# opv adjusted - strange behaviour



## bjgodefr (Jan 22, 2014)

I've just adjusted the opv of my gaggia classic.

I have a manometer or pressure reader and followed indications from this site.

Before adjustments the pressure read 11 bar. After an ant-clockwise turn off circa 135° to the valve, the pressure reading was 10 bar.

Mission accomplished I thought. But this is not the case.

I was under the impression that my regular grind setting would be too fine now for the lowererd pressure on my machine. But the extraction is now too quick and an espresso is made in a couple of seconds...

I'm thinking of setting the opv to 11 bar again, but wonder if somebody has an explanation or advice on which course to follow.

Thanks!

Bart


----------



## Mrboots2u (May 10, 2013)

Are you using a non pressurised basket in the pf?


----------



## bjgodefr (Jan 22, 2014)

Yes, indeed.

I'm using a bottomless portafilter for making espresso and the standard non-pressurised portafilter (without basket) where the manometer is screwed onto for the pressure readings.


----------



## El carajillo (Mar 16, 2013)

Try taking the innards out of the OPV (just keep turning anti clock until it comes out ) Make sure everything is clean and free to move.

NB If you measure down to the adjuster BEFORE removing it will give you the approximate position for replacing.

Refit and check with gauge adjust as necassary .Set to approx 10 bar. do not over tighten brass nut with "O" ring not necassary

Is your coffee fresh ??? older /stale coffee runs quickly


----------



## bjgodefr (Jan 22, 2014)

I adjusted the pressure back to 11 bar and the problem stays the same.

Something must have changed which causes the problem.


----------



## xiuxiuejar (Jan 24, 2012)

How old is your coffee? Remember that coffee becomes "less fresh" each day. Maybe you are tamping differently?

There should actually be very little difference once the OPV is done, but you should notice a more velvet feel in the mouthful. Great variations in grind are not usually needed.


----------



## bjgodefr (Jan 22, 2014)

The coffee isn't that fresh anymore. It's maybe three to four weeks old. I've kept it in the fridge in airtight containers.

But I don't think it's that, I used the gaggia with the same coffee this morning and the flow was completely different.

I'll try disassembling the opv.


----------



## Mrboots2u (May 10, 2013)

Don't keep coffee in the fridge. Rule no one of coffee club


----------



## bjgodefr (Jan 22, 2014)

Where do you keep it then? I've read that the freezer is the best place, I don't have one right now so I'm using the fridge.

Anyhow, I've disassembled the opv, nothing strange to see there.

Tried different pressure settings. Same results.

Maybe it is the older coffee after all. I'll stop now and try again tomorrow with a fresh head (and coffee).

Thanks for the suggestions everyone.


----------



## Mrboots2u (May 10, 2013)

Freezer great for freezing. If not freezing then thr Air tight container is great but a cool cupboard , away from sunlight


----------



## xiuxiuejar (Jan 24, 2012)

Jury is out on freezing - but if you do freeze, make sure it's airtight and there is no extra moisture in the containers. Some people freeze in valved bags too. Fridge reduces the viabile life of coffee quite considerably as it actually dries out the actual coffee very quickly. As Mrboots says, freshly roasted coffee lasts best in an airtight container in a dry, cool, dark place. I find that coffee kept this way - from fresh roasted - improves into the second week, then starts to deteriorate. By the third week the deterioration can become quite rapid depending on the bean and then, for my taste, becomes stale at the end of the third, beginning of the fourth week. If not being used, keep the coffee sealed in it's valved bag until you want to use it. Once opened, as it is not fresh, this coffee is optimum for about ten days - again depending on the roast and the bean and the conditions in which it is kept. This is just my opinion, others may tell you differently.


----------



## bjgodefr (Jan 22, 2014)

I've tried again this morning with fresh coffee: extraction of 5s for ristretto. Before the opv mod this took 15s.

So something doesn't work right.

This is my setup:

gaggia classic (2months old), ascaso imini grinder, bottomless pf, tamping routine remains the same as before opv-mod.

(static pressure reading is now 10,3 bar)

I'm also thinking of trying a friends grinder, maybe mine has become faulty.


----------



## Mrboots2u (May 10, 2013)

When you say fresh coffee ,what is the roast date on it ?


----------



## xiuxiuejar (Jan 24, 2012)

Sounds to me that you've either done the OPV wrong or you just need to go finer. As I said before, when I did my OPV a few years back, I didn't really notice a huge difference in my grinding needs. Grind finer and try - some beans just need to be finer.


----------



## kikapu (Nov 18, 2012)

I am probably talking nonsense but with a vibe pump when you reduce pressure you increase flow rate! So is it maybe the increase flowrate that is causing the issue?


----------



## bjgodefr (Jan 22, 2014)

No roast date, but very fresh coffee! 

With the results I'm getting now it would be logical to grind finer, but my grinder is now at the finest setting. If I grind finer it blocks.

I didn't need the finest grind setting in the past (it would overextract at that setting).

I'll try kikapu's hint and raise the pressure again.


----------



## DavecUK (Aug 6, 2013)

Just to chip in here, 7 or 8 years ago when testing some of the cheaper machines (Isomac venus etc..), I tested these fully unregulated at 15 bar. The pressure itself doesn't make that much difference to the extraction speed...neither does flow rate funny enough (otherwise all rotary pumped machines would have a huge problem. rather than keep moving the goalposts, stick your portafilter gauge back on, if it's 10 or 11 bar, don't worry about it (becuase the OPV is working exactly as it should, if it wasnt it would be 15 bar or 3 bar). The problem is going to be grind or beans.

Raising the pressure can press things in harder and slow things down a tad, but the effect isn't massive, as you describe.


----------



## bjgodefr (Jan 22, 2014)

Well, I've tried fresh beans and a friends grinder this morning, but the effect is the same (ie very fast extraction - which wasn't the case before the mod).

I'm now descaling the machine and if that doesn't do anything I'll try tinkering with the pressure again.


----------



## Mrboots2u (May 10, 2013)

how fresh is your coffee? Have you rested it from roast date at all, does it have a roast date ?


----------



## bjgodefr (Jan 22, 2014)

Hi, no the coffee doesn't have a roast date. But the thing is I made coffee with beans just before the mod and then with the same beans just after I adjusted the opv and the result was completely different.

I've now went for fresh beans from a roaster with a good name where I often go and the result is the same. My point is: even with old beans, the machine behaved differently.

I also adjusted the pressure to 12 bar static and now back the 10 bar. But both settings didn't alter the flow rate/extraction time. Still the same problem.

I'm at a loss now, can't think of anything else to try. Except of sending it to the factory for check-up. But what do I say the problem is? If they're used of using the pressurised pf's they can't be very concerned about extraction time ...


----------



## Mrboots2u (May 10, 2013)

Ok no worries , just trying to eliminate one of the variables in gushing extractions - the coffee hence asking roast date . Personally if a roaster can't tell me a roast date I'm dubious, but sounds like you are confident the coffee you a re using is good .

There is a guy on here gaggiamanualservices I think , is a wealth of knowledge on classics .

Perhaps he will pop up and be able to offer some advise or drop him a pm and see of he has any advice he can offer on how or where to send it to to fix


----------



## bjgodefr (Jan 22, 2014)

I've contacted gaggiamanualservices (through his website) and described the problem.

He suggested a couple of tests (constant flow through stripped brew head and constant pressure measurement) to check the integrity of the solenoid, pump and opv. Both checks were OK. The machine should be working properly.

The strange thing is that this indicates that the grind is too coarse. And this while my ascaso imini was perfectly able to grind so fine that the gaggia would choke (which obviously isn't the case anymore).

I'm now going to lend another grinder (3rd grinder that is going to be tested) from a friend (a vario) and see if it goes fine enough.


----------



## bjgodefr (Jan 22, 2014)

Finally! I was able to solve this problem.

The solution was fairly simple, if somewhat unexpected: I had to screw the cap of the opv (the one where you attach the silicone tube on) really really tight.

So it had nothing to do with grind or a damaged component, apparently the fact that this cap wasn't sealing very well caused my flow/extraction troubles.

Extraction time is back to normal and I can choke the machine again with a fine grind setting.


----------

