RegulatorJohnson wrote:maybe i should have called it the "simulated shot" instead of the "backflush cooling flush" ?
I tried this technique on the Vibiemme Domobar Super and it works very
well! The "blind flush" drops the temperature more slowly than an unimpeded flush, which plays to the strengths of a E61 thermometer adapter versus the thermocouple adapter. Less water in the driptray, less refilling and emptying.
As the unofficial keeper of heat exchanger nomenclature, the techniques to-date are:
- Flush and rebound - from the original HX Love article, a flush followed by a 30-45 second wait while the heat exchanger recovers.
- Flush and go - for fast recovery HX machines, this is a flush followed by the extraction within 10 seconds.
- Flush and wait - Eric's flush to well below the target temperature, then waiting for the thermosyphon to re-establish itself until the thermometer adapter reading matches the desired brew temperature.
- Blind flush - Jon's "flush until you're close, and then flush with blind basket" approach above; requires Eric's thermometer/thermocouple adapter.
I believe the particulars of Jon's approach will vary from machine-to-machine because of the tuning of the return versus direct flow from the thermosyphon during an extraction. That is, the water reaching the brewhead isn't only from one leg of the circuit:
Although this diagram depicts a one-way street, there's no shutoff solenoid blocking the return (blue) leg during an extraction, so the water reaching the group will be a mixture of the water that's passed by way of the heat exchanger (red) and some that's pass through the return (blue) leg. If I understand correctly what's happening, Jon's "blind flush" is forcing the water to rapidly circulate, thereby equalizing the system's thermal balance without expending water. Neat idea, Jon!