I've received my new NS Oscar with and OPV (set at 10 bars) earlier this week and have noticed that it takes often more than 10 seconds for any coffee to come out. The first ~7 seconds you can hear the pump work without any labour and then the pressure builds up.

I've read about this issue earlier and despite searching I can't really find any info on the topic. I can faintly remember that this could be typical for Oscars and not really anything you can work on, but I'd like to know more on what is going on there.

My shots are still around 1.5 - 2 ounces in 25-30 seconds so this doesn't happen to the best of my understanding because the grind is too fine. It is something else...

how does it taste? If it's good, i wouldnt worry about it.

personally, i aim for about 5-7 seconds for my first drops on my oscar and the pressure build-up time is usually only about 3-4 seconds.

as long as my coffee is fresh(i will typically never use anything more than 14 days post roast), my dose is consistent(i'm almost always using a 18-19 gram dose) and my grind is right, my results are very consistent.

give us an idea of your routine. what coffee? fresh? dose? distribution method? tamp? etc.

Roasted on monday this week by a Finnish small scale roaster, 17g, 30 pound tamp, 50ml, WDM.

what kind of basket are you using? i doubt that the small extra space of even a triple basket would cause that much of a delay, though...hmm...

what happens when you grind slightly coarser? if the extraction is too fast, maybe try to updose to make up for the coarser grind...

to see if we're on the same page, when do you start your 25-30 second timing? as soon as you start the pump?

and again, how does it taste?

Standard NS double basket. If I grind coarse, I get a fast shot... And I start the timing as soon as I press the button. Tastes OK, but not fantastic. Was using 19g of coffee... perhaps just a tad fast. I suppose the issue wasn't that bad when I dosed a couple of grams more... Perhaps I should tamp lighter too (?)

once the flow starts, it seems to be a bit faster than i normally like to see. with a spouted pf i usually like to see actual first drops that increase to a fine mousetail-like stream that angles slightly inward and then a slight bit faster but steady flow later on in the extraction.

i suspect that possibly the OPV is causing a delay in the pressure build up. i know that the oscar doesnt come with an OPV.

You might benefit from learning to time your extractions from the first drop of espresso instead of when you start the pump as your OPV might be causing you to have a completely different reference point compared to other non-opv equipped oscar owners.

if i were to guess, as a starting point, start timing as soon as you see the first drops then add about 5-6 seconds to the number when you finish. If you can, you should use a scale to measure the output while you're timing so that you can have a set of variables to use to aim for. For example, i'd start timing when i see the first drop then stop timing when i reached my target beverage weight. Then take that time and add about 6 seconds. If it's much faster or slower than your target 25-30 seconds, adjust your grind accordingly and try again.

and of course, let your taste buds dictate the success of your results.

Nuova Simonelli, as with other machine manufacturers, is continuosly improving their machines. To the extent that these improvements trickle down to the Oscar is hard to judge because their latest Oscar parts book is dated 2008. For example, their soft infusion system (SIS) or some variation thereof.

The times you are reporting (~10 seconds) that coffee first appears seem long . . . about twice the length of time I would expect. I would do two things:

a. Measure the flow of water from an empty portafilter over a period of say, 30 seconds amd report back . Start your measurement AFTER a full flow is established and be sure your water reservoir is at least 2/3 full. Your flow units should be in ml/minute.

b. Contact the dealer from whom you purchased the machine and see what they have to say about this apparent flow delay.

Approximately 340ml in 30 seconds.

I could contact the dealer, but he is in Italy and I'm in Finland so I'm not sure how much he is use in this case....

I suppose it could be the OPV, but I'm skeptical...


Edit: so about 680ml/minute

Well, just as a sorta reference, that is about 10% more than a typical Rancilio Silvia but still very reasonable. Is the OPV flowing any water back to the reservoir during a shot? Does this OPV even return to the reservoir or to the drip tray?