Breville BES900 Dual Boiler - Owners thread

[WiredArabica]

...It would be great if Phil McKnight or someone from Breville could enlighten us as to the design of this feature, and what might cause variations in the volume delivered assuming that grind and dose are actually consistent.

He has done in the past... You'll probably find it in this very thread somewhere... Hmm, yep - here.
There are two flow meters, on the inlet and low-pressure outlet of the OPV. This is used to calculate the flow rate - there was iirc a firmware update to improve this a bit but the nature of this is it will always be susceptible to flow rate to some extent - but I suspect the major contributor is dose, and perhaps coffee. They need to be programmed for your current variables - of they change, you'll need to re-program the volumetric buttons.
Only time I tend to use them is if making a number of milk based drinks in a row - program the button(s) as necessary for the session, they work very well in that situation.
Otherwise, it's best to stick with the manual.

[Banjo.au]

He has done in the past... You'll probably find it in this very thread somewhere... Hmm, yep - here.

Excellent! Thank you for finding that quote, which confirms my understanding of how the buttons work. I knew it was stated earlier in this thread but I didn't realise it was Phil who did so. You have a much better memory than I do.

Otherwise, it's best to stick with the manual.

+1

[blend52]

Yes, Phils comments did explain how the system works with 2 flow meters, but does not explain why it appears to be so unreliable/inaccurate in use.
The design principle should work and, in theory, not be affected by dose or grind etc.

[johnsmith]

i was having a look at the pre-infusion settings this morning, wanting to see if dialing it down in power would make any noticeable difference. the manual says the recommended range is 50-60%, but i was unable to dial it to under 55%. is this due to a firmware update?

i also noticed that a friend of mine who bought the black version of the BDB, and his included milk jug is smaller than mine. we both bought it at the same time in December 2012. i wonder if this is due to his being from a newer batch?

[Barry_Duncan]

Its all very confusing. That's why I will stick to the manual button and adjust the grind as required.

It is time for a coffee.

Barry

[Banjo.au]

Yes, Phils comments did explain how the system works with 2 flow meters, but does not explain why it appears to be so unreliable/inaccurate in use.
The design principle should work and, in theory, not be affected by dose or grind etc.

It has to be affected by changes in dose, grind and type of coffee, because they can all affect the volume of water that is retained in the puck! If the puck retains more water, there'll be less in the cup. If the puck retains less water, there'll be more in the cup.

Conceivably there might also be some variability in the accuracy of the flow meters that are used, which might explain variability in the volume of coffee in the cup if you actually achieve a consistent grind and dose with the same coffee from one pour to the next.

You suffer a lot less stress if you don't expect everything to perform perfectly every time, especially with a fresh food like coffee.

[Banjo.au]

Its all very confusing. That's why I will stick to the manual button and adjust the grind as required.

Works for me!

[blend52]

It has to be affected by changes in dose, grind and type of coffee, because they can all affect the volume of water that is retained in the puck! If the puck retains more water, there'll be less in the cup. If the puck retains less water, there'll be more in the cup.

very likely, but would that explain the 10 -30ml variations some have reported ?

Conceivably there might also be some variability in the accuracy of the flow meters that are used, which might explain variability in the volume of coffee in the cup if you actually achieve a consistent grind and dose with the same coffee from one pour to the next..

.. much more likely !

You suffer a lot less stress if you don't expect everything to perform perfectly every time, especially with a fresh food like coffee.

It doesnt stress me at all,... but i do believe that if a function is advertised as included , it should work as intended.
I have no doubt, that some folk will have bought this machine on the understanding that it does not need manual operation.

[clubbi4]

very likely, but would that explain the 10 -30ml variations some have reported ?


.. much more likely !

It doesnt stress me at all,... but i do believe that if a function is advertised as included , it should work as intended.
I have no doubt, that some folk will have bought this machine on the understanding that it does not need manual operation.

I agree blend52...I purchased this machine cause of that function as well as the rest of it's features. If it's a volumetric mavchine, it should give you consistent pours + or - a few ml not 10ml ++.
I hope phil can shed some light on this topic cause i'm sure this is not right.

[Banjo.au]

... but i do believe that if a function is advertised as included , it should work as intended.

A perfectly reasonable expectation, but please define "should work as intended". Is it "as intended by the manufacturer taking into account the inherent variability invoked by the design, material and parts selection and the variability inherent in those parts, sensor and software capabilities, etc, and budget"? Or is it:

... it should give you consistent pours + or - a few ml

?
+/- a few ml may well seem reasonable to you, but in my opinion you really can't reasonably expect to get pours within +/- a few ml unless you pull three consecutive shots with the same beans, the first to calibrate the button of your choice followed immediately by two more shots using the same button, while paying scrupulous attention to the dose, distribution and tamp of each shot to get each as close to identical as you can manage and hoping that the machine and especially the flow meters operate consistently the whole time.

It is my own experience and I'm pretty sure the experience of others that the grind, dose and tamp that produced a beautiful pour at breakfast time will produce a different pour at mid-morning or lunch time. Professional baristas know and are quoted on this site as saying that they must adjust the grind as the day progresses and temperature and humidity change, and as the beans age, because of the natural variability inherent in fresh coffee. I think that amount of variability alone is sufficient to change the calibration of the buttons by more than +/- 5 ml and as much as +/- 10 ml on occasion, especially if there is also a change in the dose or distribution since the button was last calibrated. YMMV and that's ok.

I'm also looking forward to Phil shedding some light on this topic.

[clubbi4]

A perfectly reasonable expectation, but please define "should work as intended". Is it "as intended by the manufacturer taking into account the inherent variability invoked by the design, material and parts selection and the variability inherent in those parts, sensor and software capabilities, etc, and budget"? Or is it:
?
+/- a few ml may well seem reasonable to you, but in my opinion you really can't reasonably expect to get pours within +/- a few ml unless you pull three consecutive shots with the same beans, the first to calibrate the button of your choice followed immediately by two more shots using the same button, while paying scrupulous attention to the dose, distribution and tamp of each shot to get each as close to identical as you can manage and hoping that the machine and especially the flow meters operate consistently the whole time.

It is my own experience and I'm pretty sure the experience of others that the grind, dose and tamp that produced a beautiful pour at breakfast time will produce a different pour at mid-morning or lunch time. Professional baristas know and are quoted on this site as saying that they must adjust the grind as the day progresses and temperature and humidity change, and as the beans age, because of the natural variability inherent in fresh coffee. I think that amount of variability alone is sufficient to change the calibration of the buttons by more than +/- 5 ml and as much as +/- 10 ml on occasion, especially if there is also a change in the dose or distribution since the button was last calibrated. YMMV and that's ok.

I'm also looking forward to Phil shedding some light on this topic.

I have to say, you are very wrong....I make coffee all day as i am a barsita and have been for 7 years now. I adjust grind all day long but that doesn't mean that I have to manually stop a shot. We have a Wega Polaris and I calibrated it and I haven't touched it since. Wether it's pouring fast or slow, the actual volume never changes. Previous to this machine, I had the 6910 which was spot on everytime.
So I'm not sure what you are on about mate.

[Banjo.au]

I'm used to being told I'm very wrong; my wife tells me often.

OK, you have the skills to be much more consistent than many home users. Good.

It seems your expectation is that the BDB will perform with the same precision in this area as a commercial machine costing between four and eight times as much, depending on whether you compare street prices or RRP. Sounds reasonable to me.

It would be interesting to compare the performance specs of the flow meters in each machine. It would also be interesting to find out how common inconsistent pour volumes are in the wild. Phil, are you reading this?

[clubbi4]

I'm used to being told I'm very wrong; my wife tells me often.

OK, you have the skills to be much more consistent than many home users. Good.

It seems your expectation is that the BDB will perform with the same precision in this area as a commercial machine costing between four and eight times as much, depending on whether you compare street prices or RRP. Sounds reasonable to me.

It would be interesting to compare the performance specs of the flow meters in each machine. It would also be interesting to find out how common inconsistent pour volumes are in the wild. Phil, are you reading this?

The 6910 cost half as much and did a more precise job....explain that!!

[J_Hutt]

Perhaps the volumetric buttons are intended as a novice feature and (intended) to be used with the dual wall baskets. This way the backpressure would possibly be normalised, depending less on the dose/tamp/grind etc.

Nit that I am advocating use of the dual walls...but it might be worth investigation.

[MarkZammit]

Breville BES900 Dual Boiler - Owners thread

Can't be a novice feature if a bar sita is using it.....

I just use manual and have never had a problem with my shot volumes.