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Bezzera BZ02 cooling flush question

Postby appa on Wed Sep 29, 2010 10:32 pm

Hi,

The BZ02 manual I have says that in order to have
the right temp for the machine, flush steam 2-3 times.

This is pretty vague, but is sounds like a cooling flush
with steam rather than flushing water. Most posts Ive
seen on HX flushing talk about drawing water from the
group.

Is this just a bad translation for something else?
I mean to try it once I know the machine a bit better,
but just wanted to see if anyone had thoughts on this

Thanks
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Postby oknewell on Wed Sep 29, 2010 10:54 pm

My guess is they are talking about the boiler temp and not the actual cooling flush that is ALSO required. The steam flush would be when you turn the machine on in the morning to get the boiler up to temp. The assumption I'm making is that you don't have one of those valves (can't remember the name) that bleeds off the steam as not give you a false pressure reading, which in turn doesn't allow the boiler to heat up all the way.
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Postby another_jim on Wed Sep 29, 2010 11:25 pm

Don't over think it.

The BZ02 warms up to shot making temperature in about 1/2 hour. No steam bleeding required.

Run the pump, to get water out of the group, until it stops boiling, and then 2 to 5 seconds more, 2 seconds for a high shot temperatue, 5 for a low one.
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Postby Heckie on Thu Sep 30, 2010 2:39 am

Appa
I also have/had difficulty getting the length of a cooling flush consistent day in and day out. Seems a thermo-filter device might initially be more helpful in nailing down an accurate flush time, as opposed to a 2-5 second secondary flush. I mean it depends on the specific machine, ambient temp, boiler temp, etc... does it not?
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Postby cannonfodder on Thu Sep 30, 2010 11:13 am

Yes, it depends on the machine, ambient temperature, inlet water temperature, how long the machine has been sitting, pressurestat setting and a dozen other variables. However, while a Scace is handy, you do not need one to find the proper temperature. All you need is a pen, paper, coffee and time. Adjust your flushing length by taste. Keep notes, flushed 4 seconds past flash boil, waited 10 seconds, pulled shot, bitter and burnt. Next time flush a few seconds longer until you get the results you are looking for. Every coffee will be different and the environmental variables will have some effect, but you will get the hang of it. Dont get hung up on gadgets, all you really need is a good grinder, good coffee, good machine (a scale is handy) and taste.
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Postby Heckie on Thu Sep 30, 2010 11:21 am

Dave, agreed. Just pointing out to OP that there's more to it than,
another_jim wrote:....Run the pump, to get water out of the group, until it stops boiling, and then 2 to 5 seconds more, 2 seconds for a high shot temperatue, 5 for a low one.

Experimenting with various flush times is imperative considering all the variables.
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Postby HB on Thu Sep 30, 2010 11:39 am

From what Jim tells me, the BZ02 behaves like the Olympia Maximatic and other HX Dragons. That means the flush routine is really less complicated than what you've read about E61 HX espresso machines. As an educated guess, I would start with 5 seconds past the end of flash boiling with a 10 second rebound. This video shows what I mean for the Maximatic:


Hint: Don't watch the video, LISTEN to the video!

If the temperature is too hot, reduce the rebound time to 5 seconds.

PS: If these terms are unfamiliar, read How I Stopped Worrying and Learned to Love HXs.
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Postby appa on Thu Sep 30, 2010 12:01 pm

wow, the video makes it super clear , thanks...

How long in between shots can I get away with not flushing?

I just wasnt sure what the manual was referring to,
was thinking it was a way of cooling down with less
water usage, but if I have to flush, I have to flush...

Ill just flush into a cup like you did Dan, and use the water
for dish washing..

Thanks again everyone...
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Postby HB on Thu Sep 30, 2010 12:24 pm

appa wrote:How long in between shots can I get away with not flushing?

Dragon HXs like yours must be flushed before each extraction. I recommend waiting at least 90 seconds between shots so the group/heat exchanger can restabilize. I know it sounds like a lot of flushing/wasted water, but the good news is that Dragon HXs have little thermal memory, so the flush routine is the same every time.
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Postby appa on Thu Sep 30, 2010 12:33 pm

Thanks HB,
Im not too worried about the wait time, cos it
usually takes about that long to grind,tamp, etc
the next shot when im playing with settings,
and ill only pull a shot here and there throughout the
day...

thanks again...
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