Oh how I wish I could delete this thread! :-) So now I realize that there is no mystery either to my experimental results, as once I know that the brew path is kept at pressure throughout the extraction any unpressurized measurement of the brew path is likely not pertinent.
Looks like the only way now to further investigate my original issue, sourness in the cup, is via a pressurized measurement of the brew path temperature via a Scace device or Eric's E61 grouphead thermocouple. On Feb 7, 10:39 pm, cgfan <[email protected]> wrote: > Charles, > > I just looked up the schematics for the Brewtus and realized a mistake > in my reply and in my original post. I believe the difference is > enough to damage my original hypothesis, but still leaves as a mystery > the cause for the observed behavior. > > The pressure of the brew boiler is isolated from the brew path by the > 3-way switch in the E-61 grouphead, and not by the pump. (Doh!) > > Then this must mean that as soon as the 3-way switch is activated the > pressure must momentarily drop a bit as the brew boiler is now > instantly open to the brew path volume. The change in volume is > minimal compared to the brew boiler volume, and so will cause a > miniscule drop in pressure and therefore only a minuscule drop in > water temperature. > > Quite a difference than what I had originally thought, which was a > very gradual increase of pressure in the grouphead from atmospheric > pressure to brewing pressure due mostly to the actions of the pump. > Now I see that it will start out at boiler pressure, then gradually > increase to brewing pressure. > > This still leaves something to be explained, which are the results of > my experiment. I did mention an earlier hypothesis in another thread > where I speculated whether or not the behavior is due to a s/w limit > inside the controller on the maximum numeric temperature used to > represent the brew boiler. > > Again I hope this is not the case, but could it be that the s/w inside > the temp controller limits Ttarget_brew_temp - > x to 100 deg C? This alternate hypothesis could still explain the > observed behavior. > > On Feb 7, 8:49 pm, cgfan <[email protected]> wrote: > > > Charles, > > > The boilers are pressurized, but the boiler pressure is isolated from > > the brew path by the pump, which at the start of the shot is > > essentially filling up an empty brew path with water. > > > It is the initial filling of this brew path at the start of each shot > > which causes the loss of pressure and the opportunity for the steam to > > escape, resulting in brew water that's at most 100 deg C. At least > > that's the hypothesis... > > > On Feb 7, 8:38 pm, Charles Haynes <[email protected]> wrote: > > > > Aren't the boilers pressurized? > > > > -- Charles --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Brewtus" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/brewtus?hl=en -~----------~----~----~----~------~----~------~--~---
