Breville Dual Boiler issue. Unable to reach 9 Bar pressure. Underextact.
Breville the Dual Boiler / Breville SmartGrinder
Controlled within 20g - 21g. (measure after tamping. I am a firm tamper)
Extract time: 27 - 30s
Shots are always very watery, extract flow fast, under-extract. (Grinder setting => finest already)
I notice in pressure gauge, it is unable to reach 9 bar, it is shifting between 7 to 8. I suspect this is the reason to cause under-extract in this situation.
Any ideas? Any adjustment for this? or could be faulty machine?
Last edited by gilzero; 30th August 2013 at 12:12 AM.
Reason: typo in subject
My first thoughts are grind setting, it sounds like you need to get it a little finer. It's already on the finest setting, have you got the shim kit installed? Contact Breville they will send you one. The shims pack out the grinding burrs and helps it get a finer grind.
To which I would add the question "How old are the beans you are using?"
Ideally you should be using beans which are no more than 2~3 weeks since they were roasted - if you're buying beans of indeterminate age then you're going to be working hard to get a decent coffee.
@MikeS. Thanks for your input. I understand how important freshness is. I get coffee from local roster. So it is within 1-3 wks.
Originally Posted by MikeS
Do you just put enough beans for a single shot each time? I find that without the weight of beans on top in the hopper does require a finer setting.
Long shot though. It may pin point your grinder is not grinding fine enough.
Or have you tried grinding a single shot first, tap your PF to collapse the grind with a light tamp on top before grinding the rest and do a proper tamp after? I found it worked well for my BES860 before.
How old is your machine? To pinpoint the problem, put the blind filter disc into your portafilter and hit the shot button. If it doesn't reach 10.5 bars (I think?), then it's a problem with your OPV. What do the grinds feel like in between your fingers?
Thanks for the shim introduction. But from my observation, the ground seems to be ok.
Originally Posted by Aidos
I use factory single wall double cup basket, am sure enough bean on top. And I consider my dosing is consistent. To test to issue, I measure every dose.
Originally Posted by okitoki
They are new machine. 1 months old.
Originally Posted by BradG
I tried your saying. Put blind dist into my single wall double cup basket. Run for 30 sec, the gauge reaches 9.5, stay quite still.
Ground on my finger quite ok, they are quite fine actually.
Actually, it should be around 9.5 bars with a blind filter. Have you tried the pinch test? Espresso: The Grind | Sweet Maria's Coffee Library
Originally Posted by gilzero
Originally Posted by BradG
thanks for referring the grind article. Good read.
I called customer service, the support told me pressure b/w 7 to 10 is normal. He doubts my coffee. Asked me to grab different coffee will solve the problem. (even I believe the blend I use is quite good, from very reputable local roaster. And is just two week old from roasted. ) So I don't quite agree with the answer.
I then tried UPDOSING. I put extra 1 - 2 gram coffee, about 22g - 23g dose, with even firmer tamp (maybe 20kg). The result is better, getting more viscous extract, normal flow. It reached 9 bar then.
So there are just many factors we need to play and adjust around. May or may not be the pressure thing.
Just my 2cent.
It would be a good idea to try another roastery. Maybe it's a lighter roast or hasn't been roasted properly? This one roastery I tried had the worst beans. They were sour and kept pouring fast. It's either that or your grinder, you shouldn't have to tamp twice. I always tamp to around 2mm under the line in the basket and have always had nice shots.
I have a problem with the bar pressure
As you mentioned in this post I have put the blind disc in the double wall cup and hit the shot button and the pressure gauge only reaches 5bars. I read that you mentioned that I should reach 9.5bar otherwise it would be a problem with the OPV. What does OPV stand for and how can we fix this problem? Thank you very much in advance
Originally Posted by BradG
OPV - Over Pressure Valve - its role is to return water back into the tank, to prevent over-pressuring the system above its rating of 15bar. It is positioned on top of the pump, as the water is still cold. Whilst the pressure is below its "open threshold" - it stays closed and allows the pump to pressurise the system. If the pressure is greater than the set threshold, it opens and it allows the water to return in the tank, maintaining the set pressure. When the OPV is open, you will see water moving in the tank - as it is returned via the OPV.
The Brevile OPV is a very simple unit - and in my experience its failure is usually due to the compression of the sealing o-ring for the return path. The o-ring is standard (can't remember the size now - #007 (I think) - see picture here: https://www.ereplacementparts.com/co...p-1439539.html)
My experience with adjusting the OPV after the first drop in pressure is that it's a futile attempt - you'll squeeze another 6 or so weeks out of it - and then it will do the same thing and you won't be able to tighten it any more as it is already nearly to the max. You either replace the o-ring - or replace the valve.
I opted for a brass valve - it should last as long as the rest of the machine. Yes - it's a bit more expensive and it's risky, but it pays out.
Have a look at these couple of links for pictures and description on how to adjust/replace it:
» My OPV adjustment journey. Nic's Stuff
» BES900 and the brass OPV… Nic's Stuff
If cracking the machine open is not your cup of coffee (so to speak), you'll have to take it to an appliance store. If you're still under warranty (unlikely) then it's an easy decision, otherwise - you may be out of pocket the price of a few coffees.
Last edited by inorog; 5th March 2018 at 08:21 PM.
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