# OPV or not to OPV?



## donski (Jan 8, 2014)

Hi.

Got my Gaggia Classic at Christmas. Out of the box with some Pods I get "OK" shots. Started on the road to do it properly. Bought a non pressurised basket (2 shot). Bought some decent beans from a proper roaster and they ground them for me ready for espresso. Still need the grinder and a bottomless PF. For the purposes of consistency I am going to stick with the same beans at the same grind for now whilst I start to get to grips with some of the other variables.

Results as follows.

With pressurised basket and pod -half decent shot with a brew time of 22 seconds from flipping the switch.

With pressurised basket and espresso grind (2 shot) - 2 oz out in 15 seconds and blonding starts at about 13 seconds. Coffee is a little bitter and too strong.

With non-pressurised basket and espresso grind (2 shot) - 2 oz out in 10-11 seconds and blonding starts at about 9 seconds (Bearing in mind this is from flipping the switch and it takes 3 seconds before coffee starts to flow). Similar results to above for taste etc.

Even if I tamp down (very) hard I can't extend these brew times.

Now I know there are lot's variables to play with here (grind, temperature, tamp, coffee, etc) but based on what I read here these brew times are far too short and I suspect that before I can really start to play with the variables and learn from them I'll need to at least get the brew time closer to the 20-25 second mark.

So, I make the following assumption from this.....the fast brew times I am experiencing are more likely caused by (though not entirely by) the high pressure setting the unit is shipped with!?? and I should really fix this asap.

Is my assumption correct? Appreciate there are some knowledgeable people on here who also say that to OPV the machine is not necessary but the majority seem in favour of it.

Thanks


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## Neill (Jun 26, 2013)

No, don't worry too much about your opv yet. The fast brew times are caused by the lack of your own grinder. You need to be able to adjust the fineness of your grind to extend the pour. Pre ground can not be properly dialled in for every machine. No one settling is right. That's why a grinder is essential. Hope that helps.


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## El carajillo (Mar 16, 2013)

I agree with Neill majority of that problem is with the coffee , too coarsely ground and beginning to dry out (once ground beans will dry out more quickly through greater air exposure). Although sellers say it is ground for espresso M/ch it is often to coarse.

As a temporary get around you could "try" using more coffee and tamping harder


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## omegabri (Jan 7, 2014)

Hi...

Sounds like my initial learning curve exactly. I found Illy to be the best pre-ground with non-pressurised baskets. Every other coffee I tried was either ground too coarse or too dry. I now have an MC2 grinder from Happy Donkey and find I can replicate the faults of pre-ground unless the grinder is properly dialed in on the fine adjustment.

Without a pressure gauge I turned my OPV down 180 degrees and have found this to pull a better shot - in my opinion at least !


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## donski (Jan 8, 2014)

Appreciate all the response. Thanks all.

I have tried the more coffee/tamp harder......not much difference and I have 16 st bearing down on that tamper







. Also appreciate the comment about the finer grind. The coffee came form a local roaster who ground it for me at the point of purchase and I had these results from day 1.

I'll ask for a finer grind when I go there later today but my concern would then be that I am having to work with a much finer grind than necessary to compensate for the pressure. Doesn't that change the characteristics of the shot?

I have much to learn don't I? The engineer in me is trying to make sense of the whole pressure vs tamp vs grind when really I should just get on and play.......

I'll let you know how I get on with a finer grind.......but bottom line.... I NEED A GRINDER!!!!!

Cheers all.


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## Neill (Jun 26, 2013)

Honestly, the pressure makes less difference than you would think. I ran mine at full pressure for years before adjusting and got good extractions.


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## El carajillo (Mar 16, 2013)

When you adjust the OPV use a gauge do not just guess at adjustment by randomly turning the screw. Good machines are set at 9 bar for a reason.

If / when you adjust yours set it at about 10 bar static, this allows for difference when water flowing and vibe pump ramp up.


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## donski (Jan 8, 2014)

Thanks Neill/El Carajillo


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## MrShades (Jul 29, 2009)

As you're quite local to me (a few hundred yards at most) why not bring your Classic round to me one evening and we can grind some fresh beans and throw em through it to see what can really be achieved with a decent grinder and freshly ground fresh beans? I'd even be happy to grind beans for you - if you buy whole beans from Rave we could grind em en masse once dialled in for your classic - but the ground beans will go off quickly, so best solution is still to buy a grinder and grind when you need to.

Drop me a PM if you ever want to get together and try any of this, or just fancy a coffee and coffee chat


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## PurpleOwl (Jan 28, 2014)

Is the OPV mod recommended for all Classics of just the Phillips made ones?


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## Charliej (Feb 25, 2012)

PurpleOwl said:


> Is the OPV mod recommended for all Classics of just the Phillips made ones?


Well I wouldn't just go blindly changing the opv on a Pre-Phillips one without checking it with a gauge, I had never altered mine and then one evening a friend came over and brought his gauge with him and we checked mine and it was sitting at just under 10.5 BAR static pressure so we didn't touch it.


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## unoll (Jan 22, 2014)

Definitely worth getting hold of a pressure gauge or buying the bits to make your own. I also bought a new classic round Xmas time and the pressure was set at round about 12bar (ish) I now have it hovering round 9.8 bar . Its definitely worth investing in a grinder, the difference it makes is huge!


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## phollingswo (Nov 29, 2013)

If there's anyone near Battersea (London) that has done this mod and fancies helping me out - it would be much appreciated. Will pay with coffee!


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## jeebsy (May 5, 2013)

I've got a gauge you can use if you want but will post it to you


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## phollingswo (Nov 29, 2013)

jeebsy said:


> I've got a gauge you can use if you want but will post it to you


That would be fantastic thank you! I'll DM you and sort something out.


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## moley (Jan 30, 2014)

Just did the OPV mod on my Classic. It was factory set at 12.5 bar, now set at 10 bar.

I'm very pleased with the results.


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## moley (Jan 30, 2014)

Original OPV setting:


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## moley (Jan 30, 2014)

New OPV setting 10 bar (which I understand is 9 bar at the group):


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## moley (Jan 30, 2014)

Here's how I made my gauge:


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## moley (Jan 30, 2014)

From the front:


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## moley (Jan 30, 2014)

The elbow joint, 3/8" plus PTFE tape:


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## mr_phillip (Jan 6, 2014)

Having just made the OPV adjustment myself today I'd recommend it to anyone. I made my own gauge with bits from Context Pneumatics via eBay for under a tenner and the whole process took inside of 15 minutes. My Classic was reading just over 12 bar, so I dialed it back to the recommended 10 bar static reading.

Before making the adjustment every shot I pulled had a sour note that I couldn't get rid of, no matter what I did. The first shot I pulled after the adjustment is the best espresso I've ever managed at home. The crema was better than I've ever seen from my Classic and there wasn't a hint of sourness or bitterness.

Assuming everything else is in place (good coffee, good grinder, good tamp, etc) I'm a total convert to the OPV mod. I reckon it's essential for anyone wanting to get the best from their Classic.


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## truegrace (Jan 29, 2014)

gonna give this ago myself i think, just need a bit of googling to find out what i need to buy


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## oracleoftruth (Jan 15, 2014)

I just went in to a plumbing merchants with my portafilter and asked for what I needed. They didn't have the gauge in stock but luckily one of the main UK importers is 2 min from my house so I popped in and got one for a fiver.

Total cost was something like £7.50 including PTFE tape.

If anyone wants to borrow it they are more than welcome; PM me.

It really is quite simple though.


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## truegrace (Jan 29, 2014)

might as well do the same, we have a plumb stop just down the road, by the time i have forked out for postage forward and back i could of made one. Wonder if they are open sundays?


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## oracleoftruth (Jan 15, 2014)

Make sure the gauge goes up to at least 11 (mine goes to 11 but needle moves beyond to about 12). Also the tape is essential; won't seal without it.

If it's all the same get a u bend so it's easier to see the gauge. Although it doesn't matter much.

If the gauge needle is vibrating around, just remove it and empty the water and then retry; seemed to do the trick for me.


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## mr_phillip (Jan 6, 2014)

Here's how I made mine, with links to the bits on eBay:

Pressure gauge (picture shows one that only goes up to 12 bar, the one you'll receive goes to 14)

3/8" to 1/8" reducer

PTFE tape (which you can get from the same supplier if you don't have any already)

I didn't bother with an angled joint, but they're out there if you need one.


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## mr_phillip (Jan 6, 2014)

Here's a couple of pictures. I angled the mount of the gauge so it was more or less straight on with the portafilter in situ.


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## peterh (Jan 16, 2014)

moley said:


> Here's how I made my gauge:


Sorry if this is a dumb question, but what is that adaptor on the portafilter spout for? Doesn't it just screw directly on to the basket?


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## peterh (Jan 16, 2014)

mr_phillip said:


> Here's how I made mine, with links to the bits on eBay:
> 
> Pressure gauge (picture shows one that only goes up to 12 bar, the one you'll receive goes to 14)
> 
> ...


Thanks for the links - just ordered the bits to have a go myself!


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## Mike mc (Apr 10, 2012)

Just about to order these bits myself.thanks for the links


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## bazschmaz (Sep 2, 2013)

Or get on the list....


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## Neill (Jun 26, 2013)

bazschmaz said:


> Or get on the list....


Have you got it yet?


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## irishcoffee42 (Jan 31, 2014)

Delighted here with the OPV, having put together a very simple pressure gauge setup earlier today: a bottomless portafilter holding a blind basket with a hole drilled in it for the thread of the pressure gauge to poke through. I needed to remove the dispersion plate for the portafilter to fit in place, and used CharlieJ's trick of a long M5 screw to convince the plate to come away. I found the pressure was at 14 bar, and reduced it to 10. Lovely looking shots since then, and no spray from the bottomless portafilter now, which is a nice bonus!


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## jamster (Feb 6, 2014)

I've just ordered the ebay part complete with portafilter (from shock-waves-shop), and a screw in replacement dual spout so I can use the portafilter when I'm done.

Let's see how the Gaggia is set.


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## oracleoftruth (Jan 15, 2014)

I'm happy to lend my gauge if anyone needs it.


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## Neill (Jun 26, 2013)

irishcoffee42 said:


> Delighted here with the OPV, having put together a very simple pressure gauge setup earlier today: a bottomless portafilter holding a blind basket with a hole drilled in it for the thread of the pressure gauge to poke through. I needed to remove the dispersion plate for the portafilter to fit in place, and used CharlieJ's trick of a long M5 screw to convince the plate to come away. I found the pressure was at 14 bar, and reduced it to 10. Lovely looking shots since then, and no spray from the bottomless portafilter now, which is a nice bonus!
> 
> View attachment 5477
> 
> ...


Where did you get the wooden handled bottomless pf?


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## irishcoffee42 (Jan 31, 2014)

I got it from the same eBay seller that jamster refers to above, "shock_waves_shop". Lovely, isn't it? Thought it'd match the Walnut & Black tamper nicely that I got from Made by Knock... Anyway, a search on the 'bay for "Bottomless Naked Portafilter Walnut" should turn it up!


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## Neill (Jun 26, 2013)

irishcoffee42 said:


> I got it from the same eBay seller that jamster refers to above, "shock_waves_shop". Lovely, isn't it? Thought it'd match the Walnut & Black tamper nicely that I got from Made by Knock... Anyway, a search on the 'bay for "Bottomless Naked Portafilter Walnut" should turn it up!


Thanks, I'll have a look.


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## truegrace (Jan 29, 2014)

did my opv yesterday. my 2006 classic was set to about 12.5.

took about 15 mins tops and is a massive improvement, £10 well spent!


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## Pompeyexile (Dec 2, 2013)

Well I've just received in the post a pressure guage and adaptor for less than a tenner delivered. I have also just bought a new portafilter and a seperate single shot spout to put on it, but before I do I will attach the pressure guage and check the pressure and if neccessary have a go at adjusting it. My last two efforts in grinding and pulling shots have been a bit of a disaster.

I've got great beans from Rave I've got a decent grinder in the Brasilia. I've descaled, backflushed, dismantled and cleaned the shower plate and holder and i've also replaced the rubber ring on my Gaggia Classic so once the pressure is put right i've only myself to blame if I still can't get it right.

Fingers crossed!


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## bazschmaz (Sep 2, 2013)

Hey, so I now have Neill's gauge, I am waiting on Colin T to let me know when he wants to pick it up seeing as he's in the same city.

Where will it head to next?

My machine initially measured 11 bar, ten minutes later it measured 9.

9 Bar is sweeter.


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## oracleoftruth (Jan 15, 2014)

Are you adjusting to 9 rather than 10? I'd thought that as nothing is flowing through it the static pressure of 10 equates to 9 when dynamic and pulling a shot. Have I got the wrong end of the portafilter again?


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## Neill (Jun 26, 2013)

Yeah, should be 10 static, think I did say that in my original thread.


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## jeebsy (May 5, 2013)

This is the definitive OPV thread


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## oracleoftruth (Jan 15, 2014)

I'm finding things much easier on my classic than evolution which was pumping out at crazy pressure. Classic was set to 12.5 ish.


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## Pompeyexile (Dec 2, 2013)

So I put together my pressure gauge and portafilter, literally a 3 minute job. Topped up the portafilter with some water and attached it to the Gaggia. So far so good.

Opened the top of the machine spied the valve with the tube sticking out as described. Turned on the machine let her warm up for 20 minutes and then flicked the switch....

View attachment 5512


As you can see the needle shot round off the scale.

So took off the tube from the valve, in with the socket and took off the nut and this is what I saw.....

View attachment 5513


Not a sign of a drop of water, it was as dry as a witches tit. Oh well I thought perhaps they don't all have water sitting in them, and carried on. Put in the allen key and to say it was stiff is an understatement. It took some force to get it moving and when it did move there was a dry grating sound.

Not to be put off I turned it about three quarters of a rotation anti-clockwise, put it all back together and pressed the switch and again the needle went off the scale. So another half turn of the allen key. Still the needle was busting to get out of the guage.

Anyway, after at least five more attempts (and now every time I opened up the valve it did have water in it) and having turned the allen key more than 2.5 revolutions anti-clockwise I got the guage to read this.....

View attachment 5514


6bar, but of course 10 bar was the holy grail and I knew a couple of tweaks and I'd be there. So a small adjustment of the allen key and.....

View attachment 5515


Almost there but this time the needle was vibrating like a Mexican jumping bean on speed. Trying to read it looked like it was somewhere near 9 bar so one more tweak should do it.

I should have left well alone because when I turned on the machine instead of the pump building up and settling into a constant thrum it seemed to cough and every time it did it seemed to be either blowing water or air back into the water reservoir and the needle on the guage jumped to max and then back with every cough of the motor/pump.

I did take a video of it doing the jitterbug but for some reason (my ineptitude with computers actually) I can't seem to upload it on here as it says something about the format being incorrect. I filmed it on the same camera I took the photos on here so I haven't a Scooby.

Anyway, after all that what I need to know is have I buggered it? Do you know what the pump is doing all of a sudden? More importantly what can I do if anything to rectify it?

I've done this in my quest to get everything as right as possible as I have had trouble getting any results worth drinking and to be honest the pressure must have been so high is it any wonder. If I've knackered it before I've begun I'll be gutted as I haven't even had a drink of coffee from it yet and I've had it since last November.

Any suggestions?


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## jeebsy (May 5, 2013)

Pompeyexile said:


> dry as a witches tit


Haha - haven't heard that in ages.


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## rodabod (Dec 4, 2011)

The OPV may be slightly sticky. Try adjusting it again maybe. They sometimes get clogged if you use hard water.


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## Pompeyexile (Dec 2, 2013)

I have tried adjusting it about five more times but with the same result a coughing pump. If I undo the adjuster all the way will it unscrew completely and come out, and then put it back in wind it down and see what happens, what do you think? Trouble is I don't want to cause any more damage.

The coughing pump is as if there are air locks. Does the OPV dump back into the water reservoir normally?

The chap who had it before me said he only ever put bottle water through it and I've done the same.


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## Charliej (Feb 25, 2012)

The function of the OPV is to dump water back into the tank if the pressure is too high, kind of sounds like you've either adjusted it too low and/or your gauge itself is faulty and maybe an issue with the opv itself. If your machine had been set to 15 BAR that would explain the initial going off the scale but that should have come down more easily than that. Try setting the pressure a little higher and see what the pump does.


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## oracleoftruth (Jan 15, 2014)

If it is still problematic it may be due to scale. Sounds like it was pretty jammed up. If you loosened the scale it could have clogged the system at some point. You could take the opv out and soak it in some citric acid and then some pulycaff or similar. The vibrating needle is normal. If you remove it and empty the water and then reattach it can sort it.


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## rodabod (Dec 4, 2011)

If you loosen all the way, then all the water will piss through back to the tank, and you'll get no pressure.

Try tightening the allen bolt back down, and see if it stays stable at 15bar or wherever the pump peaks at. This will rule out the OPV as it will not interfere with the pressure.


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## Pompeyexile (Dec 2, 2013)

Thanks guys. Pulling of a rubber tube, undoing a nut and adjusting a screw is one thing but taking the whole thing out.....blimey!

Oh well I'll try tightening it back down first thing tomorrow and go on from there and no doubt you'll be hearing from me.


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## Pompeyexile (Dec 2, 2013)

Hoozah!

Got up this morning with a clear head (which is surprising considering the amount of red wine I drank last night) took a deep breath and decided to try again. This time I undid the adjuster inside and took it out completely (counting exactly how many turns ) to see if there was any crud blocking it. Dried it out using a piece of kitchen paper and checked for any wayward bits of which surprisingly there seemed to be none. Then I took a wire brush to the adjustment nut as it had some scale on it and fitted it all back together ensuring I turned it back the 13 full turns it took to get it out. Carefully filled the portafilter with water je...je.jiggling it a bit Granville to make sure there was no air bubble in it (thanks for your advice there Frank) and put it on the machine and crossed me fingers and flicked the switch.

Well for starters the pump stopped coughing like an old lag who smokes 60 Turkish strength **** a day and the guage although vibrating a little read just under 9 bar. So little steps exile, gently does it and with the care of a bomb disposal expert I gently tweaked and tweaked and on the third attempt.......Viola!

View attachment 5539


As near to ten bar static as I'm going to get.

So once again thanks everyone for you advice and encouragement, now for the hard part; pulling a decent shot.

Who'd have thought making a cup of coffee would be so damn taxing?

Oh one other thing that might be useful for anyone else who is going to do this. I notice that when I finished and dismantled the guage from the portafilter, I was giving it a good couple of hard shakes over the sink to get the water out and loads of coffee particles came out. Now I don't know if it would have an effect on the guage (maybe why it was vibrating) but I guess it would be a good idea to back flush and clean the shower plate before you start, to prevent this from happening....unless of course the experts on here say it will have no effect, in which case...onwards and upwards!


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## El carajillo (Mar 16, 2013)

Pompeyexile said:


> Hoozah!
> 
> Got up this morning with a clear head (which is surprising considering the amount of red wine I drank last night) took a deep breath and decided to try again. This time I undid the adjuster inside and took it out completely (counting exactly how many turns ) to see if there was any crud blocking it. Dried it out using a piece of kitchen paper and checked for any wayward bits of which surprisingly there seemed to be none. Then I took a wire brush to the adjustment nut as it had some scale on it and fitted it all back together ensuring I turned it back the 13 full turns it took to get it out. Carefully filled the portafilter with water je...je.jiggling it a bit Granville to make sure there was no air bubble in it (thanks for your advice there Frank) and put it on the machine and crossed me fingers and flicked the switch.
> 
> ...


It was the RED WINE that did it real:time-out:ly!!


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## Neill (Jun 26, 2013)

It's vibrating because it's a vibe pump. The only way to reduce that is to use the fluid filled gauges that damp the needle movement.


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## Pompeyexile (Dec 2, 2013)

Thanks Neil I must admit I didn't go for the fluid filled one simply because the other guage was a lot cheaper. But I guess for complete accuracy you need to spend a few extra quid. Lesson learned but that's why I'm on this forum, you lot have such depth of experience and are always willing to share it.


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## Neill (Jun 26, 2013)

Pompeyexile said:


> Thanks Neil I must admit I didn't go for the fluid filled one simply because the other guage was a lot cheaper. But I guess for complete accuracy you need to spend a few extra quid. Lesson learned but that's why I'm on this forum, you lot have such depth of experience and are always willing to share it.


I don't think id worry too much about extra accuracy anyway!


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## ting_tang (Jul 26, 2020)

I have GC2014 and currently OPV configured to 10bar static. Tried to get 6bar, but my OPV doesn't allow to get lower than 8ish static. Is there any workaround or need to replace OPV?


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## Davebo (Jan 9, 2021)

At the moment I don't have a decent grinder so I'm using the pressurised basket. Is there any point in me reducing the OPV yet ? Should I wait until Im using an unpressurised basket with a decent grind?


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## HDAV (Dec 28, 2012)

Davebo said:


> At the moment I don't have a decent grinder so I'm using the pressurised basket. Is there any point in me reducing the OPV yet ? Should I wait until Im using an unpressurised basket with a decent grind?


 Not with the pressurised no, if your using premium preground then the unpressurised basket may well help, at that point reducing the pressure may too, it will slow the extraction but without being to control the grind your options are limited (no more limited than currently anyway)


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## simplyme (Jan 2, 2020)

I have a 2013 GCP with a newly installed PID, I presume this would be a worthwhile task next?

I've not looked into this much, I presume I will need a pressure gauge and it is just a case of adjusting the screw?


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## allikat (Jan 27, 2020)

You can ballpark it roughly into the right spot with about a half to three quarter turn on the screw assuming no-one has messed with it in the past. Be wary the screw is brass and will chew up very easily if it gets stuck and you try and force it. If it gets stuck, then leave it until you have a chance to strip it down and give the OPV a good soaking in descaler. I'm pretty sure every refurbisher of Gaggias has lost an OPV or two when being over-keen on them.


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