I have a CC1 with a PID, and I have the machine warm up about 30-60 minutes with a timer to 201F. But I find the first shot is sour and doesn't seem to hold its temp so well. Is that because there's cooler water between the boiler and the group that needs to be flushed?
Most machines, PID or not, need to be flushed and allowed to stabilize for a while even if PID'd. There is an offset programmed into the machines that heats the water in the boiler to a point above the brew temperature. This offset helps to compensate for heat loss between the boiler and the group during extraction. In many cases, the group can be cooler and the brew water hotter than is best for a good extraction, The flush stabilizes (or "evens out") the temperatures of the group and the water on the boiler.
Are we playing a semantics game? You could say that no machine requires a flush.. if the brew temperature is discarded as a factor in making the best espresso possible. But numerous examples of steam issuing forth from groups, or initial flows in the 185 degree range when a machine has been idling for some time would indicate that the vast majority of machines do benefit from a thermal stabilizing flush.
I would agree that stating that "every" machine needs to be flushed is pushing the envelope. I would guess that there are a few rare examples (possibly with heated groups and other such features meant to create thermal stability, regardless) might be usable without a flush, but it would be a rare machine destined for home use that could somehow keep the boiler/brewing water, the internal brew path, the group, and the portafilter at brewing temperature, particularly while the machine is idling for any extended period (such as the 30-60 minute warm up from cold).
Just saying "nonsense" without some data points to back it up, as well as commenting on how to best use a machine which you admit you have never used (your comment on the CC1 above) diminishes the value of your posts in this thread.
The CC1 manual says the 201 is the boiler/brew temperature, and the PID keeps it within 1 degree of where I have it set. I have not tried measuring the water as it comes out (is that worth doing?). The timer I referred to was the wall timer to bring the machine on an hour ahead of time, and then the PID keeps the temp in line.
I thought the 30-60 minute warmup would be enough, but I find my second shots better than the first which is why I'm wondering if that's due to inconsistencies or if flushing before my first shot is worth while? It gets back up to temp rather quickly.
I say the OP should try it and let us know what he finds out. I agree it seem like a flush is needed just from what he said. Mine needs a flush to cool and it could be his needs one to warm up. Either way it is a cheap easy thing to test and perfect for warming the cup....
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