Bezzera BZ10 - Tips/Advice?

Need help with equipment usage or want to share your latest discovery?
jferreir

#1: Post by jferreir »

I recently bought a Bezzera BZ10 for home use, but I'm struggling to pull a decent shot. It's been years since I used a proper espresso machine (~10), and I definitely need some help. I have no experience with HX machines, and I'm looking for simple, practical advice from other Bezzera owners. I fully acknowledge the problem lies with me, not the machine.

The biggest problem thus far is sour shots. I know this means the coffee is under-extracted, but I'm not sure how to correct it. I'm confident the grind is correct because I get great consistency with lots of crema. If I adjust the grind any finer, then the shot doesn't pour and I only get a few drops of coffee (GH pressure drops to 6/7 bars, too). BUT, it still takes anywhere between 20-30 seconds to pour.

TBH, I think the problem is two-fold: cooling flushes and improper dosing. This is my first HX machine, so I assumed cooling flushes prior to brewing were mandatory. I've found the opposite to be true - cooling flushes makes the shot more sour (even after a long warm-up time). How long should I do the cooling flush, if at all? How long should I wait before pulling another shot? Any other specific suggestions for this machine?

Concerning dosing, I'm using the Bezzera grinder (sans timer), and it grinds about 1G per second. I've tried adjusting the dose from 10-17 seconds, but I just can't seem to find the sweet spot. 90% of the time it's too sour, and 10% of the time it's too bitter. If I want to make a double-shot of espresso, what would be the ideal dose for this machine? To establish a baseline, should I weigh the beans first, then grind? Eventually, I want to be able to do this without any scales whatsoever - just my wristwatch and my eyes. I've been using a bathroom scale for tamping (lol), so I know the pressure is pretty darn close to 30lbs. Oh, and I distribute the grounds evenly when filling the portafilter.

I'm most familiar with the beans used at the local cafe, so I have 3lb on the way and I'm going to use them to dial in the machine. Any tips, suggestions, or advice would be most appreciated!

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algue

#2: Post by algue »

hello Jason,
what are your pressure settings?
I mean, did you check/set the OPV using the blind filter?
my BZ10 was factory set to about 12 bar and I found it really hard to manage.
I finally lowered it to 9-9.5 bar.
For what concerning boiler pressure, my setting is now at about 1 bar, but I know that someone could prefer some more (1.1-1.2). Be sure to check it, because your considerations about sourness and the negative effect of cooling flush make me think that somehow you have too low temperatures. For this reason I think that it could be useful if you could measure water temperature at the outlet of the portaffilter when you brew coffee.
Talking about dose, as Jim Shulman already pointed out, Bezzera/Elektra/Brasilia group is really dose-sensitive.
Overloading the group lean often to underextracted shots.
For this reason I suggest you to move towards lower doses, with consequently finer ground size.
I'm a white fly in this forum, as I shot almost exclusively singles. For this purpose I found the single filter with 8 - 8.5 grams to be the best (up to now. I'm still trying to lower the dose a bit more) When I shot with the double filter, I use 14-14.5 grams (to get two coffees).

jferreir

#3: Post by jferreir »

Well, it looks like I figured it out. I weighed the dosage this time... what a difference! I learned that the grinder operates much faster than 1G per second, contrary to what Bezzera claims. The BZ10 seems to be particularly sensitive to over-dosing; after adjusting the grind and keeping the dose down to 14G, I started to get consistently good shots using a 3 second cooling flush. I'm a little blitzed right now after 4 of them. :shock:

So, for any current or future owners, pay close attention to dosage. Duh.

ddennis

#4: Post by ddennis »

Hi Jason

Could you explain how you lowered the OPV?

I found this:
The BZ10's pressurestat is adjustable without opening the machine with an appropriately sized insulated screwdriver inserted through the warming tray (use your own judgement).
From the "Bezzera BZ10 - early experience" Bezzera BZ10 - early experience

Further more as i understood it, if the BZ10 is build after 10/30/12 it will already have a 9 bar kit installed.
Do you know of any guide on how to validate this on my machine?.

Thanks in advance - sorry if i am hijacking this thread.
/Dennis

jferreir

#5: Post by jferreir »

ddennis wrote:Hi Jason
Could you explain how you lowered the OPV?
I didn't, so I have no clue... sorry!

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algue

#6: Post by algue »

Pstat and OPV are not the same item.
Pstat controls boiler pressure.
It is actually possible to turn the adjustment screw of pstat from outside, but you need some preparation (I had to enlarge one of the holes on the top of the machine, for example).
OPV controls brewing pressure and in my opinion is almost impossible to be regulated without opening the machine.
Alberto

ddennis

#7: Post by ddennis »

Thanks for clearing that up Alberto.

Did you adjust the OPV by turning the Part no. 9
http://coffeegeek.com/images/50561/bezzera.JPG

Another image.
http://i206.photobucket.com/albums/bb94 ... 0008ml.jpg

with a blind filter or ?

/Dennis

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algue

#8: Post by algue »

You have to turn the part that is red circled in the second photo, which is part n.1 (and not n.9) in the first diagram.
You should repeat this procedure: turn a bit and try with blind filter.
Alberto

ddennis

#9: Post by ddennis »

Thanks alot for your help.