Bezzera BZ10 flushing, underdosing, etc. - Page 2

Need help with equipment usage or want to share your latest discovery?
User avatar
hankbates
Posts: 446
Joined: 13 years ago

#11: Post by hankbates »

Dr. Robert Pavlis (rpavlis) has many posts concerning the use of distilled water in an espresso machine.
Here is a good one?
Amazing 1st gen 1974 La Pavoni Europiccola!!

He has around a hundred others, to see them you can go to his profile and search for distilled in his posts.

I personally have received more useful information from his posts than from anywhere else.
Some people rescue dogs and cats, I like to rescue Livias…

Samcanadian
Posts: 148
Joined: 6 years ago

#12: Post by Samcanadian »

Is the flushing to cool the water down, or heat it up? I've been a little confused by the advice in this thread, and I always assumed that the flush was to keep the flash boiling water out of your coffee, and instead ensure you're brewing with water that isn't at peak temp.

bas
Posts: 374
Joined: 15 years ago

#13: Post by bas »

with E61 HX machines it is a cooling flush for the overheated HX water. at least for most.

with the Bezzera it is different. flushing without resistance gives a water dance but flow is much higher than with resistance. with resistance the group is able to balance the temperature because group has a lower temperature than target and HX volume and flow are very small with coffee in the group due to resistance. with flushing the group gets hotter and loses it's balancing capability.

just try with only a 1-2 sec. screen flush.

Samcanadian
Posts: 148
Joined: 6 years ago

#14: Post by Samcanadian replying to bas »

Ok, that's interesting. You're saying that the group will get hotter the longer I flush (5-6 seconds) and my brew will end up being over an optimal target, whereas a quick flush will simply get the superheated water out and let the machine do it's work when there's coffee and a PF in place?

lhkt (original poster)
Posts: 48
Joined: 7 years ago

#15: Post by lhkt (original poster) »

I've just bought a 22g VST to underdose to 20g, but still getting coffee residue on the shower screen.
Anyone with the same experience or is your shower nice and clean after removing the portafilter?
Perhaps I'll try with 19g or 18g...

DeGaulle
Posts: 545
Joined: 10 years ago

#16: Post by DeGaulle »

Just because there is coffee residue on the shower screen doesn't necessarily mean that you have dosed too much coffee. When you cut your shot, the 9+ bar pressure is instantly released via the exhaust on the 3-way solenoid into the driptray. This tends to suck some grounds onto the shower screen. I always run a quick screen flush when I take the PF out after a shot. Only if you see a profound imprint of the screen screw in the middle of the spent puck, then you may have been dosing too much.
Bert

DeGaulle
Posts: 545
Joined: 10 years ago

#17: Post by DeGaulle »

I haven't really tried underdosing my precision baskets, but VST baskets in particular seem to be non-forgiving to underdosing by > 1 gram below what they have been rated for.
Bert

DeGaulle
Posts: 545
Joined: 10 years ago

#18: Post by DeGaulle »

Ok, that's interesting. You're saying that the group will get hotter the longer I flush (5-6 seconds) and my brew will end up being over an optimal target, whereas a quick flush will simply get the superheated water out and let the machine do it's work when there's coffee and a PF in place?
The idea is that the group head acts as a heat sink shedding the surplus of heat to the atmosphere. Given its limited thermal mass, if you flush for too long with higher flow rate, the group head heats up and loses that heat sink capability. At extraction flow rate, it is better capable of this.
Bert

lhkt (original poster)
Posts: 48
Joined: 7 years ago

#19: Post by lhkt (original poster) »

DeGaulle wrote:Just because there is coffee residue on the shower screen doesn't necessarily mean that you have dosed too much coffee. When you cut your shot, the 9+ bar pressure is instantly released via the exhaust on the 3-way solenoid into the driptray. This tends to suck some grounds onto the shower screen. I always run a quick screen flush when I take the PF out after a shot. Only if you see a profound imprint of the screen screw in the middle of the spent puck, then you may have been dosing too much.
Fair enough, no shower "stamp" on the puck so I should be good. Dosing 20g into the 22g basket seems fine with only very minimal residue on the screen due to solenoid activity. Thanks for tip!

lhkt (original poster)
Posts: 48
Joined: 7 years ago

#20: Post by lhkt (original poster) »

DeGaulle wrote:I haven't really tried underdosing my precision baskets, but VST baskets in particular seem to be non-forgiving to underdosing by > 1 gram below what they have been rated for.
What do you mean by non forgiving? I dose 20g into the 22g basket because of the low shower screen and adjust grind fineness accordingly - so the flow and end result is to my liking.