Who can tell me at what point in this video the end of the water dance is there?
I'm using a Magister Stella E61 HX machine. Internals are pretty much the same as the QM andreja apart from the OPV on the cold side and a flow restrictor. Pstat upper limit is 1.1 bar.
The flash-boil stops after just a few seconds but it takes a while before there is a steady pour and no audible hissing at all. Do the same flush and rebound principles as explained in HX Love apply with a flow restricted group head. Idle group head temperature is about 196-198 degrees F when measured from the outside with a simple digital thermometer. Is this representative? Until now I just flush for a couple of seconds and immediately lock and go. Do I get more stable temps by flushing more and waiting for half a minute or so?
Thanks

The hissing stopped around 11 seconds and the water quiesced moments thereafter. Knowing nothing about your coffee preferences or the particular HX espresso machine other than the video above, I would try 4 seconds past the end of hissing, wait 10-15 seconds, then pull the shot. Fine tune to taste:

• Bitter, hotplate flavor - flush an additional 5 seconds, increase rebound 5 seconds; this flushes more water from the HX and compensates by allowing the grouphead a few extra seconds to stabilize.
• Mixture of sour/bitter - shorten flush by 3-5 seconds, shorten rebound by 3-5 seconds; this avoids overcooling and then overshooting temperature, i.e., the dreaded "U" brew temperature profile.
• Somewhat sour, dull flavor - shorten flush by 3-5 seconds, keep rebound the same or increase slightly if it shows previous symptoms. Note: I find that lightly roasted fruity single origin coffees often taste better with this low hump, declining brew temperature profile than chocolaty blends.

There's no science to the above, it's purely guesswork based on lots of practice. If you want to reduce the guesswork on the cheap, search the FAQs, there's plenty of previous discussion in threads like Seeking low tech way to measure brew temperature, What's necessary to make a thermocoupled portafilter?, and Can't tell when the HX water dance ends.

From the video I had a point from about 11-14 seconds where I could have considered the flash boiling ended. I could be somewhat consistent with this method as well documented in the links given to you above. However, and its a BIG HOWEVER, I could never get my temperatures regulated as well or as consistently using the "end of water dance" method as I can using the grouphead thermometer probe invented by EricS.

http://www.chriscoffee.com/products/hom ... mometerkit

It to me and I think everyone else whose used it is an indispensable part of making excellent espresso with e61 grouphead HX machines. It is a great investment that will pay for itself in coffee saved from the sink

I thought it was around 14-15 seconds.

For me, it is easier to identify the end of the water dance when I have a single spout portafilter attached to the group.

I was thinking around the 14 second mark as well. Even if your group idles cool, the water in the heat exchanger is still superheated and needs to be flushed out. The cool group will also absorb some of that heat and raise its temperature. I would start with Dans recommendation and simply bracket your shots in either direction by 5 seconds until you find the flush/rebound timing that suits your taste and the coffee you are using.

Fullsack wrote:For me, it is easier to identify the end of the water dance when I have a single spout portafilter attached to the group.

Really? I find it much easier without the PF attached, or with a bottomless PF.

It runs smoothly instead of bubbling down the spout.

My first reaction was at 12 seconds. After watching it again.. I would now say between 11-13.

With a 1.1Pstat reading.. I would personally use the "flush and rebound" method.. As Dan lined out. Im running just a tad hotter then you are, ~1.2BAR, and that is my preferred flush technique. Since Ive got the E-61 group Therm, Its been a while since Ive timed the flush.. But I can say my rebound time can be between 20-40 seconds.. Usually 20-25 gets me in the range.. Depending on the flush length.

It really is trial and error, and going by taste. A timer to time your flushes might speed things along a bit, so you can remember what you liked and what you wanted to change.

And I too will recommend the E-61 Group Therm.. It is an invaluable tool for E-61 HX's... Turns a guessing game into more of a sure thing. You still need to experiment.. But it makes it much easier.

JmanEspresso wrote:But I can say my rebound time can be between 20-40 seconds.. Usually 20-25 gets me in the range.. Depending on the flush length.

Other HX espresso machines don't have as long a rebound time as your Anita, I assume because Quickmill mounts the over-pressure valve on the hot side of the heat exchanger. I'm not aware of another prosumer HX espresso machine with similarly located OPV.


Diagram courtesy of erics from Can anyone explain preinfusion on the E61?

I think the Nuova Simonelli Oscar has its OPV on the hot side as well...

Fullsack wrote:For me, it is easier to identify the end of the water dance when I have a single spout portafilter attached to the group.

RapidCoffee wrote:Really? I find it much easier without the PF attached, or with a bottomless PF.

For a second I thought maybe it depends on the machine, but I'm starting to think I just agree with John. With the Vetrano (John's HX machine I believe), I had a great handle on flushing with the bare group as in the video. It was easy to hear and see the water dance. On Valentina, which has a vibe pump, it's more difficult to hear, and about the same to see. I found on both machines the single spout portafilter just muffled the sound and made the end of the dance more difficult to see.

It worked great on the Elektra T1, though. Technically, it didn't actually help identify the end of the dance, it just helped the dance from getting all over the place, without muffling or hiding it. Maybe my machines were just wonky, but I never found the smoothed flow of water out the single spout to be a hugely consistent indication on my smaller HXes... For me they just weren't consistently smooth to flow out the spout even with the water dance well over--they would cover the exit hole occasionally and bubble regardless.

Nicolas,
I was just playing around with it on the brand new to me T1 and agree with you about the end of the dance sound, but there is more splatter without a spout and I agree with myself about the visual aspect of spout vs. bottomless. I haven't tried this out on smaller machines yet.

thanks guys for your suggestions!

I've my OPV now set at 1.2 bar upper limit...and tried the strategy flush for 5 seconds after flash-boil, wait 10 seconds and go...so far I'm getting consistent shots...so this weekend I'm going to play with longer and shorter flushes...

...do I understand well that by flushing less and waiting shorter the temperature profile is flatter and with a longer rebound time there's more "hump"...are there general rules, e.g. a SO favours a flat profile and a blend a humped one...or a lighter roast versus darker?

...surprisingly, if I only flush to end of the "water dance" and lock & go...shots are not burned at all...looking at the naked PF there are no burning signs in the beginning of the shot as well...

...interesting, sometimes when the machine has been idle for a long time there is hardly any flash-boil and sometimes I've to flush for about 10 seconds to arrive at the end of the "water dance"...

I'm convinced that a group head thermometer will make life easier...on the other hand it feels nice to operate the machine intuitively

best regards,
Bas

Just FYI,

You set your pressurestat for the boiler pressure(which is 1.2 as you noted)

The OPV is for Pump Pressure on a Vibe Pump.. and works as a Safety on a Rotary pump.

thanks for your correction...you are absolutely right...my brew pressure is set at 9,5 bar (OPV) and my boiler pressure is at the moment 1.2 bar (pstat upper limit)

Snip...

bas wrote:...do I understand well that by flushing less and waiting shorter the temperature profile is flatter and with a longer rebound time there's more "hump"...are there general rules, e.g. a SO favours a flat profile and a blend a humped one...or a lighter roast versus darker?

best regards,
Bas

That could be a general rule, but more likely it is a point of debate, and some research. Not bad, fourth post and you have located one of the central bones we like to chew.

The first call was that just about any blend would benefit from a flat profile. The number of great shots I get out of the La Peppina, which is temp stable as you can ask for, there could be something to be said for this argument. That same flat profile also pulls some great SO shots.

On the other hand the S27 can give me either 'u' or 'n' shaped temp profiles on a shot, depending on the flush and how long the machine has been idle, but hardly ever flat ones. It's just the nature of the beast.

I find with the larger basket and the faster pressure ramp that I grind a bit coarser and tamp a bit harder than with the spring lever. The coffee that I get while different can be just as good if I can temp surf the same average temperature area as I am pulling from the La Peppina.

To make this long story not so much short, but to get it to go away. The take home is if the average temp of your shot is near the 'sweet spot' for that roast/blend/bean you may like the flat temp taste, or you may find that a bit of wiggle room gives you a more interesting taste.

Have fun messing with the rules Bas.
-Cecil