# OPV done - No difference. Help



## james10 (Feb 28, 2011)

So I'm relatively new to this whole coffee domain, but recently purchased a Gaggia Classic.

I've upgraded the silvia wand today and also tinkered with the OPV pressure (big thanks to the instructions / info from other members on this forum).

My problem is that, my shot of espresso is still coming out in under 10 seconds...which leads me to believe that it's either my tamping or the ground coffee isn't fine enough.

So I measured another double in the filter basket and but most of my weight on the tamper...pulled the shot...same result (10 seconds).

So by process of elimination it must be the coffee grind. Here's the part where you may accuse me of being a fool as I'm currently using Lavazza Caffe Espresso (pre-ground).

I was under the impression that pre-ground espresso coffee has it's downside's (mainly it's compromise of taste and flavour) but I thought the coarseness would be close enough to whats required and therefore enable me to pull a 25 second shot?

Any help would be appreciated

Thanks


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## CoffeeExmoor (Mar 10, 2011)

Like James, I have adjusted my OPV based on the excellent information provided within the various threads. However. it was done purely 'on spec' as I simply can't fathom out how you check the flowrate. There are many references to this but, like PaulN, I can't understand how you do it - so my OPV adjustment may be a bit out. Like James, I am getting a 10-15 second shot, even using 'fresh' pre-ground coffee

As another newbie, I would welcome any advice.


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## gaggiamanualservice.com (Dec 22, 2009)

the opv is set between 13 and 15 bar from source, it should not need to be adjusted. your coffee grinds and tamping techniques are mostly the problem. only a very old machine should warrant tampering the opv and only if you have a pressure tester to so you dont over do it. if done incorrectly you can cause a lot more damage than good.

mark


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## Glenn (Jun 14, 2008)

I echo Marks sentiments - *it should not need to be adjusted*

Very very very rarely is pressure an issue

There is usually a number of other variables that contribute to the issues you mention

Many pre-ground espresso's are ground fairly coarsely, and this suits pressurised baskets but not standard baskets

How many grams of coffee did you put into the basket?

Are you using the plastic tamper or a real one?


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## gaggiamanualservice.com (Dec 22, 2009)

the grinds on the gaggia solenoid machines, classic, baby etc need to be fine, a rule of thumb we used to use when grinding our own was to squeeze the grind between finger and thumb and if it keeps it shape and does not just crumble the grind is fine enough

mark


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## PIP (Dec 30, 2010)

A few years ago I was in the same position. Fresh beans and a grinder fixed it for me.


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## CoffeeExmoor (Mar 10, 2011)

Clearly, learned opinion is against OPV adjustment. I will reinstate the original setting and re work the other factors. Thanks to everyone for their input.


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## james10 (Feb 28, 2011)

I only adjusted the OPV, because I was under the impression, it would help me to achieve a better end result. Paired with the fact many commercial premises and other threads say 9BAR is optimum.

From my perspective, I'm new to this, therefore trying to follow experienced advice...But if pressure isn't going to make a difference then I'll revert back to the factory setting.

I'm currently using 18g per basket.

Don't laugh - I was finishing off some Lavazza Rossa, so decided to open a new pack of Lavazza Caffe Espresso (the black one) - thinking this would really make a difference....it didn't.

Yes I'm currently using the awful plastic tamper (got a proper 58mm on order).

I've tried playing around with the tamping (ensuring I get a level/flat tamp) i.e. Very gentle pressure...all the way to putting most of my weight on the tamp - but it doesn't really make a huge amount of difference.

I would say that the taste is slightly different and the puck is dry (on the hardest tamp) but overall the shot time is almost identical and nowhere near 25 seconds.


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## Eyedee (Sep 13, 2010)

Yes I'm currently using the awful plastic tamper (got a proper 58mm on order).

I've tried playing around with the tamping (ensuring I get a level/flat tamp) i.e. Very gentle pressure...all the way to putting most of my weight on the tamp - but it doesn't really make a huge amount of difference.

Just a quick line on tamping, the recommended tamping pressure=30lbs.

When I got an Espro calibrated tamper i was amazed at how little pressure is needed to achieve the necessary poundage, don't think you have to push the portafilter through the counter top it's not required. Fact---- the plastic supplied tamper is crap.


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## james10 (Feb 28, 2011)

I know the recommended pressure is 30lbs, I was tried tamping - light, medium, heavy, extra heavy - Didn't really change the shot timing though.

I feel like punching the person who suggested Gaggia supply that plastic tamper. Ridiculous!


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## Wando64 (Feb 28, 2011)

Lavazza (rossa or espresso) is ground too coarse. Like others I would recommend grinding your own freshly roasted coffee, however if you want to carry on purchasing from a supermarket give Illy a try as in my opinion is the only one grounded finely enough for espresso.


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## PaulN (Mar 10, 2011)

gaggiamanualservice.com said:


> the opv is set between 13 and 15 bar from source, it should not need to be adjusted. your coffee grinds and tamping techniques are mostly the problem. only a very old machine should warrant tampering the opv and only if you have a pressure tester to so you dont over do it. if done incorrectly you can cause a lot more damage than good.
> 
> mark


This is all interesting.

So whys this 9 bar being thrown around? I understand the idea of measuring the flow rate but as others have said its a bit hit and miss so if i do adjust my OPV ill rig up a proper pressure gauge or worst case buy one ready togo.

On a side note im getting very good espressos, around 1oz between 24-28 seconds so its not a major issue i would just like my machine set-up perfect so i know where i stand.

Got to be honest I have a fair few hobbies including detailing cars and such but espresso making seems the hardest to constantly nail down perfect as the beans are changing daily due to age.

Cheers

PaulN


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## espresso_a_day (Aug 18, 2010)

I was also confused about 9 bar pressure and OPV setting. I think I've figured it out, and here is my current understanding:

The pressure that is ideally 9 bar is the pressure just above the puck. Your grind and tamp influence this. (Of course, if you had a pump that could only do less than 9 bar, you would not be able to achieve this pressure at the puck no matter how perfect your tamp -- but the Gaggia can easily do 9 bar).

The OPV sets the max pressure that will ever get put through from the boiler to the channel that leads to the puck. If the OPV setting is 15 bar, eg, the OPV opens when pressure is higher than 15 bar, and releases water back to the tank. However, if you have ground and tamped correctly, this should not happen.

Reducing the OPV from 15 to say 9 bar should, according to this understanding, only mean that if your puck yields just a bit more resistance to 9 bar, the machine "chokes" -- where otherwise you might now get a ristretto made with a bit over 9 bar pressure (at the puck).

If your coffee gushes through in 10 seconds, the pressure at the puck is too low -- your grind is too coarse or tamp too light or both, and no pressure of 9 bar ever builds up at the puck. The OPV remains closed, whether it is set at 15 or 9 bar.


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## MonkeyHarris (Dec 3, 2010)

My understanding is pretty similar. 9 bar is like the 25 second rule. It's not the be all and end all it's just the typical value. It's upto you to adjust your pucks resistance to the pressure. You need the higher bar setting when using a higher dose or making a ristretto. In addition I think the inital pressure required to get the pour going is higher than is required once the grinds are soaked so it might start at say 12 and gradually reduce to 9 as more of the coffee particles are flushed through.


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## gaggiamanualservice.com (Dec 22, 2009)

on the gaggia machines 9 bar is the minimum required to produce a crema on your espresso

mark


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