# Stuck OPV



## TomBurtonArt (Jan 18, 2015)

Opened up my Wega Mini Nova after borrowing Jeebsy's pressure guage and measuring 12 bar+ tried turning the OPV with a coin to no avail, stepped it up a notch with a screwdriver and still nothing...

Anyone have any tips on what I can do before taking apart the plumbing to soak it?

The machine was warm when I tried to make adjustments (unless this changes anything).


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## GCGlasgow (Jul 27, 2014)

The classic is adjusted with a 17mm socket but i'm guessing there's a difference?


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## DavecUK (Aug 6, 2013)

How about a photo of the OPV...


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## marcuswar (Aug 19, 2013)

Try heating up the OPV body with an electric paint stripper heat gun. Give it a good 10-20second blast so the body expands slightly and breaks the seal and then try turning it. This worked a treat for me on my Isomac's OPV which was stuck solid.


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## El carajillo (Mar 16, 2013)

I think you need to remove the slotted screw head remove the spring and lift out the rubber seal. The seal may well be solidly stuck in its seat or possibly perished /damaged.


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## TomBurtonArt (Jan 18, 2015)

El carajillo said:


> I think you need to remove the slotted screw head remove the spring and lift out the rubber seal. The seal may well be solidly stuck in its seat or possibly perished /damaged.


Slotted screw head is the bit that won't budge. Might have to take the whole lot out if I cant expand and break the seal.


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## DavecUK (Aug 6, 2013)

Looking at the photo, I think it's time to fit another one. Try and fit a better quality one if you can.

http://coffeetime.wikidot.com/opv-over-pressure-valve


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## TomBurtonArt (Jan 18, 2015)

Just read this... Is this true? In which case, do I even need to use the OPV. http://coffeetime.wikidot.com/rotary-pump-pressure-adjustment


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## DavecUK (Aug 6, 2013)

TomBurtonArt said:


> Just read this... Is this true? In which case, do I even need to use the OPV. http://coffeetime.wikidot.com/rotary-pump-pressure-adjustment


With a rotary pump, of course not, the expansion Valve (OPV), is purely there to stop the hydraulic pressure of water as it heats and expands from fracturing pipes, fittings etc..I usually set them at around 12 bar. I think the reason you should get a new Expansion valve is because the one you have is stuck, so probably defective and is also not great, so replacement for a few pounds is a good idea. You should be adjusting your pressure via the rotary pump (acorn nut or locknut on the side of it with a slot screw head for adjustment). It's one of the reasons I asked for a photo, as I could then see the actual valve and in the background I can see the FOT rotary pump.

Before the photo, everyone was assuming you had a vibe pump I suppose....dunno?


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## TomBurtonArt (Jan 18, 2015)

DavecUK said:


> With a rotary pump, of course not, the expansion Valve (OPV), is purely there to stop the hydraulic pressure of water as it heats and expands from fracturing pipes, fittings etc..I usually set them at around 12 bar. I think the reason you should get a new Expansion valve is because the one you have is stuck, so probably defective and is also not great, so replacement for a few pounds is a good idea. You should be adjusting your pressure via the rotary pump (acorn nut or locknut on the side of it with a slot screw head for adjustment). It's one of the reasons I asked for a photo, as I could then see the actual valve and in the background I can see the FOT rotary pump.
> 
> Before the photo, everyone was assuming you had a vibe pump I suppose....dunno?


Haven't got around to replacing the OPV yet, still trying to decide which one will fit into my machine with as little fuss as possible.

Have any idea why someone might do this though?










That is the adjustment screw on the side of the (what I assume to be Fluid-o-tech) pump.










Only reason I can imagine would be that it's all very tight, makes adjusting the pressure difficult... Very difficult.


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