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different PI pressure makes a significant difference to the temperature profile?
Reiss Gunson post=13269 wrote: please see below a graph i ran last week of two LR side by side
one has been idling for 4 hours or so, boiler max 1.0 bar, PI 3.0 bar (set with a gauge)
the other is coming from a cold start in about 23-24C ambient, boiler max 1.0 bar, PI 2.0 bar (set with a gauge)
the point of posting this graph here is to show that differing PI settings make no difference to the surface temperature of the group at idle
Nice graph! Showing temp stability of the group and the warm-up time: ca 75 minutes (for I assume a 230 volt, 2400 watt machine).
But this I don’t get:
different PI pressure makes a significant difference to the temperature profile of the brew water entering the group
AFAIK The temp of the group has a direct correlation with the temp of the water in the thermo siphon (or if you will, the boiler, the heat source). This water is used for brewing coffee. Since the group temp in both cases is the same, the temp of the water entering the group should also be the same. But maybe you mean that you expect a longer PI time at a lower PI pressure so that the water for brewing coffee has more time to cool down in the group so effectively brewing at a lower temp???
Of course keeping all other variables the same: coffee, grind, amount of coffee, tamp….But in real life another coffee (roast) will likely mean another grind setting so still the PI time needs to be dialed in, I suppose, to get to a lower brewing temp. Your thoughts?
It would be interesting to know the differences in the temp of the group at different boiler pressures 1.1-1.2-1.3 bar compared to 86-87 degrees celsius for a boiler pressure at 1,0 bar.