Teme Senior Member Joined: 7 Jan 2005 Posts: 1,221 Location: Finland Expertise: I love coffee
Espresso: Izzo Alex Duetto II Grinder: Mahlkönig K30 Vario
Posted Wed May 4, 2005, 6:27pm Subject: Timing the cooling flush on E61 machines?
I have read quite a few posts on and am aware of the need for a cooling flush on E61 machines, especially if they have been idle for some time. I have read Dan Kehn's excellent article "How I Stopped Worrying and Learned to Love HXs". However, and without exception, the posts and articles that I have found refer to the cooling flush in terms of its volume (in fluid ounces).
This is not meant as a criticism by any means, but I personally find it difficult to relate to the oz volume measure not only as an European who usually talks and thinks in ml, cc or dl but mainly because actually measuring the volume is not practical in my opinion - I'd rather time it.
As regards the background, I have an Andreja Premium:
with the boiler pressure set at 1.1 bar max (0.95 bar at the low end)
with the brew pressure limited to 9.5 bar
I am currently pulling a cooling flush until I hear (and see) the gurgling/hissing stop and stop it a couple of (as in 2) seconds from there I then grind, dose, level, tamp, lock and load (I actually start the grind, then pause it momentarily to stop the cooling flush, and continue - so let's say I have 30 sec from the time I finish the flush to when I lock in the loaded PF)
I only use beans that have been roasted within the past 4-5 days
I have no digital thermometer for measuring my brew temps
The shots are currently great in my opinion (if I want to nitpick, there might be a bit of sourness) but as a CG, I am interested in seeing (and tasting) if they can be even better. Before I start experimenting and to save "re-inventing the wheel", I'd be interested in hearing views on whether or not I am on the right track and which way I should go from here with my experiments. Any comments would be much appreciated.
Exnyerinmontreal Senior Member Joined: 24 Feb 2003 Posts: 61 Location: Montreal Expertise: I love coffee
Espresso: Andreja Premium Grinder: MACAP M4
Posted Wed May 4, 2005, 8:10pm Subject: Re: Timing the cooling flush on E61 machines?
Teme:
I've been struggling with the same issues in trying to fine tune and get the best from my machine. I'm set up the same as you -- 1.1 bar boiler pressure, 9.5 max brew pressure. I've been going more by volume however -- 6 oz or so after idle for a while (30 min +), which generally works out to about 2 oz after the water flow settles down. Usually about 4 oz or so after pulling another shot or shorter idle time.
I've been trying to then play with the recovery time (15-20 sec) to pull some shots at a bit lower temp, say around 200F, but I'm not sure if this is the best approach or if I should be flushing more and allowing a longer recovery. Part of the problem is that sometimes my heater cycles during the recovery and I have to wait for it to go "green" again before I pull the shot. The flush and timings have been my biggest "unknown" over the last 2 weeks.
Exnyerinmontreal Senior Member Joined: 24 Feb 2003 Posts: 61 Location: Montreal Expertise: I love coffee
Espresso: Andreja Premium Grinder: MACAP M4
Posted Wed May 4, 2005, 8:21pm Subject: Re: Timing the cooling flush on E61 machines?
One more thing...
Based on the cooling flush info I've read on this site and written by Dan Kehn, the numbers in this table seem too high, in terms of volume. They would generally seem to exceed the rule of 2 oz after the water stream settles and the gurgling/hissing stops.
Teme Senior Member Joined: 7 Jan 2005 Posts: 1,221 Location: Finland Expertise: I love coffee
Espresso: Izzo Alex Duetto II Grinder: Mahlkönig K30 Vario
Posted Fri May 6, 2005, 12:15pm Subject: Re: Timing the cooling flush on E61 machines?
Thanks for the input Curtis and Mike.
I have re-read Dan Kehn's article and he does actually also have references to time (24 secs for the sputtering to stop and 30 sec total - from idle that is) - so, my apologies Dan!
Even though the amounts to be flushed shown on the chart that Curtis kindly posted seem excessive as Mike pointed out, it seems clear that my flushes have been way too short. I timed a 6 oz flush on my Andreja today. It took 24 sec. This is almost twice as long as the flushes I have been pulling previously when the machine has been idle (and almost twice the volume). The 2 oz after the hissing and sputtering stops translated to 8 sec instead of the 2 sec or so I have been doing thus far. I now also get the point of flushing into a separate container instead of into the drip tray - perhaps I could use the flush to pre-heat the cups...
I will need to experiment further with the longer cooling flushes and see how it effects the taste of my shots.
BTW, do you guys pull the cooling flush with the PF in place or with the PF out? So far I have been flushing with the PF out (I am grinding into it while doing the flush and tamping during the machine recovery).
Regarding my blog, I am off for a short vacation on Sunday and after a couple of days in the office I am in for a business trip to the US and Canada - not much time to play around with my machine or write up stuff for my blog during the rest of May. But there are a couple of things that I hope will realise soon thereafter. During my US trip I will be picking up a couple of naked PF's from Chris (experimenting with those will be cool) and later on I and a fellow CG are planning on doing a side by side comparison between my Andreja Premium and his Elektra MicroCasa semiauto as well as my Rocky and his Macap M4 doserless...
Posted Fri May 6, 2005, 1:24pm Subject: Re: Timing the cooling flush on E61 machines?
On the first pull of the morning, I run my cooling flush into an 8oz mason jar, portafilter in place. Makes it easy to measure.
While it's flushing I'm holding the grind button on my Rocky SD. I use the bottom half of my zass turkish mill to hold the grinds. Very clean routine, I don't drop a single speck of coffee ground.
Exnyerinmontreal Senior Member Joined: 24 Feb 2003 Posts: 61 Location: Montreal Expertise: I love coffee
Espresso: Andreja Premium Grinder: MACAP M4
Posted Fri May 6, 2005, 1:35pm Subject: Re: Timing the cooling flush on E61 machines?
I usually do my cooling flush into the double-spouted portofilter, while grinding into the single spouted portofilter. I do the flush into a measuring cup, and am watching the volume as well as the bevavior of the water. I will try timing it this weekend, out of curiousity.
My naked PF from Chris arrived this afternoon, and I look forward to playing with that this weekend as well.
Teme, if you'll be coming to Montreal, you should let me know and perhaps we could get together for a coffee :)
Posted Fri May 6, 2005, 9:59pm Subject: Re: Timing the cooling flush on E61 machines?
Teme Said:
I have re-read Dan Kehn's article and he does actually also have references to time (24 secs for the sputtering to stop and 30 sec total - from idle that is) - so, my apologies Dan!
No problem, but actually my preferred approach is listening to the sputtering with the portafilter out of the group, which is accurate and repeatable. I find a measuring cup and charts a bit cumbersome. It would be interesting from a geeky point of view to randomly check if the in-basket temperature truly correlates with what the taste tells me (yeah, I've gotten slack and haven't pulled out the TC in months, deciding instead to "Trust the Force"... it works pretty well :-).
And with all the chatter about the merits of dual boilers and PIDs, I'm curious if a practiced barista can hit say 12 shots in a row in fifteen minutes (sound familiar?) within 1F on a (*gasp*) commercial heat exchanger. It would certainly add an interesting element to the SCAA barista competitions.
Teme Senior Member Joined: 7 Jan 2005 Posts: 1,221 Location: Finland Expertise: I love coffee
Espresso: Izzo Alex Duetto II Grinder: Mahlkönig K30 Vario
Posted Sat May 7, 2005, 5:34am Subject: Re: Timing the cooling flush on E61 machines?
Thanks again for all the input. It seems that the more I learn the less I know. I'll try out several variations of doing the cooling flush and see which one is practical and I feel comfortable with.
If I could go back six months in time and take a look at where I am now, I'd probably wonder what's wrong with that guy - looks like me but definitely is "a few cards short of a full deck". Now my expression would probably be more along the lines of "a few beans short of a full hopper" (not that I actually keep my beans in the hopper ;-D ) and I would not be surprised if I found myself buying a scale to weigh my beans and digital thermometer with a TC...
Perhaps I am getting a bit too technical here, it is after all the taste of the coffee in the cup that matters.
Mike, I will be going to Toronto for sure and there is a good chance that I will alse briefly visit Montreal. I'll have this confirmed by the end of next week and let you know. It would be good to meet a fellow CG.
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