HX - Flush and go vs. Flush and wait

Beginner and pro baristas share tips and tricks for making espresso.
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#1: Post by dsblv »

I recently purchased an HX espresso machine and have been experimenting with flushing techniques. Overall, flushing has been easy to do and the tips on this web site were easy to follow.

The basic challenge was choosing between "flush and go" and "flush and wait". I initially started with "flush and wait". I would grind/tamp, flush, steam then brew. I found that flushing dropped steam pressure and impacted steaming. I had a lot of problems getting consistently good shots. Overall, this technique seemed to result in lower brew temperatures and sour shots.

Things improved greatly when I went to "flush and go". In this case, I grind/tamp, steam, flush, then brew. I flush less water than before and my shots are consistently good.

I'm wondering what others have experienced with their flushing techniques. Is there a better way to do "flush and wait"?

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#2: Post by TimEggers »

I believe it greatly depends on the machine (I'll yield to eric on this one) but for me on a Quickmill I tend to use the flush-and-wait and get good coffee.

Remember the point is to get good espresso, if flush-n-go is that for you, then use it.

In answer to your question, if your shots are running too cool then simply flush less and/or wait longer (pending machine settings).

I believe they are both acceptable methods if done right.
Tim Eggers

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#3: Post by ryguy »

It's very machine-dependent. My machine rebounds from flushing very quickly, so I start the shot within 5-10 seconds after the flush is done. If I wait much longer, it'll already be flash-boiling again. I like how Dan summarized it here.
HB wrote:Brew Temperature Management

Having written a number of reviews, I've come to recognize differing degrees of how heat exchanger-centric a particular espresso machine is. My shorthand for these distinctions are:
  • Dragon - key characteristics are lots of flash boiling, fast recovery, nearly zero thermal memory, and slowly rising brew temperature profile. Simply stated, after the cooling flush, the heat exchanger output is the brew temperature. Examples include the Elektra Semiautomatica, Gaggia Achille, and the Olympia Maximatic.
    • Mixer - key characteristics are modest flush, medium to slow recovery, considerable thermal memory, and initial rising then falling brew profile. Unlike the Dragon, the Mixer's brew temperature isn't determined solely by the output of the heat exchanger. Other factors, such as cool water mixing via an heat exchanger injector, backflow from a thermosyphon, and the attenuating effect of a heavy grouphead temper the final brew temperature. Examples include HX E61 espresso machines like the Vibiemme Domobar Super and Quickmill Vetrano.
      • Agnostic - key characteristics are small, fixed volume flush or none at all, and long thermal memory. Careful tuning of a Mixer with tweaks in the design can produce an espresso machine that is heat exchanger in name only. Examples include the Cimbali Junior and Nuova Simonelli Aurelia.
      As the last entry suggests, these categories are not immutable. With minor modifications or boiler pressure adjustments coupled with barista techniques, an espresso machine that naturally fits in one category can morph into one of the other categories (e.g, Ian's HX Heaven or 1½ Boiler).

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      #4: Post by erics »

      I'm wondering what others have experienced with their flushing techniques. Is there a better way to do "flush and wait"?
      Not on the Rocket line of espresso machines. These machines are fitted with a 3.0 mm thermosyphon restrictor in the top heat exchanger (hx) "outlet" tube and hence are much, much better suited for flush-n-go.

      A lot would, understandably, be determined by your boiler pressure setting and a value of 1.10 bar (maximum gage reading) is what I have seen and read. Flush about 5 ounces and brew away.

      Using beans of reasonable quality, taking your time in prepping the basket, a 0.1 gram capable digital pocket scale, and several of these baskets - http://www.espressoparts.com/EPMZ_107A will overshadow temperature management.

      Eric S.
      E-mail: erics at rcn dot com

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      #5: Post by dsblv (original poster) »

      That's very helpful information, Eric. It explains why my long flushes resulted in lower brewing temperature.

      It turns out I had settled on a 5 oz flush before brewing for "flush and go", so your advice is right on the money.