to keep your boiler pressurized without ever letting it become dangerously overpressurized.
DON'T adjust a safety valve, don't disable a safety valve, don't mess with it at all.

What are you trying to do? The Stella is a heat exchanger type of machine. The boiler pressure doesn't effect the brew circuit. If you want to adjust the brew pressure post a picture of the expansion valve or the pump's OPV.

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#10: Post by Nunas »

Good catch by John and good advice. On the Stella PRO (pre PID model), the OPV is mounted directly on the output of the vibe pump. On mine, it was white plastic and not adjustable. It had two output hoses, one of which went back to the reservoir, the other to the fill and brew solenoids. Have a look there and tell us what you have.