Brew Pressure on Vibration Pump Espresso Machines 

Hi AZ, Thanks for the commenty!

Our pleasure!

Hey Joh, You're welcome - Thanks for the comment! Marc

Wow, thank you!

Hi Erlyn, Will do and thanks for the comment! Marc

You're welcome!

Glad to hear that!

Very welcome

Glad you enjoyed it!

Glad I could help!

Hi Nelson, Thanks for the comment and your patronage. Todd is a great resource! I agree you could adjust the pressure up to 10 - 10.5 bar static on the machine gauge. I would not get too wrapped up in brew pressure. So long as it's not crazy low or high and you're within a couple bars of 9 you're likely to notice little difference in your extractions. Lots of caveats to that statement like lighter roasts tend to extract better at lower flow rates and darker roasts tend to be better at higher flow rates. There's no magic to a perfect 9 bar in the portafilter. Marc

Hi Ardy, Thanks for the comment and adding that info! Marc

Hi Leo, Thanks for the vote! I'll do my best to make that happen. Marc

@@Wholelattelovepage Great, thanks Marc!

@@WholelattelovepageHi, did you make that happen? Where can I see the results? Many thanks in advance!

Hi Tim, You are welcome and thanks for the comment! Actually, when using a Scace you are not measuring static pressure as the device simulates an extraction by releasing water. Group gauges typically read about 1 bar higher than Scace pressure reading during testing. Marc

@@Wholelattelovepage Thanks for clarifying. What I meant with static is that flow doesn not vary with a scace device like it does in espresso extraction. It is just fixed, right? So if we know that group pressure is typically 1 bar higher than that shown by the scace device, how does group pressure look like in an actual extraction after you have adjusted it according to the scace device? I would assume that initially it builds up and then should drop as more coffee is extracted and flow increases. So what is the proxy pressure you guys set your machines to before shipping or when servicing?

@@timgerber5563 Hey Tim, Group pressure typically does drop slightly as an extraction progresses. Depends on the grind as to how much. When we adjust pressure it's to 10 bar static for vibration pump machines.

@@Wholelattelovepage Technically, the gauges are all measuring static pressure (vs velocity pressure or total pressure), but the control volume is static, which I understand is what you are referring to when you state static pressure. The reason the Scace device is more accurate for actual brewing is, as you state in your video, it allows water to escape at an approximate rate of a puck of coffee (assuming your shot flows at the rate the Scace device is calibrated for.) If your shot flows faster, it will have less pressure, and vice versa. I believe these pumps are positive displacement and thus pump a constant volume. The pressure they develop is solely the result of the resistance to flow (coffee puck, Scace orifice, OPV). As for the video, I think you are spot on in helping us all understand the nuance of the pressure in an espresso machine, my only correction is to the way you use static pressure. Thanks for the video.

Hi DV, You are welcome for the video. When running a blind shot - so pump running but flow from the group blocked I'd look for 10-11 bar on the gauge. That should get you about 9 bar actual on the puck during an extraction. Marc

Hi PC, Thanks for the info! Marc

Hey David, You're welcome!

Hi MB, Thanks for the question.10 bar static pressure on the gauge of a vibration pump usually gets you ~9 bar max available on the puck during an extraction. That "rule" is overrated! It's become the dogma because that's what the original machines did way back when. I've had excellent shots pulled on manual lever machine that hit much higher pressures. And wonderful shots extracted at lower pressures. The only way to truly know (and honestly you shouldn't worry about it that much) is a group mounted pressure gauge or Scace or similar group pressure measuring device which can be tuned to simulate the release of water you'd have during a standard espresso extraction.

Hey DH, You're very welcome! Good luck with your testing! Marc

Translation: Thanks for that information, I have a Rancilio Epoca and I would like to know how much water should come out of the shower and in how long to know if it is within the normal range, thank you very much. Gracias por la pregunta. En general, las máquinas con una bomba de vibración funcionan con un caudal libre de 7-8 gramos por segundo. Las máquinas de bomba rotatoria funcionan a unos 10 gramos por segundo. Marc Thanks for the question. In general machines with a vibration pump run at an unencumbered flow rate of 7-8 grams per second. Rotary pump machines run at about 10 grams per second.

Great suggestion!

Please do! And BZ10 as well. Thank you!

Hey PM, Outcomes depend on the type of coffee used and subjective personal flavor preferences. I recommend leaving the machine at factory pressure setting. But, no reason you can't adjust and taste the results. Marc

Hi RGB, Measured using a portafilter gauge I'd go with 10 bar for 9 bar during extraction. Marc

Hi EK, You're welcome! I have not tested the BZ10 but I did test a Bezzera Unica. For the Unica, a static pressure of 11 bar on the machine gauge results in ~9 bar on the coffee during an extraction. I'm not 100% certain but guessing it would be similar on the BZ10 or potentially a little bit higher with more plumbing between the gauge and group. Marc

Hi Mr Za, You are welcome for the video! What's right is hard to say. As I mentioned in this video manufacturers may have reasons for setting pressures higher than 9 bar static. It may be because of lower flow rates from vibration pumps as compared to commercial rotary pumps, the difference between what one sees as a static reading on a machine gauge vs. what the pressure is in the group during an extraction, etc. Many in the espresso community take 9 bar as an unbreakable rule. Turns out the 9 bar gospel may originate from the first pumps Achille Gaggia put in machines more than 50 years ago. I did not test a BZ10 when making this video. I did test a Bezzera Unica. It was set to 12 bar static pressure which produce 10.3 bar in the portafilter during a Scace test. The Rancilio Silvia Pro in this video shows a static pressure of 12 bar on the machine gauge and the same 12 bar on a static portafilter gauge. At that setting it produced a Scace reading of 9 bar while showing the same 12 bar on the machine gauge. Based on my test of the Unica if you want 9 bar on the coffee during an extraction I'd set static pressure on the machine gauge to 11 bar. That could be off as a Unica is not a BZ10. My recommendation however is to not worry so much about pressure. Personally I believe flow rate is more important than pressure. Try this... Dial in a coffee and extract it with the machine set to 12 bar static. Then keep all other variables the same, change the pressure to 10 bar static and extract. Do a blind taste test and stick with what you like. Marc

@@WholelattelovepageHey Marc! What a helpful informations! i really appreciate your help and support :) there's no doubt that your suggestion is the best option. i definitely try it. Again huge thanks !

Hi MA, Yes, a hair over 10 static gets you 9 on the puck. Marc

Hi x, You are welcome! To produce 9 bar in the group during an extraction we set vibration pump machines like the 400 and 500 to about 10bar when measuring static pressure on a machine's gauge.

Hi mb, Unfortunately I'm not familiar with that machine. If it uses a vibration pump like machine in this video then you be looking for an OPV: Over Pressure Valve to adjust. If a powered by a rotary pump then there usually a bypass scree on the side of the pump to adjust the maximum static brew pressure.

Hey J, Well, I try every once in awhile. A Pro X would be a sick upgrade! Marc

Also would like to see the data

Hi ander, thanks for the comment and question. Unfortunately not as simple as setting to 9 bar static. To be precise you'll need a device like a Scace which can measure pressure in the portafilter as some brew water is released which simulates an extraction. However Scace and similar are relatively expensive. If you can measure static pressure in the group, ~8 bar there should get you ~6 during an extraction.

Hi M, You did not mention what type of machine. I'm assuming it's an HX boiler with E61 group. .8 bar in the boiler gives you an in boiler temp of ~117C. That temperature is reduced a bit in the HX section of the boiler due to the thermosiphon loop which circulates water out to the group and back. 1 bar in the boiler results in an in boiler temp of ~120C. Every HX machine is a little different in the offset between the in boiler temp and the temp delivered to the group head. Machines controlled by pressurestat tend to have a wider temperature range than those controlled by PID. Also this type of machine will overheat if left on and idle for long periods. Normal operating procedure of an HX pressurestat machine is to do a cooling flush from the group head prior to pulling an extraction. It flushes out overheated water and reduces brew temps. Generally you'd flush until water flow from the group is no longer extra steamy and turbulent due to flash boiling. It's usually a 2 - 6 second flush to reduce temps but depends on when machine was last used and how long it's been idle. Hope that helps!

Thank you for replay. I'm sorry for not mentioning earlier, but the machine I have is the Rocket Appartemento. The temperature of 117C excessively high; nevertheless, your recommendation is to promptly power off the machine after every use if I'm correct?. Furthermore, I am considering seeking a method to autonomously control the heater by utilizing a sensor and electronic mechanisms.

Hi AB, You are welcome and thank you for the kind comment. Yes 10 bar static should get you about 9 when actually pulling a shot - assuming grind is dialed in properly. Marc

@@Wholelattelovepage Thanks for that. Subscribed.

Hi DA, Yes, we set the OPV on Profitec machines with vibration pumps like the Pro 600 to produce 10 bar on the machine gauge when running the pump with blind filter basket inserted. Maarc

Hi SK, It can be difficult to find info including diagrams for made in China products. You will likely need to open up the machine and find the expansion valve aka OPV. I do not have a Valentina to guide you but near 100% certain it is a vibration pump machine so once you find the OPV process is similar to what's shown in this video. I did locate this thread on Home Barista which may be helpful: www.home-barista.com/espresso-machines/valentina-brew-pressure-adjustment-t263.html

Yes please MARK

Hi JG, Thanks for the request. I will visit rotary pumps in a future video! Until then, know that rotary pumps run much with less of change in pressure between machine gauge and what's on the coffee. That's due to the higher volume of wter they move at a given pressure as compared to vibration pump machines. Unencumbered rotary pump machines moves about 11g/s of water through the group. For vibration pumps it's 7-8g/s. Marc

@@Wholelattelovepage Good to know but anyway - waiting for rotary pump video. Cheerz Marc ( I have Quick Mill Aquilla Black ☕️)

Hi JODE, Both the Silvia and Silvia Pro use similar if not identical pumps so chances are yes 10 bar static on a PF gauge will get you ~9 bar during an extraction with properly dialed in grind size. Basket in or out makes no difference. I do suggest cleaning the group head of any residual coffee debri prior to using a PF mounted gauge. Hope that helps! Marc

Hi CL, Set to a static pressure of 10 bar if using a portafilter mounted pressure gauge.

Hi C-A F, Here is a video featuring our 5 favorite super autos of 2021: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5vB6ctmFJZQ.html Marc

@@Wholelattelovepage Thank you, Marc. This video is for countertop super autos. Do you have a video for built in super autos?

Hey 54, I'd go with 10 bar static on a Bezzera machine with vibration pump, 9 bar on machines with rotary pump.

Hi rp, Hard to be certain from here but sounds like the gauge is malfunctioning if machine is otherwise working normally. If you purchased machine from us and would like assitance you can submit a ticket to our tech support staff here: www.wholelattelove.com/pages/contact-us

Hi AG, thanks for sharing!

Hi Miguel, A hair over 10 bar on the group gauge measured static gets you 9 on the puck when extracting. Marc

Hi PC, Thanks for the question. Been awhile since I've seen a Brewtus III. I have not tested that machine with a Scace so cannot say with 100% certainty. But if Vibration pump I'd try setting at 10.5 bar static. If rotary try 9.5 static.

@@Wholelattelovepage I'll give it a try. Thanks Mark!

Hi AG, Machines which come with a pressurized portafilter (Breville calls it Dual Wall) often run at higher pressure to accommodate brewing with a pressurized basket. To the best of my knowledge I do not believe brew pressure is user adjustable ob the Barista Express. You may need to compromise with a slightly coarser grind if worried about the pressure being too high.

@@Wholelattelovepage yes, is not factory user adjustable, but, by internal dimmer mod we could trick the pump controlling the entering voltages producing less pressure, and we could adjust using this method... Or not? I never ever use pressurized basket, always non pressurized. Thank you for reply :)

La pompe rotative monte plus vite en pression, elle permet par exemple de mieux gérer une préinfusion, est "beaucoup "plus stable et enfin elle permet d'etre raccordé au réseau d'eau mais elle est aussi plus chère...

good morning Marc Very good topic, thank you for your commitment. I have a question which vibrating or rotary pump do you the expert prefer to equip your machine without taking into account the noise parameter. Comme le mentionne @pinard Fr, la pression monte plus rapidement avec une pompe rotative et la plupart des machines à pompe rotative peuvent être connectées à l'alimentation en eau domestique. Les pompes rotatives ont un débit d'eau libre plus élevé d'environ 11 grammes par seconde. La vibration de la pompe est d'environ 8 grammes par seconde. Étant donné le choix, je préfère une pompe rotative pour la possibilité de se connecter à la conduite d'eau, un débit plus élevé et un son plus agréable. J'espère que ça t'as aidé! Marc As @pinard Fr mentions the pressure rises faster with a rotary pump and most rotary pump machines can be connected to household water supply. Rotary pumps have a higher unencumbered water flow rate of about 11 grams per second. Vibration pump is about 8 grams per second. Given the choice I prefer a rotary pump for the ability to connect to waterline, higher flow rate and more pleasant sound. Hope that Helps! Marc

Hi s, Thanks for the question. If that's a static pressure reading I'd leave as is. The 11 bar static on the gauge is likely producing ~9bar inside the portafilter during an actual extraction. Marc

Hi Gavin, thanks for the question. For a static pressure gauge at the group head I recommend setting pressure to produce 10 bar on the gauge. No worries on spelling! It's spelled Scace. Marc

Thanks Marc - love the videos and thank you for responding so quickly 😊

hi c, As I recall it's a drop of 1-1.5bar from reading on machine pressure gauge. Marc

@@Wholelattelovepage thanks so much for the quick response!

Hi MJ, Thanks for the comment. It's always about the taste in the end! Marc

I was thinking the same thing until I read the linked interview with Scace. There's more to it than just making a few bits. My immediate question was how big is the hole that lets the water out to simulate the extraction flow rate? In the interview he also says he uses a plastic 'fake puck'. Then there is the problem of getting a temperature sensor quick and accurate enough. I'm a software developer & amateur machinist so I have some of the skill necessary to build and run one, but I don't have the metrology that Greg has! Making an adjustable OPV and static pressure tester is no great challenge, but I think one of these is a bit of a mission and without the metrology expertise would probably just be misleading.

"as machinist I can make a copy of the Scace for peanuts" Man, I think you have an eBay business waiting for you. I certainly would be a buyer at a decent price.

Hi Steve, Thanks for the question. Yes, I'd set ~11bar on machine gauge.

Hi user, I recommend setting to 10 bar static pressure.

Termoblok digunakan untuk memanaskan air pada mesin berbiaya lebih rendah sehingga tidak ada hubungannya dengan tekanan boiler. Jika Anda menyesuaikan OPV, Anda mengubah tekanan maksimum yang dapat diterapkan pada kopi bubuk. Mengubah tekanan minuman mungkin memerlukan perubahan ukuran gilingan. Marc translation: Hello Marc, is there a difference between thermoblock and boiler pressure? For example, if we adjust the OPV, of course it will change and calibrate the grind size of the coffee grinder, right? Thks Thermoblocks are used to heat water in lower cost machines so has nothing to do boiler pressure. If you adjust the OPV you are changing the maximum pressure which can be applied to the ground coffee. Changing brew pressure may require change to grind size. Marc

Yes we have! www.wholelattelove.com/products/lelit-bianca-v3-dual-boiler-espresso-machine-matte-black?variant=40644730224694

Yes, your grind size and puck prep are how you "normally" dial in the extraction time. But the pump in most machines is capable of producing more pressure than you would want, some issues that you may have for example is channeling if the pressure and flow is too high, or in general not being able to find a grindsize that produces good extraction times while not being too fine. The OPV's main function is not safety, it is exactly meant to set brew pressure.

Hi slow, on most all OPV's it's clockwise to increase the pressure.

Hi S, Thanks for sharing. As mentioned in the video manufacturers have their reasons for setting pressures as they do. Personally I believe flow rates are more important than brewing pressure and in our testing as well as others there seems to be little difference in extraction yields through a surprisingly wide range of brew pressures. Marc

Hi Marc - you mention the static pressure to get 9 bars on the Scase [not sure if I spelt that correctly] on all the machines except the Rocket. What would you suggest for static if I fitted a pressure gauge to the group head? Jan23

Hi BF, Yes, you can for sure use a group gauge. Static pressure measurements give you a read of the maximum possible pressure (minus the losses in machine plumbing) the machine can apply to the coffee. Pressure on the group gauge during an extraction can be different depending on grind size of the coffee. Marc

Hi bp, we do not have a chart with all machines and there is some variance. On the Pathfinder which uses a vibration pump 10 bar static should get you a max of ~9 at the group during an extraction.

@@Wholelattelovepage my pathfinder shows 10 bar at gauge and 11 at group head, strange.

Hi s, Well, it's the only dual boiler in the group here so a little more room under the hood is needed! Marc

Hi Dave, You're welcome! The group gauge is further back in the system. Not a lot further but enough it holds at a higher pressure than what's read within the portafilter where water is exiting. Marc

The pressure reading on the Scace higher than the group gauge was due to Scace emulates the espresso extraction, water goes through and you get the lower pressure reading as well, essentially we need 9bar limited at the coffee puck not the pipe line.

@@Wholelattelovepage hello hello, can you please please write if you know how much pressure is lost between group head measurement and Scace. For example if you install group head pressure gauge and do real extraction and it shows 9bar, what will than show Scace, 8-8.5? I just need that info to complete this puzzle of pump pressure 🙂 thanks a lot

Hi CT, Static pressure is measured when there is no flow from the group - like if a backflush disc is installed in the portafilter. Most machine face mounted gauges measure pressure before the boiler (in cold water) and very near the pump. During an extraction those gauges do give an idea of pressure on the coffee but it's not as accurate as a group mounted gauge within the flow of brew water. It varies by machine and pump type but face mounted gauges may read a bar or 2 higher than actual pressure on the coffee during an extraction.

Hey C, thnks for the request. Here's a video featuring our favorites of 2021: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ysndMubg4ds.html Marc

Hi d, Honestly people get too wrapped up in brew pressure. Many manufacturers use a higher static pressure setting in machines with vibration pumps as they move less water than rotary pumps. Understand that the pressure reading is taken deeper in the machine near the pump in the cold water before the boiler and does not represent perfectly represent the pressure in the portafilter during an extraction. 12 bar should be fine on your machine.

@@Wholelattelovepage thank you so much for the detailed reply! So, no need to Adjust the OPV the 9 bar read at the gauge? Thanks!

@@daniwello I'd leave as is.

Hi s, A lot of lower end machines advertise 15 bar etc. It's all marketing based on the more is better mentality. Technically pumps may be able to produce 15 bar but you really do not want to extract espresso at that pressure.

There ya go! Marc

Hi m, Thanks for the question. Flow rate is not measured unless machine has a flow meter. Flow and pressure while not the same are "cousins" with higher pressures resulting in higher flow rates. Marc

Hi Sharing, Your machine is not defective. Perfectly normal that pressure reads a bit higher on the group gauge. Here's a video explaining why: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2ArWAtuUTOM.htmlsi=RK-ZouF6r1PcNljq The video demonstrates on a Pro 700 but reasons are the same.

But why the machines here in this video is reading same pressure?? Dont understand why.. see 3:36 1:01

Please advise!

Hi MC, Flow control controls the flow rate of brew water. OPV controls maximum pressure of brew water. Marc

Hi IT, Thanks for sharing your thoughts. Marc

Hoffman knows a lot about coffee, roasting and commercial machines but his domestic machine reviews were very poorly researched. He just clearly didn't understand the machines or how to use them.

We have our specialties. I'm lucky with nearly instant access to most every prosumer level espresso machine available in North America. Marc

@@davidk7262 You might be on to something. I've got my BZ13 at 9 bar on the gage cause Hoffmann recommended this. Testing to see if I can get a good shot. I will say that high pressures lead to channeling. At least in my experience. Maybe I need to work on puck prep. In any case, I have work todo.

@@damienhull6497 Did you solve this or dial back the pressure? I'm very interested in this machine, but I'm really frustrated that there's no information available on this and many many people seem to complain about the factory pressure set too high...

The problem is, that this video is misleading and confusing as hell. There is no way to calibrate a machine to a "true" dynamic brewing pressure of 9 bar, not even with a Scace device. Which coffee puck does that device even resemble? A 16g or a 22g puck? A finer or a coarser grind setting? Setting the static pressure higher than 9 bars means that in the worst case a finely ground high dose will be extracted with more than 9 bars. Calibrating the static pressure on a closed system means calibrating the maximum pressure which shouldn't get higher than 9 bar in the portafilter, even if no water is released.

Hey Chris, Thanks for adding your thoughts. I wish you were more specific about what you feel is misleading. I have to mention if what you want is say 9 bar on your coffee inside the PF during an extraction that's not what you will get if you set to 9 bar static pressure. Also mention it seems a lot of folks get a little to obsessive with brew pressure. I get comments all the time from people worrying about not being at exactly 9 bar. Nothing magical happens at 9 bar. Just happened to be the pressure in machines (who knows where that was measured) from many years ago so it's been the espresso dogma since.

@@Wholelattelovepage Hi there! I'll try to be a bit more specific… When I mount a pressure testing gauge onto my portafilter (unscrew the spout, then mount the gauge), tighten it and start the pump, it will show the static pressure inside the portafilter, right? As no water can escape the portafilter in that scenario, the pump will go up to maximum pressure and the OPV will regulate that it does not exceed that specific maximum pressure by releasing water out of the system. The mounted pressure gauge on the portafilter will now show the maximum pressure that is build up in the portafilter and that could get built up during an extraction. Let’s say I want to calibrate that static maximum pressure to 7 bar (don’t get me wrong, I don’t care about 9 bar being set), so what I am going to do now is changing the OPV setting until my pressure gauge on the portafilter shows 7 bar. What I find misleading is - if I understood you correctly - that you say that I don't get true 7 bar in my portafilter with that setting as I need to use a Scace device for calibration instead. The misleading thing here is, that a Scace device relases water at a specific flow rate that cannot be used as a generic rate value as every puck has its own flow rate depending on the dose, the coarseness of the grinds, etc. which results in a different resistance from puck to puck and which also results in a different brew pressure from puck to puck. Therefore it is impossible to set the brew pressure to exactly 7 (or 9) bar as every puck releases its own specific amount of water. But what you most likely want is to limit the pressure that can be build up to your desired brew pressure to make sure it won’t be exceeded during extraction. I know that 9 bar of static pressure will supposably not result in a dynamic brewing pressure of 9 bar as long as the flow rate allows the machine to run on less pressure. But that is totally fine and nothing bad. The bad thing would be if I‘d choose a finer grind size for a ristretto and my machine would go up to 10 or 11 bar as the resistance increases because of the finer grinds. Hope that this clarifies my thoughts…

Hi v, have not put a scace with pressure reading device to determine group pressure during simulated extraction. My guess is it's significantly lower than 12.

@@Wholelattelovepage i have added one that shows the pressure at the group head - it shows 11 bar on my unica - 12 bar on the machine - i am not worried about this 9 bar etc, debate - my only reason is being that my Unica has a whistle most times - due to the OPV - i have contacted Bezzera - they told me to contact you WLL for updates - they may release a new OPV or solution to it - how long do i wait before asking WLL about this - thanks - Machine is great - not a problem - 12 bar is fine for me - its the whistle that happens at most times -

@@Wholelattelovepage i can show you a pic of it showing 11 bar - not sure how to add a picture here if you can - if you want to see it - where can i send it - thanks