Breville Barista Express brew pressure and channeling issues

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MichaelScarn

#1: Post by MichaelScarn »

Hi,
I have had the BBE for about 6 months now. I have experienced that when my shots come out in about 30 seconds, the "pressure gauge" is always way over the espresso area on the gauge. I recently saw this photo on a forum that shows where on the BBE gauge 9 bar actually is.


I tried to dial in to this pressure while brewing, but found it impossible to get the flow slow enough when the pump kicked in. I saw somewhere else online that one trick is to hold the shot button in for the entire duration of the shot so that the pump does not kick in and send the pressure through the roof. Does anyone have experiences similar to this with the BBE? Is it simply not able to keep to 9 bars when used normally? I have seen someone mention that it is possible to adjust an OPV(over pressure valve) so that the pressure does not spike too high, but I'm a bit hesitant making modifications to the machine.

I made a video to illustrate my issues and the experiment with preinfusion mode only. Let me know what you think, I am very interested to hear if someone has any tips or similar experiences to share. In this video I use a DF64 flat burr grinder, 17g freshly roasted coffe, WDT and palm tamper and distributor.

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slaughter

#2: Post by slaughter »

Hi. I have this machine and I totally understand your frustration. The only way to get a decent flow rate is at the end of the presure gauge. I tried different grinder different coffee etc. Also naked portafilter is soooo messy that I ditched it after a few shots. Ended up with a different machine

mycatsnameisbernie

#3: Post by mycatsnameisbernie »

I have a Barista Express. Like several other machines (Gaggia Classic, Lelit Bianca, just to name 2), it comes from the factory with the OPV set above 9 bar.

I get my best shots with the maximum pressure that the OPV is set to, which means that my pressure gauge reads very high. I think it is futile to coarsen the grind to reduce the pressure - this results in a very fast under-extracted shot.

There are some videos on YouTube that show how to adjust or replace the Barista Express's OPV to get the pressure down to 9 bar. I would be nervous about doing this, since it would slow down the water flow through the thermocoil and possibly result in an overly high shot temperature.

I am really happy with the shots I pull on my BE at maximum pressure. I don't get any channeling (as long as my puck prep is on point). I don't see any reason to worry about it.

K7

#4: Post by K7 »

That's a pretty neat trick to work around a major shortcoming of the Breville/Sage Barista Express (and Infuser).

The reason for the first two shots (gusher at 9 bar, ok flow but at 14 bar) is because the machine's OPV is factory set to ~15 bar and the normal flow vs pressure curve for the Ulka pump on these machines is pretty fast. I think during the pre-infusion the pump gets lower voltage to operate at a different flow vs pressure curve and your hack (3rd shot) is exploiting that. I heard of this hack in the past but this is the 1st video I've seen demonstrating it works. Nice! I wonder if it works on all units or varies unit to unit.

You can read more about the Ulka pump operating curve and voltage here:
Voltage Controlled Pump Pressure (Ulka)

MichaelScarn (original poster)

#5: Post by MichaelScarn (original poster) »

K7 wrote: You can read more about the Ulka pump operating curve and voltage here:
Voltage Controlled Pump Pressure (Ulka)
Appreciate the link to the thread on the Ulka pump, that was very thorough and insightful. It seems like the rheostat modification in that thread accomplishes something pretty similar to what my "preinfusion only" technique is doing, would you agree? In my very non-expert opinion this technique does produce better tasting coffee than the regular ~14/15 bar shots on the BBE, so I would recommend others with similar machines to give it a try.

K7

#6: Post by K7 »

MichaelScarn wrote:Appreciate the link to the thread on the Ulka pump, that was very thorough and insightful. It seems like the rheostat modification in that thread accomplishes something pretty similar to what my "preinfusion only" technique is doing, would you agree?
Correct. Your video even shows a bit of declining pressure after peaking at 8 bar a la lever machines! :D
In my very non-expert opinion this technique does produce better tasting coffee than the regular ~14/15 bar shots on the BBE, so I would recommend others with similar machines to give it a try.
Although not impossible, it's hard to avoid channeling at 14 bar so one tends to get harsh shots. So no surprise it tastes better at ~8 bar.

Make sure the thermoblock temperature management is still okay with this hack (use your taste judgement). If so, you got yourself a decent machine, I think.

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slipchuck

#7: Post by slipchuck »

Don't worry about what the gauge reads as it's only a guide. Taste should be your number one concern




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titan

#8: Post by titan »

I've read that multiple times in the forum but I do not know the source, explaining why the gauge is only a guide and not at all corelated with pressure. OP shows the correspondence between the gauge and pressure and even though what we all ultimately care about is the taste in the cup, we can get a hint about how to debug the cup based on the readings.

PIXIllate
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#9: Post by PIXIllate »

An espresso puck experiences primary compression around 4 bars of pressure. Somewhere between 6-9 bars of peak pressure the entire history of good tasting shots has been written. At around 10 bar the puck experiences a secondary compression that actually SLOWS the flow of water through the puck. This is a categorically bad thing and is a fundamental parameter to avoid based on the physics of espresso.

Bottom line, find a way to adjust your OPV to 8-9 bar or get a machine you can do this with.

I've been where you are with a Gaggia Classic stuck at 13 bar. One morning, after yet another randomly bad set of shots, I cleaned it up, put it back in the box and sold it that night. My mornings became less frustrating and stressful. I gave up coffee for 8 months, saved the money I would have spent at my local cafe and bought a Profitec 600 dual boiler. Only then did I feel like I was working towards learning how to make great espresso. My tools were no longer roadblocks, just things to be learned and mastered.

Great espresso at home is not a beverage, its a fairly demanding hobby at least until you reach a certain level of proficiency. Don't be too hard on yourself, I think anyone here who has preserved long enough to get through the learning curve has a similar story of frustrations in the initial stages of this "hobby".

I now make stress free, great tasting espresso at home. It only took a year and a half and a huge budget overrun to get here. You'll see this comment by a lot of experienced home baristas not to discourage people but as a bit of a reality check about what expectations should be for people starting out. Good luck!

titan

#10: Post by titan »

I tried this mod only once, since reaching 9 bars in PI mode requires finer grind and a little fuller basket, and the cup tasted more acidic, less sour (more mouth-watering) with a hint of salt (something I could never get out of BE). I do not know if operating PI for 30s would hurt anything in the machine but I will definitely give it a few more shots (intended :D).
BTW, I found some more info regarding this mode of operation in another thread:
Breville Infuser - Manometer pressure vs pour time mystery?