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Rancilio S26 running off tank letting hot water back through inlet hose

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  • #31
    Of my checklist, I still need to read up on a number of these things to learn what they are, how they work, where they are in the S26. I’m learning as I go.

    Ok, 'how's the coffee' is an excellent question but I've got the flu at the moment which is quite limiting my sense of smell and taste. I had a double espresso at Sensory Lab this morning and could barely relate to anything in their tasting notes. Anyways...

    It seemed a good time to pull back to back shots with S26 vs Silvia and compare. Each had:
    * 18g of 13 day old Mecca espresso blend beans (past prime but on hand...)
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    * same grind, tamp, basket & portafilter
    * 26 sec extraction from hitting brew button.

    Result:

    S26 (6 bar @ grouphead)
    * 9 sec dwell time
    * 29.4g output
    Video: https://www.youtube.com/watch?v=SANYShkphJ0

    Silvia (9-9.5 bar @ grouphead)
    * 5 sec dwell time
    * 32.5g output
    Video: https://www.youtube.com/watch?v=Tq8YDOqM77Y

    Considering the pressure and dwell time differences, I was surprised to see the shots come out at similar weights.

    Limited taste impressions:
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    Silvia - right - good syrupy mouthfeel, balanced start but finished with a less than ideal burnt orange peel aftertaste.
    S26 - left- thinner mouthfeel, bitter start with sour mouth puckering finish.

    Not smitten with either but it's a start.

    Comment


    • #32
      voice coils,
      Looking at both videos you made,seems you have two winners there,taste is difficult to judge from my end and as far as you are concerned it's up to your experimentation with flavours/blends.
      Both brews looks splendid, can't fault either,S26 hasitated initially but recovered and poured beautifully.
      Once your check list is completed,by all means have another look at the pressure produced by the procon,don't sell your soul on it though!
      Enjoy your lovely rebuilt espresso machine and rest easy knowing you have" achieved mightly"
      Thank you for the entertainment!
      cheers,
      Mick.

      Comment


      • #33
        G'day v-c...

        Just looking at the beans you are using, I imagine that they will produce quite a bright result in the cup independent of the brew method/machine used. Given the S-26 is running under pressure, you would expect the result in the cup to be quite a bit less than optimal. You might notice a bit of an improvement if you tightened the shots up a bit, never hurts to experiment...

        Mal.

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        • #34
          Thanks Mal. When you say tighten the shot... Updose/grind finer? Sorry I'm a still a noob!

          Found the cause of the hot water backflow today: the check valve at the tee between the pump and boiler fill solenoid had a mangled spring. I need to locate and replace the spring or whole unit.

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          I also found one of the connections to the boiler heating element was poorly repaired/connected previously with low conductivity nuts and bolts causing high resistance and enough heat to totally melt a screw down terminal block. I redid this wiring and it now has good enough conductivity not to even get warm when the boiler heating indicator light is on.

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          Lastly I pulled apart the procon and could see signs of wear but no obvious damage. I'll try swapping in the spare procon after I get my check valve in the machine sorted.

          Comment


          • #35
            Originally posted by voicecoils View Post
            Thanks Mal. When you say tighten the shot... Updose/grind finer?
            Just gradually set the grinder a little finer until the resulting pour starts off with a few glutinous drops that slowly develops into a continuous stream that is lovingly referred to as a mouse-tail. When it starts get a bit watery and paler (called blonding), stop the shot and sample the brew... Repeat until such time as you're happy with the results in the cup...

            Mal.

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            • #36
              Thanks Mal, I'll work on my mouse tails

              After some more cleaning, descaling and oring changing on the internal check valve returning from the boiler, I think I've got my hot water backflow problem fixed.

              That gave me the confidence to swap the procon out and I'm happy to report the new pump is hitting full pressure with ease :-)

              A little explanation and group head pressure demo here:

              https://youtu.be/d2NfPojL-5U

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              • #37
                Excellent stuff mate...

                Mal.

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                • #38
                  Have a look at your OPV - is it returning water (too much bypass?) or dumping it into the drain tray?

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                  • #39
                    Your pump may be generating enough pressures but a bad OPV will bleed it off before it gets through your puck.

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                    • #40
                      Oops! Just read that new pump solved issue: I'll just say I covet your Park tools [emoji14]

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                      • #41
                        Originally posted by sprezzatura View Post
                        Have a look at your OPV - is it returning water (too much bypass?) or dumping it into the drain tray?
                        These don't use an OPV as such, rather, they have a bypass valve fitted to the pump itself which recirculates water from the high-pressure side back to the low-pressure side, once the preset pressure adjustment has been reached... Nothing gets vented back to the drain-tray, or at least, it shouldn't...

                        Mal.

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                        • #42
                          Ah, ok. My bad. Must be some sort of check valve or expansion valve system between the pump and boiler fill and h.e. system maybe then?

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                          • #43
                            Originally posted by sprezzatura View Post
                            Oops! Just read that new pump solved issue: I'll just say I covet your Park tools [emoji14]
                            Yes, I'm really happy the new pump worked! I imagine the previous owner's connection to main pressure plus the old worn pump's 4-6bar combined to give ok or just slightly low pressure so it went unnoticed.

                            I do have good bike tools from quite a few years working in bike shops, they're quite handy on the coffee machine

                            This morning I pulled a great double ristretto shot and enjoyed it immensely as a piccolo. Hopefully many more good pours to come

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                            • #44
                              Cool! Nice machine. I like Rancilio machines - always have. The Park tools would be GREAT to get inside machines! I'm going to look for some spanners.

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                              • #45
                                I reckon a good set of Flare Nut Spanners are worth their weight in gold when working on commercial/prosumer espresso machines. Wouldn't be without mine...

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                                Mal.

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