Newbie Introduction to Espresso - Heat Exchanger vs. Double Boier
Diagram courtesy of ECM Manufacture
To better explain how the barista varies the HX flush routine based on idle time, I put together a short video. It demonstrates the required flush for the ECM Technika after it's been idle for a long interval, medium interval, and short interval:
The Technika is tuned to reduce the need to flush (hence the "short" and "mini" flush described in the video), but this increases its shot-to-shot recovery time to a minimum of 2 minutes. The temperaturereproducibility is best with recovery time around 3 minutes. Keep in mind as you watch the video above that the "sss-s-s" sound is the best indicator of how long you should flush (long, short, or mini) rather than keeping track of idle time. To put it another way, long "sss-s-s" sound = long flush + mini flush, medium-short "sss-s-s" sound = short flush, no or little "sss-s-s" sound = little or no flush.
As I mentioned in theHeat Exchanger vs. Double Boiler Espresso Machinesvideo, double boiler espresso machines have the edge on simplicity and consistency of brew temperature, but heat exchangers like the Technika deliver respectable reproducibility under varying conditions. Below are the start/end temperatures from the flush video:
Long idle = 202.5 / 199.8°F
Medium idle = 201.5 / 199.2°F
Short idle = 200.9 / 197.9°F
Long idle (redux) = 200.1 / 197.8°F
Not surprisingly, the first long idle time has the greatest variance from the median temperature of ~199°F. That's because the water in the heat exchanger had ample time to reach its highest idle temperature. In the video above, I did a long + mini flush if the espresso machine was idle for a long time, but for improved first-time reproducibility, if you have the time, it's better to do a long flush, wait a few minutes, then do a short flush. This initial "wake up" flush improves the temperature stability of nearly all espresso machines, but especially for HX espresso machines.
Newbie Introduction to Espresso - Heat Exchanger vs. Double Boier Diagram courtesy of ECM Manufacture To better explain how the barista varies the HX flush routine based on idle time, I put together a ...
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