Pulling shots at 14 bar

Beginner and pro baristas share tips and tricks.
crwper

#1: Post by crwper »

I recently bought my first home espresso equipment: a Gaggia Classic Pro and Eureka Mignon Specialita. I am a tinkerer, so I have big plans for the Gaggia. I've got an OPV spring kit on the way from Shades of Coffee, and a PID controller coming from Banggood. I design electronics for a living, so one of the things that drew me to the Gaggia was the active modding community.

In the meantime, though, I'm temperature surfing and pulling shots with the stock OPV and double basket (non-pressurized).

Typical advice for a 9 bar system seems to be to adjust grind so that the pull is 25-30 seconds with a 1.5 to 3 ratio of output to input. Lots of sources seem to say things will be different with 14 bars, but I haven't been able to find any specific advice.

While I'm waiting for mods to come in, I'd love to hear any tips and tricks you all have for pulling the best shots I can with the stock 14 bar OPV. How should I adjust conventional technique? On a technical level, how does the higher pressure affect extraction?

Thanks!

baldheadracing
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#2: Post by baldheadracing »

The higher pressures work best with traditional Northern Italian espresso blends in my experience.

(Pretty much all the espresso machine manufacturers who set their vibration pump machines' pressures "too high" are from Northern Italy.)

Once you get down to lower pressures, then Southern Italian blends and a wider variety of roasts like "Modern Espresso" will be more accessible.

Enjoy!

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SandraF

#3: Post by SandraF »

I doubt while pulling a shot you'll get to 14 bars of pressure. It's marketing to sell an espresso machine. Most people making espresso are shooting somewhere between 6-9 bar.

Someone with better knowledge of electronics will come along here shortly and clarify.

K7

#4: Post by K7 »

I lived with 14 bar pulls for many months back when I had the Breville Barista Express which, like yours, has OPV factory set to 14 or 15 bar.

You can still pull at 9 bar with these machines with a less resistive puck, but it will be a 8-15 sec gusher due to the pressure-vs-flow curve of the Ulka pump these machines have. Usually they taste not good. To get a ~25 sec pull, you end up operating at ~14 bar.

So to answer your question, because of very fine grind for 14 bar, your shots tend to be ristretto type that takes a while to preinfuse and start to flow. You will also see once it starts to flow, it tends to blond rather quickly. In my experience, short ratio works better. Think 1:0.9 to 1:1.3 ratio. YMMV depending on coffee. But espresso life at 14 bar is tough because it's hard to avoid channeling. If you see only minor spritzes on naked PF, you are doing good LOL. GL!

crwper (original poster)

#5: Post by crwper (original poster) »

baldheadracing wrote:I doubt while pulling a shot you'll get to 14 bars of pressure. It's marketing to sell an espresso machine. Most people making espresso are shooting somewhere between 6-9 bar.
I gather the Gaggia Classic Pro uses an Ulka E5 pump. These now seem to be produced by CEME, who provides the following spec for pressure vs. flow rate:



I'm definitely not getting 14 bar with a little flow through the pump, but it doesn't hit 10 bar until about 200 cc/min, which would be about 100 g of output in 30 seconds. At 100 cc/min, which would be about 50 g of output in 30 seconds, it should give about 13 bar.

crwper (original poster)

#6: Post by crwper (original poster) »

K7 wrote:So to answer your question, because of very fine grind for 14 bar, your shots tend to be ristretto type that takes a while to preinfuse and start to flow. You will also see once it starts to flow, it tends to blond rather quickly. In my experience, short ratio works better. Think 1:0.9 to 1:1.3 ratio. YMMV depending on coffee. But espresso life at 14 bar is tough because it's hard to avoid channeling. If you see only minor spritzes on naked PF, you are doing good LOL. GL!
This is pretty close to my experience. I'm honestly pretty new to espresso tasting as well, so I'm trying to figure out what the different flavours are at the same time as I'm learning how these variables affect flavour.

With the first batch of beans I tried (Bows & Arrows, "The Hathaway") I would have said that I'm getting the most rounded flavour at around 16 grams in and 50 grams out in 25 seconds. When I go shorter than that, say, 16 grams in and 25 grams out in 25 seconds, I would say that the coffee gets more acidic and the puck afterward is quite dry and brittle. This makes me think it's under extracted.

At the moment I'm weighing the beans, then grinding straight into the portafilter, then weighing the grounds. Then I do a little stirring with a toothpick, tap the sides of the portafilter with my hand to level the bed, then tamp firmly. Finally, I wait for the light on the Gaggia to go off, install the portafilter, get everything set up, and about 10 seconds after the light comes on again I start the shot.

I figured I'd hold off on the naked portafilter until I had the OPV kit installed, as my research has led me to believe that using it before will just make a mess of the counter. :-)

crwper (original poster)

#7: Post by crwper (original poster) »

baldheadracing wrote:The higher pressures work best with traditional Northern Italian espresso blends in my experience.
Interesting. This is the challenging part for me. Like, I'd say the technical side of things come easy, but appreciating the importance of using the right beans is a little harder.

So far, I've been feeding it "The Hathaway" from Bows & Arrows, which is an "espresso" roast made up of a blend of Peruvian beans. I've just picked up something from a local roaster, Rosso's "Basecamp", which is a dark roast made up of Colombian and Brazilian beans. I'll see if I can find something from Northern Italy locally.

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Jeff
Team HB

#8: Post by Jeff »

My experience is that above 8-9 bar in the basket, the flavors go "flat" and subtlety is lost.

I think that OPV kit will prove to be a good choice.

baldheadracing
Supporter ♡

#9: Post by baldheadracing »

I haven't had a subscription to BXA in quite a few years as I homeroast now. Back then BXA was one of the best roasters in Canada but they did roast very light. IIRC, I would have pulled the Hathaway at 6 bar brew pressure - but again, that was five+ years ago.

As you're in Calgary, you have some of the best roasters in Canada local to you - Phil&Sebastian, Monogram, Fratello, Rosso ... IIRC, Fratello roasts darker so they should have something ... but yeah, if I was in Calgary, I'd want the brew pressure set to 7.5 bar at the most, and enjoy the high quality medium and light roasts available locally.

(Brew pressure is lower than OPV pressure, but I don't know which pressure the kit is referring too. Typically 9 bar vibe pump is about 8 bar when actually pulling a shot.)

Also, I am being somewhat a hypocrite as I often pull light roasts on a Elektra vibe pump machine with no OPV(!), but the BZ/Elektra group design does play a pretty significant role ... on a Gaggia/Silvia/E-61, I'd want a lower pressure for sure (and my Silvia is set to 7.5 bar brew pressure).

AZRich

#10: Post by AZRich »

Until you get your new opv spring kit, the simple way to reduce the pressure at the puck is to slightly open the steam valve when you pull a shot. That will bleed off some water (into a container) to get you down to a much more appropriate pressure.
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